/*
    * Copyright 2007 - 2009 JEuclid, http://jeuclid.sf.net
    * 
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /* $Id: MathRenderer.java,v d5b416878097 2009/08/28 07:30:22 max $ */
  
  package net.sourceforge.jeuclid.swt;
  
  import java.awt.image.BufferedImage;
  import java.awt.image.DataBuffer;
  import java.awt.image.DataBufferByte;
  import java.awt.image.Raster;
  import java.io.IOException;
  
  import net.sourceforge.jeuclid.LayoutContext;
  import net.sourceforge.jeuclid.converter.Converter;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.eclipse.swt.graphics.ImageData;
  import org.eclipse.swt.graphics.PaletteData;
  import org.w3c.dom.Node;
  
  /**
   * Renders MathML to SWT ImageData.
   * 
   * @version $Revision: d5b416878097 $
   */
  public final class MathRenderer {
  
      private static final int COLOR_ENTRIES = 3;
  
      private static final int BITS_PER_PIXEL = MathRenderer.COLOR_ENTRIES * 8;
  
      private static final PaletteData PALETTE_BGR = new PaletteData(0xff,
              0xff00, 0xff0000);
  
      private static final class SingletonHolder {
          private static final MathRenderer INSTANCE = new MathRenderer();
  
          private SingletonHolder() {
          }
      }
  
      /**
       * Logger for this class
       */
      private static final Log LOGGER = LogFactory.getLog(MathRenderer.class);
  
      private final Converter converter = Converter.getInstance();
  
      /**
       * Default constructor.
       */
      private MathRenderer() {
          // Empty on purpose.
      }
  
      /**
       * Retrieve an instance of the converter singleton class.
       * 
       * @return a Converter object.
       */
      public static MathRenderer getInstance() {
          return MathRenderer.SingletonHolder.INSTANCE;
      }
  
      /**
       * Renders MathML into ImageData.
       * 
       * @param document
       *            The MathML Document to render
       * @param layoutContext
       *            LayoutContext to use
       * @return an ImageData instance or null if an error occurred.
       */
      public ImageData render(final Node document,
              final LayoutContext layoutContext) {
          ImageData renderedFormula;
          if (document == null) {
              renderedFormula = null;
          } else {
              try {
                  final BufferedImage bi = this.converter.render(document,
                          layoutContext, BufferedImage.TYPE_3BYTE_BGR);
                  final Raster r = bi.getRaster();
                  final DataBuffer b = r.getDataBuffer();
                 final DataBufferByte db = (DataBufferByte) b;
                 final byte[] data = db.getData();
                 final int w = bi.getWidth();
                 renderedFormula = new ImageData(w, bi.getHeight(),
                         MathRenderer.BITS_PER_PIXEL, MathRenderer.PALETTE_BGR,
                         MathRenderer.COLOR_ENTRIES * w, data);
             } catch (IOException io) {
                 MathRenderer.LOGGER.warn(io.getMessage(), io);
                 renderedFormula = null;
             }
         }
         return renderedFormula;
     }
 
 }