Make refresh rate of DeferredUpdateManager & TargetingTool configurable

CHANGELOG.md

@@ -1,7 +1,11 @@
 # GEF Classic 3.22.0
 
+## Draw2D
+ - The refresh rate of the [Thumbnail](https://github.com/eclipse/gef-classic/blob/master/org.eclipse.draw2d/src/org/eclipse/draw2d/parts/Thumbnail.java) and [DeferredUpdateManager](https://github.com/eclipse/gef-classic/blob/master/org.eclipse.draw2d/src/org/eclipse/draw2d/DeferredUpdateManager.java) classes can be configured via the `setRefreshRate(int)` method. Events are then updated only once every given number of milliseconds, to reduce the CPU load when processing large amounts of update requests.
+
 ## GEF
  - _Linux Only_ The overlay scrolling of the palette can be configured via the _PaletteViewerPreferences.PREFERENCE_SCROLLBARS_MODE_ preference. Supported values are _SWT.NONE_ and _SWT.SCROLLBAR_OVERLAY_.
+ - The refresh rate of the [TargetingTool](https://github.com/eclipse/gef-classic/blob/master/org.eclipse.gef/src/org/eclipse/gef/tools/TargetingTool.java) class can be configured via the `setRefreshRate(int)` method. Events are then updated only once every given number of milliseconds, to reduce the CPU load when processing large amounts of update requests.
 
 ## Zest
  - Integration of Zest 2.0 development branch. See the [wiki](https://github.com/eclipse/gef-classic/wiki/Zest#zest-2x) for more details. In case only default layout algorithms are used, the initial migration should be seamless. Otherwise the algorithms can be adapted to run in legacy mode by extending `AbstractLayoutAlgorithm.Zest1` or have to be re-implemented using the new API by extending `AbstractLayoutAlgorithm`. Note that this legacy mode will be removed in a future release. The following list contains the most significant, deprecated features:

org.eclipse.draw2d/src/org/eclipse/draw2d/DeferredUpdateManager.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2023 IBM Corporation and others.
+ * Copyright (c) 2000, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
@@ -58,6 +58,7 @@ public void run() {
 	private boolean updating;
 	private boolean validating;
 	private RunnableChain afterUpdate;
+	private int refreshRate = -1;
 
 	private static class RunnableChain {
 		RunnableChain next;
@@ -263,7 +264,11 @@ protected void sendUpdateRequest() {
 		if (display == null) {
 			throw new SWTException(SWT.ERROR_THREAD_INVALID_ACCESS);
 		}
-		display.asyncExec(new UpdateRequest());
+		if (refreshRate <= 0) {
+			display.asyncExec(new UpdateRequest());
+		} else {
+			display.timerExec(refreshRate, new UpdateRequest());
+		}
 	}
 
 	/**
@@ -348,6 +353,24 @@ public void setRoot(IFigure figure) {
 		root = figure;
 	}
 
+	/**
+	 * Sets the rate with paint requests are executed. If set to either {@code 0} or
+	 * a negative value, requests are executed as fast as possible (default
+	 * behavior), otherwise every {@code refreshRate}ms.
+	 *
+	 * Example:
+	 *
+	 * <pre>
+	 * setRefreshRate(500); // Paints every 500ms
+	 * </pre>
+	 *
+	 * @param refreshRate The rate with which paint requests are executed.
+	 * @since 3.18
+	 */
+	public void setRefreshRate(int refreshRate) {
+		this.refreshRate = refreshRate;
+	}
+
 	/**
 	 * Validates all invalid figures on the update queue and calls
 	 * {@link UpdateManager#fireValidating()} unless there are no invalid figures.

org.eclipse.draw2d/src/org/eclipse/draw2d/parts/Thumbnail.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2023 IBM Corporation and others.
+ * Copyright (c) 2000, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
@@ -283,7 +283,11 @@ public void start() {
 
 			setScales(targetSize.width / (float) sourceSize.width, targetSize.height / (float) sourceSize.height);
 
-			Display.getCurrent().asyncExec(this);
+			if (refreshRate <= 0) {
+				Display.getCurrent().asyncExec(this);
+			} else {
+				Display.getCurrent().timerExec(refreshRate, this);
+			}
 		}
 
 		/** Create new GC, SWTGraphics, and ScaledGraphics instances */
@@ -379,6 +383,7 @@ public void stop() {
 
 	private Dimension thumbnailImageSize;
 	private final ThumbnailUpdater updater = new ThumbnailUpdater();
+	private int refreshRate = -1;
 
 	/**
 	 * Creates a new Thumbnail. The source Figure must be set separately if you use
@@ -609,4 +614,21 @@ protected Dimension getTargetSize() {
 		return targetSize;
 	}
 
+	/**
+	 * Sets the rate with which the thumbnail is updated. If set to either {@code 0}
+	 * or a negative value, the update is done as fast as possible (default
+	 * behavior), otherwise every {@code refreshRate}ms.
+	 *
+	 * Example:
+	 *
+	 * <pre>
+	 * setRefreshRate(500); // Update every 500ms
+	 * </pre>
+	 *
+	 * @param refreshRate The rate with which the thumbnail is updated.
+	 * @since 3.18
+	 */
+	public void setRefreshRate(int refreshRate) {
+		this.refreshRate = refreshRate;
+	}
 }

org.eclipse.gef/src/org/eclipse/gef/tools/TargetingTool.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2010 IBM Corporation and others.
+ * Copyright (c) 2000, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
@@ -59,6 +59,7 @@ public abstract class TargetingTool extends AbstractTool {
 	private Request targetRequest;
 	private EditPart targetEditPart;
 	private AutoexposeHelper exposeHelper;
+	private int refreshRate = -1;
 
 	/**
 	 * Creates the target request that will be used with the target editpart. This
@@ -101,7 +102,11 @@ protected void doAutoexpose() {
 		}
 		if (exposeHelper.step(getLocation())) {
 			handleAutoexpose();
-			Display.getCurrent().asyncExec(new QueuedAutoexpose());
+			if (refreshRate <= 0) {
+				Display.getCurrent().asyncExec(new QueuedAutoexpose());
+			} else {
+				Display.getCurrent().timerExec(refreshRate, new QueuedAutoexpose());
+			}
 		} else {
 			setAutoexposeHelper(null);
 		}
@@ -476,4 +481,21 @@ protected AutoexposeHelper getAutoexposeHelper() {
 		return exposeHelper;
 	}
 
+	/**
+	 * Sets the rate with which the auto-expose helper is evaluated. If set to
+	 * either {@code 0} or a negative value, the evaluation is done as fast as
+	 * possible (default behavior), otherwise every {@code refreshRate}ms.
+	 *
+	 * Example:
+	 *
+	 * <pre>
+	 * setRefreshRate(500); // Validate every 500ms
+	 * </pre>
+	 *
+	 * @param refreshRate The rate with which the auto-expose helper is validated.
+	 * @since 3.20
+	 */
+	public void setRefreshRate(int refreshRate) {
+		this.refreshRate = refreshRate;
+	}
 }