/*******************************************************************************
 * Copyright (c) 2000, 2005 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
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.draw2d.AbstractHintLayout;

import dwt.dwthelper.utils;

import dwtx.draw2d.geometry.Dimension;
import dwtx.draw2d.AbstractLayout;
import dwtx.draw2d.IFigure;


/**
 * The foundation for layout managers which are sensitive to width and/or height hints.
 * This class will cache preferred and minimum sizes for a given set of hints. If the
 * hints change in a meaningful way, the cached size is thrown out and redetermined.
 * <P>
 * Subclasses may be sensitive to one or both hints. By default, this class assumes both
 * hints are important. Subclasses may override this behavior in {@link
 * #isSensitiveHorizontally(IFigure)} and {@link #isSensitiveVertically(IFigure)}. At
 * least one of these method should return <code>true</code>.
 *
 * @author hudsonr
 * @since 2.0
 */
public abstract class AbstractHintLayout
    : AbstractLayout
{

private Dimension minimumSize = null;
private Dimension cachedPreferredHint;
private Dimension cachedMinimumHint;

this(){
    cachedPreferredHint = new Dimension(-1, -1);
    cachedMinimumHint = new Dimension(-1, -1);
}
/**
 * Calculates the minimum size using the given width and height hints. This method is
 * called from {@link #getMinimumSize(IFigure, int, int)} whenever the cached minimum size
 * has been flushed.
 * <P>
 * By default, this method just calls {@link #getPreferredSize(IFigure, int, int)},
 * meaning minimum and preferres sizes will be the same unless this method is overridden.
 *
 * @param container the Figure on which this layout is installed
 * @param wHint the width hint
 * @param hHint the height hint
 *
 * @return the layout's minimum size
 */
protected Dimension calculateMinimumSize(IFigure container, int wHint, int hHint) {
    return getPreferredSize(container, wHint, hHint);
}

/**
 * @see dwtx.draw2d.LayoutManager#getMinimumSize(IFigure, int, int)
 */
public Dimension getMinimumSize(IFigure container, int w, int h) {
    bool flush = cachedMinimumHint.width !is w
        && isSensitiveHorizontally(container);
    flush |= cachedMinimumHint.height !is h
        && isSensitiveVertically(container);
    if (flush) {
        minimumSize = null;
        cachedMinimumHint.width = w;
        cachedMinimumHint.height = h;
    }
    if (minimumSize is null)
        minimumSize = calculateMinimumSize(container, w, h);
    return minimumSize;
}

/**
 * @see dwtx.draw2d.LayoutManager#getPreferredSize(IFigure, int, int)
 */
public final Dimension getPreferredSize(IFigure container, int w, int h) {
    bool flush = cachedPreferredHint.width !is w
        && isSensitiveHorizontally(container);
    flush |= cachedPreferredHint.height !is h
        && isSensitiveVertically(container);
    if (flush) {
        preferredSize = null;
        cachedPreferredHint.width = w;
        cachedPreferredHint.height = h;
    }
    return super.getPreferredSize(container, w, h);
}

/**
 * Extends the superclass implementation to flush the cached minimum size.
 * @see dwtx.draw2d.LayoutManager#invalidate()
 */
public void invalidate() {
    minimumSize = null;
    super.invalidate();
}

/**
 * Returns whether this layout manager is sensitive to changes in the horizontal hint. By
 * default, this method returns <code>true</code>.
 * @param container the layout's container
 * @return <code>true</code> if this layout is sensite to horizontal hint changes
 */
protected bool isSensitiveHorizontally(IFigure container) {
    return true;
}

/**
 * Returns whether this layout manager is sensitive to changes in the vertical hint. By
 * default, this method returns <code>true</code>.
 * @param container the layout's container
 * @return <code>true</code> if this layout is sensite to vertical hint changes
 */
protected bool isSensitiveVertically(IFigure container) {
    return true;
}

}