Extend ImageGcDrawer to support transparency

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

@@ -903,8 +903,17 @@ public Image(Device device, ImageGcDrawer imageGcDrawer, int width, int height)
 }
 
 private ImageData drawWithImageGcDrawer(ImageGcDrawer imageGcDrawer, int width, int height, int zoom) {
-	Image image = new Image(device, width, height);
-	GC gc = new GC(image);
+	int gcStyle = imageGcDrawer.getGcStyle();
+	Image image;
+	if ((gcStyle & SWT.TRANSPARENT) != 0) {
+		/* Create a 24 bit image data with alpha channel */
+		final ImageData resultData = new ImageData (width, height, 24, new PaletteData (0xFF, 0xFF00, 0xFF0000));
+		resultData.alphaData = new byte [width * height];
+		image = new Image(device, resultData);
+	} else {
+		image = new Image(device, width, height);
+	}
+	GC gc = new GC(image, gcStyle);
 	try {
 		imageGcDrawer.drawOn(gc, width, height);
 		ImageData imageData = image.getImageData(zoom);

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/DPIUtil.java

@@ -306,16 +306,21 @@ private static ImageData autoScaleImageData (Device device, final ImageData imag
 	boolean useSmoothScaling = isSmoothScalingEnabled() && imageData.getTransparencyType() != SWT.TRANSPARENCY_MASK;
 	if (useSmoothScaling) {
 		Image original = new Image (device, (ImageDataProvider) zoom -> imageData);
-		/* 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 resultImage = new Image (device, (ImageDataProvider) zoom -> resultData);
-		GC gc = new GC (resultImage);
-		gc.setAntialias (SWT.ON);
-		Image.drawScaled(gc, original, width, height, scaleFactor);
-		gc.dispose ();
+		ImageGcDrawer drawer =  new ImageGcDrawer() {
+			@Override
+			public void drawOn(GC gc, int imageWidth, int imageHeight) {
+				gc.setAntialias (SWT.ON);
+				Image.drawScaled(gc, original, width, height, scaleFactor);
+			};
+
+			@Override
+			public int getGcStyle() {
+				return SWT.TRANSPARENT;
+			}
+		};
+		Image resultImage = new Image (device, drawer, scaledWidth, scaledHeight);
+		ImageData result = resultImage.getImageData (100);
 		original.dispose ();
-		ImageData result = resultImage.getImageData (getDeviceZoom ());
 		resultImage.dispose ();
 		return result;
 	} else {

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

@@ -437,11 +437,14 @@ public Image(Device device, Rectangle bounds) {
  * @see #dispose()
  */
 public Image(Device device, ImageData data) {
+	this(device, DPIUtil.autoScaleUp(device, data), DPIUtil.getDeviceZoom());
+}
+
+private Image(Device device, ImageData data, int zoom) {
 	super(device);
 	if (data == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
-	currentDeviceZoom = DPIUtil.getDeviceZoom();
-	data = DPIUtil.autoScaleUp (device, data);
-	init(data);
+	currentDeviceZoom = zoom;
+	init(data, zoom);
 	init();
 }
 
@@ -695,9 +698,9 @@ public Image(Device device, ImageGcDrawer imageGcDrawer, int width, int height)
 		SWT.error(SWT.ERROR_NULL_ARGUMENT);
 	}
 	this.imageGcDrawer = imageGcDrawer;
-	currentDeviceZoom = DPIUtil.getDeviceZoom();
+	currentDeviceZoom = 100;
 	ImageData imageData = drawWithImageGcDrawer(width, height, currentDeviceZoom);
-	init (imageData);
+	init (imageData, currentDeviceZoom);
 	init ();
 }
 
@@ -1162,8 +1165,17 @@ public ImageData getImageData (int zoom) {
 }
 
 private ImageData drawWithImageGcDrawer(int width, int height, int zoom) {
-	Image image = new Image(device, width, height);
-	GC gc = new GC(image);
+	int gcStyle = imageGcDrawer.getGcStyle();
+	Image image;
+	if ((gcStyle & SWT.TRANSPARENT) != 0) {
+		/* Create a 24 bit image data with alpha channel */
+		final ImageData resultData = new ImageData(width, height, 24, new PaletteData (0xFF, 0xFF00, 0xFF0000));
+		resultData.alphaData = new byte [width * height];
+		image = new Image(device, resultData, zoom);
+	} else {
+		image = new Image(device, width, height);
+	}
+	GC gc = new GC(image, gcStyle);
 	try {
 		imageGcDrawer.drawOn(gc, width, height);
 		ImageData imageData = image.getImageData(zoom);
@@ -1274,6 +1286,10 @@ void init(int width, int height) {
 }
 
 void init(ImageData image) {
+	init(image, DPIUtil.getDeviceZoom());
+}
+
+private void init(ImageData image, int zoom) {
 	if (image == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
 
 	PaletteData palette = image.palette;
@@ -1286,7 +1302,7 @@ void init(ImageData image) {
 	int imageDataHeight = image.height;
 
 	// Scale dimensions of Image object to 100% scale factor
-	double scaleFactor = DPIUtil.getDeviceZoom() / 100f;
+	double scaleFactor = zoom / 100f;
 	this.width = (int) Math.round(imageDataWidth / scaleFactor);
 	this.height = (int) Math.round(imageDataHeight / scaleFactor);
 

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

@@ -380,6 +380,15 @@ public Image(Device device, ImageData data) {
 	this.device.registerResourceWithZoomSupport(this);
 }
 
+private Image(Device device, ImageData data, int zoom) {
+	super(device);
+	if (data == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
+	initialNativeZoom = zoom;
+	this.imageProvider = new PlainImageDataProviderWrapper(data, zoom);
+	init();
+	this.device.registerResourceWithZoomSupport(this);
+}
+
 /**
  * Constructs an instance of this class, whose type is
  * <code>SWT.ICON</code>, from the two given <code>ImageData</code>
@@ -1956,27 +1965,34 @@ private ImageHandle initializeHandleFromSource(int zoom) {
 }
 
 private class PlainImageDataProviderWrapper extends ImageFromImageDataProviderWrapper {
-	private ImageData imageDataAt100;
+	private ImageData imageDataAtBaseZoom;
+	private int baseZoom;
 
 	PlainImageDataProviderWrapper(ImageData imageData) {
-		this.imageDataAt100 = (ImageData) imageData.clone();
+		this(imageData, 100);
+	}
+
+	private PlainImageDataProviderWrapper(ImageData imageData, int zoom) {
+		this.imageDataAtBaseZoom = (ImageData) imageData.clone();
+		this.baseZoom = zoom;
 		initImage();
 	}
 
 	@Override
 	protected Rectangle getBounds(int zoom) {
-		Rectangle rectangle = new Rectangle(0, 0, imageDataAt100.width, imageDataAt100.height);
+		Rectangle rectangle = new Rectangle(0, 0, imageDataAtBaseZoom.width, imageDataAtBaseZoom.height);
+		rectangle = DPIUtil.scaleDown(rectangle, baseZoom);
 		return DPIUtil.scaleUp(rectangle, zoom);
 	}
 
 	@Override
 	protected ElementAtZoom<ImageData> loadImageData(int zoom) {
-		return new ElementAtZoom<>(imageDataAt100, 100);
+		return new ElementAtZoom<>(imageDataAtBaseZoom, baseZoom);
 	}
 
 	@Override
 	AbstractImageProviderWrapper createCopy(Image image) {
-		return image.new PlainImageDataProviderWrapper(this.imageDataAt100);
+		return image.new PlainImageDataProviderWrapper(this.imageDataAtBaseZoom);
 	}
 }
 
@@ -2478,8 +2494,19 @@ ImageData newImageData(int zoom) {
 	@Override
 	protected ImageHandle newImageHandle(int zoom) {
 		initialNativeZoom = zoom;
-		Image image = new Image(device, width, height, zoom);
-		GC gc = new GC(image, drawer.getGcStyle());
+		int gcStyle = drawer.getGcStyle();
+		Image image;
+		if ((gcStyle & SWT.TRANSPARENT) != 0) {
+			int scaledHeight = DPIUtil.scaleUp(height, zoom);
+			int scaledWidth = DPIUtil.scaleUp(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);
+		} else {
+			image = new Image(device, width, height, zoom);
+		}
+		GC gc = new GC(image, gcStyle);
 		try {
 			gc.data.nativeZoom = zoom;
 			drawer.drawOn(gc, width, height);

examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet367.java

@@ -36,6 +36,8 @@ public class Snippet367 {
 	private static final String IMAGE_PATH_200 = IMAGES_ROOT + IMAGE_200;
 
 	public static void main (String [] args) {
+		final Display display = new Display ();
+
 		final ImageFileNameProvider filenameProvider = zoom -> {
 			switch (zoom) {
 			case 100:
@@ -65,7 +67,17 @@ public static void main (String [] args) {
 			gc.drawLine(3, 3, width - 3, height - 3);
 		};
 
-		final Display display = new Display ();
+		Image imageWithDataProvider = new Image (display, imageDataProvider);
+		final ImageGcDrawer transparentImageGcDrawer = new ImageGcDrawer() {
+			@Override
+			public void drawOn(GC gc, int width, int height) {
+				gc.drawImage(imageWithDataProvider, 0, 0);
+			}
+			@Override
+			public int getGcStyle() {
+				return SWT.TRANSPARENT;
+			}
+		};
 		final Shell shell = new Shell (display);
 		shell.setText("Snippet367");
 		shell.setLayout (new GridLayout (3, false));
@@ -99,13 +111,17 @@ public static void main (String [] args) {
 		new Button(shell, SWT.NONE).setImage (new Image (display, filenameProvider));
 
 		new Label (shell, SWT.NONE).setText ("ImageDataProvider:");
-		new Label (shell, SWT.NONE).setImage (new Image (display, imageDataProvider));
-		new Button(shell, SWT.NONE).setImage (new Image (display, imageDataProvider));
+		new Label (shell, SWT.NONE).setImage (imageWithDataProvider);
+		new Button(shell, SWT.NONE).setImage (imageWithDataProvider);
 
 		new Label (shell, SWT.NONE).setText ("ImageGcDrawer:");
 		new Label (shell, SWT.NONE).setImage (new Image (display, imageGcDrawer, 20, 20));
 		new Button(shell, SWT.NONE).setImage (new Image (display, imageGcDrawer, 20, 20));
 
+		new Label (shell, SWT.NONE).setText ("Transparent ImageGcDrawer:");
+		new Label (shell, SWT.NONE).setImage (new Image (display, transparentImageGcDrawer, 20, 20));
+		new Button(shell, SWT.NONE).setImage (new Image (display, transparentImageGcDrawer, 20, 20));
+
 		createSeparator(shell);
 
 		new Label (shell, SWT.NONE).setText ("1. Canvas\n(PaintListener)");

examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet382.java

@@ -64,13 +64,44 @@ public static void main (String [] args) {
 
 		final Display display = new Display ();
 
+		final Image imageWithFileNameProvider = new Image (display, filenameProvider);
+		final Image disabledImageWithFileNameProvider = new Image (display,imageWithFileNameProvider, SWT.IMAGE_DISABLE);
+		final Image greyImageWithFileNameProvider = new Image (display,imageWithFileNameProvider, SWT.IMAGE_GRAY);
+
+		final Image imageWithDataProvider = new Image (display, imageDataProvider);
+		final Image disabledImageWithDataProvider = new Image (display,imageWithDataProvider, SWT.IMAGE_DISABLE);
+		final Image greyImageWithDataProvider = new Image (display,imageWithDataProvider, SWT.IMAGE_GRAY);
+
+		final Image imageWithData = new Image (display, IMAGE_PATH_100);
+		final Image disabledImageWithData = new Image (display,imageWithData, SWT.IMAGE_DISABLE);
+		final Image greyImageWithData = new Image (display,imageWithData, SWT.IMAGE_GRAY);
+
 		final ImageGcDrawer imageGcDrawer = (gc, width, height) -> {
 			gc.setBackground(display.getSystemColor(SWT.COLOR_RED));
 			gc.fillRectangle(0, 0, width, height);
 			gc.setForeground(display.getSystemColor(SWT.COLOR_YELLOW));
 			gc.drawRectangle(4, 4, width - 8, height - 8);
 		};
 
+		final Image imageWithGcDrawer = new Image (display, imageGcDrawer, 16, 16);
+		final Image disabledImageWithGcDrawer = new Image (display, imageWithGcDrawer, SWT.IMAGE_DISABLE);
+		final Image greyImageWithGcDrawer = new Image (display, imageWithGcDrawer, SWT.IMAGE_GRAY);
+
+		final ImageGcDrawer transparentImageGcDrawer = new ImageGcDrawer() {
+			@Override
+			public void drawOn(GC gc, int width, int height) {
+				gc.drawImage(imageWithDataProvider, 0, 0);
+			}
+			@Override
+			public int getGcStyle() {
+				return SWT.TRANSPARENT;
+			}
+		};
+
+		final Image imageWithTransparentGcDrawer = new Image (display, transparentImageGcDrawer, 16, 16);
+		final Image disabledImageWithTransparentGcDrawer = new Image (display, imageWithTransparentGcDrawer, SWT.IMAGE_DISABLE);
+		final Image greyImageWithTransparentGcDrawer = new Image (display, imageWithTransparentGcDrawer, SWT.IMAGE_GRAY);
+
 		final Shell shell = new Shell (display);
 		shell.setText("Snippet382");
 		shell.setLayout (new GridLayout (3, false));
@@ -80,21 +111,7 @@ public void handleEvent(Event e)  {
 				if (e.type == SWT.Paint) {
 					GC mainGC = e.gc;
 					GCData gcData = mainGC.getGCData();
-					final Image imageWithFileNameProvider = new Image (display, filenameProvider);
-					final Image disabledImageWithFileNameProvider = new Image (display,imageWithFileNameProvider, SWT.IMAGE_DISABLE);
-					final Image greyImageWithFileNameProvider = new Image (display,imageWithFileNameProvider, SWT.IMAGE_GRAY);
 
-					final Image imageWithDataProvider = new Image (display, imageDataProvider);
-					final Image disabledImageWithDataProvider = new Image (display,imageWithDataProvider, SWT.IMAGE_DISABLE);
-					final Image greyImageWithDataProvider = new Image (display,imageWithDataProvider, SWT.IMAGE_GRAY);
-
-					final Image imageWithData = new Image (display, IMAGE_PATH_100);
-					final Image disabledImageWithData = new Image (display,imageWithData, SWT.IMAGE_DISABLE);
-					final Image greyImageWithData = new Image (display,imageWithData, SWT.IMAGE_GRAY);
-
-					final Image imageWithGcDrawer = new Image (display, imageGcDrawer, 16, 16);
-					final Image disabledImageWithGcDrawer = new Image (display, imageWithGcDrawer, SWT.IMAGE_DISABLE);
-					final Image greyImageWithGcDrawer = new Image (display, imageWithGcDrawer, SWT.IMAGE_GRAY);
 
 					try {
 						drawImages(mainGC, gcData, "Normal",40, imageWithFileNameProvider);
@@ -112,6 +129,10 @@ public void handleEvent(Event e)  {
 						drawImages(mainGC, gcData, "Normal", 400, imageWithGcDrawer);
 						drawImages(mainGC, gcData, "Disabled", 440, disabledImageWithGcDrawer);
 						drawImages(mainGC, gcData, "Greyed", 480, greyImageWithGcDrawer);
+
+						drawImages(mainGC, gcData, "Normal", 520, imageWithTransparentGcDrawer);
+						drawImages(mainGC, gcData, "Disabled", 560, disabledImageWithTransparentGcDrawer);
+						drawImages(mainGC, gcData, "Greyed", 600, greyImageWithTransparentGcDrawer);
 					} finally {
 						mainGC.dispose ();
 					}
@@ -130,7 +151,7 @@ private void drawImages(GC mainGC, GCData gcData, String text, int y, final Imag
 		};
 		shell.addListener(SWT.Paint, l);
 
-		shell.setSize(400, 550);
+		shell.setSize(400, 750);
 		shell.open ();
 		while (!shell.isDisposed ()) {
 			if (!display.readAndDispatch ()) display.sleep ();