Use the existing image to initialize the GC in ImageGcDrawerWrapper

In ImageGCDrawerWrapper#newImageHandle, we create a new image with
existing data to initialize the GC, instead we could use the existing
image object and the base handle should be created as it is done in
PlainImageDataProvider.

Author: ShahzaibIbrahim

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

@@ -1951,6 +1951,46 @@ protected final ImageHandle newImageHandle(ImageData data, int zoom) {
 			return init(data, zoom);
 		}
 	}
+
+	protected final ImageHandle createHandle(int width, int height, int zoom) {
+		long handle = initHandle(width, height, zoom);
+		ImageHandle imageHandle = new ImageHandle(handle, zoom);
+		zoomLevelToImageHandle.put(zoom, imageHandle);
+		return imageHandle;
+	}
+
+	private long initHandle(int width, int height, int zoom) {
+		if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
+		int scaledWidth = Win32DPIUtils.pointToPixel (width, zoom);
+		int scaledHeight = Win32DPIUtils.pointToPixel (height, zoom);
+		long hDC = device.internal_new_GC(null);
+		long newHandle = OS.CreateCompatibleBitmap(hDC, scaledWidth, scaledHeight);
+		/*
+		* Feature in Windows.  CreateCompatibleBitmap() may fail
+		* for large images.  The fix is to create a DIB section
+		* in that case.
+		*/
+		if (newHandle == 0) {
+			int bits = OS.GetDeviceCaps(hDC, OS.BITSPIXEL);
+			int planes = OS.GetDeviceCaps(hDC, OS.PLANES);
+			int depth = bits * planes;
+			if (depth < 16) depth = 16;
+			if (depth > 24) depth = 24;
+			newHandle = createDIB(scaledWidth, scaledHeight, depth);
+		}
+		if (newHandle != 0) {
+			long memDC = OS.CreateCompatibleDC(hDC);
+			long hOldBitmap = OS.SelectObject(memDC, newHandle);
+			OS.PatBlt(memDC, 0, 0, scaledWidth, scaledHeight, OS.PATCOPY);
+			OS.SelectObject(memDC, hOldBitmap);
+			OS.DeleteDC(memDC);
+		}
+		device.internal_dispose_GC(hDC, null);
+		if (newHandle == 0) {
+			SWT.error(SWT.ERROR_NO_HANDLES, null, device.getLastError());
+		}
+		return newHandle;
+	}
 }
 
 private class ExistingImageHandleProviderWrapper extends AbstractImageProviderWrapper {
@@ -2179,55 +2219,15 @@ protected ImageHandle newImageHandle(int zoom) {
 		if (memGC != null) {
 			GC currentGC = memGC;
 			memGC = null;
-			createHandle(zoom);
+			createHandle(this.width, this.height, zoom);
 			currentGC.refreshFor(new DrawableWrapper(Image.this, zoom), zoom);
 			return zoomLevelToImageHandle.get(zoom);
 		}
 		return super.newImageHandle(zoom);
 	}
 	private ImageHandle createBaseHandle(int zoom) {
 		baseZoom = zoom;
-		return createHandle(zoom);
-	}
-
-	private ImageHandle createHandle(int zoom) {
-		long handle = initHandle(zoom);
-		ImageHandle imageHandle = new ImageHandle(handle, zoom);
-		zoomLevelToImageHandle.put(zoom, imageHandle);
-		return imageHandle;
-	}
-
-	private long initHandle(int zoom) {
-		if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
-		int scaledWidth = Win32DPIUtils.pointToPixel (width, zoom);
-		int scaledHeight = Win32DPIUtils.pointToPixel (height, zoom);
-		long hDC = device.internal_new_GC(null);
-		long newHandle = OS.CreateCompatibleBitmap(hDC, scaledWidth, scaledHeight);
-		/*
-		* Feature in Windows.  CreateCompatibleBitmap() may fail
-		* for large images.  The fix is to create a DIB section
-		* in that case.
-		*/
-		if (newHandle == 0) {
-			int bits = OS.GetDeviceCaps(hDC, OS.BITSPIXEL);
-			int planes = OS.GetDeviceCaps(hDC, OS.PLANES);
-			int depth = bits * planes;
-			if (depth < 16) depth = 16;
-			if (depth > 24) depth = 24;
-			newHandle = createDIB(scaledWidth, scaledHeight, depth);
-		}
-		if (newHandle != 0) {
-			long memDC = OS.CreateCompatibleDC(hDC);
-			long hOldBitmap = OS.SelectObject(memDC, newHandle);
-			OS.PatBlt(memDC, 0, 0, scaledWidth, scaledHeight, OS.PATCOPY);
-			OS.SelectObject(memDC, hOldBitmap);
-			OS.DeleteDC(memDC);
-		}
-		device.internal_dispose_GC(hDC, null);
-		if (newHandle == 0) {
-			SWT.error(SWT.ERROR_NO_HANDLES, null, device.getLastError());
-		}
-		return newHandle;
+		return createHandle(this.width, this.height, zoom);
 	}
 
 	@Override
@@ -2596,27 +2596,26 @@ ImageData newImageData(int zoom) {
 	protected ImageHandle newImageHandle(int zoom) {
 		currentZoom = zoom;
 		int gcStyle = drawer.getGcStyle();
-		Image image;
 		if ((gcStyle & SWT.TRANSPARENT) != 0) {
 			int scaledHeight = Win32DPIUtils.pointToPixel(height, zoom);
 			int scaledWidth = Win32DPIUtils.pointToPixel(width, zoom);
 			/* Create a 24 bit image data with alpha channel */
 			final ImageData resultData = new ImageData (scaledWidth, scaledHeight, 24, new PaletteData (0xFF, 0xFF00, 0xFF0000));
 			resultData.alphaData = new byte [scaledWidth * scaledHeight];
-			image = new Image(device, resultData, zoom);
+			init(resultData, zoom);
 		} else {
-			image = new Image(device, width, height);
+			createHandle(width, height, zoom);
 		}
-		GC gc = new GC(new DrawableWrapper(image, zoom), gcStyle);
+		GC gc = new GC(new DrawableWrapper(Image.this, zoom), gcStyle);
 		try {
 			drawer.drawOn(gc, width, height);
-			ImageData imageData = image.getImageMetadata(zoom).getImageData();
+			ImageData imageData = Image.this.getImageMetadata(zoom).getImageData();
 			drawer.postProcess(imageData);
-			ImageData newData = adaptImageDataIfDisabledOrGray(imageData);
-			return init(newData, zoom);
+			zoomLevelToImageHandle.get(zoom).destroy();
+			init(imageData, zoom);
+			return zoomLevelToImageHandle.get(zoom);
 		} finally {
 			gc.dispose();
-			image.dispose();
 		}
 	}