[win32] refactor Image::init with ImageData

This commit refactors Image#init for ImageData in the win32
implementation. Currently this method serves two purposes. Creating
handles for the given ImageData or additionally initializing an image
with those handles. This two use cases are made more explicit refactoring
this logic out into concrete methods.

Author: akoch-yatta

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

@@ -325,7 +325,7 @@ public Cursor(Device device, ImageData source, int hotspotX, int hotspotY) {
 		if (hMask == 0) SWT.error(SWT.ERROR_NO_HANDLES);
 	} else {
 		ImageData mask = source.getTransparencyMask();
-		long [] result = Image.init(this.device, null, source, mask, null);	// Since the image is null, the device zoom can be null
+		long [] result = Image.initIcon(this.device, source, mask);
 		hBitmap = result[0];
 		hMask = result[1];
 	}

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

@@ -412,7 +412,7 @@ public Image(Device device, ImageData source, ImageData mask) {
 	source = DPIUtil.autoScaleUp(device, source);
 	mask = DPIUtil.autoScaleUp(device, mask);
 	mask = ImageData.convertMask(mask);
-	init(this.device, this, source, mask, getZoom());
+	initIconHandle(this.device, source, mask, getZoom());
 	init();
 	this.device.registerResourceWithZoomSupport(this);
 }
@@ -781,7 +781,7 @@ private ImageHandle getImageMetadata(int zoom) {
 			// to image data without transparency mask, this will create invalid images
 			// so this fallback will "repair" the image data by explicitly passing
 			// the transparency mask created from the scaled image data
-			init(this.device, this, newData, newData.getTransparencyMask(), zoom);
+			initIconHandle(this.device, newData, newData.getTransparencyMask(), zoom);
 		} else {
 			init(newData, zoom);
 		}
@@ -1574,7 +1574,9 @@ static ImageData directToDirect(ImageData src, int newDepth, PaletteData newPale
 	return img;
 }
 
-static long [] init(Device device, Image image, ImageData i, Integer zoom) {
+private record HandleForImageDataContainer(int type, ImageData imageData, long[] handles) {}
+
+private static HandleForImageDataContainer init(Device device, ImageData i) {
 	/* Windows does not support 2-bit images. Convert to 4-bit image. */
 	if (i.depth == 2) {
 		i = indexToIndex(i, 4);
@@ -1740,7 +1742,6 @@ else if (i.alphaData != null) {
 	}
 	OS.MoveMemory(pBits[0], data, data.length);
 
-	long [] result = null;
 	if (i.getTransparencyType() == SWT.TRANSPARENCY_MASK) {
 		/* Get the HDC for the device */
 		long hDC = device.internal_new_GC(null);
@@ -1767,31 +1768,10 @@ else if (i.alphaData != null) {
 		OS.DeleteDC(hdcDest);
 		OS.DeleteObject(hDib);
 
-		if (image == null) {
-			result = new long []{hBitmap, hMask};
-		} else {
-			/* Create the icon */
-			ICONINFO info = new ICONINFO();
-			info.fIcon = true;
-			info.hbmColor = hBitmap;
-			info.hbmMask = hMask;
-			long hIcon = OS.CreateIconIndirect(info);
-			if (hIcon == 0) SWT.error(SWT.ERROR_NO_HANDLES);
-			OS.DeleteObject(hBitmap);
-			OS.DeleteObject(hMask);
-			image.type = SWT.ICON;
-			image.new ImageHandle(hIcon, zoom);
-		}
+		return new HandleForImageDataContainer(SWT.ICON, i, new long []{hBitmap, hMask});
 	} else {
-		if (image == null) {
-			result = new long []{hDib};
-		} else {
-			image.type = SWT.BITMAP;
-			image.transparentPixel = i.transparentPixel;
-			image.new ImageHandle(hDib, zoom);
-		}
+		return new HandleForImageDataContainer(SWT.BITMAP, i, new long []{hDib});
 	}
-	return result;
 }
 
 private void setImageMetadataForHandle(ImageHandle imageMetadata, Integer zoom) {
@@ -1803,9 +1783,35 @@ private void setImageMetadataForHandle(ImageHandle imageMetadata, Integer zoom)
 	zoomLevelToImageHandle.put(zoom, imageMetadata);
 }
 
-static long [] init(Device device, Image image, ImageData source, ImageData mask, Integer zoom) {
+private ImageHandle initIconHandle(Device device, ImageData source, ImageData mask, Integer zoom) {
 	ImageData imageData = applyMask(source, mask);
-	return init(device, image, imageData, zoom);
+	HandleForImageDataContainer imageDataHandle = init(device, imageData);
+	return initIconHandle(imageDataHandle.handles, zoom);
+}
+
+private ImageHandle initIconHandle(long[] handles, int zoom) {
+	/* Create the icon */
+	ICONINFO info = new ICONINFO();
+	info.fIcon = true;
+	info.hbmColor = handles[0];
+	info.hbmMask = handles[1];
+	long hIcon = OS.CreateIconIndirect(info);
+	if (hIcon == 0) SWT.error(SWT.ERROR_NO_HANDLES);
+	OS.DeleteObject(handles[0]);
+	OS.DeleteObject(handles[1]);
+	type = SWT.ICON;
+	return new ImageHandle(hIcon, zoom);
+}
+
+private ImageHandle initBitmapHandle(ImageData imageData, long handle, Integer zoom) {
+	type = SWT.BITMAP;
+	transparentPixel = imageData.transparentPixel;
+	return new ImageHandle(handle, zoom);
+}
+
+static long [] initIcon(Device device, ImageData source, ImageData mask) {
+	ImageData imageData = applyMask(source, mask);
+	return init(device, imageData).handles;
 }
 
 private static ImageData applyMask(ImageData source, ImageData mask) {
@@ -1883,9 +1889,19 @@ private static ImageData applyMask(ImageData source, ImageData mask) {
 }
 
 
-void init(ImageData i, Integer zoom) {
+void init(ImageData i, int zoom) {
 	if (i == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
-	init(device, this, i, zoom);
+	HandleForImageDataContainer imageDataHandle = init(device, i);
+	switch (imageDataHandle.type()) {
+		case SWT.ICON: {
+			initIconHandle(imageDataHandle.handles(), zoom);
+			break;
+		}
+		case SWT.BITMAP: {
+			initBitmapHandle(imageDataHandle.imageData(), imageDataHandle.handles()[0], zoom);
+			break;
+		}
+	}
 }
 
 /**