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/*******************************************************************************
 * Copyright (c) 2000, 2008, 2012 IBM Corporation, Gerhardt Informatics Kft. 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
 *     Gerhardt Informatics Kft. - GEFGWT port
 *******************************************************************************/
package org.eclipse.swt.custom;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Layout;
import org.eclipse.swt.widgets.ScrollBar;

/**
 * This class provides the layout for ScrolledComposite
 * 
 * @see ScrolledComposite
 */
class ScrolledCompositeLayout extends Layout {

	boolean inLayout = false;
	static final int DEFAULT_WIDTH = 64;
	static final int DEFAULT_HEIGHT = 64;

	protected Point computeSize(Composite composite, int wHint, int hHint,
			boolean flushCache) {
		ScrolledComposite sc = (ScrolledComposite) composite;
		Point size = new Point(DEFAULT_WIDTH, DEFAULT_HEIGHT);
		if (sc.content != null) {
			Point preferredSize = sc.content.computeSize(wHint, hHint,
					flushCache);
			Point currentSize = sc.content.getSize();
			size.x = sc.getExpandHorizontal() ? preferredSize.x : currentSize.x;
			size.y = sc.getExpandVertical() ? preferredSize.y : currentSize.y;
		}
		size.x = Math.max(size.x, sc.minWidth);
		size.y = Math.max(size.y, sc.minHeight);
		if (wHint != SWT.DEFAULT)
			size.x = wHint;
		if (hHint != SWT.DEFAULT)
			size.y = hHint;
		return size;
	}

	protected boolean flushCache(Control control) {
		return true;
	}

	protected void layout(Composite composite, boolean flushCache) {
		if (inLayout)
			return;
		ScrolledComposite sc = (ScrolledComposite) composite;
		if (sc.content == null)
			return;
		ScrollBar hBar = sc.getHorizontalBar();
		ScrollBar vBar = sc.getVerticalBar();
		if (hBar != null) {
			if (hBar.getSize().y >= sc.getSize().y) {
				return;
			}
		}
		if (vBar != null) {
			if (vBar.getSize().x >= sc.getSize().x) {
				return;
			}
		}
		inLayout = true;
		Rectangle contentRect = sc.content.getBounds();
		if (!sc.alwaysShowScroll) {
			boolean hVisible = sc.needHScroll(contentRect, false);
			boolean vVisible = sc.needVScroll(contentRect, hVisible);
			if (!hVisible && vVisible)
				hVisible = sc.needHScroll(contentRect, vVisible);
			if (hBar != null)
				hBar.setVisible(hVisible);
			if (vBar != null)
				vBar.setVisible(vVisible);
		}
		Rectangle hostRect = sc.getClientArea();
		if (sc.expandHorizontal) {
			contentRect.width = Math.max(sc.minWidth, hostRect.width);
		}
		if (sc.expandVertical) {
			contentRect.height = Math.max(sc.minHeight, hostRect.height);
		}

		if (hBar != null) {
			hBar.setMaximum(contentRect.width);
			hBar.setThumb(Math.min(contentRect.width, hostRect.width));
			int hPage = contentRect.width - hostRect.width;
			int hSelection = hBar.getSelection();
			if (hSelection >= hPage) {
				if (hPage <= 0) {
					hSelection = 0;
					hBar.setSelection(0);
				}
				contentRect.x = -hSelection;
			}
		}

		if (vBar != null) {
			vBar.setMaximum(contentRect.height);
			vBar.setThumb(Math.min(contentRect.height, hostRect.height));
			int vPage = contentRect.height - hostRect.height;
			int vSelection = vBar.getSelection();
			if (vSelection >= vPage) {
				if (vPage <= 0) {
					vSelection = 0;
					vBar.setSelection(0);
				}
				contentRect.y = -vSelection;
			}
		}

		sc.content.setBounds(contentRect);
		inLayout = false;
	}
}