[win32] Allow disablement of autoscale per Widget

This commit introduces the data attribute AUTOSCALE_DISABLED for the
windows implementation for Widget. This will disable autoscaling for this
Widget and all of its children. This is a necessary requirement for some
complex usages utilizing GC. Without disabling autoscaling rendering
artifacts will be introduced when only parts of the GC are redrawn. This
commit serves as starting point to harden this feature before considering
extracting an API out of it.

Author: akoch-yatta

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

@@ -3257,7 +3257,8 @@ void setBoundsInPixels (int x, int y, int width, int height, int flags, boolean
 public void setBounds (Rectangle rect) {
 	checkWidget ();
 	if (rect == null) error (SWT.ERROR_NULL_ARGUMENT);
-	setBoundsInPixels(DPIUtil.scaleUp(rect, getZoom()));
+	int zoom = autoScaleDisabled ? parent.getZoom() : getZoom();
+	setBoundsInPixels(DPIUtil.scaleUp(rect, zoom));
 }
 
 void setBoundsInPixels (Rectangle rect) {

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

@@ -65,6 +65,7 @@ public abstract class Widget {
 	 * @noreference This field is not intended to be referenced by clients.
 	 */
 	public int nativeZoom;
+	boolean autoScaleDisabled = false;
 	int style, state;
 	Display display;
 	EventTable eventTable;
@@ -132,6 +133,9 @@ public abstract class Widget {
 	/* Bidi flag and for auto text direction */
 	static final int AUTO_TEXT_DIRECTION = SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT;
 
+	private static final String DATA_AUTOSCALE_DISABLED = "AUTOSCALE_DISABLED";
+	private static final String DATA_NATIVE_ZOOM = "NATIVE_ZOOM";
+
 	/* Initialize the Common Controls DLL */
 	static {
 		INITCOMMONCONTROLSEX icce = new INITCOMMONCONTROLSEX ();
@@ -182,9 +186,11 @@ public Widget (Widget parent, int style) {
 	checkParent (parent);
 	this.style = style;
 	this.nativeZoom = parent != null ? parent.nativeZoom : DPIUtil.getNativeDeviceZoom();
+	this.autoScaleDisabled = parent.autoScaleDisabled;
 	display = parent.display;
 	reskinWidget ();
 	notifyCreationTracker();
+	this.setData(DATA_NATIVE_ZOOM, this.nativeZoom);
 }
 
 void _addListener (int eventType, Listener listener) {
@@ -1457,6 +1463,10 @@ public void setData (String key, Object value) {
 		}
 	}
 	if (key.equals(SWT.SKIN_CLASS) || key.equals(SWT.SKIN_ID)) this.reskin(SWT.ALL);
+
+	if (DATA_AUTOSCALE_DISABLED.equals(key)) {
+		autoScaleDisabled = Boolean.parseBoolean(value.toString());
+	}
 }
 
 boolean sendFocusEvent (int type) {
@@ -2686,20 +2696,30 @@ void notifyDisposalTracker() {
 }
 
 GC createNewGC(long hDC, GCData data) {
-	data.nativeZoom = nativeZoom;
+	data.nativeZoom = getNativeZoom();
+	if (autoScaleDisabled && data.font != null) {
+		data.font = SWTFontProvider.getFont(display, data.font.getFontData()[0], 100);
+	}
 	return GC.win32_new(hDC, data);
 }
 
 int getNativeZoom() {
+	if (autoScaleDisabled) {
+		return 100;
+	}
 	return nativeZoom;
 }
 
 int getZoom() {
+	if (autoScaleDisabled) {
+		return 100;
+	}
 	return DPIUtil.getZoomForAutoscaleProperty(nativeZoom);
 }
 
 private static void handleDPIChange(Widget widget, int newZoom, float scalingFactor) {
 	widget.nativeZoom = newZoom;
+	widget.setData(DATA_NATIVE_ZOOM, newZoom);
 }
 
 int getSystemMetrics(int nIndex) {