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

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 <H3>
 org.eclipse.ui.editors</H3>

 <P >
 An editor is a workbench part that allows a user to edit an object (often a
 file). Editors operate in a manner similar to file system editing tools, except that they are tightly integrated into the platform workbench UI. An editor is always associated with an input object
 (<a href="../reference/api/org/eclipse/ui/IEditorInput.html"><b>IEditorInput</b></a>). You can think of the input object as
 the document or file that is being edited. Changes made in an editor are not
 committed until the user saves them. </P>
 <P >
 Only one editor can be open for any particular editor input in a workbench page. For example, if the user is editing
 <b> readme.txt</b> in the workbench, opening it again
 in the same perspective will activate the same editor. (You can open another
 editor on the same file from a different workbench window or perspective).&nbsp;
 Unlike views, however, the same editor type, such as a text editor, may be open
 many times
 within one workbench page for different inputs.  The editor input can also be a path
 to an in memory model, as in the InfoEditor example.</P>
 <P >
 The workbench extension point <b><a href="../reference/extension-points/org_eclipse_ui_editors.html">org.eclipse.ui.editors</a></b>
 is used by plug-ins to add editors to the workbench. Plug-ins that contribute an editor must register the editor
 extension in their <b>plugin.xml </b> file, along with configuration information
 for the editor. Some
 of the editor information, such as the implementation <b> class</b> and the
 <b> name</b> and the <b>icon</b>  to be used in the workbench menus and
 labels, is similar to the view information. In addition, editor extensions specify the file extensions or file name patterns of the file types that the editor understands.
 Editors also use <a href="workbench_cmd_commands.htm" class="XRef">org.eclipse.ui.commands</a> and <a href="workbench_cmd_menus.htm" class="XRef">org.eclipse.ui.menus</a>
 to contribute to the workbench menus and toolbars when that editor is active.</P>
 <P >
 The interface for editors is defined in <b><a href="../reference/api/org/eclipse/ui/IEditorPart.html">IEditorPart</a></b>, but plug-ins
 can choose to extend the
 <b><a href="../reference/api/org/eclipse/ui/part/EditorPart.html"> EditorPart</a></b> class rather than implement an
 <b><a href="../reference/api/org/eclipse/ui/IEditorPart.html">IEditorPart</a></b>
 from scratch.</P>
 <blockquote><i>
 Note:&nbsp; An editor extension can also be configured to launch an external program
 or to call pre-existing java code. In this discussion, we are focusing on those editors that are actually tightly integrated with the workbench and
 are implemented using
 <b><a href="../reference/api/org/eclipse/ui/IEditorPart.html">IEditorPart</a></b>.</i></blockquote>
 <P >
 The editor can contribute its own content outliner page to the
 workbench outline view.&nbsp;&nbsp;</P>
 <P >
  The configuration for the editor extension is defined as follows.</P>
 <pre>
 &lt;extension
     point = &quot;org.eclipse.ui.editors&quot;&gt;
       &lt;editor
             class="org.eclipse.ui.examples.contributions.editor.InfoEditor"
             icon="icons/editor.gif"
             id="org.eclipse.ui.examples.contributions.editor"
             name="%contributions.editor.name"&gt;
       &lt;/editor&gt;
 &lt;/extension&gt;</pre>
 <P >
 We see the familiar configuration markup for <b>id</b>,
 <b>name</b>,
 <b>icon</b> (which must be specified when specifying <b>class</b>),
 and <b>class</b>.&nbsp;&nbsp; You could use the <b>extensions</b> attribute
 describes the file types that the editor understands, like <b>extensions=&quot;person&quot;</b>,
 although this example doesn't need it.
 (You could also
 specify <b>filenames</b> if you need to be more specific.)&nbsp; The <b>class</b>
 implements the editor.</P>

 <P >
 Editor menus and editor toolbars are placed in the main menu and main toolbar.  See
 <a href="workbench_cmd_menus.htm" class="XRef">org.eclipse.ui.menus</a> for how to use the
 <b>locationURI</b> to place the commands correctly.</P>
 <img src="images/contributions_global.png" alt="Showing a global menu additions" border="0" >
 <P>
 These menu and tool bar items can be shown only when the editor is active using core expressions.
 To define a re-usable core expression for your editor, use
 <b><a href="../reference/extension-points/org_eclipse_core_expressions_definitions.html">org.eclipse.core.expressions.definitions</a></b></P>
 <pre>
 &lt;extension
     point = &quot;org.eclipse.core.expressions.definitions&quot;&gt;
       &lt;definition id="org.eclipse.ui.examples.contributions.view.activeEditor"&gt;
          &lt;with variable="activeEditorId"&gt;
             &lt;equals value="org.eclipse.ui.examples.contributions.editor"/&gt;
          &lt;/with&gt;
       &lt;/definition&gt;
 &lt;/extension&gt;</pre>

 <H4>
 Editors and content outliners
 </h4>
 <P >
 Although the Info Editor does not, editors often have corresponding content outliners
 that provide a structured
 view of the editor's contents and assist the user in navigating through the
 contents of the editor.&nbsp; See <a href="editors_workbench_outliner.htm">Content
 outliners</a> for more detail. </P>


 <P >
 We'll look at the implementation of text editors in <a href="editors_jface.htm">Text
 editors and platform text</a>. </P>


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	<link rel="stylesheet" type="text/css" HREF="../book.css">
	</HEAD>
	<BODY BGCOLOR="#ffffff">
	<H3>
	org.eclipse.ui.editors</H3>

	<P >
	An editor is a workbench part that allows a user to edit an object (often a
	file). Editors operate in a manner similar to file system editing tools, except that they are tightly integrated into the platform workbench UI. An editor is always associated with an input object
	(<a href="../reference/api/org/eclipse/ui/IEditorInput.html"><b>IEditorInput</b></a>). You can think of the input object as
	the document or file that is being edited. Changes made in an editor are not
	committed until the user saves them. </P>
	<P >
	Only one editor can be open for any particular editor input in a workbench page. For example, if the user is editing
	<b> readme.txt</b> in the workbench, opening it again
	in the same perspective will activate the same editor. (You can open another
	editor on the same file from a different workbench window or perspective).
	Unlike views, however, the same editor type, such as a text editor, may be open
	many times
	within one workbench page for different inputs. The editor input can also be a path
	to an in memory model, as in the InfoEditor example.</P>
	<P >
	The workbench extension point <b><a href="../reference/extension-points/org_eclipse_ui_editors.html">org.eclipse.ui.editors</a></b>
	is used by plug-ins to add editors to the workbench. Plug-ins that contribute an editor must register the editor
	extension in their <b>plugin.xml </b> file, along with configuration information
	for the editor. Some
	of the editor information, such as the implementation <b> class</b> and the
	<b> name</b> and the <b>icon</b> to be used in the workbench menus and
	labels, is similar to the view information. In addition, editor extensions specify the file extensions or file name patterns of the file types that the editor understands.
	Editors also use <a href="workbench_cmd_commands.htm" class="XRef">org.eclipse.ui.commands</a> and <a href="workbench_cmd_menus.htm" class="XRef">org.eclipse.ui.menus</a>
	to contribute to the workbench menus and toolbars when that editor is active.</P>
	<P >
	The interface for editors is defined in <b><a href="../reference/api/org/eclipse/ui/IEditorPart.html">IEditorPart</a></b>, but plug-ins
	can choose to extend the
	<b><a href="../reference/api/org/eclipse/ui/part/EditorPart.html"> EditorPart</a></b> class rather than implement an
	<b><a href="../reference/api/org/eclipse/ui/IEditorPart.html">IEditorPart</a></b>
	from scratch.</P>
	<blockquote><i>
	Note:  An editor extension can also be configured to launch an external program
	or to call pre-existing java code. In this discussion, we are focusing on those editors that are actually tightly integrated with the workbench and
	are implemented using
	<b><a href="../reference/api/org/eclipse/ui/IEditorPart.html">IEditorPart</a></b>.</i></blockquote>
	<P >
	The editor can contribute its own content outliner page to the
	workbench outline view.  </P>
	<P >
	The configuration for the editor extension is defined as follows.</P>
	<pre>
	<extension
	point = "org.eclipse.ui.editors">
	<editor
	class="org.eclipse.ui.examples.contributions.editor.InfoEditor"
	icon="icons/editor.gif"
	id="org.eclipse.ui.examples.contributions.editor"
	name="%contributions.editor.name">
	</editor>
	</extension></pre>
	<P >
	We see the familiar configuration markup for <b>id</b>,
	<b>name</b>,
	<b>icon</b> (which must be specified when specifying <b>class</b>),
	and <b>class</b>.   You could use the <b>extensions</b> attribute
	describes the file types that the editor understands, like <b>extensions="person"</b>,
	although this example doesn't need it.
	(You could also
	specify <b>filenames</b> if you need to be more specific.)  The <b>class</b>
	implements the editor.</P>

	<P >
	Editor menus and editor toolbars are placed in the main menu and main toolbar. See
	<a href="workbench_cmd_menus.htm" class="XRef">org.eclipse.ui.menus</a> for how to use the
	<b>locationURI</b> to place the commands correctly.</P>
	<img src="images/contributions_global.png" alt="Showing a global menu additions" border="0" >
	<P>
	These menu and tool bar items can be shown only when the editor is active using core expressions.
	To define a re-usable core expression for your editor, use
	<b><a href="../reference/extension-points/org_eclipse_core_expressions_definitions.html">org.eclipse.core.expressions.definitions</a></b></P>
	<pre>
	<extension
	point = "org.eclipse.core.expressions.definitions">
	<definition id="org.eclipse.ui.examples.contributions.view.activeEditor">
	<with variable="activeEditorId">
	<equals value="org.eclipse.ui.examples.contributions.editor"/>
	</with>
	</definition>
	</extension></pre>

	<H4>
	Editors and content outliners
	</h4>
	<P >
	Although the Info Editor does not, editors often have corresponding content outliners
	that provide a structured
	view of the editor's contents and assist the user in navigating through the
	contents of the editor.  See <a href="editors_workbench_outliner.htm">Content
	outliners</a> for more detail. </P>


	<P >
	We'll look at the implementation of text editors in <a href="editors_jface.htm">Text
	editors and platform text</a>. </P>


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