[Win32] Avoid duplicate application of gray/disabled image adaptation

When an image is created with SWT.IMAGE_GRAY or SWT.IMAGE_DISABLE, an
adaptation of the loaded/created image data is performed to make it look
grayed/disabled. The according functionality is currently applied by
callers of loadImageData() right afterwards. Since for every consumption
of an image data/handle the loadImageData() method needs to be called,
this ensures that the image data is always adapted correctly.

In the implementation for an ImageGcDrawer, the adaptation for
gray/disabled is currently executed within the loadImageData() method.
The same applies to implementation for an existing handle and a plain
image, as they will simply scale existing image data (which already have
the gray/disabled adaptation applied).
Since consumers of that method perform the adaptation as well, this
leads to an unnecessary duplicate application of the adaptation and to
inconsistent behavior throughout the implementations of loadImageData().

This change streamlines the implementation in the Image class by
properly assigning the responsibility for applying gray/disabled
adaptations as follows:
- the copy constructor accepting the gray/disabled flag applies the
style to copied handles, just like it does now
- on retrieval of new image data or handles for zoom/sizes, the
loadImageData() and loadImageDataAtExactSize() method of the provider
classes are responsible for delivering data with the styling being
applied
This relieves all consumers of those methods from taking care of
applying the style and properly assign it to those two methods and the
implementation.

Author: HeikoKlare

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

@@ -238,8 +238,7 @@ private boolean isReusable(int width, int height) {
 		private Optional<InternalImageHandle> createHandleAtExactSize(int width, int height) {
 			Optional<ImageData> imageData = imageProvider.loadImageDataAtExactSize(width, height);
 			if (imageData.isPresent()) {
-				ImageData adaptedData = adaptImageDataIfDisabledOrGray(imageData.get());
-				temporaryHandleContainer = init(adaptedData, -1);
+				temporaryHandleContainer = init(imageData.get(), -1);
 				return Optional.of(temporaryHandleContainer);
 			}
 			return Optional.empty();
@@ -253,8 +252,7 @@ private InternalImageHandle getOrCreateImageHandleAtClosestSize(int widthHint, i
 			InternalImageHandle bestFittingHandle = imageHandleManager.get(imageZoom);
 			if (bestFittingHandle == null) {
 				ImageData bestFittingImageData = imageProvider.loadImageData(imageZoom).element();
-				ImageData adaptedData = adaptImageDataIfDisabledOrGray(bestFittingImageData);
-				bestFittingHandle = temporaryHandleContainer = init(adaptedData, -1);
+				bestFittingHandle = temporaryHandleContainer = init(bestFittingImageData, -1);
 			}
 			return bestFittingHandle;
 		}
@@ -771,6 +769,10 @@ public Image(Device device, ImageGcDrawer imageGcDrawer, int width, int height)
 	init();
 }
 
+private ElementAtZoom<ImageData> adaptImageDataIfDisabledOrGray(ElementAtZoom<ImageData> dataAtZoom) {
+	return new ElementAtZoom<>(adaptImageDataIfDisabledOrGray(dataAtZoom.element()), dataAtZoom.zoom());
+}
+
 private ImageData adaptImageDataIfDisabledOrGray(ImageData data) {
 	ImageData returnImageData = null;
 	switch (this.styleFlag) {
@@ -2058,6 +2060,10 @@ protected boolean isPersistentImageHandleRequriedForImageData() {
 		return false;
 	}
 
+	/**
+	 * Returns image data at the best-fitting available zoom for the given zoom.
+	 * The returned data will have a potential gray/disable style applied.
+	 */
 	protected abstract ElementAtZoom<ImageData> loadImageData(int zoom);
 
 	abstract ImageData newImageData(int zoom);
@@ -2071,6 +2077,10 @@ ElementAtZoom<ImageData> getClosestAvailableImageData(int zoom) {
 		return new ElementAtZoom<>(imageData, closestZoom);
 	}
 
+	/**
+	 * Returns image data at the exact requested size if available.
+	 * The returned data will have a potential gray/disable style applied.
+	 */
 	protected Optional<ImageData> loadImageDataAtExactSize(int width, int height) {
 		return Optional.empty(); // exact size not available
 	}
@@ -2174,7 +2184,6 @@ protected DestroyableImageHandle newImageHandle(ZoomContext zoomContext) {
 	private DestroyableImageHandle initializeHandleFromSource(ZoomContext zoomContext) {
 		ElementAtZoom<ImageData> imageDataAtZoom = loadImageData(zoomContext.targetZoom());
 		ImageData imageData = DPIUtil.scaleImageData(device, imageDataAtZoom.element(), zoomContext.targetZoom(), imageDataAtZoom.zoom());
-		imageData = adaptImageDataIfDisabledOrGray(imageData);
 		return newImageHandle(imageData, zoomContext);
 	}
 }
@@ -2202,7 +2211,8 @@ protected Rectangle getBounds(int zoom) {
 
 	@Override
 	protected ElementAtZoom<ImageData> loadImageData(int zoom) {
-		return new ElementAtZoom<>(imageDataAtBaseZoom, baseZoom);
+		ImageData adaptedImageData = adaptImageDataIfDisabledOrGray(imageDataAtBaseZoom);
+		return new ElementAtZoom<>(adaptedImageData, baseZoom);
 	}
 
 	@Override
@@ -2233,7 +2243,8 @@ protected ElementAtZoom<ImageData> loadImageData(int zoom) {
 		ImageData scaledMask = DPIUtil.scaleImageData(device, maskAt100, zoom, 100);
 		scaledMask = ImageData.convertMask(scaledMask);
 		ImageData mergedData = applyMask(scaledSource, scaledMask);
-		return new ElementAtZoom<>(mergedData, zoom);
+		ImageData adaptedData = adaptImageDataIfDisabledOrGray(mergedData);
+		return new ElementAtZoom<>(adaptedData, zoom);
 	}
 
 	@Override
@@ -2260,7 +2271,8 @@ private ImageDataLoaderStreamProviderWrapper(byte[] inputStreamData) {
 
 	@Override
 	protected ElementAtZoom<ImageData> loadImageData(int zoom) {
-		return ImageDataLoader.loadByZoom(new ByteArrayInputStream(inputStreamData), FileFormat.DEFAULT_ZOOM, zoom);
+		ElementAtZoom<ImageData> imageDataAtZoom = ImageDataLoader.loadByZoom(new ByteArrayInputStream(inputStreamData), FileFormat.DEFAULT_ZOOM, zoom);
+		return adaptImageDataIfDisabledOrGray(imageDataAtZoom);
 	}
 
 	@Override
@@ -2278,7 +2290,8 @@ AbstractImageProviderWrapper createCopy(Image image) {
 	protected Optional<ImageData> loadImageDataAtExactSize(int targetWidth, int targetHeight) {
 		if (ImageDataLoader.isDynamicallySizable(new ByteArrayInputStream(this.inputStreamData))) {
 			ImageData imageDataAtSize = ImageDataLoader.loadBySize(new ByteArrayInputStream(this.inputStreamData), targetWidth, targetHeight);
-			return Optional.of(imageDataAtSize);
+			ImageData adaptedImageDataAtSize = adaptImageDataIfDisabledOrGray(imageDataAtSize);
+			return Optional.of(adaptedImageDataAtSize);
 		}
 		return Optional.empty();
 	}
@@ -2470,7 +2483,6 @@ protected DestroyableImageHandle newImageHandle(ZoomContext zoomContext) {
 	private DestroyableImageHandle initializeHandleFromSource(int zoom) {
 		ElementAtZoom<ImageData> imageDataAtZoom = loadImageData(zoom);
 		ImageData imageData = DPIUtil.scaleImageData (device, imageDataAtZoom.element(), zoom, imageDataAtZoom.zoom());
-		imageData = adaptImageDataIfDisabledOrGray(imageData);
 		return init(imageData, zoom);
 	}
 
@@ -2497,7 +2509,8 @@ protected ElementAtZoom<ImageData> loadImageData(int zoom) {
 		// Load at appropriate zoom via loader
 		if (fileForZoom.zoom() != zoom && ImageDataLoader.canLoadAtZoom(fileForZoom.element(), fileForZoom.zoom(), zoom)) {
 			ElementAtZoom<ImageData> imageDataAtZoom = ImageDataLoader.loadByZoom(fileForZoom.element(), fileForZoom.zoom(), zoom);
-			return new ElementAtZoom<>(imageDataAtZoom.element(), zoom);
+			ImageData adaptedImageData = adaptImageDataIfDisabledOrGray(imageDataAtZoom.element());
+			return new ElementAtZoom<>(adaptedImageData, zoom);
 		}
 
 		// Load at file zoom (native or via loader) and rescale
@@ -2517,7 +2530,7 @@ protected ElementAtZoom<ImageData> loadImageData(int zoom) {
 				temporaryImageHandle.destroy();
 			}
 		}
-		return imageDataAtZoom;
+		return adaptImageDataIfDisabledOrGray(imageDataAtZoom);
 	}
 
 	@Override
@@ -2727,7 +2740,8 @@ protected Optional<ImageData> loadImageDataAtExactSize(int targetWidth, int targ
 		String fileName = DPIUtil.validateAndGetImagePathAtZoom(this.provider, 100).element();
 		if (ImageDataLoader.isDynamicallySizable(fileName)) {
 			ImageData imageDataAtSize = ImageDataLoader.loadBySize(fileName, targetWidth, targetHeight);
-			return Optional.of(imageDataAtSize);
+			ImageData adaptedImageDataAtSize = adaptImageDataIfDisabledOrGray(imageDataAtSize);
+			return Optional.of(adaptedImageDataAtSize);
 		}
 		return Optional.empty();
 	}
@@ -2740,7 +2754,8 @@ private class ImageDataProviderWrapper extends BaseImageProviderWrapper<ImageDat
 
 	@Override
 	protected ElementAtZoom<ImageData> loadImageData(int zoom) {
-		return DPIUtil.validateAndGetImageDataAtZoom (provider, zoom);
+		ElementAtZoom<ImageData> imageDataAtZoom = DPIUtil.validateAndGetImageDataAtZoom (provider, zoom);
+		return adaptImageDataIfDisabledOrGray(imageDataAtZoom);
 	}
 
 	@Override
@@ -2756,7 +2771,8 @@ protected Optional<ImageData> loadImageDataAtExactSize(int targetWidth, int targ
 				SWT.error(SWT.ERROR_INVALID_ARGUMENT, null,
 						" ImageDataAtSizeProvider returned null for width=" + targetWidth + ", height=" + targetHeight);
 			}
-			return Optional.of(imageData);
+			ImageData adaptedImageData = adaptImageDataIfDisabledOrGray(imageData);
+			return Optional.of(adaptedImageData);
 		}
 		return Optional.empty();
 	}