IconCache.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 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 Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.examples.fileviewer;

import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.Hashtable;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.program.Program;
import org.eclipse.swt.widgets.Display;

/**
 * Manages icons for the application. This is necessary as we could easily end up creating thousands of icons bearing
 * the same image.
 */
class IconCache {
	// Stock cursors
	public final int		cursorDefault		= 0, cursorWait = 1;
	// Stock images
	public final int		shellIcon			= 0, iconClosedDrive = 1, iconClosedFolder = 2, iconFile = 3,
			iconOpenDrive = 4, iconOpenFolder = 5, cmdCopy = 6, cmdCut = 7, cmdDelete = 8, cmdParent = 9,
			cmdPaste = 10, cmdPrint = 11, cmdRefresh = 12, cmdRename = 13, cmdSearch = 14;
	public Cursor			stockCursors[];

	public final String[]	stockImageLocations	= { "generic_example.gif", "icon_ClosedDrive.gif",
			"icon_ClosedFolder.gif", "icon_File.gif", "icon_OpenDrive.gif", "icon_OpenFolder.gif", "cmd_Copy.gif",
			"cmd_Cut.gif", "cmd_Delete.gif", "cmd_Parent.gif", "cmd_Paste.gif", "cmd_Print.gif", "cmd_Refresh.gif",
			"cmd_Rename.gif", "cmd_Search.gif"	};
	public Image			stockImages[];
	// Cached icons
	private Hashtable		iconCache;														/* map Program to Image */

	public IconCache() {
	}

	/**
	 * Frees the resources
	 */
	public void freeResources() {
		if (stockImages != null) {
			for (int i = 0; i < stockImages.length; ++i) {
				final Image image = stockImages[i];
				if (image != null)
					image.dispose();
			}
			stockImages = null;
		}
		if (iconCache != null)
			for (Enumeration it = iconCache.elements(); it.hasMoreElements();) {
				Image image = (Image) it.nextElement();
				image.dispose();
			}
		if (stockCursors != null) {
			for (int i = 0; i < stockCursors.length; ++i) {
				final Cursor cursor = stockCursors[i];
				if (cursor != null)
					cursor.dispose();
			}
			stockCursors = null;
		}
	}

	/**
	 * Gets an image for a file associated with a given program
	 * 
	 * @param program
	 *            the Program
	 */
	public Image getIconFromProgram(Program program) {
		Image image = (Image) iconCache.get(program);
		if (image == null) {
			ImageData imageData = program.getImageData();
			if (imageData != null) {
				image = new Image(null, imageData, imageData.getTransparencyMask());
				iconCache.put(program, image);
			} else
				image = stockImages[iconFile];
		}
		return image;
	}

	/**
	 * Loads the resources
	 * 
	 * @param display
	 *            the display
	 */
	public void initResources(Display display) {
		if (stockImages == null) {
			stockImages = new Image[stockImageLocations.length];

			for (int i = 0; i < stockImageLocations.length; ++i) {
				Image image = createStockImage(display, stockImageLocations[i]);
				if (image == null) {
					freeResources();
					throw new IllegalStateException(FileViewer.getResourceString("error.CouldNotLoadResources"));
				}
				stockImages[i] = image;
			}
		}
		if (stockCursors == null)
			stockCursors = new Cursor[] { null, new Cursor(display, SWT.CURSOR_WAIT) };
		iconCache = new Hashtable();
	}

	/**
	 * Creates a stock image
	 * 
	 * @param display
	 *            the display
	 * @param path
	 *            the relative path to the icon
	 */
	private Image createStockImage(Display display, String path) {
		InputStream stream = IconCache.class.getResourceAsStream(path);
		ImageData imageData = new ImageData(stream);
		ImageData mask = imageData.getTransparencyMask();
		Image result = new Image(display, imageData, mask);
		try {
			stream.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return result;
	}
}