如何以编程方式在SVG文件中进行组转换?

2022-09-03 03:01:01

我有SVG文件,如下图所示:

Image

每个箭头都由如下代码表示:

<g
   transform="matrix(-1,0,0,-1,149.82549,457.2455)"
   id="signS"
   inkscape:label="#sign">
  <title
     id="title4249">South, 180</title>
  <path
     sodipodi:nodetypes="ccc"
     inkscape:connector-curvature="0"
     id="path4251"
     d="m 30.022973,250.04026 4.965804,-2.91109 4.988905,2.91109"
     style="fill:none;fill-rule:evenodd;stroke:#000000;stroke-width:0.6855976px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1" />
  <rect
     y="250.11305"
     x="29.768578"
     height="2.6057031"
     width="10.105703"
     id="rect4253"
     style="fill:#008000;fill-opacity:1;stroke:#000000;stroke-width:0.53715414;stroke-opacity:1" />
</g>

我想计算矩形(节点)的绝对位置。为此,我需要计算标记标记内的表达式(在上面的示例中)。recttransformgmatrix(-1,0,0,-1,149.82549,457.2455)

我该怎么做?

我假设第一步是使用Apache Batik读取文件:SVGDocument

import java.io.IOException;

import org.apache.batik.dom.svg.SAXSVGDocumentFactory;
import org.apache.batik.util.XMLResourceDescriptor;

import org.w3c.dom.Document;

try {
    String parser = XMLResourceDescriptor.getXMLParserClassName();
    SAXSVGDocumentFactory f = new SAXSVGDocumentFactory(parser);
    String uri = "http://www.example.org/diagram.svg";
    Document doc = f.createDocument(uri);
} catch (IOException ex) {
    // ...
}

据我所知,可以投射到SVGDocumentdoc

如何从SVG文档到矩形或组的绝对位置?

注意:我需要一些现有的代码,它执行上面的转换(不要告诉我自己实现这些转换 - 它们必须已经实现,我想重用该代码)。

更新 1 (08.11.2015 12:56 MSK):

第一次尝试实现Robert Longson的建议:

public final class BatikTest {
    @Test
    public void test() throws XPathExpressionException {
        try {
            final File initialFile =
                new File("src/main/resources/trailer/scene05_signs.svg");
            InputStream sceneFileStream = Files.asByteSource(initialFile).openStream();


            String parser = XMLResourceDescriptor.getXMLParserClassName();
            SAXSVGDocumentFactory f = new SAXSVGDocumentFactory(parser);
            String uri = "http://www.example.org/diagram.svg";
            final SVGOMDocument doc = (SVGOMDocument) f.createDocument(
                uri, sceneFileStream);

            final NodeList nodes =
                doc.getDocumentElement().getElementsByTagName("g");
            SVGOMGElement signSouth = null;


            for (int i=0; (i < nodes.getLength()) && (signSouth == null); i++) {
                final Node curNode = nodes.item(i);
                final Node id = curNode.getAttributes().getNamedItem("id");
                if ("signS".equals(id.getTextContent())) {
                    signSouth = (SVGOMGElement) curNode;
                }

                System.out.println("curNode: " + nodes);
            }
            System.out.println("signSouth: " + signSouth);

            final NodeList rectNodes = signSouth.getElementsByTagName("rect");
            System.out.println("rectNodes: " + rectNodes);

            SVGOMRectElement rectNode = (SVGOMRectElement) rectNodes.item(0);

            System.out.println("rectNode: " + rectNode);

            final SVGMatrix m2 =
                signSouth.getTransformToElement(rectNode);

            System.out.println("m2: " + m2);
        } catch (IOException ex) {
            Assert.fail(ex.getMessage());
        }
    }
}

调用 - 导致 s。m2.getA()m2.getF()NullPointerException

更新 2 (08.11.2015 13:38 MSK):

添加了以下代码以创建矩阵转换并对其应用:SVGPoint

final SVGSVGElement docElem = (SVGSVGElement)
    doc.getDocumentElement();
final SVGPoint svgPoint = docElem.createSVGPoint();
svgPoint.setX((float) x);
svgPoint.setY((float) y);
final SVGPoint svgPoint1 =
    svgPoint.matrixTransform(signSouth.getScreenCTM()); // Line 77

System.out.println("x: " + svgPoint1.getX());
System.out.println("y: " + svgPoint1.getY());

结果:

java.lang.NullPointerException
    at org.apache.batik.dom.svg.SVGLocatableSupport$3.getAffineTransform(Unknown Source)
    at org.apache.batik.dom.svg.AbstractSVGMatrix.getA(Unknown Source)
    at org.apache.batik.dom.svg.SVGOMPoint.matrixTransform(Unknown Source)
    at org.apache.batik.dom.svg.SVGOMPoint.matrixTransform(Unknown Source)
    at [...].BatikTest.test(BatikTest.java:77)

更新3,赏金条款(10.11.2015 MSK):

为了获得赏金,必须满足的条件:

我将赏金授予英雄或女英雄,他们设法实现这些方法,并在JUnit测试BatikTest中,这样我就可以在我的Java代码中获得形状的坐标,这些形状显示在InkScape中(请参阅以下屏幕截图以获取示例)。magicallyCalculateXCoordinatemagicallyCalculateYCoordinate

Image with coordinates

所提出的计算SVG文件中形状位置的方法必须适用于以下两种方法

  1. 对于组节点(如图片和示例文件中的节点)或
  2. 对于三角形。

您提供的代码必须适用于示例文件中的所有四个形状,即使用它,我必须能够在Java代码中计算它们的坐标,这些坐标等于Inkscape中显示的坐标。

可以向 方法 和 添加参数,也可以创建自己的方法来计算坐标。magicallyCalculateXCoordinatemagicallyCalculateYCoordinate

您可以使用任何库,这些库可以合法地用于商业目的。

与此请求相关的所有文件都可以在 GitHub 上找到。我设法使用IntelliJ Idea Community Edition 14.1.5编译了测试。


答案 1

我知道,我迟到了,但我偶然发现了这个问题,并喜欢这个谜语;-)

svg中的原点是左上角,而inkscape使用左下角作为原点。

origin and reference point in svg (left) and inkscape (right)

因此,我们需要应用抚摸和变换,然后找到左下角的点四舍五入三个小数。我使用GVTBuilder获取应用了样式的边界框,然后转换了边界框,请求了转换组的边界框,然后使用xMin和yMax作为参考点。使用视图框确定高度,我变换了 y 坐标,最后对坐标进行了四舍五入。(请参阅 github 上的拉取请求)

package test.java.svgspike;

import org.apache.batik.anim.dom.SAXSVGDocumentFactory;
import org.apache.batik.anim.dom.SVGOMDocument;
import org.apache.batik.anim.dom.SVGOMGElement;
import org.apache.batik.bridge.BridgeContext;
import org.apache.batik.bridge.GVTBuilder;
import org.apache.batik.bridge.UserAgentAdapter;
import org.apache.batik.gvt.GraphicsNode;
import org.apache.batik.util.XMLResourceDescriptor;

import javax.xml.xpath.XPathExpressionException;

import java.awt.geom.Point2D;
import java.awt.geom.Path2D;
import java.awt.geom.Rectangle2D;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigDecimal;

import com.google.common.io.Files;

import org.junit.Assert;
import org.junit.Test;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * Created by pisarenko on 10.11.2015.
 */
public final class BatikTest {

    @Test
    public void test() throws XPathExpressionException {
        try {
            final File initialFile =
                    new File("src/test/resources/scene05_signs.svg");
            InputStream sceneFileStream = Files.asByteSource(initialFile).openStream();

            String parser = XMLResourceDescriptor.getXMLParserClassName();
            SAXSVGDocumentFactory f = new SAXSVGDocumentFactory(parser);
            String uri = "http://www.example.org/diagram.svg";
            final SVGOMDocument doc = (SVGOMDocument) f.createDocument(
                    uri, sceneFileStream);

            String viewBox = doc.getDocumentElement().getAttribute("viewBox");

            Point2D referencePoint = getReferencePoint(doc, getGroupElement(doc, "signS"));

            double signSouthX = magicallyCalculateXCoordinate(referencePoint);
            double signSouthY = magicallyCalculateYCoordinate(referencePoint, viewBox);

            Assert.assertEquals(109.675, signSouthX, 0.0000001);
            Assert.assertEquals(533.581, signSouthY, 0.0000001);

            referencePoint = getReferencePoint(doc, getGroupElement(doc, "signN"));
            Assert.assertEquals(109.906, magicallyCalculateXCoordinate(referencePoint), 0.0000001);
            Assert.assertEquals(578.293, magicallyCalculateYCoordinate(referencePoint, viewBox), 0.0000001);

            referencePoint = getReferencePoint(doc, getGroupElement(doc, "signE"));
            Assert.assertEquals(129.672, magicallyCalculateXCoordinate(referencePoint), 0.0000001);
            Assert.assertEquals(554.077, magicallyCalculateYCoordinate(referencePoint, viewBox), 0.0000001);

            referencePoint = getReferencePoint(doc, getGroupElement(doc, "signW"));
            Assert.assertEquals(93.398, magicallyCalculateXCoordinate(referencePoint), 0.0000001);
            Assert.assertEquals(553.833, magicallyCalculateYCoordinate(referencePoint, viewBox), 0.0000001);


        } catch (IOException ex) {
            Assert.fail(ex.getMessage());
        }
    }

    private SVGOMGElement getGroupElement(SVGOMDocument doc, String id){
        final NodeList nodes = doc.getDocumentElement().getElementsByTagName("g");
        SVGOMGElement signGroup = null;
        for (int i=0; (i < nodes.getLength()) && (signGroup == null); i++) {
            final Node curNode = nodes.item(i);
            final Node idNode = curNode.getAttributes().getNamedItem("id");
            if (id.equals(idNode.getTextContent())) signGroup = (SVGOMGElement) curNode;
        }
        return signGroup;
    }

    /**
     * @param doc
     * @param signGroup
     * @return the reference point, inkscape uses for group (bottom left corner of group)
     */
    private Point2D getReferencePoint(SVGOMDocument doc, SVGOMGElement signGroup){

        Point2D referencePoint = new Point2D.Double(0, 0);

        try {

            BridgeContext ctx = new BridgeContext(new UserAgentAdapter());
            new GVTBuilder().build(ctx, doc);
            GraphicsNode gvtElement = new GVTBuilder().build(ctx, signGroup);

            Rectangle2D rc = gvtElement.getSensitiveBounds();
            rc = ((Path2D) gvtElement.getTransform().createTransformedShape(rc)).getBounds2D();

          //find xMin and yMax in poi
            referencePoint = new Point2D.Double(rc.getMinX(), rc.getMaxY());

        } catch (Exception e) {
            e.printStackTrace();
        }
        return referencePoint;
    }

    /**
     * inkscape states y coordinate with origin in left bottom corner, while svg uses top left corner as origin
     * @param referencePoint bottom left corner of group
     * @param viewBox in "originX originY width height" notation
     * @return corrected y coordinate, rounded to three decimal figures (half up)
     */
    private double magicallyCalculateYCoordinate(Point2D referencePoint, String viewBox) {
        String[] viewBoxValues = viewBox.split(" ");
        BigDecimal roundedY = new BigDecimal(Double.parseDouble(viewBoxValues[3])-referencePoint.getY());
        roundedY = roundedY.setScale(3, BigDecimal.ROUND_HALF_UP);
        return roundedY.doubleValue();
    }

    /**
     * @param referencePoint bottom left corner of group
     * @return x coordinate, rounded to three decimal figures (half up)
     */
    private double magicallyCalculateXCoordinate(Point2D referencePoint) {
        BigDecimal roundedX = new BigDecimal(referencePoint.getX()).setScale(3, BigDecimal.ROUND_HALF_UP);
        return roundedX.doubleValue();
    }

}

它应该适用于所有组和所有转换。


答案 2