/*******************************************************************************

 * Copyright (c) 2000, 2006 IBM Corporation and others.

 * Portion Copyright (c) 2008 Nokia Corporation and/or its subsidiary(-ies).

 * 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

 *     Nokia Corporation - Qt implementation

 *******************************************************************************/

package org.eclipse.swt.widgets;

import org.eclipse.swt.graphics.Rectangle;

import org.eclipse.swt.internal.qt.OS;

/**

 * Instances of this class provide a surface for drawing

 * arbitrary graphics.

 * <dl>

 * <dt><b>Styles:</b></dt>

 * <dd>(none)</dd>

 * <dt><b>Events:</b></dt>

 * <dd>(none)</dd>

 * </dl>

 * <p>

 * This class may be subclassed by custom control implementors

 * who are building controls that are <em>not</em> constructed

 * from aggregates of other controls. That is, they are either

 * painted using SWT graphics calls or are handled by native

 * methods.

 * </p>

 *

 * @see Composite

 */

public class Canvas extends Composite {

Canvas () {}

/**

 * Constructs a new instance of this class given its parent

 * and a style value describing its behavior and appearance.

 * <p>

 * The style value is either one of the style constants defined in

 * class <code>SWT</code> which is applicable to instances of this

 * class, or must be built by <em>bitwise OR</em>'ing together 

 * (that is, using the <code>int</code> "|" operator) two or more

 * of those <code>SWT</code> style constants. The class description

 * lists the style constants that are applicable to the class.

 * Style bits are also inherited from superclasses.

 * </p>

 *

 * @param parent a composite control which will be the parent of the new instance (cannot be null)

 * @param style the style of control to construct

 *

 * @exception IllegalArgumentException <ul>

 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>

 * </ul>

 * @exception SWTException <ul>

 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>

 * </ul>

 *

 * @see SWT

 * @see Widget#checkSubclass

 * @see Widget#getStyle

 */

public Canvas (Composite parent, int style) {

	super (parent, style);

}

/**

 * Scrolls a rectangular area of the receiver by first copying 

 * the source area to the destination and then causing the area

 * of the source which is not covered by the destination to

 * be repainted. Children that intersect the rectangle are

 * optionally moved during the operation. In addition, outstanding

 * paint events are flushed before the source area is copied to

 * ensure that the contents of the canvas are drawn correctly.

 *

 * @param destX the x coordinate of the destination

 * @param destY the y coordinate of the destination

 * @param x the x coordinate of the source

 * @param y the y coordinate of the source

 * @param width the width of the area

 * @param height the height of the area

 * @param all <code>true</code>if children should be scrolled, and <code>false</code> otherwise

 *

 * @exception SWTException <ul>

 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>

 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>

 * </ul>

 */

public void scroll (int destX, int destY, int x, int y, int width, int height, boolean all) {

	checkWidget();

    if (width <= 0 || height <= 0)

        return;

    int deltaX = destX - x, deltaY = destY - y;

    if (deltaX == 0 && deltaY == 0)

        return;

    if (!isVisible())

        return;

    _update();

    if(isDisposed()) return;

    OS.QWidget_scroll(handle, deltaX, deltaY, x, y, width, height);

    if (all) {

        Control[] children = _getChildren();

        for (int i = 0; i < children.length; i++) {

            Control child = children[i];

            Rectangle rect = child.getBounds();

            if (Math.min(x + width, rect.x + rect.width) >= Math.max(x, rect.x)

                    && Math.min(y + height, rect.y + rect.height) >= Math.max(

                            y, rect.y)) {

                child.setLocation(rect.x + deltaX, rect.y + deltaY);

            }

        }

    }

}

void setTraversalFlags_pp(int type, int key, int modifier, int character) {

    // Canvas by default doesn't traverse. This is the SWT behavior and it's

    // there to better support custom controls. If Canvas would traverse then a

    // custom control would have to explicitly undo all unwanted key handling.

    traverseDoit = false;

    traverseCancel = true;

    return;

}

}