Use large program icons on Windows

Icons for files associated with an external program area always loaded
in small size using the Windows API. The API also provides an option to
load large icons, which have twice the size of the small ones.

In order to improve the icon sharpness when retrieving the icon for
(monitor) scale value of more than 100%, this change ensures that the
higher resolution icon is used and scaled appropriately.

bundles/org.eclipse.swt/Eclipse SWT Program/win32/org/eclipse/swt/program/Program.java

@@ -20,6 +20,7 @@
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.internal.*;
+import org.eclipse.swt.internal.DPIUtil.*;
 import org.eclipse.swt.internal.win32.*;
 import org.eclipse.swt.widgets.*;
 
@@ -377,6 +378,21 @@ public ImageData getImageData () {
  * @since 3.125
  */
 public ImageData getImageData (int zoom) {
+	boolean useLargeIcon = zoom > 100;
+	ElementAtZoom<Image> zoomedIcon = loadIcon(useLargeIcon);
+	if (zoomedIcon == null) {
+		return null;
+	}
+	// Windows API returns image data according to primary monitor zoom factor
+	// rather than at original scaling
+	int nativeZoomFactor = zoomedIcon.zoom() * Display.getCurrent().getPrimaryMonitor().getZoom() / DPIUtil.getDeviceZoom();
+	Image image = zoomedIcon.element();
+	ImageData imageData = image.getImageData (100 * zoom / nativeZoomFactor);
+	image.dispose ();
+	return imageData;
+}
+
+private ElementAtZoom<Image> loadIcon(boolean useLargeIconIfAvailable) {
 	int nIconIndex = 0;
 	String fileName = iconName;
 	int index = iconName.indexOf (',');
@@ -395,15 +411,16 @@ public ImageData getImageData (int zoom) {
 	}
 	TCHAR lpszFile = new TCHAR (0, fileName, true);
 	long [] phiconSmall = new long[1], phiconLarge = null;
+	if (useLargeIconIfAvailable) {
+		phiconLarge = new long[1];
+	}
 	OS.ExtractIconEx (lpszFile, nIconIndex, phiconLarge, phiconSmall, 1);
-	if (phiconSmall [0] == 0) return null;
-	Image image = Image.win32_new (null, SWT.ICON, phiconSmall [0]);
-	// Windows API returns image data according to primary monitor zoom factor
-	// rather than at original scaling
-	int nativeZoomFactor = 100 * Display.getCurrent().getPrimaryMonitor().getZoom() / DPIUtil.getDeviceZoom();
-	ImageData imageData = image.getImageData (100 * zoom / nativeZoomFactor);
-	image.dispose ();
-	return imageData;
+	if (useLargeIconIfAvailable && phiconLarge[0] != 0) {
+		return new ElementAtZoom<>(Image.win32_new (null, SWT.ICON, phiconLarge[0]), 200);
+	} else if (phiconSmall[0] != 0) {
+		return new ElementAtZoom<>(Image.win32_new (null, SWT.ICON, phiconSmall[0]), 100);
+	}
+	return null;
 }
 
 /**