Add support for SVG images

SWT currently loads icons exclusively as raster graphics (e.g., PNGs)
without support for vector formats like SVG (except for Linux). A major
drawback of raster graphics is their inability to scale without
degrading image quality. Additionally, generating icons of different
sizes requires manually rasterization of SVGs as a preparatory step,
leading to unnecessary effort and many icon files.

This change introduces support for vector graphics in images, enabling
SVGs to be used for images. An SVG rasterizer can be provided via an SWT
fragment. This change adds an according fragment based on the JSVG
library. An according FileFormat implementation is added, which utilized
a present SVG rasterization fragment to rasterize images for the desired
zoom factor.

Fixes eclipse-platform#1438

Author: Michael5601

bundles/org.eclipse.swt.svg/META-INF/MANIFEST.MF

@@ -1,9 +1,10 @@
 Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
-Bundle-Name: SWT SVG Rendering Support
 Bundle-SymbolicName: org.eclipse.swt.svg
 Bundle-Version: 3.130.0.qualifier
 Automatic-Module-Name: org.eclipse.swt.svg
+Bundle-Name: %fragmentName
+Bundle-Vendor: %providerName
 Bundle-RequiredExecutionEnvironment: JavaSE-17
 Fragment-Host: org.eclipse.swt
 Import-Package: com.github.weisj.jsvg;version="[1.7.0,2.0.0)",

bundles/org.eclipse.swt.svg/build.properties

@@ -1,7 +1,9 @@
 source.. = src/
 output.. = bin/
 bin.includes = META-INF/,\
-               .
+               .,\
+               fragment.properties
+
 tycho.pomless.parent = ../../local-build/local-build-parent
 jars.extra.classpath = platform:/plugin/org.eclipse.swt.cocoa.macosx.aarch64,\
                        platform:/plugin/org.eclipse.swt.cocoa.macosx.x86_64,\

bundles/org.eclipse.swt.svg/fragment.properties

@@ -0,0 +1,14 @@
+###############################################################################
+# Copyright (c) 2025 Vector Informatik GmbH and others.
+#
+# This program and the accompanying materials are made available under the terms of the Eclipse
+# Public License 2.0 which accompanies this distribution, and is available at
+# https://www.eclipse.org/legal/epl-2.0/
+#
+# SPDX-License-Identifier: EPL-2.0
+#
+# Contributors:
+#     Michael Bangas (Vector Informatik GmbH) - initial API and implementation
+###############################################################################
+fragmentName = SWT SVG Rendering Support
+providerName = Eclipse.org

bundles/org.eclipse.swt.svg/src/org/eclipse/swt/svg/JSVGRasterizer.java

@@ -100,23 +100,17 @@ public ImageData rasterizeSVG(InputStream inputStream, int zoom, int flag) throw
 				SWT.error(SWT.ERROR_INVALID_IMAGE);
 		}
 		SVGDocument svgDocument = loadSVG(inputStream);
-		if (svgDocument != null) {
-			return generateRasterizedImageData(svgDocument, zoom);
-		} else {
+		if (svgDocument == null) {
 			SWT.error(SWT.ERROR_INVALID_IMAGE);
 		}
-		return null;
+		BufferedImage rasterizedImage = renderSVG(svgDocument, zoom);
+		return convertToSWTImageData(rasterizedImage);
 	}
 
 	private SVGDocument loadSVG(InputStream inputStream) {
 		return SVG_LOADER.load(inputStream, null, LoaderContext.createDefault());
 	}
 
-	private ImageData generateRasterizedImageData(SVGDocument svgDocument, int zoom) {
-		BufferedImage rasterizedImage = renderSVG(svgDocument, zoom);
-		return convertToSWTImageData(rasterizedImage);
-	}
-
 	private BufferedImage renderSVG(SVGDocument svgDocument, int zoom) {
 		float scalingFactor = zoom / 100.0f;
 		BufferedImage image = createImageBase(svgDocument, scalingFactor);

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

@@ -4465,7 +4465,6 @@ public class SWT {
 
 	/**
 	 * Image format constant indicating a SVG format image (value is 8).
-	 * <br>Note that this is a <em>HINT</em> and is currently only supported on GTK.
 	 *
 	 * @since 3.113
 	 */

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/image/SVGFileFormat.java

@@ -55,8 +55,8 @@ List<ElementAtZoom<ImageData>> loadFromByteStream(int fileZoom, int targetZoom,
 			return List.of(new ElementAtZoom<>(rasterizedImageData, targetZoom));
 		} catch (IOException e) {
 			SWT.error(SWT.ERROR_INVALID_IMAGE, e);
+			return List.of();
 		}
-		return Collections.emptyList();
 	}
 
 	@Override

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/image/SVGRasterizer.java

@@ -23,14 +23,13 @@
 public interface SVGRasterizer {
 	/**
 	 * Rasterizes an SVG image from the provided {@code InputStream} using the
-	 * specified zoom factor.
+	 * specified zoom.
 	 *
 	 * @param stream the SVG image as an {@link InputStream}.
-	 * @param zoom   the scaling factor (in percent) e.g. 200 for doubled size. This
-	 *               value must not be 0.
+	 * @param zoom   the scaling factor (in percent) e.g. {@code 200} for doubled
+	 *               size. This value must be greater zero.
 	 * @return the {@link ImageData} for the rasterized image, or {@code null} if
 	 *         the input is not a valid SVG file or cannot be processed.
-	 * @throws IOException
 	 */
 	public ImageData rasterizeSVG(InputStream stream, int zoom, int flag) throws IOException;
 }

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

@@ -14,6 +14,7 @@
 
 import static org.eclipse.swt.tests.junit.SwtTestUtil.assertSWTProblem;
 import static org.junit.Assert.fail;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.File;
@@ -39,24 +40,14 @@ public class Test_org_eclipse_swt_internal_SVGRasterizer {
 
 	@Test
 	public void test_ConstructorLorg_eclipse_swt_graphics_Device_ImageFileNameProvider() {
-		ImageFileNameProvider validImageFileNameProvider = zoom -> {
-			String fileName = "collapseall.svg";
-			return getPath(fileName);
-		};
+		ImageFileNameProvider validImageFileNameProvider = zoom -> getPath("collapseall.svg");
 		Image image = new Image(Display.getDefault(), validImageFileNameProvider);
 		image.dispose();
 
-		ImageFileNameProvider corruptImageFileNameProvider = zoom -> {
-			String fileName = "corrupt.svg";
-			return getPath(fileName);
-		};
-		try {
-			image = new Image(Display.getDefault(), corruptImageFileNameProvider);
-			image.dispose();
-			fail("No exception thrown for corrupt image file.");
-		} catch (SWTException e) {
-			assertSWTProblem("Incorrect exception thrown for provider with corrupt images", SWT.ERROR_INVALID_IMAGE, e);
-		}
+		ImageFileNameProvider corruptImageFileNameProvider = zoom -> getPath("corrupt.svg");
+		SWTException e = assertThrows(SWTException.class,
+				() -> new Image(Display.getDefault(), corruptImageFileNameProvider));
+		assertSWTProblem("Incorrect exception thrown for provider with corrupt images", SWT.ERROR_INVALID_IMAGE, e);
 	}
 
 	@Test
@@ -72,13 +63,9 @@ public void test_ConstructorLorg_eclipse_swt_graphics_Device_ImageDataProvider()
 			String fileName = "corrupt.svg";
 			return new ImageData(getPath(fileName));
 		};
-		try {
-			image = new Image(Display.getDefault(), corruptImageDataProvider);
-			image.dispose();
-			fail("No exception thrown for corrupt image file.");
-		} catch (SWTException e) {
-			assertSWTProblem("Incorrect exception thrown for provider with corrupt images", SWT.ERROR_INVALID_IMAGE, e);
-		}
+		SWTException e = assertThrows(SWTException.class,
+				() -> new Image(Display.getDefault(), corruptImageDataProvider));
+		assertSWTProblem("Incorrect exception thrown for provider with corrupt images", SWT.ERROR_INVALID_IMAGE, e);
 	}
 
 	String getPath(String fileName) {