bundles/org.eclipse.platform.doc.isv/guide/swt_layouts.htm - gerrit/platform/eclipse.platform.common - Git at Google

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html lang="en">
 <HEAD>

 <meta name="copyright" content="Copyright (c) IBM Corporation and others 2000, 2013. This page is made available under license. For full details see the LEGAL in the documentation book that contains this page." >

 <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1">
 <META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">

 <LINK REL="STYLESHEET" HREF="../book.css" CHARSET="ISO-8859-1" TYPE="text/css">
 <TITLE>Layouts</TITLE>

 <link rel="stylesheet" type="text/css" HREF="../book.css">
 </HEAD>
 <BODY BGCOLOR="#ffffff">

 <H2>Layouts</H2>

 <P>Often the best way to handle simple widget positioning is in a resize event
 listener.  However, there are common patterns used by applications when placing
 widgets.  These patterns can be structured as configurable layout algorithms
 that can be reused by many different applications.</P>

 <P>SWT defines <em>layouts</em> that provide general purpose positioning and
 sizing of child widgets in a composite.  Layouts are subclasses of the abstract
 class <strong><a href="../reference/api/org/eclipse/swt/widgets/Layout.html">Layout</a></strong>.
 The SWT standard layouts can be found in the
 <strong><a href="../reference/api/org/eclipse/swt/layout/package-summary.html">org.eclipse.swt.layout</a></strong>
 package.</P>

 <P>There are some general definitions used when resizing and positioning
 widgets:</P>

 <ul>
   <li>The <em>location</em> of a widget is its x,y coordinate location within
     its parent widget.</li>
   <li>The <em>preferred size</em> of a widget is the minimum size needed to
     show its content. This is computed differently for each kind of widget.</li>
   <li>The <em>clientArea</em> is the area in which a child can be placed without
     being clipped.</li>
   <li>The <em>trim</em> is the distance between a widget's client area and its
     actual border.  Trim is occupied by the widget's borders or extra space
     at its edge.  The size and appearance of the trim is widget and platform
     dependent.</li>
 </ul>

 <P>These concepts are relevant for applications regardless of whether a layout
 is used. You can think of a layout as a convenient way to package resize
 functionality for reuse.</P>

 <P>Some additional concepts are introduced by layouts:</P>

 <ul>
   <li>Some layouts support <em>spacing</em> between widgets in the layout.</li>
   <li>Some layouts support a <em>margin</em> between the edge of the layout and
     the widget adjacent to the edge.</li>
 </ul>

 <P>See <a href="http://www.eclipse.org/articles/Article-Understanding-Layouts/Understanding-Layouts.htm">Understanding
 layouts in SWT</a> for further discussion and pictures demonstrating these concepts.</P>

 <P>The following code snippet shows the simple case of an application using a
 resize callback to size a label to the size of its parent shell:</P>

 <pre>
    Display display = new Display ();
    Shell shell = new Shell (display);
    Label label = new Label (shell, SWT.CENTER);
    shell.addControlListener (new ControlAdapter () {
       public void controlResized (ControlEvent e) {
          label.setBounds (shell.getClientArea ());
       }
    });
 </pre>

 <P>The next snippet uses a layout to achieve the same effect:</P>

 <pre>
    Display display = new Display ();
    Shell shell = new Shell (display);
    Label label = new Label (shell, SWT.CENTER);
    shell.setLayout (new FillLayout ());
 </pre>

 <P>Even for this simple example, using a layout reduces the application code.
 For more complex layouts, the simplification is much greater.</P>

 <p>The following table summarizes the standard layouts provided by SWT.</p>

 <table border="1" width="600">
 <colgroup>
     <col width="34%">
     <col width="66%">
 </colgroup>
 <tr>
 <th><div CLASS="CellHeading">Layout</div></th>
 <th><div CLASS="CellHeading">Purpose</div></th>
 </tr>

 <TR>
 <td><strong><a href="../reference/api/org/eclipse/swt/layout/FillLayout.html">FillLayout</a></strong></td>
 <td>Lays out controls in a single row or column, forcing them to be the same
 size.</td>
 </tr>
 <TR>
 <td><strong><a href="../reference/api/org/eclipse/swt/layout/FormLayout.html">FormLayout</a></strong></td>
 <td>Positions the children by using FormAttachments to optionally configure the
 left, top, right and bottom edges of each child.</td>
 </tr>

 <TR>
 <td><strong><a href="../reference/api/org/eclipse/swt/layout/GridLayout.html">GridLayout</a></strong></td>
 <td>Positions the children by rows and columns.</td>
 </tr>

 <TR>
 <td><strong><a href="../reference/api/org/eclipse/swt/layout/RowLayout.html">RowLayout</a></strong></td>
 <td>Places the children either in horizontal rows or vertical columns.</td>

 </tr>
 </table>

 </BODY>
 </HTML>
	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html lang="en">
	<HEAD>

	<meta name="copyright" content="Copyright (c) IBM Corporation and others 2000, 2013. This page is made available under license. For full details see the LEGAL in the documentation book that contains this page." >

	<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1">
	<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">

	<LINK REL="STYLESHEET" HREF="../book.css" CHARSET="ISO-8859-1" TYPE="text/css">
	<TITLE>Layouts</TITLE>

	<link rel="stylesheet" type="text/css" HREF="../book.css">
	</HEAD>
	<BODY BGCOLOR="#ffffff">

	<H2>Layouts</H2>

	<P>Often the best way to handle simple widget positioning is in a resize event
	listener. However, there are common patterns used by applications when placing
	widgets. These patterns can be structured as configurable layout algorithms
	that can be reused by many different applications.</P>

	<P>SWT defines <em>layouts</em> that provide general purpose positioning and
	sizing of child widgets in a composite. Layouts are subclasses of the abstract
	class <strong><a href="../reference/api/org/eclipse/swt/widgets/Layout.html">Layout</a></strong>.
	The SWT standard layouts can be found in the
	<strong><a href="../reference/api/org/eclipse/swt/layout/package-summary.html">org.eclipse.swt.layout</a></strong>
	package.</P>

	<P>There are some general definitions used when resizing and positioning
	widgets:</P>

	<ul>
	<li>The <em>location</em> of a widget is its x,y coordinate location within
	its parent widget.</li>
	<li>The <em>preferred size</em> of a widget is the minimum size needed to
	show its content. This is computed differently for each kind of widget.</li>
	<li>The <em>clientArea</em> is the area in which a child can be placed without
	being clipped.</li>
	<li>The <em>trim</em> is the distance between a widget's client area and its
	actual border. Trim is occupied by the widget's borders or extra space
	at its edge. The size and appearance of the trim is widget and platform
	dependent.</li>
	</ul>

	<P>These concepts are relevant for applications regardless of whether a layout
	is used. You can think of a layout as a convenient way to package resize
	functionality for reuse.</P>

	<P>Some additional concepts are introduced by layouts:</P>

	<ul>
	<li>Some layouts support <em>spacing</em> between widgets in the layout.</li>
	<li>Some layouts support a <em>margin</em> between the edge of the layout and
	the widget adjacent to the edge.</li>
	</ul>

	<P>See <a href="http://www.eclipse.org/articles/Article-Understanding-Layouts/Understanding-Layouts.htm">Understanding
	layouts in SWT</a> for further discussion and pictures demonstrating these concepts.</P>

	<P>The following code snippet shows the simple case of an application using a
	resize callback to size a label to the size of its parent shell:</P>

	<pre>
	Display display = new Display ();
	Shell shell = new Shell (display);
	Label label = new Label (shell, SWT.CENTER);
	shell.addControlListener (new ControlAdapter () {
	public void controlResized (ControlEvent e) {
	label.setBounds (shell.getClientArea ());
	}
	});
	</pre>

	<P>The next snippet uses a layout to achieve the same effect:</P>

	<pre>
	Display display = new Display ();
	Shell shell = new Shell (display);
	Label label = new Label (shell, SWT.CENTER);
	shell.setLayout (new FillLayout ());
	</pre>

	<P>Even for this simple example, using a layout reduces the application code.
	For more complex layouts, the simplification is much greater.</P>

	<p>The following table summarizes the standard layouts provided by SWT.</p>

	<table border="1" width="600">
	<colgroup>
	<col width="34%">
	<col width="66%">
	</colgroup>
	<tr>
	<th><div CLASS="CellHeading">Layout</div></th>
	<th><div CLASS="CellHeading">Purpose</div></th>
	</tr>

	<TR>
	<td><strong><a href="../reference/api/org/eclipse/swt/layout/FillLayout.html">FillLayout</a></strong></td>
	<td>Lays out controls in a single row or column, forcing them to be the same
	size.</td>
	</tr>
	<TR>
	<td><strong><a href="../reference/api/org/eclipse/swt/layout/FormLayout.html">FormLayout</a></strong></td>
	<td>Positions the children by using FormAttachments to optionally configure the
	left, top, right and bottom edges of each child.</td>
	</tr>

	<TR>
	<td><strong><a href="../reference/api/org/eclipse/swt/layout/GridLayout.html">GridLayout</a></strong></td>
	<td>Positions the children by rows and columns.</td>
	</tr>

	<TR>
	<td><strong><a href="../reference/api/org/eclipse/swt/layout/RowLayout.html">RowLayout</a></strong></td>
	<td>Places the children either in horizontal rows or vertical columns.</td>

	</tr>
	</table>

	</BODY>
	</HTML>