move SVG-File check out of JSVGRasterizer and adjust check

The caller needs to make sure the method is called with an SVG file.
The check now only checks the first byte.

Author: Michael5601

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

@@ -63,24 +63,22 @@ public ImageData rasterizeSVG(byte[] bytes, float scalingFactor) throws IOExcept
 			svgLoader = new SVGLoader();
 		}
 		SVGDocument svgDocument = null;
-		if (isSVGFile(bytes)) {
-			try (InputStream stream = new ByteArrayInputStream(bytes)) {
-				svgDocument = svgLoader.load(stream, null, LoaderContext.createDefault());
-			}
-			if (svgDocument != null) {
-				FloatSize size = svgDocument.size();
-				double originalWidth = size.getWidth();
-				double originalHeight = size.getHeight();
-				int scaledWidth = (int) Math.round(originalWidth * scalingFactor);
-				int scaledHeight = (int) Math.round(originalHeight * scalingFactor);
-				BufferedImage image = new BufferedImage(scaledWidth, scaledHeight, BufferedImage.TYPE_INT_ARGB);
-				Graphics2D g = image.createGraphics();
-				g.setRenderingHints(RENDERING_HINTS);
-				g.scale(scalingFactor, scalingFactor);
-				svgDocument.render(null, g);
-				g.dispose();
-				return convertToSWT(image);
-			}
+		try (InputStream stream = new ByteArrayInputStream(bytes)) {
+			svgDocument = svgLoader.load(stream, null, LoaderContext.createDefault());
+		}
+		if (svgDocument != null) {
+			FloatSize size = svgDocument.size();
+			double originalWidth = size.getWidth();
+			double originalHeight = size.getHeight();
+			int scaledWidth = (int) Math.round(originalWidth * scalingFactor);
+			int scaledHeight = (int) Math.round(originalHeight * scalingFactor);
+			BufferedImage image = new BufferedImage(scaledWidth, scaledHeight, BufferedImage.TYPE_INT_ARGB);
+			Graphics2D g = image.createGraphics();
+			g.setRenderingHints(RENDERING_HINTS);
+			g.scale(scalingFactor, scalingFactor);
+			svgDocument.render(null, g);
+			g.dispose();
+			return convertToSWT(image);
 		}
 		return null;
 	}
@@ -155,16 +153,11 @@ else if (bufferedImage.getColorModel() instanceof ComponentColorModel) {
 	    return null;
 	}
 
-	private boolean isSVGFile(byte[] data) throws IOException {
-		String content = new String(data, 0, Math.min(data.length, 512), StandardCharsets.UTF_8);
-		return content.contains("<svg");
-	}
-
 	public boolean isSVGFile(InputStream inputStream) throws IOException {
-		if (inputStream == null) {
-			throw new IllegalArgumentException("InputStream cannot be null");
-		}
-		byte[] data = inputStream.readNBytes(512);
-		return isSVGFile(data);
+	    if (inputStream == null) {
+	        throw new IllegalArgumentException("InputStream cannot be null");
+	    }
+	    int firstByte = inputStream.read();
+	    return firstByte == '<';
 	}
 }

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

@@ -186,16 +186,18 @@ public ImageData[] load(InputStream stream, int zoom) {
 	}
 	SVGRasterizer rasterizer = SVGRasterizerRegistry.getRasterizer();
 	if (rasterizer != null && zoom != 0) {
-	    	float scalingFactor = zoom / 100.0f;
-			try {
+		try (InputStream imageStream = new ByteArrayInputStream(bytes)) {
+			if (rasterizer.isSVGFile(imageStream)) {
+				float scalingFactor = zoom / 100.0f;
 				ImageData rasterizedData = rasterizer.rasterizeSVG(bytes, scalingFactor);
 				if (rasterizedData != null) {
 					data = new ImageData[]{rasterizedData};
 				    return data;
 				}
-			} catch (IOException e) {
-				//ignore.
 			}
+		} catch (IOException e) {
+			//ignore.
+		}
 	}
 	try (InputStream fallbackStream = new ByteArrayInputStream(bytes)) {
 		return loadDefault(fallbackStream);