[Win32] Combine duplicate initialization logic for image from providers

Images based on ImageFileNameProvider and ImageDataProvider are
initialized with data based on the default zoom and can later on be
reinitialized with data for others zooms when `getImageData()` is
called. At both places, the same functionality is implemented twice.

This change makes the initial creation of image data use the already
existing implementation for reinitializing it for another zoom. It also
unifies the previous two implementations and removes obsolete calls to
init() which are just required once for starting resource tracking.

Author: HeikoKlare

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

@@ -552,16 +552,7 @@ public Image(Device device, ImageFileNameProvider imageFileNameProvider) {
 	super(device);
 	this.imageProvider = new ImageFileNameProviderWrapper(imageFileNameProvider);
 	initialNativeZoom = DPIUtil.getNativeDeviceZoom();
-	ElementAtZoom<String> fileName = DPIUtil.validateAndGetImagePathAtZoom (imageFileNameProvider, getZoom());
-	if (fileName.zoom() == getZoom()) {
-		ImageHandle imageMetadata = initNative (fileName.element(), getZoom());
-		if (imageMetadata == null) {
-			init(new ImageData (fileName.element()), getZoom());
-		}
-	} else {
-		ImageData resizedData = DPIUtil.autoScaleImageData (device, new ImageData (fileName.element()), fileName.zoom());
-		init(resizedData, getZoom());
-	}
+	imageProvider.getImageMetadata(getZoom());
 	init();
 	this.device.registerResourceWithZoomSupport(this);
 }
@@ -599,9 +590,7 @@ public Image(Device device, ImageDataProvider imageDataProvider) {
 	super(device);
 	this.imageProvider = new ImageDataProviderWrapper(imageDataProvider);
 	initialNativeZoom = DPIUtil.getNativeDeviceZoom();
-	ElementAtZoom<ImageData> data =  DPIUtil.validateAndGetImageDataAtZoom(imageDataProvider, getZoom());
-	ImageData resizedData = DPIUtil.scaleImageData(device, data.element(), getZoom(), data.zoom());
-	init (resizedData, getZoom());
+	imageProvider.getImageMetadata(getZoom());
 	init();
 	this.device.registerResourceWithZoomSupport(this);
 }
@@ -2143,17 +2132,18 @@ ImageData getImageData(int zoom) {
 
 	@Override
 	ImageHandle getImageMetadata(int zoom) {
-		ElementAtZoom<String> imageCandidate = DPIUtil.validateAndGetImagePathAtZoom (provider, zoom);
-		ImageData imageData = new ImageData (imageCandidate.element());
-		if (imageCandidate.zoom() == zoom) {
-			/* Release current native resources */
-			ImageHandle imageMetadata = initNative(imageCandidate.element(), zoom);
-			if (imageMetadata == null) init(imageData, zoom);
-			init();
-		} else {
-			ImageData resizedData = DPIUtil.scaleImageData(device, imageData, zoom, imageCandidate.zoom());
-			ImageData newData = adaptImageDataIfDisabledOrGray(resizedData);
-			init(newData, zoom);
+		ElementAtZoom<String> fileForZoom = DPIUtil.validateAndGetImagePathAtZoom (provider, zoom);
+		ImageHandle nativeInitializedImage = null;
+		if (fileForZoom.zoom() == zoom) {
+			nativeInitializedImage = initNative(fileForZoom.element(), zoom);
+		}
+		if (nativeInitializedImage == null) {
+			ImageData imageData = new ImageData (fileForZoom.element());
+			if (fileForZoom.zoom() != zoom) {
+				imageData = DPIUtil.scaleImageData(device, imageData, zoom, fileForZoom.zoom());
+			}
+			imageData = adaptImageDataIfDisabledOrGray(imageData);
+			init(imageData, zoom);
 		}
 		return zoomLevelToImageHandle.get(zoom);
 	}
@@ -2210,7 +2200,6 @@ ImageHandle getImageMetadata(int zoom) {
 		ImageData resizedData = DPIUtil.scaleImageData (device, imageCandidate.element(), zoom, imageCandidate.zoom());
 		ImageData newData = adaptImageDataIfDisabledOrGray(resizedData);
 		init(newData, zoom);
-		init();
 		return zoomLevelToImageHandle.get(zoom);
 	}