Improved transcoding from SVG to Image

[stephanr]

This PR was part of #1202 and the SvgImageTranscoder get reworked, as it was used there i a different way.

It replaces the the current way of transcoding (SVG -> PNG-Stream -> BufferedImage) by implementing org.apache.batik.transcoder.image.ImageTranscoder which gives direct access to the BufferedImage instead of using org.apache.batik.transcoder.image.PNGTranscoder .

A simple performance comparison was done on my local system by executing the following class five times with 100 iterations each.

package org.deegree.rendering.r2d;

import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import org.deegree.style.styling.components.Graphic;

public class SvgRenderPerformanceTest {

    public static void main( String[] args ) {
        new SvgRenderPerformanceTest().run();
    }

    public void run(){
        Rectangle2D.Double rect = new Rectangle2D.Double( 0, 0, 50, 50 );
        Graphic g = new Graphic();
        g.size = 50;
        g.imageURL = getClass().getResource( "similaritytests/gym.svg"  ).toExternalForm();
        BufferedImage img;

        long  tend, tstart = System.currentTimeMillis();
        for ( int i = 0; i < 100; i++ ) {
            // recreate renderer to prevent cacheing
            img = ( new SvgRenderer() ).prepareSvg( rect, g );
        }
        tend = System.currentTimeMillis();
        System.out.println("100 iteration took " + (tend-tstart)+" ms");

    }
}

This results into roughly 25% less time used to render a single SVG image 100 times. (Win10, Temurin 11, CPU 6x3.0Ghz)

• Before (ms):
  • 2464
  • 2379
  • 2461
  • 2396
  • 2441
• After/With SvgImageTranscoder (ms):
  • 1813
  • 1812
  • 1798
  • 1834
  • 1855