Guard smooth scaling for images not having transparency mask

Enabling the smooth scaling for images with a transparency mask produce
erroneous results with a loss of transparency. This guards the
application of smooth scaling with the given image not having a
transparency mask.

Author: ShahzaibIbrahim

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

@@ -292,8 +292,9 @@ private static ImageData autoScaleImageData (Device device, final ImageData imag
 	int height = imageData.height;
 	int scaledWidth = Math.round (width * scaleFactor);
 	int scaledHeight = Math.round (height * scaleFactor);
-	return switch (autoScaleMethod) {
-	case SMOOTH -> {
+	ImageData result;
+	boolean useSmoothScaling = autoScaleMethod == AutoScaleMethod.SMOOTH && imageData.getTransparencyType() != SWT.TRANSPARENCY_MASK;
+	if (useSmoothScaling) {
 		Image original = new Image (device, (ImageDataProvider) zoom -> imageData);
 		/* Create a 24 bit image data with alpha channel */
 		final ImageData resultData = new ImageData (scaledWidth, scaledHeight, 24, new PaletteData (0xFF, 0xFF00, 0xFF0000));
@@ -305,15 +306,16 @@ private static ImageData autoScaleImageData (Device device, final ImageData imag
 				/* 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(..).
 				 */
-				0, 0, Math.round (autoScaleDown (width * scaleFactor)), Math.round (autoScaleDown (height * scaleFactor)));
-		gc.dispose ();
-		original.dispose ();
-		ImageData result = resultImage.getImageData (getDeviceZoom ());
-		resultImage.dispose ();
-		yield result;
+				0, 0, Math.round(autoScaleDown(width * scaleFactor)), Math.round(autoScaleDown(height * scaleFactor)));
+		gc.dispose();
+		original.dispose();
+		result = resultImage.getImageData(getDeviceZoom());
+		resultImage.dispose();
+	} else {
+		result = imageData.scaledTo (scaledWidth, scaledHeight);
 	}
-	default -> imageData.scaledTo (scaledWidth, scaledHeight);
-	};
+
+	return result;
 }
 
 /**