Fixed Program Icon Scaling for Multi Zoom

This contribution reimplements the logic for scaling the Program Icons
while getting rid of the DPIUtil::getDeviceZoom usage and enhancing the image
quality of icons on scaling up.

contributes to #62 and #127

Author: amartya4256

bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/ImageTransfer.java

@@ -184,7 +184,7 @@ public Object nativeToJava(TransferData transferData) {
 					pSourceBits -= scanline;
 				}
 			}
-			Image image = Image.win32_new(null, SWT.BITMAP, memDib);
+			Image image = Image.win32_new(null, SWT.BITMAP, memDib, DPIUtil.getNativeDeviceZoom());
 			ImageData data = image.getImageData (DPIUtil.getDeviceZoom ());
 			OS.DeleteObject(memDib);
 			image.dispose();

bundles/org.eclipse.swt/Eclipse SWT PI/win32/org/eclipse/swt/internal/win32/OS.java

@@ -1210,6 +1210,7 @@ public class OS extends C {
 	public static final int SHADEBLENDCAPS = 120;
 	public static final int SHGFI_ICON = 0x000000100;
 	public static final int SHGFI_SMALLICON= 0x1;
+	public static final int SHGFI_LARGEICON= 0x0;
 	public static final int SHGFI_USEFILEATTRIBUTES = 0x000000010;
 	public static final int SIGDN_FILESYSPATH = 0x80058000;
 	public static final int SIF_ALL = 0x17;

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

@@ -19,7 +19,6 @@
 
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
-import org.eclipse.swt.internal.*;
 import org.eclipse.swt.internal.win32.*;
 import org.eclipse.swt.widgets.*;
 
@@ -382,16 +381,22 @@ public ImageData getImageData () {
 public ImageData getImageData (int zoom) {
 	// 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();
-	int imageZoomFactor = 100 * zoom / nativeZoomFactor;
+	int initialNativeZoom = Display.getCurrent().getPrimaryMonitor().getZoom();
 	if (extension != null) {
 		SHFILEINFO shfi = new SHFILEINFO ();
-		int flags = OS.SHGFI_ICON | OS.SHGFI_SMALLICON | OS.SHGFI_USEFILEATTRIBUTES;
+		int flags = OS.SHGFI_ICON | OS.SHGFI_USEFILEATTRIBUTES;
+		boolean useLargeIcon = 100 * zoom /  initialNativeZoom >= 200;
+		if(useLargeIcon) {
+			flags |= OS.SHGFI_LARGEICON;
+			initialNativeZoom *= 2;
+		} else {
+			flags |= OS.SHGFI_SMALLICON;
+		}
 		TCHAR pszPath = new TCHAR (0, extension, true);
 		OS.SHGetFileInfo (pszPath.chars, OS.FILE_ATTRIBUTE_NORMAL, shfi, SHFILEINFO.sizeof, flags);
 		if (shfi.hIcon != 0) {
-			Image image = Image.win32_new (null, SWT.ICON, shfi.hIcon);
-			ImageData imageData = image.getImageData (imageZoomFactor);
+			Image image = Image.win32_new (null, SWT.ICON, shfi.hIcon, initialNativeZoom);
+			ImageData imageData = image.getImageData (zoom);
 			image.dispose ();
 			return imageData;
 		}
@@ -416,8 +421,8 @@ public ImageData getImageData (int zoom) {
 	long [] phiconSmall = new long[1], phiconLarge = null;
 	OS.ExtractIconEx (lpszFile, nIconIndex, phiconLarge, phiconSmall, 1);
 	if (phiconSmall [0] == 0) return null;
-	Image image = Image.win32_new (null, SWT.ICON, phiconSmall [0]);
-	ImageData imageData = image.getImageData (imageZoomFactor);
+	Image image = Image.win32_new (null, SWT.ICON, phiconSmall [0], initialNativeZoom);
+	ImageData imageData = image.getImageData (zoom);
 	image.dispose ();
 	return imageData;
 }

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/graphics/Image.java

@@ -127,8 +127,12 @@ public final class Image extends Resource implements Drawable {
  * Prevents uninitialized instances from being created outside the package.
  */
 Image (Device device) {
+	this(device, DPIUtil.getNativeDeviceZoom());
+}
+
+private Image (Device device, int nativeZoom) {
 	super(device);
-	initialNativeZoom = DPIUtil.getNativeDeviceZoom();
+	initialNativeZoom = nativeZoom;
 	this.device.registerResourceWithZoomSupport(this);
 }
 
@@ -2030,10 +2034,10 @@ public String toString () {
  *
  * @noreference This method is not intended to be referenced by clients.
  */
-public static Image win32_new(Device device, int type, long handle) {
-	Image image = new Image(device);
+public static Image win32_new(Device device, int type, long handle, int nativeZoom) {
+	Image image = new Image(device, nativeZoom);
 	image.type = type;
-	image.new ImageHandle(handle, image.getZoom());
+	image.new ImageHandle(handle, nativeZoom);
 	return image;
 }
 

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

@@ -1204,7 +1204,7 @@ static Image createIcon (Image image, int zoom) {
 	if (hIcon == 0) SWT.error(SWT.ERROR_NO_HANDLES);
 	OS.DeleteObject (hBitmap);
 	OS.DeleteObject (hMask);
-	return Image.win32_new (device, SWT.ICON, hIcon);
+	return Image.win32_new (device, SWT.ICON, hIcon, zoom);
 }
 
 long getTextSearchIcon(int size) {
@@ -2543,27 +2543,28 @@ Font getSystemFont (int zoom) {
  */
 public Image getSystemImage (int id) {
 	checkDevice ();
+	int primaryMonitorNativeZoom = getPrimaryMonitor().getZoom();
 	switch (id) {
 		case SWT.ICON_ERROR: {
 			if (errorImage != null) return errorImage;
 			long hIcon = OS.LoadImage (0, OS.OIC_HAND, OS.IMAGE_ICON, 0, 0, OS.LR_SHARED);
-			return errorImage = Image.win32_new (this, SWT.ICON, hIcon);
+			return errorImage = Image.win32_new (this, SWT.ICON, hIcon, primaryMonitorNativeZoom);
 		}
 		case SWT.ICON_WORKING:
 		case SWT.ICON_INFORMATION: {
 			if (infoImage != null) return infoImage;
 			long hIcon = OS.LoadImage (0, OS.OIC_INFORMATION, OS.IMAGE_ICON, 0, 0, OS.LR_SHARED);
-			return infoImage = Image.win32_new (this, SWT.ICON, hIcon);
+			return infoImage = Image.win32_new (this, SWT.ICON, hIcon, primaryMonitorNativeZoom);
 		}
 		case SWT.ICON_QUESTION: {
 			if (questionImage != null) return questionImage;
 			long hIcon = OS.LoadImage (0, OS.OIC_QUES, OS.IMAGE_ICON, 0, 0, OS.LR_SHARED);
-			return questionImage = Image.win32_new (this, SWT.ICON, hIcon);
+			return questionImage = Image.win32_new (this, SWT.ICON, hIcon, primaryMonitorNativeZoom);
 		}
 		case SWT.ICON_WARNING: {
 			if (warningIcon != null) return warningIcon;
 			long hIcon = OS.LoadImage (0, OS.OIC_BANG, OS.IMAGE_ICON, 0, 0, OS.LR_SHARED);
-			return warningIcon = Image.win32_new (this, SWT.ICON, hIcon);
+			return warningIcon = Image.win32_new (this, SWT.ICON, hIcon, primaryMonitorNativeZoom);
 		}
 	}
 	return null;

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

@@ -166,7 +166,7 @@ IShellLink createShellLink (MenuItem item) {
 				ImageData data;
 				if (item.hBitmap != 0) {
 					long handle = OS.CopyImage(item.hBitmap, SWT.BITMAP, 0, 0, 0);
-					Image image2 = Image.win32_new (display, SWT.BITMAP, handle);
+					Image image2 = Image.win32_new (display, SWT.BITMAP, handle, nativeZoom);
 					data = image2.getImageData (DPIUtil.getDeviceZoom ());
 					image2.dispose();
 				} else {