eclipse插件（RCP）SWT资源管理工具类

╰半夏微凉° 2023-10-05 21:45 34阅读 0赞

RCP或GEF开发中，经常会使用到Color、Font、Image等资源，这部分资源很好性能，同时使用完后一般要求关闭，不然可能造成内存泄漏，使得程序运行存在诸多风险。  
该类提供了一个对这些资源管理的工具，它一般在类加载时被实例化，建议应用程序所有的Color、Font、Image应从该工具中获取，并且在应用程序关闭时调用他的销毁方法以释放相关资源。

/*******************************************************************************
     * 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 java.io.FileInputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.HashMap;
    import java.util.Map;
    
    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;
    
    /**
     * 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 SWTResourceManager {
        
    	
    	//
    	// 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();
    	}
    	
    	/**
    	 * 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();
    	}
    }