[MacOS] Support loading and drawing images at desired size

With the support of SVGs and the addition of the
ImageDataAtSizeProvider, it is possible for many Image instances to
provide a handle that represents the image at sharply rendered specific
size in addition to the existing support of providing an image at
different zooms of a base size.

This change adds according support to the MacOS implementations of GC
and Image. The GC#drawImage() method accepting only destination position
and size now makes use of enhanced Image capabilities to load the image
at the desired size if possible instead of just using the best fitting
zoomed handle.

Author: HeikoKlare

bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/graphics/GC.java

@@ -1238,7 +1238,9 @@ public void drawImage(Image image, int destX, int destY, int destWidth, int dest
 	if (image.isDisposed()) {
 		SWT.error(SWT.ERROR_INVALID_ARGUMENT);
 	}
-	drawImage(image, 0, 0, 0, 0, destX, destY, destWidth, destHeight, false);
+	image.executeOnImageAtSizeBestFittingSize(imageAtSize -> {
+		drawImage(imageAtSize, 0, 0, imageAtSize.width, imageAtSize.height, destX, destY, destWidth, destHeight, false);
+	}, destWidth, destHeight);
 }
 
 void drawImage(Image srcImage, int srcX, int srcY, int srcWidth, int srcHeight, int destX, int destY, int destWidth, int destHeight, boolean simple) {

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

@@ -14,6 +14,7 @@
 package org.eclipse.swt.graphics;
 
 
+import static org.eclipse.swt.internal.DPIUtil.pointToPixel;
 import static org.eclipse.swt.internal.image.ImageColorTransformer.DEFAULT_DISABLED_IMAGE_TRANSFORMER;
 
 import java.io.*;
@@ -1177,6 +1178,7 @@ private NSBitmapImageRep createRepresentation(ImageData imageData, AlphaInfo alp
 
 @Override
 void destroy() {
+	cachedImageAtSize.destroy();
 	if (memGC != null) memGC.dispose();
 	handle.release();
 	handle = null;
@@ -1837,5 +1839,73 @@ public static void drawAtSize(GC gc, ImageData imageData, int width, int height)
 	});
 }
 
+void executeOnImageAtSizeBestFittingSize(Consumer<Image> imageAtBestFittingSizeConsumer, int destWidth, int destHeight) {
+	Optional<Image> imageAtSize = cachedImageAtSize.refresh(destWidth, destHeight);
+	imageAtBestFittingSizeConsumer.accept(imageAtSize.orElse(this));
+}
+
+private CachedImageAtSize cachedImageAtSize = new CachedImageAtSize();
+
+private class CachedImageAtSize {
+	private Image image;
+
+	public void destroy() {
+		if (image != null) {
+			image.dispose();
+			image = null;
+		}
+	}
+
+	private Optional<Image> refresh(int destWidth, int destHeight) {
+		int scaledWidth = pointToPixel(destWidth, DPIUtil.getDeviceZoom());
+		int scaledHeight = pointToPixel(destHeight, DPIUtil.getDeviceZoom());
+		if (isReusable(scaledWidth, scaledHeight)) {
+			return Optional.of(image);
+		} else {
+			destroy();
+			Optional<Image> imageAtSize = loadImageAtSize(scaledWidth, scaledHeight);
+			image = imageAtSize.orElse(null);
+			return imageAtSize;
+		}
+	}
+
+	private boolean isReusable(int width, int height) {
+		return image != null && image.height == height && image.width == width;
+	}
+
+	private Optional<Image> loadImageAtSize(int destWidth, int destHeight) {
+		Optional<ImageData> imageData = loadImageDataAtExactSize(destWidth, destHeight);
+		if (imageData.isEmpty()) {
+			return Optional.empty();
+		}
+		Image image = new Image(device, imageData.get());
+		if (styleFlag != SWT.IMAGE_COPY) {
+			NSBitmapImageRep representation = image.getRepresentation(100);
+			image.createRepFromSourceAndApplyFlag(representation, destWidth, destHeight, styleFlag);
+			image.handle.removeRepresentation(representation);
+		}
+		return Optional.of(image);
+	}
+
+	private Optional<ImageData> loadImageDataAtExactSize(int targetWidth, int targetHeight) {
+		if (imageDataProvider instanceof ImageDataAtSizeProvider imageDataAtSizeProvider) {
+			ImageData imageData = imageDataAtSizeProvider.getImageData(targetWidth, targetHeight);
+			if (imageData == null) {
+				SWT.error(SWT.ERROR_INVALID_ARGUMENT, null,
+						" ImageDataAtSizeProvider returned null for width=" + targetWidth + ", height=" + targetHeight);
+			}
+			return Optional.of(imageData);
+		}
+		if (imageFileNameProvider != null) {
+			String fileName = DPIUtil.validateAndGetImagePathAtZoom(imageFileNameProvider, 100).element();
+			if (ImageDataLoader.isDynamicallySizable(fileName)) {
+				ImageData imageDataAtSize = ImageDataLoader.loadBySize(fileName, targetWidth, targetHeight);
+				return Optional.of(imageDataAtSize);
+			}
+		}
+		return Optional.empty();
+	}
+}
+
 }
 

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_graphics_GC.java

@@ -54,7 +54,7 @@
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.DisabledOnOs;
 import org.junit.jupiter.api.condition.OS;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
@@ -442,7 +442,7 @@ public void test_drawImageLorg_eclipse_swt_graphics_ImageIIII_ImageDataProvider(
 }
 
 @Test
-@EnabledOnOs(value = OS.WINDOWS)
+@DisabledOnOs(value = OS.LINUX)
 public void test_drawImageLorg_eclipse_swt_graphics_ImageIIII_ImageDataAtSizeProvider_invalid() {
 	ImageDataAtSizeProvider provider = new ImageDataAtSizeProvider() {
 		@Override
@@ -469,7 +469,7 @@ public ImageData getImageData(int width, int height) {
 
 @ParameterizedTest
 @ValueSource(ints = {SWT.IMAGE_COPY, SWT.IMAGE_DISABLE, SWT.IMAGE_GRAY, -1})
-@EnabledOnOs(value = OS.WINDOWS)
+@DisabledOnOs(value = OS.LINUX)
 public void test_drawImageLorg_eclipse_swt_graphics_ImageIIII_ImageDataAtSizeProvider(int styleFlag) {
 	int width = 50;
 	int height = 70;