ghostpreview.java

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/*
 * Created on May 5, 2005
 */
package org.flexdock.docking.drag.preview;

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Component;
import java.awt.Composite;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.util.Map;

import org.flexdock.docking.Dockable;
import org.flexdock.docking.DockingPort;
import org.flexdock.docking.drag.effects.DefaultPreview;
import org.flexdock.util.SwingUtility;

/**
 * @author Christopher Butler
 */
public class GhostPreview extends DefaultPreview {
	private static final String PREVIOUS_BOUNDS = "TestPreview.PREVIOUS_BOUNDS";
	private static final String PREVIEW_IMG = "TestPreview.PREVIEW_IMG";

	public Polygon createPreviewPolygon(Component dockable, DockingPort port, Dockable hover, String targetRegion, Component paintingTarget, Map dragInfo) {
		// create the standard preview polygon
		Polygon polygon = super.createPreviewPolygon(dockable, port, hover, targetRegion, paintingTarget, dragInfo);
		if(polygon==null)
			return null;
		
		// check to see if the current polygon bounds differ from the 
		// last time we calculated them.
		Rectangle prevBounds = (Rectangle)dragInfo.get(PREVIOUS_BOUNDS);
		Rectangle bounds = polygon.getBounds();
		// if the polygon bounds have changed, create a new BufferedImage
		// to represent the dockable preview.  this image will be used
		// in drawPreview()
		if(!bounds.equals(prevBounds)) {
			// store the original dockable size
			Dimension origSize = dockable.getSize();
			// change the dockable to match the preview size while
			// we generate an image off of it
			dockable.setSize(bounds.getSize());
			BufferedImage img = SwingUtility.createImage(dockable);
			// store the image for use in drawPreview()
			dragInfo.put(PREVIEW_IMG, img);
			// restore the original dockable size
			dockable.setSize(origSize);
		}
		// store the current preview bounds so we'll know the next time we need 
		// to regenerate the preview image
		dragInfo.put(PREVIOUS_BOUNDS, bounds);
		// return the polygon
		return polygon;
	}
	
	public void drawPreview(Graphics2D g, Polygon poly, Dockable dockable, Map dragInfo) {
		// grab the preview image created in createPreviewPolygon()
		BufferedImage image = (BufferedImage)dragInfo.get(PREVIEW_IMG);
		if(image==null)
			return;
		
		// create a solid preview outline
		Rectangle bounds = poly.getBounds();
		g.setColor(Color.BLACK);
		g.drawRect(bounds.x, bounds.y, bounds.width, bounds.height);
		
		// make the graphics 50% translucent
		Composite composite = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f); 
		g.setComposite(composite);
		// now draw the preview image
		g.drawImage(image, bounds.x, bounds.y, null);
	}
	
	protected Rectangle createTabbedPaneRect(DockingPort port, Component hover) {
		if(hover!=null)
			return hover.getBounds();
		return super.createTabbedPaneRect(port, hover);
	}
}