ExtendedFontRegistry.java

/**
 * Copyright (c) 2008-2010 IBM Corporation and others.
 * All rights reserved.   This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: 
 *   IBM - Initial API and implementation
 */
package org.eclipse.emf.edit.ui.provider;


import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;

import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.edit.provider.IItemFontProvider;
import org.eclipse.emf.edit.ui.EMFEditUIPlugin;
import org.eclipse.jface.resource.DeviceResourceException;
import org.eclipse.jface.resource.FontDescriptor;
import org.eclipse.rwt.SessionSingletonBase;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.widgets.Display;


/**
 * A font registry for turning a font description into an actual font object.
 * @see IItemFontProvider
 */
public class ExtendedFontRegistry
{

  public static final ExtendedFontRegistry INSTANCE = new ExtendedFontRegistry()
    {
      @Override
      public Font getFont(Font baseFont, Object object)
      {
        return ((ExtendedFontRegistry)SessionSingletonBase.getInstance(ExtendedFontRegistry.class)).getFont(baseFont, object);
      }
    };

  protected Display display;
  protected HashMap<Collection<?>, Font> table = new HashMap<Collection<?>, Font>(10);

  public ExtendedFontRegistry()
  {
    display = Display.getCurrent();
    hookDisplayDispose(display);
  }

  public ExtendedFontRegistry(Display display)
  {
    this.display = display;
    hookDisplayDispose(display);
  }

  public Font getFont(Font baseFont, Object object)
  {
    if (object instanceof Font)
    {
      return (Font)object;
    }
    else
    {
      Collection<Object> key = new ArrayList<Object>(2);
      key.add(baseFont);
      key.add(object);

      Font result = table.get(key);
      if (result == null)
      {
        if (object instanceof FontDescriptor)
        {
          FontDescriptor fontDescriptor = (FontDescriptor)object;
          try
          {
            result = fontDescriptor.createFont(display);
          }
          catch (DeviceResourceException exception)
          {
            EMFEditUIPlugin.INSTANCE.log(exception);
          }
        }
        else if (object instanceof URI)
        {
          URI fontURI = (URI)object;
          if (!"font".equals(fontURI.scheme()))
          {
            throw new IllegalArgumentException("Only 'font' scheme is recognized" + fontURI);
          }
          String fontNameSpecification = fontURI.authority();
          if ("".equals(fontNameSpecification))
          {
            fontNameSpecification = null;
          }
          String heightSpecification = fontURI.segment(0);
          boolean delta;
          int height;
          if (heightSpecification.startsWith("+"))
          {
            delta = true;
            height = Integer.parseInt(heightSpecification.substring(1));
          }
          else if ("".equals(heightSpecification))
          {
            delta = true;
            height = 0;
          }
          else
          {
            height = Integer.parseInt(heightSpecification);
            delta = height < 0;
          }

          String styleSpecification = fontURI.segment(1);
          int style =
             "bold".equals(styleSpecification) ?
               SWT.BOLD :
               "italic".equals(styleSpecification) ?
                 SWT.ITALIC :
                 "italic+bold".equals(styleSpecification) || "bold+italic".equals(styleSpecification) ?
                   SWT.ITALIC | SWT.BOLD :
                   "normal".equals(styleSpecification) ?
                     SWT.NORMAL :
                     -1;

          FontData [] baseFontData = baseFont.getFontData();
          FontData [] fontData = new FontData[baseFontData.length];

          for (int i = 0; i < baseFontData.length; ++i)
          {
            fontData[i] =
              new FontData
                (fontNameSpecification == null ? baseFontData[i].getName() : fontNameSpecification,
                 delta ? baseFontData[i].getHeight() + height : height,
                 style == -1 ? baseFontData[i].getStyle() : style);
          }

          try
          {
            result = FontDescriptor.createFrom(fontData).createFont(display);
          }
          catch (DeviceResourceException exception)
          {
            EMFEditUIPlugin.INSTANCE.log(exception);
          }
        }

        if (result != null)
        {
          table.put(key, result);
        }
      }
      return result;
    }
  }

  protected void handleDisplayDispose()
  {
    for (Font image : table.values())
    {
      image.dispose();
    }
    table = null;
  }

  protected void hookDisplayDispose(Display display)
  {
    display.disposeExec
      (new Runnable()
       {
         public void run()
         {
           handleDisplayDispose();
         }
       });
  }
}