org.eclipse.gmf.runtime.common.ui.util.ShiftedImageDescriptor.java Source code

Introduction

Here is the source code for org.eclipse.gmf.runtime.common.ui.util.ShiftedImageDescriptor.java

Source

/******************************************************************************
 * Copyright (c) 2004 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.gmf.runtime.common.ui.util;

import org.eclipse.jface.resource.CompositeImageDescriptor;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.Point;

/**
 * An image descriptor that is cached and shifted from the left or from the
 * top or both.  The shifted area contains the original image and the area
 * on the left or top contains a background color.  Both the original image
 * and background color are specified in the constructor.
 * 
 * @author wdiu, Wayne Diu
 */
public class ShiftedImageDescriptor extends CompositeImageDescriptor {

    /**
     * The cached size of the shifted image
     */
    private Point size = null;

    /**
     * How much to shift from the left
     */
    private short shiftX = 0;

    /**
     * How much to shift from the top
     */
    private short shiftY = 0;

    /**
     * Original image data for the image that will be shifted
     */
    private ImageData imageData = null;

    /**
     * Make a new image descriptor of an image that is shifted.
     * 
     * @param shiftX
     *            how much to shift from the left
     * @param shiftY
     *            how much to shift from the top
     * @param imageDescriptor
     *            original image to shift by shiftX and shiftY
     */
    public ShiftedImageDescriptor(short shiftX, short shiftY, ImageDescriptor imageDescriptor) {

        assert (shiftX >= 0);
        assert (shiftY >= 0);
        assert (imageDescriptor.getImageData().width >= 0);
        assert (imageDescriptor.getImageData().height >= 0);
        assert null != imageDescriptor;

        this.shiftX = shiftX;
        this.shiftY = shiftY;
        this.imageData = imageDescriptor.getImageData();
    }

    /**
     * Draw the image in the shifted position
     * 
     * @param width
     *            int ignored
     * @param height
     *            int ignored
     * 
     * @see org.eclipse.jface.resource.CompositeImageDescriptor#drawCompositeImage(int,
     *      int)
     */
    protected void drawCompositeImage(int width, int height) {
        drawImage(imageData, shiftX, shiftY);

    }

    /**
     * Return the size of the shifted image and cache it
     * 
     * @return Point with the size of the shifted image 
     * 
     * @see org.eclipse.jface.resource.CompositeImageDescriptor#getSize()
     */
    protected Point getSize() {
        if (size == null) {
            size = new Point(imageData.width + shiftX, imageData.height + shiftY);
        }
        return size;
    }
}