Fix stack overflow in DPIUtil.autoScaleImageData #2353

Recently, a strict check was introduced that ImageData should be
linearly scaled for other zoom levels. ImageDataProviders inside SWT
not following this strict checks were modified (e.g., to return only
image data at 100%).

However, this change broke DPIUtil.autoScaleImageData. That function
creates an Image using the system zoom level, draws it on a GC at scaled
dimensions, and then requests ImageData at 100% zoom from the image.
Since the ImageDataProvider was now restricted to 100% zoom only,
requesting imageData at other zoom levels while creating an image at
system zoom level triggered recursive calls, causing a stack overflow
error.

This commit reverts the behavior of the ImageDataProvider used in
DPIUtil.autoScaleImageData to return the same ImageData at all zoom
levels.
We also disable the strict zoom check in this specific case, because the
scaling is done by GC.drawImage() and the ImageData used to create the
is expected to be same.

Fixes #2353

Author: arunjose696

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/widgets/ControlWin32Tests.java

@@ -14,12 +14,15 @@
 package org.eclipse.swt.widgets;
 
 import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.internal.*;
 import org.junit.jupiter.api.*;
 import org.junit.jupiter.api.extension.*;
+import org.junit.jupiter.params.*;
+import org.junit.jupiter.params.provider.*;
 
 /**
  * Automated Tests for class org.eclipse.swt.widgets.Control for Windows
@@ -107,6 +110,28 @@ public void testCorrectScaleUpUsingDifferentSetBoundsMethod() {
 				new Rectangle(0, 82, 350, 83), button.getBoundsInPixels());
 	}
 
+	@ParameterizedTest
+	@CsvSource({ "0.5, 100, true", "1.0, 200, true", "2.0, 200, true", "2.0, quarter, true", "0.5, 100, false",
+			"1.0, 200, false", "2.0, 200, false", "2.0, quarter, false", })
+	public void testAutoScaleImageData(float scaleFactor, String autoScale, boolean monitorSpecificScaling) {
+		DPIUtil.setMonitorSpecificScaling(monitorSpecificScaling);
+		DPIUtil.runWithAutoScaleValue(autoScale, () -> {
+			Display display = new Display();
+			try {
+				ImageData imageData = new ImageData(100, 100, 1, new PaletteData(new RGB(0, 0, 0)));
+				int width = imageData.width;
+				int height = imageData.height;
+				int scaledWidth = Math.round(width * scaleFactor);
+				int scaledHeight = Math.round(height * scaleFactor);
+				ImageData scaledImageData = DPIUtil.autoScaleImageData(display, imageData, scaleFactor);
+				assertEquals(scaledWidth, scaledImageData.width);
+				assertEquals(scaledHeight, scaledImageData.height);
+			} finally {
+				display.dispose();
+			}
+		});
+	}
+
 	record FontComparison(int originalFontHeight, int currentFontHeight) {
 	}
 

bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/graphics/Image.java

@@ -1811,18 +1811,19 @@ public String toString () {
  * API for Image. It is marked public only so that it
  * can be shared within the packages provided by SWT.
  *
- * Draws a scaled image using the GC by another image.
+ * Draws a scaled image using the GC for a given imageData.
  *
  * @param gc the GC to draw on the resulting image
- * @param original the image which is supposed to be scaled and drawn on the resulting image
+ * @param imageData the imageData which is used to draw the scaled Image
  * @param width the width of the original image
  * @param height the height of the original image
  * @param scaleFactor the factor with which the image is supposed to be scaled
  *
  * @noreference This method is not intended to be referenced by clients.
  */
-public static void drawScaled(GC gc, Image original, int width, int height, float scaleFactor) {
-	gc.drawImage (original, 0, 0, CocoaDPIUtil.pixelToPoint (width), CocoaDPIUtil.pixelToPoint (height),
+public static void drawScaled(GC gc, ImageData imageData, int width, int height, float scaleFactor) {
+	Image imageToDraw = new Image(gc.device, (ImageDataProvider) zoom ->  imageData);
+	gc.drawImage (imageToDraw, 0, 0, CocoaDPIUtil.pixelToPoint (width), CocoaDPIUtil.pixelToPoint (height),
 			/* E.g. destWidth here is effectively DPIUtil.autoScaleDown (scaledWidth), but avoiding rounding errors.
 			 * Nevertheless, we still have some rounding errors due to the point-based API GC#drawImage(..).
 			 */

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/DPIUtil.java

@@ -153,12 +153,11 @@ public static ImageData autoScaleImageData (Device device, final ImageData image
 	int defaultZoomLevel = 100;
 	boolean useSmoothScaling = isSmoothScalingEnabled() && imageData.getTransparencyType() != SWT.TRANSPARENCY_MASK;
 	if (useSmoothScaling) {
-		Image original = new Image(device, (ImageDataProvider) zoom -> (zoom == defaultZoomLevel) ? imageData : null);
 		ImageGcDrawer drawer =  new ImageGcDrawer() {
 			@Override
 			public void drawOn(GC gc, int imageWidth, int imageHeight) {
 				gc.setAntialias (SWT.ON);
-				Image.drawScaled(gc, original, width, height, scaleFactor);
+				Image.drawScaled(gc, imageData, width, height, scaleFactor);
 			};
 
 			@Override
@@ -168,7 +167,6 @@ public int getGcStyle() {
 		};
 		Image resultImage = new Image (device, drawer, scaledWidth, scaledHeight);
 		ImageData result = resultImage.getImageData (defaultZoomLevel);
-		original.dispose ();
 		resultImage.dispose ();
 		return result;
 	} else {

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/graphics/Image.java

@@ -1572,18 +1572,19 @@ public String toString () {
  * API for Image. It is marked public only so that it
  * can be shared within the packages provided by SWT.
  *
- * Draws a scaled image using the GC by another image.
+ * Draws a scaled image using the GC for a given imageData.
  *
  * @param gc the GC to draw on the resulting image
- * @param original the image which is supposed to be scaled and drawn on the resulting image
+ * @param imageData the imageData which is used to draw the scaled Image
  * @param width the width of the original image
  * @param height the height of the original image
  * @param scaleFactor the factor with which the image is supposed to be scaled
  *
  * @noreference This method is not intended to be referenced by clients.
  */
-public static void drawScaled(GC gc, Image original, int width, int height, float scaleFactor) {
-	gc.drawImage (original, 0, 0, width, height,
+public static void drawScaled(GC gc, ImageData imageData, int width, int height, float scaleFactor) {
+	Image imageToDraw = new Image(gc.device, (ImageDataProvider) zoom -> imageData);
+	gc.drawImage (imageToDraw, 0, 0, width, height,
 			/* E.g. destWidth here is effectively DPIUtil.autoScaleDown (scaledWidth), but avoiding rounding errors.
 			 * Nevertheless, we still have some rounding errors due to the point-based API GC#drawImage(..).
 			 */

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/graphics/Image.java

@@ -839,19 +839,23 @@ public static long win32_getHandle (Image image, int zoom) {
  * API for Image. It is marked public only so that it
  * can be shared within the packages provided by SWT.
  *
- * Draws a scaled image using the GC by another image.
+ * Draws a scaled image using the GC for a given imageData.
  *
  * @param gc the GC to draw on the resulting image
- * @param original the image which is supposed to be scaled and drawn on the resulting image
+ * @param imageData the imageData which is used to draw the scaled Image
  * @param width the width of the original image
  * @param height the height of the original image
  * @param scaleFactor the factor with which the image is supposed to be scaled
  *
  * @noreference This method is not intended to be referenced by clients.
  */
-public static void drawScaled(GC gc, Image original, int width, int height, float scaleFactor) {
-	gc.drawImage (original, 0, 0, width, height,
+public static void drawScaled(GC gc, ImageData imageData, int width, int height, float scaleFactor) {
+	boolean originalStrictChecks = Device.strictChecks;
+	Device.strictChecks = false;
+	Image imageToDraw = new Image(gc.device, (ImageDataProvider) zoom ->  imageData);
+	gc.drawImage (imageToDraw, 0, 0, width, height,
 			0, 0, Math.round (width * scaleFactor), Math.round (height * scaleFactor), false);
+	Device.strictChecks = originalStrictChecks;
 }
 
 long [] createGdipImage(Integer zoom) {