MenuItem Image Half Scaling #62

This commit contributes to enforcing half scaling on the MenuItem
Image. On Win32, the OS is responsible for painting the Image of a
MenuItem and it expects images to be in standard sizes i.e. 16px, 24 px,
32 px, etc. If the images are not provided within these sizes, Windows
tries to rescale them, leading to unexpected sizes and masking. Since,
half scaling yields the images in standard sizes, MenuItems are scaled
accordingly.

contributes to
#62 and
#127

Author: amartya4256

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

@@ -37,6 +37,10 @@
  */
 public class DPIUtil {
 
+	public static final String AUTOSCALE_QUARTER = "quarter";
+	public static final String AUTOSCALE_HALF = "half";
+	public static final String AUTOSCALE_EXACT = "exact";
+
 	private static final int DPI_ZOOM_100 = 96;
 
 	private static int deviceZoom = 100;
@@ -632,6 +636,10 @@ public static boolean useCairoAutoScale() {
 }
 
 public static int getZoomForAutoscaleProperty (int nativeDeviceZoom) {
+	return getZoomForAutoscaleProperty(nativeDeviceZoom, autoScaleValue);
+}
+
+public static int getZoomForAutoscaleProperty (int nativeDeviceZoom, String autoScaleValue) {
 	int zoom = 0;
 	if (autoScaleValue != null) {
 		if ("false".equalsIgnoreCase (autoScaleValue)) {

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/MenuItem.java

@@ -782,7 +782,10 @@ public void setImage (Image image) {
 	} else {
 		if (OS.IsAppThemed ()) {
 			if (hBitmap != 0) OS.DeleteObject (hBitmap);
-			info.hbmpItem = hBitmap = image != null ? Display.create32bitDIB (image, getZoom()) : 0;
+			// MenuItem images are painted badly/squeezed down by windows on quarter
+			// scaling size, e.g. at zoom 125%, 175%, etc.
+			int zoom = DPIUtil.getZoomForAutoscaleProperty(nativeZoom, DPIUtil.AUTOSCALE_HALF);
+			info.hbmpItem = hBitmap = image != null ? Display.create32bitDIB (image, zoom) : 0;
 		} else {
 			info.hbmpItem = image != null ? OS.HBMMENU_CALLBACK : 0;
 		}