resourcemanager.java

Eclipse从入门到精通源代码/第二篇 SWT_JFace篇(6-16章)

package com.swtdesigner;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Iterator;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * Utility class for managing OS resources associated with SWT controls such as
 * colors, fonts, images, etc.
 * 
 * !!! 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)
 * 
 * This class may be freely distributed as part of any application or plugin.
 * <p>
 * Copyright (c) 2003 - 2004, Instantiations, Inc. <br>
 * All Rights Reserved
 * 
 * @version $Revision: 1.13 $
 * @author scheglov_ke
 * @author Dan Rubel
 */
public class ResourceManager {

    /**
     * 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();
        disposeFonts();
        disposeImages();
        disposeCursors();
    }

    //////////////////////////////
    // Color support
    //////////////////////////////

    /**
     * Maps RGB values to colors
     */
    private static HashMap m_ColorMap = new HashMap();

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

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

    /**
     * Returns a color given its RGB value
     * 
     * @param rgb
     *            RGB The RGB value of the color
     * @return Color The color matching the RGB value
     */
    public static Color getColor(RGB rgb) {
        Color 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 colors
     */
    public static void disposeColors() {
        for (Iterator iter = m_ColorMap.values().iterator(); iter.hasNext();)
            ((Color) iter.next()).dispose();
        m_ColorMap.clear();
    }

    //////////////////////////////
    // Image support
    //////////////////////////////

    /**
     * Maps image names to images
     */
    private static HashMap m_ClassImageMap = new HashMap();

    /**
     * Maps image descriptors to images
     */
    private static HashMap m_DescriptorImageMap = new HashMap();

    /**
     * Maps images to image decorators
     */
    private static HashMap m_ImageToDecoratorMap = new HashMap();

    /**
     * Returns an image encoded by the specified input stream
     * 
     * @param is
     *            InputStream The input stream encoding the image data
     * @return Image The image encoded by the specified input stream
     */
    private static Image getImage(InputStream is) {
        Display display = Display.getCurrent();
        ImageData data = new ImageData(is);
        if (data.transparentPixel > 0)
            return new Image(display, data, data.getTransparencyMask());
        return new Image(display, data);
    }

    /**
     * Returns an image stored in the file at the specified path
     * 
     * @param path
     *            String The path to the image file
     * @return Image The image stored in the file at the specified path
     */
    public static Image getImage(String path) {
        String key = ResourceManager.class.getName() + "|" + path;
        Image image = (Image) m_ClassImageMap.get(key);
        if (image == null) {
            try {
                FileInputStream fis = new FileInputStream(path);
                image = getImage(fis);
                m_ClassImageMap.put(key, image);
                fis.close();
            } catch (Exception e) {
                return null;
            }
        }
        return image;
    }

    /**
     * Returns an image stored in the file at the specified path relative to the
     * specified class
     * 
     * @param clazz
     *            Class The class relative to which to find the image
     * @param path
     *            String The path to the image file
     * @return Image The image stored in the file at the specified path
     */
    public static Image getImage(Class clazz, String path) {
        String key = clazz.getName() + "|" + path;
        Image image = (Image) m_ClassImageMap.get(key);
        if (image == null) {
            if (path.length() > 0 && path.charAt(0) == '/') {
                String newPath = path.substring(1, path.length());
                image = getImage(clazz.getClassLoader().getResourceAsStream(newPath));
            } else {
                image = getImage(clazz.getResourceAsStream(path));
            }
            m_ClassImageMap.put(key, image);
        }
        return image;
    }

    /**
     * Returns an image descriptor stored in the file at the specified path
     * relative to the specified class
     * 
     * @param clazz
     *            Class The class relative to which to find the image descriptor
     * @param path
     *            String The path to the image file
     * @return ImageDescriptor The image descriptor stored in the file at the
     *         specified path
     */
    public static ImageDescriptor getImageDescriptor(Class clazz, String path) {
        return ImageDescriptor.createFromFile(clazz, path);
    }

    /**
     * Returns an image descriptor stored in the file at the specified path
     * 
     * @param path
     *            String The path to the image file
     * @return ImageDescriptor The image descriptor stored in the file at the
     *         specified path
     */
    public static ImageDescriptor getImageDescriptor(String path) {
        try {
            return ImageDescriptor.createFromURL((new File(path)).toURL());
        } catch (MalformedURLException e) {
            return null;
        }
    }

    /**
     * Returns an image based on the specified image descriptor
     * 
     * @param descriptor
     *            ImageDescriptor The image descriptor for the image
     * @return Image The image based on the specified image descriptor
     */
    public static Image getImage(ImageDescriptor descriptor) {
        if (descriptor == null)
            return null;
        Image image = (Image) m_DescriptorImageMap.get(descriptor);
        if (image == null) {
            image = descriptor.createImage();
            m_DescriptorImageMap.put(descriptor, image);
        }
        return image;
    }

    /**
     * Returns an image composed of a base image decorated by another image
     * 
     * @param baseImage
     *            Image The base image that should be decorated
     * @param decorator
     *            Image The image to decorate teh base image
     * @return Image The resulting decorated image