visualization/plugins/org.eclipse.mylar.zest.core/src/org/eclipse/mylar/zest/core/internal/gefx/CachedLabel.java

/*******************************************************************************
 * Copyright 2005-2006, CHISEL Group, University of Victoria, Victoria, BC, Canada.
 * 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:
 *     The Chisel Group, University of Victoria
 *******************************************************************************/
package org.eclipse.mylar.zest.core.internal.gefx;

import org.eclipse.draw2d.Animation;
import org.eclipse.draw2d.Graphics;
import org.eclipse.draw2d.Label;
import org.eclipse.draw2d.SWTGraphics;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.mylar.zest.core.ZestPlugin;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;

/**
 * A cached label to improve performance of text drawing under linux
 * @author Ian Bull
 *
 */
public abstract class CachedLabel extends Label {

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.draw2d.Label#paintFigure(org.eclipse.draw2d.Graphics)
	 */
	Image cachedImage = null;
	boolean cacheLabel = false;
	boolean invalidationRequired = false;
	

	/**
	 * CachedLabel constructor.  
	 * @param cacheLabel Should the label be cached, or should the text be re-layedout each time
	 */
	public CachedLabel(boolean cacheLabel) {
		this.cacheLabel = cacheLabel;
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.draw2d.Label#setIcon(org.eclipse.swt.graphics.Image)
	 */
	public void setIcon(Image image) {
		updateInvalidation();
		super.setIcon(image);
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.draw2d.Figure#setForegroundColor(org.eclipse.swt.graphics.Color)
	 */
	public void setForegroundColor(Color fg) {
		updateInvalidation();
		super.setForegroundColor(fg);
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.draw2d.Figure#setBackgroundColor(org.eclipse.swt.graphics.Color)
	 */
	public void setBackgroundColor(Color bg) {
		updateInvalidation();
		super.setBackgroundColor(bg);
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.draw2d.Figure#setFont(org.eclipse.swt.graphics.Font)
	 */
	public void setFont(Font f) {
		updateInvalidation();
		super.setFont(f);
	}
	
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.draw2d.Label#setText(java.lang.String)
	 */
	public void setText(String s) {
		updateInvalidation();
		super.setText(s);
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.draw2d.Figure#setSize(int, int)
	 */
	public void setSize(int w, int h) {
		updateInvalidation();
		
		if ( cachedImage != null && shouldInvalidateCache() ) {
			cleanImage();
		}
		super.setSize(w, h);
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.draw2d.Figure#setBounds(org.eclipse.draw2d.geometry.Rectangle)
	 */
	public void setBounds(Rectangle rect) {
		boolean resize = (rect.width != bounds.width) || (rect.height != bounds.height);
	
		if ( resize && Animation.isAnimating() ) {
			updateInvalidation();
		}
		if ( resize && shouldInvalidateCache() && cachedImage != null) {
			cleanImage();
		}
			
		super.setBounds(rect);
	}
	

	/**
	 * Override this method to return the background colour for the text
	 * Note: Text must have a background color since it is being stored in 
	 * an image (You can set it to white if you want)
	 * @return
	 */
	protected abstract Color getBackgroundTextColor();	
		
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.draw2d.Label#paintFigure(org.eclipse.draw2d.Graphics)
	 */
	protected void paintFigure(Graphics graphics) {
		if ( !cacheLabel ) {
			super.paintFigure(graphics);
			return;
		}
		
		if (isOpaque())
			graphics.fillRectangle(getBounds());
		Rectangle bounds = getBounds();
		graphics.translate(bounds.x, bounds.y);
		
		Image icon = getIcon();
		
		if (icon != null)
			graphics.drawImage(icon, getIconLocation());	

		int width = getSubStringTextSize().width;
		int height = getSubStringTextSize().height;

		if (cachedImage == null || shouldInvalidateCache()) {
			invalidationRequired = false;	
			cleanImage();
			cachedImage = new Image(Display.getCurrent(), width, height);
			
			ZestPlugin.getDefault().addImage(cachedImage.toString(), cachedImage);
			
			GC gc = new GC(cachedImage);
			
			Graphics graphics2 = new SWTGraphics(gc);
			graphics2.setBackgroundColor(getBackgroundTextColor());
			graphics2.fillRectangle(0,0,width,height);
			graphics2.setForegroundColor(getForegroundColor());
			graphics2.drawText(getSubStringText(),new Point(0,0));
			gc.dispose();
			
		}
		graphics.drawImage(cachedImage, getTextLocation());
		graphics.translate(-bounds.x, -bounds.y);
		this.paintBorder(graphics);
		
	}
	
	/**
	 * Determine if the image should be remade or not
	 * @return
	 */
	private boolean shouldInvalidateCache() {
		if ( invalidationRequired && !Animation.isAnimating())
			return true;
		else
			return false;
	}
	
	/**
	 * Notifies the cache that the image will need updating.
	 */
	private void updateInvalidation() {
		invalidationRequired = true;
	}	
	
	protected void cleanImage() {
		if ( cachedImage != null ) {
			
			ZestPlugin.getDefault().removeImage(cachedImage.toString());
			cachedImage.dispose();
			cachedImage = null;
		}
	}
}