OverlayScrollPaneLayout.java

/*******************************************************************************
 * Copyright (c) 2000, 2007 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.gef.internal.ui.palette.editparts;

import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.ScrollBar;
import org.eclipse.draw2d.ScrollPane;
import org.eclipse.draw2d.ScrollPaneLayout;
import org.eclipse.draw2d.Viewport;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Insets;
import org.eclipse.draw2d.geometry.Rectangle;

public class OverlayScrollPaneLayout
	extends ScrollPaneLayout
{

/**
 * {@inheritDoc}
 * In OverlayScrollPane, scrollbars are overlayed on top of the Viewport,
 * so the preferred size is just the Viewports preferred size.
 * @since 2.0
 */
protected Dimension calculatePreferredSize(IFigure container, int wHint, int hHint) {
	ScrollPane scrollpane = (ScrollPane)container;
	Insets insets = scrollpane.getInsets();

	int excludedWidth = insets.getWidth();
	int excludedHeight = insets.getHeight();

	return scrollpane
		.getViewport()
		.getPreferredSize(wHint - excludedWidth, hHint - excludedHeight)
		.getExpanded(excludedWidth, excludedHeight);
}

/**{@inheritDoc}*/
public void layout(IFigure parent) {
	ScrollPane scrollpane = (ScrollPane)parent;
	Rectangle clientArea = parent.getClientArea();

	ScrollBar hBar = scrollpane.getHorizontalScrollBar(),
		    vBar = scrollpane.getVerticalScrollBar();
	Viewport viewport = scrollpane.getViewport();

	Insets insets = new Insets();
	insets.bottom = hBar.getPreferredSize(clientArea.width, clientArea.height).height;
	insets.right  = vBar.getPreferredSize(clientArea.width, clientArea.height).width;

	int hVis = scrollpane.getHorizontalScrollBarVisibility(),
	    vVis = scrollpane.getVerticalScrollBarVisibility();

	Dimension available = clientArea.getSize(),
		preferred =
			viewport.getPreferredSize(available.width, available.height).getCopy();

	boolean none = available.contains(preferred),
		  both = !none && vVis != NEVER && hVis != NEVER && preferred.contains(available),
		  showV = both || preferred.height > available.height,
		  showH = both || preferred.width > available.width;

	//Adjust for visibility override flags
	showV = !(vVis == NEVER) && (showV || vVis == ALWAYS);
	showH = !(hVis == NEVER) && (showH || hVis == ALWAYS);

	if (!showV) insets.right = 0;
	if (!showH) insets.bottom = 0;
	Rectangle bounds, viewportArea = clientArea;

	if (showV) {
		bounds = new Rectangle(
			viewportArea.right() - insets.right,
			viewportArea.y, insets.right, viewportArea.height);
		vBar.setBounds(bounds);
		//vBar.setMaximum(preferred.height);
	}
	if (showH) {
		bounds = new Rectangle(viewportArea.x, 
			viewportArea.bottom() - insets.bottom,
			viewportArea.width, insets.bottom);
		hBar.setBounds(bounds);
		//hBar.setMaximum(preferred.width);
	}
	vBar.setVisible(showV);
	hBar.setVisible(showH);
	viewport.setBounds(viewportArea);
}

}