如何从SVG获取缓冲图像？

svg java batik

2022-09-01 18:44:20

我正在使用蜡染来处理SVG图像。有没有办法从SVG文件中获取java.awt.image.BufferedImage？

我知道有转码器，通过它，我可以将SVG转码为PNG，然后用ImageIO.read（）加载该PNG。但我不想有临时文件。

答案 1

使用蜡染，如下所示：

public static BufferedImage rasterize(File svgFile) throws IOException {

    final BufferedImage[] imagePointer = new BufferedImage[1];

    // Rendering hints can't be set programatically, so
    // we override defaults with a temporary stylesheet.
    // These defaults emphasize quality and precision, and
    // are more similar to the defaults of other SVG viewers.
    // SVG documents can still override these defaults.
    String css = "svg {" +
            "shape-rendering: geometricPrecision;" +
            "text-rendering:  geometricPrecision;" +
            "color-rendering: optimizeQuality;" +
            "image-rendering: optimizeQuality;" +
            "}";
    File cssFile = File.createTempFile("batik-default-override-", ".css");
    FileUtils.writeStringToFile(cssFile, css);

    TranscodingHints transcoderHints = new TranscodingHints();
    transcoderHints.put(ImageTranscoder.KEY_XML_PARSER_VALIDATING, Boolean.FALSE);
    transcoderHints.put(ImageTranscoder.KEY_DOM_IMPLEMENTATION,
            SVGDOMImplementation.getDOMImplementation());
    transcoderHints.put(ImageTranscoder.KEY_DOCUMENT_ELEMENT_NAMESPACE_URI,
            SVGConstants.SVG_NAMESPACE_URI);
    transcoderHints.put(ImageTranscoder.KEY_DOCUMENT_ELEMENT, "svg");
    transcoderHints.put(ImageTranscoder.KEY_USER_STYLESHEET_URI, cssFile.toURI().toString());

    try {

        TranscoderInput input = new TranscoderInput(new FileInputStream(svgFile));

        ImageTranscoder t = new ImageTranscoder() {

            @Override
            public BufferedImage createImage(int w, int h) {
                return new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
            }

            @Override
            public void writeImage(BufferedImage image, TranscoderOutput out)
                    throws TranscoderException {
                imagePointer[0] = image;
            }
        };
        t.setTranscodingHints(transcoderHints);
        t.transcode(input, null);
    }
    catch (TranscoderException ex) {
        // Requires Java 6
        ex.printStackTrace();
        throw new IOException("Couldn't convert " + svgFile);
    }
    finally {
        cssFile.delete();
    }

    return imagePointer[0];
}

答案 2

一个非常简单的方法是使用 TwelveMonkeys 库，它为 java 的添加了额外的图像类型支持ImageIO

例如，您只需将这些添加到您的专家中（或复制所需的jar）：

    <dependency>
        <groupId>com.twelvemonkeys.imageio</groupId>
        <artifactId>imageio-batik</artifactId> <!-- svg -->
        <version>3.2.1</version>
    </dependency>
    <dependency>
        <groupId>batik</groupId>
        <artifactId>batik-transcoder</artifactId>
        <version>1.6-1</version>
    </dependency>

然后你只需阅读它

BufferedImage image = ImageIO.read(svg-file);

要检查svg阅读器是否正确注册，您可以打印出图像阅读器：

Iterator<ImageReader> readers = ImageIO.getImageReadersByFormatName("SVG");
while (readers.hasNext()) {
    System.out.println("reader: " + readers.next());
}

该库还支持其他参数，请参阅github上的自述文件。