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| <title>Writing Your Own Widget</title> |
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| <o:Author>OTI EMPLOYEE</o:Author> |
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| |
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| |
| <p class=MsoNormal align=right style='margin-top:14.2pt;margin-right:0in; |
| margin-bottom:0in;margin-left:25.5pt;margin-bottom:.0001pt;text-align:right'><a |
| name="_Toc496069418"></a><a name="_Toc506634621"><span style='mso-bookmark: |
| _Toc496069418'><span style='font-size:8.0pt;mso-bidi-font-size:10.0pt'>Copyright |
| © 2001 Object Technology International, Inc.<o:p></o:p></span></span></a></p> |
| |
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| <td valign=top style='background:#0080C0;padding:1.5pt 1.5pt 1.5pt 1.5pt'> |
| <p class=MsoNormal><span style='mso-bookmark:_Toc506634621'><span |
| style='mso-bookmark:_Toc496069418'><b><span style='font-family:Arial; |
| color:white'> Eclipse Corner Article</span></b></span></span><span |
| style='mso-bookmark:_Toc506634621'><span style='mso-bookmark:_Toc496069418'><span |
| style='mso-bidi-font-size:12.0pt'><o:p></o:p></span></span></span></p> |
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| <span style='mso-bookmark:_Toc506634621'><span style='mso-bookmark:_Toc496069418'></span></span> |
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| |
| <h1 style='margin-left:25.5pt'><span style='mso-bookmark:_Toc506634621'><span |
| style='mso-bookmark:_Toc496069418'><img width=120 height=86 id="_x0000_i1043" |
| src="Writing%20Your%20Own%20Widget_files/Idea.jpg" align=CENTER></span></span><span |
| style='mso-bookmark:_Toc506634621'><span style='mso-bookmark:_Toc496069418'><span |
| style='font-size:8.0pt;mso-bidi-font-size:10.0pt'><o:p></o:p></span></span></span></h1> |
| |
| <h1 align=center style='margin-left:25.5pt;text-align:center'><span |
| style='mso-bookmark:_Toc506634621'><span style='mso-bookmark:_Toc496069418'>Creating |
| Your Own Widgets using SWT</span></span></h1> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;text-indent:.5in'><span |
| style='mso-bookmark:_Toc506634621'><span style='mso-bookmark:_Toc496069418'><b><![if !supportEmptyParas]> <![endif]><o:p></o:p></b></span></span></p> |
| |
| <p class=MsoNormal style='margin-top:0in;margin-right:.5in;margin-bottom:0in; |
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| style='mso-bookmark:_Toc496069418'><b>Summary</b> <br> |
| When writing applications, you typically use the standard widgets provided by |
| SWT. On occasion, you will need to create your own custom widgets. For example, |
| you might want to add a new type of widget not provided by the standard |
| widgets, or extend the functionality of an existing widget.<span |
| style="mso-spacerun: yes"> </span>This article explains the different SWT |
| extension strategies and shows you how to use them. </span></span></p> |
| |
| <p class=MsoNormal style='margin-top:0in;margin-right:.5in;margin-bottom:0in; |
| margin-left:61.5pt;margin-bottom:.0001pt'><span style='mso-bookmark:_Toc506634621'><span |
| style='mso-bookmark:_Toc496069418'><b><![if !supportEmptyParas]> <![endif]><o:p></o:p></b></span></span></p> |
| |
| <p class=MsoNormal style='margin-top:0in;margin-right:.5in;margin-bottom:0in; |
| margin-left:61.5pt;margin-bottom:.0001pt'><span style='mso-bookmark:_Toc506634621'><span |
| style='mso-bookmark:_Toc496069418'><b>By Steve Northover & Carolyn MacLeod, |
| OTI<br> |
| </b></span></span><span style='mso-bookmark:_Toc506634621'><span |
| style='mso-bookmark:_Toc496069418'><span style='font-size:10.0pt'>March 22, |
| 2001</span><b><o:p></o:p></b></span></span></p> |
| |
| <p class=MsoNormal style='margin-top:0in;margin-right:.5in;margin-bottom:0in; |
| margin-left:61.5pt;margin-bottom:.0001pt'><span style='mso-bookmark:_Toc506634621'><span |
| style='mso-bookmark:_Toc496069418'><b><span style='font-size:8.0pt;mso-bidi-font-size: |
| 10.0pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></span></b></span></span></p> |
| |
| |
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| |
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| |
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| |
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| "Times New Roman";mso-font-kerning:14.0pt;mso-ansi-language:EN-US;mso-fareast-language: |
| EN-US;mso-bidi-language:AR-SA'><br clear=all style='page-break-before:always'> |
| </span></b> |
| |
| <h1 style='margin-left:25.5pt'><span style='mso-bookmark:_Toc506634621'><span |
| style='mso-bookmark:_Toc496069418'>Creating Your Own Widgets</span></span></h1> |
| |
| <h2 style='margin-left:25.5pt'><a name="_Toc496069419"></a><a |
| name="_Toc496069776"></a><a name="_Toc506634622"><span style='mso-bookmark: |
| _Toc496069776'><span style='mso-bookmark:_Toc496069419'>Overview</span></span></a></h2> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'>When writing applications, you |
| typically use the standard widgets provided by SWT. On occasion, you will need |
| to create your own custom widgets. There are several reasons that you might |
| want to do this:</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>To add a new type of widget not provided by the |
| standard widgets</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>To extend the functionality of an existing widget</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Custom widgets are |
| created by subclassing in the existing widget class hierarchy.</p> |
| |
| <h2 style='margin-left:25.5pt'><a name="_Toc506634623">Portability Issues</a></h2> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'>It is very important to think |
| about portability before writing a custom widget. SWT can be extended in the |
| following ways:</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>Write a new widget that is 100% Java™ portable</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>Extend an existing widget in a 100% Java portable |
| manner</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>Write a new widget that wraps an existing native widget |
| not portable</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>Extend an existing widget by calling natives not |
| portable</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'>In addition, a combination of |
| these can be used on different platforms:</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>Write a new widget that wraps an existing native widget |
| on one platform, but is 100% Java portable on other platforms</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>Extend an existing widget by calling natives on one |
| platform, but call 100% Java portable code on other platforms</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'>This of course involves |
| implementing the widget twice using native calls on the one platform and |
| portable code on the others while maintaining the same API for both.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'>Each SWT platform is shipped with |
| both a shared library (for example, a DLL on Windows®) and a jar (for the Java |
| class files). The shared library contains all of the native function required |
| for SWT, but it was not meant to be a complete set of the functions available |
| on the platform. Thus to expose native function or native widgets that were not |
| exposed by SWT, you need to write your own shared library. If you are using a |
| combination of native code on one platform and portable code on another, make |
| sure you call your shared library on the platform with the native widget, and |
| your jar on the platform with the portable widget.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'>One final note: SWTs interface |
| to its shared libraries is internal SWT code. It was not meant to provide a framework |
| for applications to access all possible native function on all platforms that |
| would be a daunting task. One of the purposes of this document is to show how |
| you can integrate C code with SWT, not model the operating system. As such, the |
| approach taken to writing natives in this document is different from the |
| approach taken by SWT.<br clear=all style='mso-special-character:line-break; |
| page-break-before:always'> |
| </p> |
| |
| <h2 style='margin-left:25.5pt;mso-list:skip'><a name="_Toc496069420"></a><a |
| name="_Toc496069777"></a><a name="_Toc506634624"><span style='mso-bookmark: |
| _Toc496069777'><span style='mso-bookmark:_Toc496069420'>Writing Portable |
| Widgets</span></span></a></h2> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>The SWT library |
| provides two widget classes that are typically used as the basis for a custom |
| 100% Java portable widget:</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]><i style='mso-bidi-font-style:normal'>Canvas</i> - to |
| create basic widgets</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]><i style='mso-bidi-font-style:normal'>Composite</i> - |
| to create compound widgets</p> |
| |
| <h3 style='margin-left:25.5pt'><a name="_Toc496069421"></a><a |
| name="_Toc496069778"></a><a name="_Toc506634625"><span style='mso-bookmark: |
| _Toc496069778'><span style='mso-bookmark:_Toc496069421'>Basic Widgets</span></span></a></h3> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Basic widgets do |
| not contain any other widgets, and are not built from any other widgets. Basic |
| widgets draw themselves. An example of a basic widget is <i style='mso-bidi-font-style: |
| normal'>Button</i>. Another example is <i style='mso-bidi-font-style:normal'>Text</i>. |
| To create a custom basic widget, subclass <i style='mso-bidi-font-style:normal'>Canvas</i>.</p> |
| |
| <h3 style='margin-left:25.5pt;mso-list:skip'><a name="_Toc496069422"></a><a |
| name="_Toc496069779"></a><a name="_Toc506634626"><span style='mso-bookmark: |
| _Toc496069779'><span style='mso-bookmark:_Toc496069422'>Compound Widgets</span></span></a></h3> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Compound widgets |
| contain other widgets, and/or are composed of other widgets. An example of a |
| compound widget is <i style='mso-bidi-font-style:normal'>Combo</i>. It contains |
| a <i style='mso-bidi-font-style:normal'>Text</i>, a <i style='mso-bidi-font-style: |
| normal'>Button</i> and a <i style='mso-bidi-font-style:normal'>List</i>. |
| Another example is <i style='mso-bidi-font-style:normal'>Group</i>. It can contain |
| any number of children. To create a custom compound widget, subclass <i |
| style='mso-bidi-font-style:normal'>Composite</i>.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'>The astute reader may have |
| noticed that <i style='mso-bidi-font-style:normal'>Canvas</i> is actually a |
| subclass of <i style='mso-bidi-font-style:normal'>Composite</i>. This is an |
| artifact of the underlying implementation. We treat <i style='mso-bidi-font-style: |
| normal'>Canvas</i> as something you draw on and <i style='mso-bidi-font-style: |
| normal'>Composite</i> as something that has children. Therefore the rule for |
| deciding which class to subclass is this: If your widget has or will have |
| children, subclass <i style='mso-bidi-font-style:normal'>Composite</i>. If your |
| widget does not have and never will have children, subclass <i |
| style='mso-bidi-font-style:normal'>Canvas</i>.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'>Note also that we do not |
| distinguish between a compound widget that is intended to contain and lay out |
| children, and one that is merely composed of other widgets. Both will be a |
| subclass of <i style='mso-bidi-font-style:normal'>Composite</i>, and as such we |
| are describing implementation, rather than type, inheritance. When writing 100% |
| Java portable widgets, we can think of <i style='mso-bidi-font-style:normal'>Composite |
| </i>as the portable entry point into the SWT class hierarchy for all compound |
| widgets, and <i style='mso-bidi-font-style:normal'>Canvas </i>as the portable |
| entry point into the SWT class hierarchy for all basic widgets, regardless of |
| widget type.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <b><span style='font-size:18.0pt;font-family:Arial;mso-fareast-font-family: |
| "Times New Roman";mso-ansi-language:EN-US;mso-fareast-language:EN-US; |
| mso-bidi-language:AR-SA'><br clear=all style='page-break-before:always'> |
| </span></b> |
| |
| <h2 style='margin-left:25.5pt'><a name="_Toc496069423"></a><a |
| name="_Toc496069780"><span style='mso-bookmark:_Toc496069423'>Basic Widget |
| Example</span></a><span style='mso-bookmark:_Toc496069423'></span><span |
| style='mso-bookmark:_Toc496069780'></span><span style='font-size:12.0pt; |
| mso-bidi-font-size:18.0pt;font-family:"Times New Roman";font-weight:normal'><o:p></o:p></span></h2> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Imagine we are |
| building an application where we need a widget that displays an image with a |
| line of text to the right, something like this:</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><!--[if gte vml 1]><o:wrapblock><v:shapetype |
| id="_x0000_t75" coordsize="21600,21600" o:spt="75" o:preferrelative="t" |
| path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f"> |
| <v:stroke joinstyle="miter"/> |
| <v:formulas> |
| <v:f eqn="if lineDrawn pixelLineWidth 0"/> |
| <v:f eqn="sum @0 1 0"/> |
| <v:f eqn="sum 0 0 @1"/> |
| <v:f eqn="prod @2 1 2"/> |
| <v:f eqn="prod @3 21600 pixelWidth"/> |
| <v:f eqn="prod @3 21600 pixelHeight"/> |
| <v:f eqn="sum @0 0 1"/> |
| <v:f eqn="prod @6 1 2"/> |
| <v:f eqn="prod @7 21600 pixelWidth"/> |
| <v:f eqn="sum @8 21600 0"/> |
| <v:f eqn="prod @7 21600 pixelHeight"/> |
| <v:f eqn="sum @10 21600 0"/> |
| </v:formulas> |
| <v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"/> |
| <o:lock v:ext="edit" aspectratio="t"/> |
| </v:shapetype><v:shape id="_x0000_s1033" type="#_x0000_t75" style='position:absolute; |
| left:0;text-align:left;margin-left:154.8pt;margin-top:-14.25pt;width:51.75pt; |
| height:17.25pt;z-index:3;mso-position-horizontal-relative:text; |
| mso-position-vertical-relative:text' o:allowincell="f"> |
| <v:imagedata src="./Writing%20Your%20Own%20Widget_files/image001.png" |
| o:title=""/> |
| <w:wrap type="topAndBottom" anchorx="page"/> |
| </v:shape><![if gte mso 9]><o:OLEObject Type="Embed" ProgID="PBrush" |
| ShapeID="_x0000_s1033" DrawAspect="Content" ObjectID="_1053168690"> |
| </o:OLEObject> |
| <![endif]><![endif]--><![if !vml]><span style='mso-ignore:vglayout'> |
| <table cellpadding=0 cellspacing=0 align=left> |
| <tr> |
| <td width=206 height=0></td> |
| </tr> |
| <tr> |
| <td></td> |
| <td><img width=69 height=23 |
| src="./Writing%20Your%20Own%20Widget_files/image002.jpg" v:shapes="_x0000_s1033"></td> |
| </tr> |
| </table> |
| </span><![endif]><!--[if gte vml 1]></o:wrapblock><![endif]--><br |
| style='mso-ignore:vglayout' clear=ALL> |
| <![if !supportEmptyParas]> <![endif]><o:p></o:p><p></p> |
| |
| <br style='mso-ignore:vglayout' clear=ALL> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Since we plan to |
| draw both the image and the text, we subclass <i style='mso-bidi-font-style: |
| normal'>Canvas</i>.</p> |
| |
| <p style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:25.5pt; |
| margin-bottom:.0001pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>import</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> org.eclipse.swt.*;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>import</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> |
| org.eclipse.swt.graphics.*;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>import</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> org.eclipse.swt.widgets.*;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>import</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> org.eclipse.swt.events.*;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><![if !supportEmptyParas]> <![endif]><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>class</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> PictureLabel </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>extends</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> Canvas {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>Image image;<span style='mso-tab-count:1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>String text;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Our widget needs to |
| be created. To do this, we must write at least one constructor. Because widgets |
| in SWT cannot be created without a parent, the constructor must take at least |
| one argument that is the parent. The convention in SWT is to have a constructor |
| with two arguments, <b style='mso-bidi-font-weight:normal'>parent</b> and <b |
| style='mso-bidi-font-weight:normal'>style</b>. Style bits are used to control |
| the look of widgets. Neither the parent nor the style bits can be changed after |
| the widget is created. Your widget can use style bits too.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>PictureLabel(Composite parent, </span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>int</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| style) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>super</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>(parent, style);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<span style='mso-tab-count:1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>The parent of any |
| widget must be a <i style='mso-bidi-font-style:normal'>Composite</i>. The style |
| is an integer, where some bits are already used by the system. For example, <b |
| style='mso-bidi-font-weight:normal'><span style='font-size:10.0pt'>SWT.BORDER</span></b> |
| will cause a <i style='mso-bidi-font-style:normal'>Canvas</i> to have a border.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Next we need to |
| initialize our widget. The convention in SWT is to do all initialization in the |
| constructor. Certainly, any initialization that requires the parent or the |
| style bits must be done here. We have decided that our <i style='mso-bidi-font-style: |
| normal'>PictureLabel</i> widget will default to a white background, so we need |
| to add a <i style='mso-bidi-font-style:normal'>Color</i> field, allocate a <i |
| style='mso-bidi-font-style:normal'>Color</i>, and initialize the background.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>class</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> PictureLabel </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>extends</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> Canvas {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>Image image;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>String text;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>Color white;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>PictureLabel(Composite parent, </span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>int</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| style) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>super</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>(parent, style);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>white = </span><span style='font-size:9.0pt;mso-bidi-font-size: |
| 10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| Color(</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family: |
| "Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>null</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>, 255, 255, 255);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>setBackground(white);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Colors are graphics |
| resources that must be disposed. How can we dispose of the white color that we |
| allocated? We add a dispose listener. Every widget provides notification when |
| it is destroyed. We add the dispose listener in the constructor.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>addDisposeListener(</span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| DisposeListener() {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>void</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> |
| widgetDisposed(DisposeEvent e) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 4'> </span>white.dispose();<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>});<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><b |
| style='mso-bidi-font-weight:normal'>Note:</b> Do not just override dispose() to |
| release the color. This only works in the case where dispose is actually sent |
| to the widget. When the shell is disposed this does not happen, so overriding |
| dispose will leak the color. To ensure that your widget is informed of an event |
| no matter how it was generated, add an event listener instead of overriding |
| methods that generate events. </p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Our widget is |
| created and initialized, and it can be destroyed without leaking graphics |
| resources. Now it needs some functionality. We need to draw the image and the |
| text, and this will require another listener: the paint listener. Implementing |
| a widget often requires adding many listeners. We could implement the listener |
| interfaces as part of our new widget class, but that would make the interface |
| methods public in our class. Instead, the SWT convention is to use anonymous inner |
| classes to forward the functionality to non-public methods of the same name. |
| For consistency, we will rewrite the dispose listener to follow this |
| convention, moving the color dispose code into the <b style='mso-bidi-font-weight: |
| normal'>widgetDisposed</b> method. We write the paint listener the same way.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>addDisposeListener(</span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| DisposeListener() {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>void</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> |
| widgetDisposed(DisposeEvent e) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 4'> </span>PictureLabel.</span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>this</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'>.widgetDisposed(e);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>});<span style='mso-tab-count:1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>addPaintListener(</span><span style='font-size:9.0pt;mso-bidi-font-size: |
| 10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| PaintListener() {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>void</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> paintControl(PaintEvent e) |
| {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 4'> </span>PictureLabel.</span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>this</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'>.paintControl(e);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>});<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>By choosing the |
| same names, we have the option of easily implementing the interfaces if we |
| decide to do so later. Here is the <b style='mso-bidi-font-weight:normal'>paintControl</b> |
| method to draw the widget.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>void</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> paintControl(PaintEvent e) |
| {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>GC gc = e.gc;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>int</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> x = 1;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>if</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> (image != </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>null</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>gc.drawImage(image, x, 1); <o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>x = image.getBounds().width + 5;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>if</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> (text != </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>null</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>gc.drawString(text, x, 1);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>}<span style='mso-tab-count:1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<o:p></o:p></span></p> |
| |
| <p style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:25.5pt; |
| margin-bottom:.0001pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Now we can draw the |
| image and the text, but we need to let the user set them. So we write set and |
| get methods for each of them.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> Image getImage() {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>return</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> image;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><![if !supportEmptyParas]> <![endif]><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>void</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> setImage(Image image) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>this</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>.image = image;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>redraw();<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><![if !supportEmptyParas]> <![endif]><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> String getText() {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>return</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> text;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><![if !supportEmptyParas]> <![endif]><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>void</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> setText(String text) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>this</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>.text = text;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>redraw();<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>The get methods are |
| trivial. They simply answer the fields. The set methods set the fields and then |
| redraw the widget to show the change. The easiest way to do this is to damage |
| the widget by calling <b style='mso-bidi-font-weight:normal'>redraw()</b>, |
| which queues a paint event for the widget. This approach has the advantage that |
| setting both the image and the text will cause only one paint event because |
| multiple paints are collapsed in the event queue.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>We are not done |
| yet. Our widget does not know its preferred size. This information is needed in |
| order to lay out the widget. In our case, the best size is simply the size of |
| the text plus the size of the image, plus a little bit of space in between. |
| Also, we will add a 1 pixel margin all the way around.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>To return the |
| preferred size of the widget, we must implement the <b style='mso-bidi-font-weight: |
| normal'>computeSize</b> method. The <b style='mso-bidi-font-weight:normal'>computeSize</b> |
| method can be quite complicated. Its job is to calculate the preferred size of |
| the widget based on the current contents. The simplest implementation ignores |
| the arguments and just computes the size.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> Point computeSize(</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>int</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> wHint, </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>int</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> hHint, </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>boolean</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> changed) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>int</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> width = 0, height = 0;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>if</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> (image != </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>null</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>Rectangle bounds = image.getBounds();<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>width = bounds.width + 5;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>height = bounds.height;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>if</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> (text != </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>null</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>GC gc = </span><span style='font-size:9.0pt;mso-bidi-font-size: |
| 10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| GC(</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family: |
| "Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>this</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>Point extent = gc.stringExtent(text);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>gc.dispose();<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>width += extent.x;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>height = Math.max(height, extent.y);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>return</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>new</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> Point(width + 2, height + |
| 2);<span style='mso-tab-count:1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>What are <b |
| style='mso-bidi-font-weight:normal'>wHint</b>, <b style='mso-bidi-font-weight: |
| normal'>hHint</b>, and <b style='mso-bidi-font-weight:normal'>changed</b>? The |
| hint arguments allow you to ask a widget questions such as Given a particular |
| width, how high does the widget need to be to show all of the contents? For |
| example, a word-wrapping <i style='mso-bidi-font-style:normal'>Label</i> widget |
| might be asked this. To indicate that the client does not care about a |
| particular hint, the special value <b style='mso-bidi-font-weight:normal'><span |
| style='font-size:10.0pt'>SWT.DEFAULT</span></b> is used. The following example |
| asks a label for its preferred size given a width of 100 pixels: </p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>Point extent = label.computeSize(100, </span><span |
| style='font-size:8.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>SWT.DEFAULT</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>, </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>false</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>For our <i |
| style='mso-bidi-font-style:normal'>PictureLabel</i> widget, we could be fancy |
| and stack the image over the text when the width is too small, and/or wrap the text |
| in order to meet a width request, but for simplicity we have decided not to do |
| so. Still, we need to honour the hints. So, our widget will clip. The easiest |
| way to do this is to perform the calculation and then filter the results.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> Point computeSize(</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>int</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> wHint, </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>int</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> hHint, </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>boolean</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> changed) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>int</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> width = 0, height = 0;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>if</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> (image != </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>null</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>Rectangle bounds = image.getBounds();<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>width = bounds.width + 5;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>height = bounds.height;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>if</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> (text != </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>null</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>GC gc = </span><span style='font-size:9.0pt;mso-bidi-font-size: |
| 10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| GC(</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family: |
| "Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>this</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>Point extent = gc.stringExtent(text);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>gc.dispose();<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>width += extent.x;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>height = Math.max(height, extent.y);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>if</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> (wHint != </span><span |
| style='font-size:8.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>SWT.DEFAULT</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>) width = wHint;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>if</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> (hHint != </span><span |
| style='font-size:8.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>SWT.DEFAULT</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>) height = hHint;<span |
| style='mso-tab-count:2'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>return</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>new</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> Point(width + 2, height + |
| 2);<span style='mso-tab-count:1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Notice that we do |
| not return the hint sizes exactly as specified. We have added the 1-pixel |
| border. Why do we do this? All widgets have a <i style='mso-bidi-font-style: |
| normal'>client area</i> and <i style='mso-bidi-font-style:normal'>trim</i>. The |
| hint parameters specify the desired size of the client area. We must set the |
| size of the widget so that the size of the client area is the same as the hint, |
| so the size we return from <b style='mso-bidi-font-weight:normal'>computeSize</b> |
| must include the trim.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>What about the <b |
| style='mso-bidi-font-weight:normal'>changed</b> flag? This is used in |
| conjunction with SWT layout managers and is ignored for basic widgets. This |
| will be discussed when we talk about compound widgets.</p> |
| |
| <span style='font-size:18.0pt;font-family:Arial;mso-fareast-font-family:"Times New Roman"; |
| mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA; |
| mso-bidi-font-weight:bold'><br clear=all style='page-break-before:always'> |
| </span> |
| |
| <h2 style='margin-left:25.5pt;mso-list:skip'><a name="_Toc496069424"></a><a |
| name="_Toc496069781"></a><a name="_Ref506190201"></a><a name="_Toc506634627"><span |
| style='mso-bookmark:_Ref506190201'><span style='mso-bookmark:_Toc496069781'><span |
| style='mso-bookmark:_Toc496069424'>Compound Widget Example</span></span></span></a></h2> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Now we will recode |
| the <i style='mso-bidi-font-style:normal'>PictureLabel</i> widget as a compound |
| widget. Note that this section assumes that you have read the basic widget |
| example section. This time the widget will be implemented using two <i |
| style='mso-bidi-font-style:normal'>Label</i> children: one to display the |
| image, and one to display the text. Since we are using other widgets to |
| implement our widget, we subclass <i style='mso-bidi-font-style:normal'>Composite</i>.</p> |
| |
| <p class=Code style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>class</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> PictureLabel </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>extends</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> Composite {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>Label image, text;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>Color white;<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 1'> </span>PictureLabel(Composite parent, </span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>int</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| style) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>super</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>(parent, style);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>white = </span><span style='font-size:9.0pt;mso-bidi-font-size: |
| 10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| Color(</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family: |
| "Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>null</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>, 255, 255, 255);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>image = </span><span style='font-size:9.0pt;mso-bidi-font-size: |
| 10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| Label(</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family: |
| "Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>this</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>, 0);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>text = </span><span style='font-size:9.0pt;mso-bidi-font-size: |
| 10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| Label(</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family: |
| "Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>this</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'>, 0);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>setBackground(white);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>image.setBackground(white);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>text.setBackground(white);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>addDisposeListener(</span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| DisposeListener() {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>void</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> |
| widgetDisposed(DisposeEvent e) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 4'> </span>PictureLabel.</span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>this</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'>.widgetDisposed(e);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>});<span style='mso-tab-count:1'> </span><o:p></o:p></span></p> |
| |
| <p class=Code style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>As well as |
| initializing the graphics resources in the constructor, we need to create the child |
| widgets and set their background color. A common mistake is to create the child |
| widgets as children of the parent. This would make them peers of our widget. |
| Instead, make sure to create them as children of <b style='mso-bidi-font-weight: |
| normal'>this</b>. The dispose listener frees the color, as before.</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>Now that we have |
| handled creation and destruction, we need to lay out the children. There are |
| two possibilities:</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>position the children when the widget is resized</p> |
| |
| <p class=MsoNormal style='margin-left:43.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span |
| style='font-family:Symbol'>·<span style='font:7.0pt "Times New Roman"'> |
| </span></span><![endif]>use a layout manager</p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>We will implement |
| both here for comparison.</p> |
| |
| <h3 style='margin-left:25.5pt;mso-list:skip'><a name="_Toc496069425"></a><a |
| name="_Toc496069782"></a><a name="_Toc506634628"><span style='mso-bookmark: |
| _Toc496069782'><span style='mso-bookmark:_Toc496069425'>Positioning Children on |
| Resize</span></span></a></h3> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip'>First, we will |
| position the children when the widget is resized. We need to add a resize |
| listener.</p> |
| |
| <p class=Code style='margin-left:25.5pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>addControlListener(</span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>new</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'> |
| ControlAdapter() {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span></span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:navy'>public</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> </span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:navy'>void</span><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'> |
| controlResized(ControlEvent e) {<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 4'> </span>PictureLabel.</span><span style='font-size:9.0pt; |
| mso-bidi-font-size:10.0pt;font-family:"Courier New";mso-bidi-font-family:"Times New Roman"; |
| color:navy'>this</span><span style='font-size:9.0pt;mso-bidi-font-size:10.0pt; |
| font-family:"Courier New";mso-bidi-font-family:"Times New Roman";color:black'>.controlResized(e);<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 3'> </span>}<o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count: |
| 2'> </span>});<span style='mso-tab-count:1'> </span><o:p></o:p></span></p> |
| |
| <p class=MsoNormal style='margin-left:25.5pt;mso-list:skip;tab-stops:.25in .5in .75in 1.0in 1.25in 1.5in'><span |
| style='font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:"Courier New"; |
| mso-bidi-font-family:"Times New Roman";color:black'><span style='mso-tab-count:<
|
