bundles/org.eclipse.draw2d/src/org/eclipse/draw2d/ScrollPaneLayout.java

/*******************************************************************************
 * Copyright (c) 2000, 2010 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.draw2d;

import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Insets;
import org.eclipse.draw2d.geometry.Rectangle;

/**
 * The ScrollPaneLayout is responsible for laying out the {@link Viewport} and
 * {@link ScrollBar ScrollBars} of a {@link ScrollPane}.
 */
public class ScrollPaneLayout extends AbstractHintLayout {

	/** @see ScrollPane#NEVER */
	protected static final int NEVER = ScrollPane.NEVER;
	/** @see ScrollPane#AUTOMATIC */
	protected static final int AUTO = ScrollPane.AUTOMATIC;
	/** @see ScrollPane#ALWAYS */
	protected static final int ALWAYS = ScrollPane.ALWAYS;

	/**
	 * @see AbstractHintLayout#calculateMinimumSize(IFigure, int, int)
	 */
	public Dimension calculateMinimumSize(IFigure figure, int w, int h) {
		ScrollPane scrollpane = (ScrollPane) figure;
		Insets insets = scrollpane.getInsets();
		Dimension d = scrollpane.getViewport().getMinimumSize(w, h);
		return d.getExpanded(insets.getWidth(), insets.getHeight());
	}

	/**
	 * Calculates and returns the preferred size of the container based on the
	 * given hints. If the given ScrollPane's (<i>container</i>) horizontal and
	 * vertical scroll bar visibility is not {@link ScrollPane#NEVER}, then
	 * space for those bars is always deducted from the hints (whether or not we
	 * actually need the scroll bars).
	 * 
	 * @param container
	 *            the ScrollPane whose preferred size needs to be calculated
	 * @param wHint
	 *            the width hint
	 * @param hHint
	 *            the height hint
	 * @return the preferred size of the given container
	 * @since 2.0
	 */
	protected Dimension calculatePreferredSize(IFigure container, int wHint,
			int hHint) {
		ScrollPane scrollpane = (ScrollPane) container;
		ScrollBar hBar = scrollpane.getHorizontalScrollBar();
		ScrollBar vBar = scrollpane.getVerticalScrollBar();
		Insets insets = scrollpane.getInsets();

		int reservedWidth = insets.getWidth();
		int reservedHeight = insets.getHeight();

		if (scrollpane.getVerticalScrollBarVisibility() != ScrollPane.NEVER)
			reservedWidth += vBar.getPreferredSize().width;
		if (scrollpane.getHorizontalScrollBarVisibility() != ScrollPane.NEVER)
			reservedHeight += hBar.getPreferredSize().height;

		if (wHint > -1)
			wHint = Math.max(0, wHint - reservedWidth);
		if (hHint > -1)
			hHint = Math.max(0, hHint - reservedHeight);

		return scrollpane.getViewport().getPreferredSize(wHint, hHint)
				.getExpanded(reservedWidth, reservedHeight);
	}

	/**
	 * @see org.eclipse.draw2d.LayoutManager#layout(IFigure)
	 */
	public void layout(IFigure parent) {
		ScrollPane scrollpane = (ScrollPane) parent;
		Viewport viewport = scrollpane.getViewport();
		ScrollBar hBar = scrollpane.getHorizontalScrollBar(), vBar = scrollpane
				.getVerticalScrollBar();

		ScrollPaneSolver.Result result = ScrollPaneSolver.solve(
				parent.getClientArea(), viewport,
				scrollpane.getHorizontalScrollBarVisibility(),
				scrollpane.getVerticalScrollBarVisibility(),
				vBar.getPreferredSize().width, hBar.getPreferredSize().height);

		if (result.showV) {
			vBar.setBounds(new Rectangle(result.viewportArea.right(),
					result.viewportArea.y, result.insets.right,
					result.viewportArea.height));
		}
		if (result.showH) {
			hBar.setBounds(new Rectangle(result.viewportArea.x,
					result.viewportArea.bottom(), result.viewportArea.width,
					result.insets.bottom));
		}
		vBar.setVisible(result.showV);
		hBar.setVisible(result.showH);

		int vStepInc = vBar.getStepIncrement();
		int vPageInc = vBar.getRangeModel().getExtent() - vStepInc;
		if (vPageInc < vStepInc)
			vPageInc = vStepInc;
		vBar.setPageIncrement(vPageInc);

		int hStepInc = hBar.getStepIncrement();
		int hPageInc = hBar.getRangeModel().getExtent() - hStepInc;
		if (hPageInc < hStepInc)
			hPageInc = hStepInc;
		hBar.setPageIncrement(hPageInc);
	}

}