[win32] Calculate value for NATIVE_ZOOM on demand

To remove the memory footprint of Widget this commit removes the value
for NATIVE_ZOOM from the data attribute and replaces it by calculating
the value in Control#getData on demand. Additionally the naming is changed
to SHELL_ZOOM.

Author: akoch-yatta

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

@@ -78,6 +78,8 @@ public abstract class Control extends Widget implements Drawable {
 	Font font;
 	int drawCount, foreground, background, backgroundAlpha = 255;
 
+	private static final String DATA_SHELL_ZOOM = "SHELL_ZOOM";
+
 /**
  * Prevents uninitialized instances from being created outside the package.
  */
@@ -1256,6 +1258,15 @@ public Cursor getCursor () {
 	return cursor;
 }
 
+@Override
+public Object getData(String key) {
+	if (DATA_SHELL_ZOOM.equals(key)) {
+		Shell shell = getShell();
+		return shell == null ? null : shell.nativeZoom;
+	}
+	return super.getData(key);
+}
+
 /**
  * Returns <code>true</code> if the receiver is detecting
  * drag gestures, and  <code>false</code> otherwise.

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

@@ -134,7 +134,6 @@ public abstract class Widget {
 	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 {
@@ -189,7 +188,6 @@ public Widget (Widget parent, int style) {
 	display = parent.display;
 	reskinWidget ();
 	notifyCreationTracker();
-	this.setData(DATA_NATIVE_ZOOM, this.nativeZoom);
 	registerDPIChangeListener();
 }
 
@@ -2725,9 +2723,7 @@ int getZoom() {
 }
 
 void handleDPIChange(Event event, float scalingFactor) {
-	int newZoom = event.detail;
-	this.nativeZoom = newZoom;
-	this.setData(DATA_NATIVE_ZOOM, newZoom);
+	this.nativeZoom = event.detail;
 }
 
 int getSystemMetrics(int nIndex) {