ExampleSWTResourceManager.java

/*******************************************************************************
 * Copyright (c) 2011 Google, Inc.
 * 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:
 *    Google, Inc. - initial API and implementation
 *******************************************************************************/
package org.eclipse.wb.swt;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Display;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;

/**
 * Utility class for managing OS resources associated with SWT controls such as colors, fonts, images, etc.
 * <p>
 * !!! IMPORTANT !!! Application code must explicitly invoke the <code>dispose()</code> method to release the
 * operating system resources managed by cached objects when those objects and OS resources are no longer
 * needed (e.g. on application shutdown)
 * <p>
 * This class may be freely distributed as part of any application or plugin.
 * <p>
 * @author scheglov_ke
 * @author Dan Rubel
 */
public class ExampleSWTResourceManager
{
  // //////////////////////////////////////////////////////////////////////////
  //
  // Color
  //
  // //////////////////////////////////////////////////////////////////////////
  private static Map<RGB, Color> m_colorMap = new HashMap<RGB, Color>();

  /**
   * Returns the system {@link Color} matching the specific ID.
   *
   * @param systemColorID
   *            the ID value for the color
   * @return the system {@link Color} matching the specific ID
   */
  public static Color getColor(int systemColorID)
  {
    Display display = Display.getCurrent();
    return display.getSystemColor(systemColorID);
  }

  /**
   * Returns a {@link Color} given its red, green and blue component values.
   *
   * @param r
   *            the red component of the color
   * @param g
   *            the green component of the color
   * @param b
   *            the blue component of the color
   * @return the {@link Color} matching the given red, green and blue component values
   */
  public static Color getColor(int r, int g, int b)
  {
    return getColor(new RGB(r, g, b));
  }

  /**
   * Returns a {@link Color} given its RGB value.
   *
   * @param rgb
   *            the {@link RGB} value of the color
   * @return the {@link Color} matching the RGB value
   */
  public static Color getColor(RGB rgb)
  {
    Color color = m_colorMap.get(rgb);
    if (color == null)
    {
      Display display = Display.getCurrent();
      color = new Color(display, rgb);
      m_colorMap.put(rgb, color);
    }
    return color;
  }

  /**
   * Dispose of all the cached {@link Color}'s.
   */
  public static void disposeColors()
  {
    for (Color color : m_colorMap.values())
    {
      color.dispose();
    }
    m_colorMap.clear();
  }

  // //////////////////////////////////////////////////////////////////////////
  //
  // Image
  //
  // //////////////////////////////////////////////////////////////////////////
  /**
   * Maps image paths to images.
   */
  private static Map<String, Image> m_imageMap = new HashMap<String, Image>();

  /**
   * Returns an {@link Image} encoded by the specified {@link InputStream}.
   *
   * @param stream
   *            the {@link InputStream} encoding the image data
   * @return the {@link Image} encoded by the specified input stream
   */
  protected static Image getImage(InputStream stream) throws IOException
  {
    try
    {
      Display display = Display.getCurrent();
      ImageData data = new ImageData(stream);
      if (data.transparentPixel > 0)
      {
        return new Image(display, data, data.getTransparencyMask());
      }
      return new Image(display, data);
    }
    finally
    {
      stream.close();
    }
  }

  /**
   * Returns an {@link Image} stored in the file at the specified path.
   *
   * @param path
   *            the path to the image file
   * @return the {@link Image} stored in the file at the specified path
   */
  public static Image getImage(String path)
  {
    Image image = m_imageMap.get(path);
    if (image == null)
    {
      try
      {
        image = getImage(new FileInputStream(path));
        m_imageMap.put(path, image);
      }
      catch (Exception e)
      {
        image = getMissingImage();
        m_imageMap.put(path, image);
      }
    }
    return image;
  }

  /**
   * Returns an {@link Image} stored in the file at the specified path relative to the specified class.
   *
   * @param clazz
   *            the {@link Class} relative to which to find the image
   * @param path
   *            the path to the image file, if starts with <code>'/'</code>
   * @return the {@link Image} stored in the file at the specified path
   */
  public static Image getImage(Class<?> clazz, String path)
  {
    String key = clazz.getName() + '|' + path;
    Image image = m_imageMap.get(key);
    if (image == null)
    {
      try
      {
        image = getImage(clazz.getResourceAsStream(path));
        m_imageMap.put(key, image);
      }
      catch (Exception e)
      {
        image = getMissingImage();
        m_imageMap.put(key, image);
      }
    }
    return image;
  }

  private static final int MISSING_IMAGE_SIZE = 10;

  /**
   * @return the small {@link Image} that can be used as placeholder for missing image.
   */
  private static Image getMissingImage()
  {
    Image image = new Image(Display.getCurrent(), MISSING_IMAGE_SIZE, MISSING_IMAGE_SIZE);
    //
    GC gc = new GC(image);
    gc.setBackground(getColor(SWT.COLOR_RED));
    gc.fillRectangle(0, 0, MISSING_IMAGE_SIZE, MISSING_IMAGE_SIZE);
    gc.dispose();
    //
    return image;
  }

  /**
   * Style constant for placing decorator image in top left corner of base image.
   */
  public static final int TOP_LEFT = 1;

  /**
   * Style constant for placing decorator image in top right corner of base image.
   */
  public static final int TOP_RIGHT = 2;

  /**
   * Style constant for placing decorator image in bottom left corner of base image.
   */
  public static final int BOTTOM_LEFT = 3;

  /**
   * Style constant for placing decorator image in bottom right corner of base image.
   */
  public static final int BOTTOM_RIGHT = 4;

  /**
   * Internal value.
   */
  protected static final int LAST_CORNER_KEY = 5;

  /**
   * Maps images to decorated images.
   */
  @SuppressWarnings("unchecked")
  private static Map<Image, Map<Image, Image>>[] m_decoratedImageMap = new Map[LAST_CORNER_KEY];

  /**
   * Returns an {@link Image} composed of a base image decorated by another image.
   *
   * @param baseImage
   *            the base {@link Image} that should be decorated
   * @param decorator
   *            the {@link Image} to decorate the base image
   * @return {@link Image} The resulting decorated image
   */
  public static Image decorateImage(Image baseImage, Image decorator)
  {
    return decorateImage(baseImage, decorator, BOTTOM_RIGHT);
  }

  /**
   * Returns an {@link Image} composed of a base image decorated by another image.
   *
   * @param baseImage
   *            the base {@link Image} that should be decorated
   * @param decorator
   *            the {@link Image} to decorate the base image
   * @param corner
   *            the corner to place decorator image
   * @return the resulting decorated {@link Image}
   */
  public static Image decorateImage(final Image baseImage, final Image decorator, final int corner)
  {
    if (corner <= 0 || corner >= LAST_CORNER_KEY)
    {
      throw new IllegalArgumentException("Wrong decorate corner");
    }
    Map<Image, Map<Image, Image>> cornerDecoratedImageMap = m_decoratedImageMap[corner];
    if (cornerDecoratedImageMap == null)
    {
      cornerDecoratedImageMap = new HashMap<Image, Map<Image, Image>>();
      m_decoratedImageMap[corner] = cornerDecoratedImageMap;
    }
    Map<Image, Image> decoratedMap = cornerDecoratedImageMap.get(baseImage);
    if (decoratedMap == null)
    {
      decoratedMap = new HashMap<Image, Image>();
      cornerDecoratedImageMap.put(baseImage, decoratedMap);
    }
    //
    Image result = decoratedMap.get(decorator);
    if (result == null)
    {
      Rectangle bib = baseImage.getBounds();
      Rectangle dib = decorator.getBounds();
      //
      result = new Image(Display.getCurrent(), bib.width, bib.height);
      //
      GC gc = new GC(result);
      gc.drawImage(baseImage, 0, 0);
      if (corner == TOP_LEFT)
      {
        gc.drawImage(decorator, 0, 0);
      }
      else if (corner == TOP_RIGHT)
      {
        gc.drawImage(decorator, bib.width - dib.width, 0);
      }
      else if (corner == BOTTOM_LEFT)
      {
        gc.drawImage(decorator, 0, bib.height - dib.height);
      }
      else if (corner == BOTTOM_RIGHT)
      {
        gc.drawImage(decorator, bib.width - dib.width, bib.height - dib.height);
      }
      gc.dispose();
      //
      decoratedMap.put(decorator, result);
    }
    return result;
  }

  /**
   * Dispose all of the cached {@link Image}'s.
   */
  public static void disposeImages()
  {
    // dispose loaded images
    {
      for (Image image : m_imageMap.values())
      {
        image.dispose();
      }
      m_imageMap.clear();
    }
    // dispose decorated images
    for (int i = 0; i < m_decoratedImageMap.length; i++)
    {
      Map<Image, Map<Image, Image>> cornerDecoratedImageMap = m_decoratedImageMap[i];
      if (cornerDecoratedImageMap != null)
      {
        for (Map<Image, Image> decoratedMap : cornerDecoratedImageMap.values())
        {
          for (Image image : decoratedMap.values())
          {
            image.dispose();
          }
          decoratedMap.clear();
        }
        cornerDecoratedImageMap.clear();
      }
    }
  }

  // //////////////////////////////////////////////////////////////////////////
  //
  // Font
  //
  // //////////////////////////////////////////////////////////////////////////
  /**
   * Maps font names to fonts.
   */
  private static Map<String, Font> m_fontMap = new HashMap<String, Font>();

  /**
   * Maps fonts to their bold versions.
   */
  private static Map<Font, Font> m_fontToBoldFontMap = new HashMap<Font, Font>();

  /**
   * Returns a {@link Font} based on its name, height and style.
   *
   * @param name
   *            the name of the font
   * @param height
   *            the height of the font
   * @param style
   *            the style of the font
   * @return {@link Font} The font matching the name, height and style
   */
  public static Font getFont(String name, int height, int style)
  {
    return getFont(name, height, style, false, false);
  }

  /**
   * Returns a {@link Font} based on its name, height and style. Windows-specific strikeout and underline
   * flags are also supported.
   *
   * @param name
   *            the name of the font
   * @param size
   *            the size of the font
   * @param style
   *            the style of the font
   * @param strikeout
   *            the strikeout flag (warning: Windows only)
   * @param underline
   *            the underline flag (warning: Windows only)
   * @return {@link Font} The font matching the name, height, style, strikeout and underline
   */
  public static Font getFont(String name, int size, int style, boolean strikeout, boolean underline)
  {
    String fontName = name + '|' + size + '|' + style + '|' + strikeout + '|' + underline;
    Font font = m_fontMap.get(fontName);
    if (font == null)
    {
      FontData fontData = new FontData(name, size, style);
      if (strikeout || underline)
      {
        try
        {
          Class<?> logFontClass = Class.forName("org.eclipse.swt.internal.win32.LOGFONT"); //$NON-NLS-1$
          Object logFont = FontData.class.getField("data").get(fontData); //$NON-NLS-1$
          if (logFont != null && logFontClass != null)
          {
            if (strikeout)
            {
              logFontClass.getField("lfStrikeOut").set(logFont, Byte.valueOf((byte)1)); //$NON-NLS-1$
            }
            if (underline)
            {
              logFontClass.getField("lfUnderline").set(logFont, Byte.valueOf((byte)1)); //$NON-NLS-1$
            }
          }
        }
        catch (Throwable e)
        {
          System.err.println("Unable to set underline or strikeout" + " (probably on a non-Windows platform). " + e); //$NON-NLS-1$ //$NON-NLS-2$
        }
      }
      font = new Font(Display.getCurrent(), fontData);
      m_fontMap.put(fontName, font);
    }
    return font;
  }

  /**
   * Returns a bold version of the given {@link Font}.
   *
   * @param baseFont
   *            the {@link Font} for which a bold version is desired
   * @return the bold version of the given {@link Font}
   */
  public static Font getBoldFont(Font baseFont)
  {
    Font font = m_fontToBoldFontMap.get(baseFont);
    if (font == null)
    {
      FontData fontDatas[] = baseFont.getFontData();
      FontData data = fontDatas[0];
      font = new Font(Display.getCurrent(), data.getName(), data.getHeight(), SWT.BOLD);
      m_fontToBoldFontMap.put(baseFont, font);
    }
    return font;
  }

  /**
   * Dispose all of the cached {@link Font}'s.
   */
  public static void disposeFonts()
  {
    // clear fonts
    for (Font font : m_fontMap.values())
    {
      font.dispose();
    }
    m_fontMap.clear();
    // clear bold fonts
    for (Font font : m_fontToBoldFontMap.values())
    {
      font.dispose();
    }
    m_fontToBoldFontMap.clear();
  }

  // //////////////////////////////////////////////////////////////////////////
  //
  // Cursor
  //
  // //////////////////////////////////////////////////////////////////////////
  /**
   * Maps IDs to cursors.
   */
  private static Map<Integer, Cursor> m_idToCursorMap = new HashMap<Integer, Cursor>();

  /**
   * Returns the system cursor matching the specific ID.
   *
   * @param id
   *            int The ID value for the cursor
   * @return Cursor The system cursor matching the specific ID
   */
  public static Cursor getCursor(int id)
  {
    Integer key = Integer.valueOf(id);
    Cursor cursor = m_idToCursorMap.get(key);
    if (cursor == null)
    {
      cursor = new Cursor(Display.getDefault(), id);
      m_idToCursorMap.put(key, cursor);
    }
    return cursor;
  }

  /**
   * Dispose all of the cached cursors.
   */
  public static void disposeCursors()
  {
    for (Cursor cursor : m_idToCursorMap.values())
    {
      cursor.dispose();
    }
    m_idToCursorMap.clear();
  }

  // //////////////////////////////////////////////////////////////////////////
  //
  // General
  //
  // //////////////////////////////////////////////////////////////////////////
  /**
   * Dispose of cached objects and their underlying OS resources. This should only be called when the cached
   * objects are no longer needed (e.g. on application shutdown).
   */
  public static void dispose()
  {
    disposeColors();
    disposeImages();
    disposeFonts();
    disposeCursors();
  }
}