Dave Jarvis' Repositories

/*
 * Copyright 2020 White Magic Software, Ltd.
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  o Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 *  o Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.scrivenvar.preview;

import com.scrivenvar.Services;
import com.scrivenvar.service.events.Notifier;
import org.apache.batik.anim.dom.SAXSVGDocumentFactory;
import org.apache.batik.gvt.renderer.ImageRenderer;
import org.apache.batik.transcoder.TranscoderException;
import org.apache.batik.transcoder.TranscoderInput;
import org.apache.batik.transcoder.TranscoderOutput;
import org.apache.batik.transcoder.image.ImageTranscoder;
import org.apache.batik.util.XMLResourceDescriptor;
import org.w3c.dom.Document;

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.StringReader;
import java.net.URL;
import java.util.Map;

import static java.awt.Color.WHITE;
import static java.awt.RenderingHints.*;
import static java.awt.image.BufferedImage.TYPE_INT_RGB;
import static org.apache.batik.transcoder.SVGAbstractTranscoder.KEY_WIDTH;
import static org.apache.batik.transcoder.image.ImageTranscoder.KEY_BACKGROUND_COLOR;
import static org.apache.batik.util.XMLResourceDescriptor.getXMLParserClassName;

/**
 * Responsible for converting SVG images into rasterized PNG images.
 */
public class SVGRasterizer {
  private final static Notifier NOTIFIER = Services.load( Notifier.class );

  private final static SAXSVGDocumentFactory mFactory =
      new SAXSVGDocumentFactory( getXMLParserClassName() );

  public final static Map<Object, Object> RENDERING_HINTS = Map.of(
      KEY_ANTIALIASING,
      VALUE_ANTIALIAS_ON,
      KEY_ALPHA_INTERPOLATION,
      VALUE_ALPHA_INTERPOLATION_QUALITY,
      KEY_COLOR_RENDERING,
      VALUE_COLOR_RENDER_QUALITY,
      KEY_DITHERING,
      VALUE_DITHER_DISABLE,
      KEY_FRACTIONALMETRICS,
      VALUE_FRACTIONALMETRICS_ON,
      KEY_INTERPOLATION,
      VALUE_INTERPOLATION_BICUBIC,
      KEY_RENDERING,
      VALUE_RENDER_QUALITY,
      KEY_STROKE_CONTROL,
      VALUE_STROKE_PURE,
      KEY_TEXT_ANTIALIASING,
      VALUE_TEXT_ANTIALIAS_ON
  );

  public final static Image BROKEN_IMAGE_PLACEHOLDER;

  static {
    // A FontAwesome camera icon, cleft asunder.
    final String BROKEN_IMAGE_SVG = "<svg height='19pt' viewBox='0 0 25 19' " +
        "width='25pt' xmlns='http://www.w3.org/2000/svg'><g " +
        "fill='#454545'><path d='m8.042969 11.085938c.332031 1.445312 1" +
        ".660156 2.503906 3.214843 2.558593zm0 0'/><path d='m6.792969 9" +
        ".621094-.300781.226562.242187.195313c.015625-.144531.03125-.28125" +
        ".058594-.421875zm0 0'/><path d='m10.597656.949219-2.511718.207031c-" +
        ".777344.066406-1.429688.582031-1.636719 1.292969l-.367188 1.253906-3" +
        ".414062.28125c-1.027344.085937-1.792969.949219-1.699219 1.925781l" +
        ".976562 10.621094c.089844.976562.996094 1.699219 2.023438 1" +
        ".613281l11.710938-.972656-3.117188-2.484375c-.246094.0625-.5.109375-" +
        ".765625.132812-2.566406.210938-4.835937-1.597656-5.0625-4.039062-" +
        ".023437-.25-.019531-.496094 0-.738281l-.242187-.195313.300781-" +
        ".226562c.359375-1.929688 2.039062-3.472656 4.191406-3.652344.207031-" +
        ".015625.414063-.015625.617187-.007812l.933594-.707032zm0 0'/><path " +
        "d='m10.234375 11.070312 2.964844 2.820313c.144531.015625.285156" +
        ".027344.433593.027344 1.890626 0 3.429688-1.460938 3.429688-3.257813" +
        " 0-1.792968-1.539062-3.257812-3.429688-3.257812-1.890624 0-3.429687 " +
        "1.464844-3.429687 3.257812 0 .140625.011719.277344.03125.410156zm0 " +
        "0'/><path d='m14.488281.808594 1.117188 4.554687-1.042969.546875c2" +
        ".25.476563 3.84375 2.472656 3.636719 4.714844-.199219 2.191406-2" +
        ".050781 3.871094-4.285157 4.039062l2.609376 2.957032 4.4375.371094c1" +
        ".03125.085937 1.9375-.640626 2.027343-1.617188l.976563-10.617188c" +
        ".089844-.980468-.667969-1.839843-1.699219-1.925781l-3.414063-" +
        ".285156-.371093-1.253906c-.207031-.710938-.859375-1.226563-1" +
        ".636719-1.289063zm0 0'/></g></svg>";

    // The width and height cannot be embedded in the SVG above because the
    // path element values are relative to the viewBox dimensions.
    final int w = 75;
    final int h = 75;
    Image image;

    try( final StringReader reader = new StringReader( BROKEN_IMAGE_SVG ) ) {
      final String parser = XMLResourceDescriptor.getXMLParserClassName();
      final SAXSVGDocumentFactory factory = new SAXSVGDocumentFactory( parser );
      final Document document = factory.createDocument( "", reader );

      image = rasterize( document, w );
    } catch( final Exception e ) {
      image = new BufferedImage( w, h, TYPE_INT_RGB );
      final var graphics = (Graphics2D) image.getGraphics();
      graphics.setRenderingHints( RENDERING_HINTS );

      // Fall back to a (\) symbol.
      graphics.setColor( new Color( 204, 204, 204 ) );
      graphics.fillRect( 0, 0, w, h );
      graphics.setColor( new Color( 255, 204, 204 ) );
      graphics.setStroke( new BasicStroke( 4 ) );
      graphics.drawOval( w / 4, h / 4, w / 2, h / 2 );
      graphics.drawLine( w / 4 + (int) (w / 4 / Math.PI),
                         h / 4 + (int) (w / 4 / Math.PI),
                         w / 2 + w / 4 - (int) (w / 4 / Math.PI),
                         h / 2 + h / 4 - (int) (w / 4 / Math.PI) );
    }

    BROKEN_IMAGE_PLACEHOLDER = image;
  }

  private static class BufferedImageTranscoder extends ImageTranscoder {
    private BufferedImage mImage;

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

    @Override
    public void writeImage(
        final BufferedImage image, final TranscoderOutput output ) {
      mImage = image;
    }

    public Image getImage() {
      return mImage;
    }

    @Override
    protected ImageRenderer createRenderer() {
      final ImageRenderer renderer = super.createRenderer();
      final RenderingHints hints = renderer.getRenderingHints();
      hints.putAll( RENDERING_HINTS );

      renderer.setRenderingHints( hints );

      return renderer;
    }
  }

  /**
   * Rasterizes the vector graphic file at the given URL. If any exception
   * happens, a red circle is returned instead.
   *
   * @param url   The URL to a vector graphic file, which must include the
   *              protocol scheme (such as file:// or https://).
   * @param width The number of pixels wide to render the image. The aspect
   *              ratio is maintained.
   * @return Either the rasterized image upon success or a red circle.
   */
  public static Image rasterize( final String url, final int width ) {
    try {
      return rasterize( new URL( url ), width );
    } catch( final Exception e ) {
      NOTIFIER.notify( e );
      return BROKEN_IMAGE_PLACEHOLDER;
    }
  }

  /**
   * Converts an SVG drawing into a rasterized image that can be drawn on
   * a graphics context.
   *
   * @param url   The path to the image (can be web address).
   * @param width Scale the image width to this size (aspect ratio is
   *              maintained).
   * @return The vector graphic transcoded into a raster image format.
   * @throws IOException         Could not read the vector graphic.
   * @throws TranscoderException Could not convert the vector graphic to an
   *                             instance of {@link Image}.
   */
  public static Image rasterize( final URL url, final int width )
      throws IOException, TranscoderException {
    return rasterize(
        mFactory.createDocument( url.toString() ), width );
  }

  public static Image rasterize(
      final Document svg, final int width ) throws TranscoderException {
    final var transcoder = new BufferedImageTranscoder();
    final var input = new TranscoderInput( svg );

    transcoder.addTranscodingHint( KEY_BACKGROUND_COLOR, WHITE );
    transcoder.addTranscodingHint( KEY_WIDTH, (float) width );
    transcoder.transcode( input, null );

    return transcoder.getImage();
  }
}