Make disposal of BufferedGraphicsSource more robust #875

The call to GC.drawImage() may throw an IllegalArgumentException when
dealing with fractional scaling. In such a case, not all SWT resources
are destroyed, leading to memory leaks.

Any exception thrown by this operation is caught and logged, in order to
allow the disposal to finish gracefully.

Closes #875

Author: ptziegler

org.eclipse.draw2d/src/org/eclipse/draw2d/BufferedGraphicsSource.java

@@ -21,9 +21,10 @@
 import org.eclipse.swt.widgets.Control;
 
 import org.eclipse.draw2d.geometry.Rectangle;
+import org.eclipse.draw2d.internal.Logger;
 
 class BufferedGraphicsSource implements GraphicsSource {
-
+	private static final Logger LOGGER = Logger.getLogger(BufferedGraphicsSource.class);
 	private Image imageBuffer;
 	private GC imageGC;
 	private GC controlGC;
@@ -66,8 +67,14 @@ public void flushGraphics(Rectangle region) {
 		 */
 		if (imageBuffer != null) {
 			imageGC.dispose();
-			controlGC.drawImage(getImage(), 0, 0, inUse.width, inUse.height, inUse.x, inUse.y, inUse.width,
-					inUse.height);
+			try {
+				// Make sure the SWT resources are properly disposed in case of an error
+				// See https://github.com/eclipse-gef/gef-classic/issues/875
+				controlGC.drawImage(getImage(), 0, 0, inUse.width, inUse.height, inUse.x, inUse.y, inUse.width,
+						inUse.height);
+			} catch (IllegalArgumentException e) {
+				LOGGER.error(e.getMessage(), e);
+			}
 			imageBuffer.dispose();
 			imageBuffer = null;
 			imageGC = null;