/*
    * 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: MathView.java,v 2986a8eeaebc 2009/09/24 12:53:08 max $ */
  
  package net.sourceforge.jeuclid.swt;
  
  import net.sourceforge.jeuclid.MutableLayoutContext;
  import net.sourceforge.jeuclid.context.LayoutContextImpl;
  import net.sourceforge.jeuclid.elements.generic.DocumentElement;
  
  import org.eclipse.swt.events.DisposeEvent;
  import org.eclipse.swt.events.DisposeListener;
  import org.eclipse.swt.events.PaintEvent;
  import org.eclipse.swt.events.PaintListener;
  import org.eclipse.swt.graphics.Color;
  import org.eclipse.swt.graphics.Device;
  import org.eclipse.swt.graphics.GC;
  import org.eclipse.swt.graphics.Image;
  import org.eclipse.swt.graphics.ImageData;
  import org.eclipse.swt.widgets.Canvas;
  import org.eclipse.swt.widgets.Composite;
  import org.w3c.dom.Node;
  
  /**
   * Contains a display component for SWT.
   * <p>
   * TODO: This is a very basic implementation.
   * 
   * @version $Revision: 2986a8eeaebc $
   */
  public final class MathView extends Canvas {
  
      // /**
      // * Logger for this class
      // */
      // private static final Log LOGGER = LogFactory.getLog(MathView.class);
  
      private final MathRenderer mathRenderer = MathRenderer.getInstance();
  
      private Node document;
  
      private ImageData renderedFormula;
  
      private MutableLayoutContext layoutContext = new LayoutContextImpl(
              LayoutContextImpl.getDefaultLayoutContext());
  
      /**
       * Create a new MathView Widget.
       * 
       * @param parent
       *            Parent component
       * @param style
       *            SWT style attributes.
       */
      public MathView(final Composite parent, final int style) {
          super(parent, style);
          this.setDocument(new DocumentElement());
          this.addDisposeListener(new DisposeListener() {
              public void widgetDisposed(final DisposeEvent e) {
                  MathView.this.widgetDisposed(e);
              }
          });
          this.addPaintListener(new PaintListener() {
              public void paintControl(final PaintEvent e) {
                  MathView.this.paintControl(e);
              }
          });
      }
  
      private void paintControl(final PaintEvent e) {
          final GC gc = e.gc;
          final Device device = gc.getDevice();
          final Color c = new Color(device, 255, 255, 255);
          gc.setBackground(c);
          gc.fillRectangle(e.x, e.y, e.width, e.height);
          c.dispose();
          if (this.renderedFormula != null) {
              final Image im = new Image(device, this.renderedFormula);
              gc.drawImage(im, 0, 0);
              im.dispose();
          }
      }
  
      private void widgetDisposed(final DisposeEvent e) {
          this.document = null;
         this.renderedFormula = null;
     }
 
     private void recreate() {
         this.renderedFormula = this.mathRenderer.render(this.document,
                 this.layoutContext);
     }
 
     /**
      * @param doc
      *            the document to set
      */
     public void setDocument(final Node doc) {
         final Node oldValue = this.document;
         this.document = doc;
         if (doc != oldValue) {
             this.recreate();
             this.redraw();
         }
     }
 
     /**
      * @return the document
      */
     public Node getDocument() {
         return this.document;
     }
 
 }