/*******************************************************************************
 * Copyright (c) 2000, 2008 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.swt.widgets;


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

import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;

/**
 * Instances of this class are controls which are capable
 * of containing other controls.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>NO_BACKGROUND, NO_FOCUS, NO_MERGE_PAINTS, NO_REDRAW_RESIZE, NO_RADIO_GROUP, EMBEDDED, DOUBLE_BUFFERED</dd>
 * <dt><b>Events:</b></dt>
 * <dd>(none)</dd>
 * </dl>
 * <p>
 * Note: The <code>NO_BACKGROUND</code>, <code>NO_FOCUS</code>, <code>NO_MERGE_PAINTS</code>,
 * and <code>NO_REDRAW_RESIZE</code> styles are intended for use with <code>Canvas</code>.
 * They can be used with <code>Composite</code> if you are drawing your own, but their
 * behavior is undefined if they are used with subclasses of <code>Composite</code> other
 * than <code>Canvas</code>.
 * </p><p>
 * Note: The <code>CENTER</code> style, although undefined for composites, has the
 * same value as <code>EMBEDDED</code> which is used to embed widgets from other
 * widget toolkits into SWT.  On some operating systems (GTK, Motif), this may cause
 * the children of this composite to be obscured.
 * </p><p>
 * This class may be subclassed by custom control implementors
 * who are building controls that are constructed from aggregates
 * of other controls.
 * </p>
 *
 * @see Canvas
 * @see <a href="http://www.eclipse.org/swt/snippets/#composite">Composite snippets</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */
public class Composite extends Scrollable {
	Layout layout;
	Control[] tabList;
	int scrolledVisibleRgn, siblingsVisibleRgn;
	int layoutCount, backgroundMode;

Composite () {
	/* Do nothing */
}

/**
 * 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 widget which will be the parent of the new instance (cannot be null)
 * @param style the style of widget 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#NO_BACKGROUND
 * @see SWT#NO_FOCUS
 * @see SWT#NO_MERGE_PAINTS
 * @see SWT#NO_REDRAW_RESIZE
 * @see SWT#NO_RADIO_GROUP
 * @see SWT#EMBEDDED
 * @see SWT#DOUBLE_BUFFERED
 * @see Widget#getStyle
 */
public Composite (Composite parent, int style) {
	super (parent, style);
}

Control [] _getChildren () {
	short [] buffer = new short [1];
	OS.CountSubControls (handle, buffer);
	int count = buffer [0];
	Control [] children = new Control [count];
	int i = 0, j = 0;
	int child = OS.HIViewGetFirstSubview (handle);
	while (i < count) {
		if (child != 0) {
			Widget widget = display.getWidget (child);
			if (widget != null && widget != this) {
				if (widget instanceof Control) {
					children [j++] = (Control) widget;
				}
			}
		}
		child = OS.HIViewGetNextView (child);
		i++;
	}
	if (j == count) return children;
	Control [] newChildren = new Control [j];
	System.arraycopy (children, 0, newChildren, 0, j);
	return newChildren;
}

Control [] _getTabList () {
	if (tabList == null) return null;
	int count = 0;
	for (int i=0; i<tabList.length; i++) {
		if (!tabList [i].isDisposed ()) count++;
	}
	if (count == tabList.length) return tabList;
	Control [] newList = new Control [count];
	int index = 0;
	for (int i=0; i<tabList.length; i++) {
		if (!tabList [i].isDisposed ()) {
			newList [index++] = tabList [i];
		}
	}
	tabList = newList;
	return tabList;
}

int callFocusEventHandler (int nextHandler, int theEvent) {
	if ((state & CANVAS) != 0) return OS.noErr;
	return super.callFocusEventHandler (nextHandler, theEvent);
}

/**
 * Clears any data that has been cached by a Layout for all widgets that 
 * are in the parent hierarchy of the changed control up to and including the 
 * receiver.  If an ancestor does not have a layout, it is skipped.
 * 
 * @param changed an array of controls that changed state and require a recalculation of size
 * 
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the changed array is null any of its controls are null or have been disposed</li> 
 *    <li>ERROR_INVALID_PARENT - if any control in changed is not in the widget tree of the receiver</li>
 * </ul>
 * @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>
 *
 * @since 3.1
 */
public void changed (Control[] changed) {
	checkWidget ();
	if (changed == null) error (SWT.ERROR_INVALID_ARGUMENT);
	for (int i=0; i<changed.length; i++) {
		Control control = changed [i];
		if (control == null) error (SWT.ERROR_INVALID_ARGUMENT);
		if (control.isDisposed ()) error (SWT.ERROR_INVALID_ARGUMENT);
		boolean ancestor = false;
		Composite composite = control.parent;
		while (composite != null) {
			ancestor = composite == this;
			if (ancestor) break;
			composite = composite.parent;
		}
		if (!ancestor) error (SWT.ERROR_INVALID_PARENT);
	}
	for (int i=0; i<changed.length; i++) {
		Control child = changed [i];
		Composite composite = child.parent;
		while (child != this) {
			if (composite.layout == null || !composite.layout.flushCache (child)) {
				composite.state |= LAYOUT_CHANGED;
			}
			child = composite;
			composite = child.parent;
		}
	}
}

public Point computeSize (int wHint, int hHint, boolean changed) {
	checkWidget();
	Point size;
	if (layout != null) {
		if ((wHint == SWT.DEFAULT) || (hHint == SWT.DEFAULT)) {
			changed |= (state & LAYOUT_CHANGED) != 0;
			size = layout.computeSize (this, wHint, hHint, changed);
			state &= ~LAYOUT_CHANGED;
		} else {
			size = new Point (wHint, hHint);
		}
	} else {
		size = minimumSize (wHint, hHint, changed);
	}
	if (size.x == 0) size.x = DEFAULT_WIDTH;
	if (size.y == 0) size.y = DEFAULT_HEIGHT;
	if (wHint != SWT.DEFAULT) size.x = wHint;
	if (hHint != SWT.DEFAULT) size.y = hHint;
	Rectangle trim = computeTrim (0, 0, size.x, size.y);
	return new Point (trim.width, trim.height);
}

protected void checkSubclass () {
	/* Do nothing - Subclassing is allowed */
}

Control [] computeTabList () {
	Control result [] = super.computeTabList ();
	if (result.length == 0) return result;
	Control [] list = tabList != null ? _getTabList () : _getChildren ();
	for (int i=0; i<list.length; i++) {
		Control child = list [i];
		Control [] childList = child.computeTabList ();
		if (childList.length != 0) {
			Control [] newResult = new Control [result.length + childList.length];
			System.arraycopy (result, 0, newResult, 0, result.length);
			System.arraycopy (childList, 0, newResult, result.length, childList.length);
			result = newResult;
		}
	}
	return result;
}

void createHandle () {
	state |= CANVAS | GRAB;
	boolean scrolled = (style & (SWT.H_SCROLL | SWT.V_SCROLL)) != 0;
	if (!scrolled)  state |= THEME_BACKGROUND;
	if (scrolled || (style & SWT.BORDER) != 0) {
		createScrolledHandle (parent.handle);
	} else {
		createHandle (parent.handle);
	}
}

void createHandle (int parentHandle) {
	int features = OS.kControlSupportsEmbedding | OS.kControlSupportsFocus;
	int [] outControl = new int [1];
	int window = OS.GetControlOwner (parentHandle);
	OS.CreateUserPaneControl (window, null, features, outControl);
	if (outControl [0] == 0) error (SWT.ERROR_NO_HANDLES);
	handle = outControl [0];
	OS.HIObjectSetAccessibilityIgnored (handle, true);
}

void createScrolledHandle (int parentHandle) {
	int features = OS.kControlSupportsEmbedding;
	int [] outControl = new int [1];
	int window = OS.GetControlOwner (parentHandle);
	OS.CreateUserPaneControl (window, null, features, outControl);
	if (outControl [0] == 0) error (SWT.ERROR_NO_HANDLES);
	scrolledHandle = outControl [0];
	outControl [0] = 0;
	features |= OS.kControlSupportsFocus;
	OS.CreateUserPaneControl (window, null, features, outControl);
	if (outControl [0] == 0) error (SWT.ERROR_NO_HANDLES);
	handle = outControl [0];
	OS.HIObjectSetAccessibilityIgnored (scrolledHandle, true);
	OS.HIObjectSetAccessibilityIgnored (handle, true);
}

void drawBackground (int control, int context) {
	if (control == scrolledHandle) {
		Composite parent = this;
		Shell shell = getShell ();
		if (shell != this) parent = this.parent;
		boolean drawBackground = (style & SWT.TRANSPARENT) == 0;
		if ((style & SWT.NO_FOCUS) == 0 && hooksKeys ()) {
			parent.drawFocus (control, context, hasFocus () && drawFocusRing (), hasBorder (), drawBackground, inset ());
		} else {
			if (hasBorder ()) {
				parent.drawFocus (control, context, false, hasBorder (), drawBackground, inset ());
			} else {
				parent.fillBackground (control, context, null);
			}
		}
	} else {
		if ((state & CANVAS) != 0) {
			if ((style & (SWT.NO_BACKGROUND | SWT.TRANSPARENT)) == 0) {
				fillBackground (control, context, null);
			}	
		}
	}
}

void enableWidget (boolean enabled) {
	//NOT DONE - take into account current scroll bar state
	if ((state & CANVAS) != 0) {
		if (horizontalBar != null) horizontalBar.enableWidget (enabled);
		if (verticalBar != null) verticalBar.enableWidget (enabled);
		return;
	}
	super.enableWidget (enabled);
}

Composite findDeferredControl () {
	return layoutCount > 0 ? this : parent.findDeferredControl ();
}

Menu [] findMenus (Control control) {
	if (control == this) return new Menu [0];
	Menu result [] = super.findMenus (control);
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
		Control child = children [i];
		Menu [] menuList = child.findMenus (control);
		if (menuList.length != 0) {
			Menu [] newResult = new Menu [result.length + menuList.length];
			System.arraycopy (result, 0, newResult, 0, result.length);
			System.arraycopy (menuList, 0, newResult, result.length, menuList.length);
			result = newResult;
		}
	}
	return result;
}

void fixChildren (Shell newShell, Shell oldShell, Decorations newDecorations, Decorations oldDecorations, Menu [] menus) {
	super.fixChildren (newShell, oldShell, newDecorations, oldDecorations, menus);
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
		children [i].fixChildren (newShell, oldShell, newDecorations, oldDecorations, menus);
	}
}

void fixTabList (Control control) {
	if (tabList == null) return;
	int count = 0;
	for (int i=0; i<tabList.length; i++) {
		if (tabList [i] == control) count++;
	}
	if (count == 0) return;
	Control [] newList = null;
	int length = tabList.length - count;
	if (length != 0) {
		newList = new Control [length];
		int index = 0;
		for (int i=0; i<tabList.length; i++) {
			if (tabList [i] != control) {
				newList [index++] = tabList [i];
			}
		}
	}
	tabList = newList;
}

/**
 * Returns the receiver's background drawing mode. This
 * will be one of the following constants defined in class
 * <code>SWT</code>:
 * <code>INHERIT_NONE</code>, <code>INHERIT_DEFAULT</code>,
 * <code>INHERTIT_FORCE</code>.
 *
 * @return the background mode
 *
 * @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>
 *
 * @see SWT
 * 
 * @since 3.2
 */
public int getBackgroundMode () {
	checkWidget ();
	return backgroundMode;
}

/**
 * Returns a (possibly empty) array containing the receiver's children.
 * Children are returned in the order that they are drawn.  The topmost
 * control appears at the beginning of the array.  Subsequent controls
 * draw beneath this control and appear later in the array.
 * <p>
 * Note: This is not the actual structure used by the receiver
 * to maintain its list of children, so modifying the array will
 * not affect the receiver. 
 * </p>
 *
 * @return an array of children
 * 
 * @see Control#moveAbove
 * @see Control#moveBelow
 *
 * @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 Control [] getChildren () {
	checkWidget();
	return _getChildren ();
}

int getChildrenCount () {
	/*
	* NOTE:  The current implementation will count
	* non-registered children.
	*/
	short [] count = new short [1];
	OS.CountSubControls (handle, count);
	return count [0];
}

/**
 * Returns layout which is associated with the receiver, or
 * null if one has not been set.
 *
 * @return the receiver's layout or null
 *
 * @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 Layout getLayout () {
	checkWidget();
	return layout;
}

/**
 * Returns <code>true</code> if the receiver has deferred
 * the performing of layout, and <code>false</code> otherwise.
 *
 * @return the receiver's deferred layout state
 *
 * @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>
 * 
 * @see #setLayoutDeferred(boolean)
 * @see #isLayoutDeferred()
 *
 * @since 3.1
 */
public boolean getLayoutDeferred () {
	checkWidget ();
	return layoutCount > 0 ;
}

/**
 * Gets the (possibly empty) tabbing order for the control.
 *
 * @return tabList the ordered list of controls representing the tab order
 *
 * @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>
 * 
 * @see #setTabList
 */
public Control [] getTabList () {
	checkWidget ();
	Control [] tabList = _getTabList ();
	if (tabList == null) {
		int count = 0;
		Control [] list =_getChildren ();
		for (int i=0; i<list.length; i++) {
			if (list [i].isTabGroup ()) count++;
		}
		tabList = new Control [count];
		int index = 0;
		for (int i=0; i<list.length; i++) {
			if (list [i].isTabGroup ()) {
				tabList [index++] = list [i];
			}
		}
	}
	return tabList;
}

int getVisibleRegion (int control, boolean clipChildren) {
	if (!clipChildren && control == handle) {
		if (siblingsVisibleRgn == 0) {
			siblingsVisibleRgn = OS.NewRgn ();
			calculateVisibleRegion (control, siblingsVisibleRgn, clipChildren);
		}
		int result = OS.NewRgn ();
		OS.CopyRgn (siblingsVisibleRgn, result);
		return result;
	}
	if (control == scrolledHandle) {
		if (!clipChildren) return super.getVisibleRegion (control, clipChildren);
		if (scrolledVisibleRgn == 0) {
			scrolledVisibleRgn = OS.NewRgn ();
			calculateVisibleRegion (control, scrolledVisibleRgn, clipChildren);
		}
		int result = OS.NewRgn ();
		OS.CopyRgn (scrolledVisibleRgn, result);
		return result;
	}
	return super.getVisibleRegion (control, clipChildren);
}

int kEventControlClick (int nextHandler, int theEvent, int userData) {
	int result = super.kEventControlClick (nextHandler, theEvent, userData);
	if (result == OS.noErr) return result;
	if ((state & CANVAS) != 0) {
		if (!isEnabled ()) return result;
		if ((style & SWT.NO_FOCUS) == 0 && hooksKeys ()) {
			int [] theControl = new int [1];
			int window = OS.GetControlOwner (handle);
			OS.GetKeyboardFocus (window, theControl);
			if (handle != theControl [0]) {
				short [] count = new short [1];
				OS.CountSubControls (handle, count);
				if (count [0] == 0) {
					if (OS.SetKeyboardFocus (window, handle, (short) focusPart ()) == OS.noErr) {
						return OS.noErr;
					}
				}
			}
		}
	}
	return result;
}

int kEventControlGetFocusPart (int nextHandler, int theEvent, int userData) {
	if ((state & CANVAS) != 0) return OS.noErr;
	return super.kEventControlGetFocusPart (nextHandler, theEvent, userData);
}

int kEventControlSetFocusPart (int nextHandler, int theEvent, int userData) {
	int result = super.kEventControlSetFocusPart (nextHandler, theEvent, userData);
	if (result == OS.noErr) {
		if ((state & CANVAS) != 0) {
			if (scrolledHandle != 0) {
				if ((style & SWT.NO_FOCUS) == 0 && hooksKeys ()) {
					short [] part = new short [1];
					OS.GetEventParameter (theEvent, OS.kEventParamControlPart, OS.typeControlPartCode, null, 2, null, part);
					redrawWidget (scrolledHandle, false);
				}
			}
		}
	}
	return result;
}

int kEventMouseDown (int nextHandler, int theEvent, int userData) {
	int result = super.kEventMouseDown (nextHandler, theEvent, userData);
	if (result == OS.noErr) return result;
	if ((state & CANVAS) != 0) {
		if ((style & SWT.NO_FOCUS) != 0) {
			Shell shell = getShell ();
			int bits = SWT.ON_TOP | SWT.NO_FOCUS;
			if ((shell.style & bits) == bits) return OS.noErr;
		}
	}
	return result;
}

int kEventRawKeyPressed (int nextHandler, int theEvent, int userData) {
	/*
	* For some reason the next event handler for embedded controls
	* stops the event chain and does not let the default handler
	* process the raw key event into unicode.  The fix to send
	* the key from kEventRawKeyDown instead.
	* 
	* Note: should the embedded control no longer stop the event
	* chain, there will be two key events issued for one key press.
	*/	
	if ((state & CANVAS) != 0  && (style & SWT.EMBEDDED) != 0) {
		int [] theControl = new int[1];
		OS.GetKeyboardFocus (OS.GetControlOwner(handle), theControl);
		if (theControl[0] != handle) {
			if (!sendKeyEvent (SWT.KeyDown, theEvent)) return OS.noErr;
			return OS.eventNotHandledErr;
		}
	}
	
	/*
	* Feature in the Macintosh.  For some reason, the default handler
	* does not issue kEventTextInputUnicodeForKeyEvent when the user
	* types Command+Space.  The fix is to look for this case and
	* send the key from kEventRawKeyDown instead.
	* 
	* NOTE: This code relies on Command+Space being consumed and
	* will deliver two events if this ever changes.
	*/	
	if ((state & CANVAS) != 0) {
		int [] keyCode = new int [1];
		OS.GetEventParameter (theEvent, OS.kEventParamKeyCode, OS.typeUInt32, null, keyCode.length * 4, null, keyCode);
		if (keyCode [0] == 49 /* Space */) {
			int [] modifiers = new int [1];
			OS.GetEventParameter (theEvent, OS.kEventParamKeyModifiers, OS.typeUInt32, null, 4, null, modifiers);
			if (modifiers [0] == OS.cmdKey) {
				if (!sendKeyEvent (SWT.KeyDown, theEvent)) return OS.noErr;
			}
		}
	}
	return OS.eventNotHandledErr;
}

int kEventUnicodeKeyPressed (int nextHandler, int theEvent, int userData) {
	int result = super.kEventUnicodeKeyPressed (nextHandler, theEvent, userData);
	if ((state & CANVAS) != 0) {
		int [] keyboardEvent = new int [1];
		OS.GetEventParameter (theEvent, OS.kEventParamTextInputSendKeyboardEvent, OS.typeEventRef, null, keyboardEvent.length * 4, null, keyboardEvent);
		int [] keyCode = new int [1];
		OS.GetEventParameter (keyboardEvent [0], OS.kEventParamKeyCode, OS.typeUInt32, null, keyCode.length * 4, null, keyCode);
		switch (keyCode [0]) {
			case 76: /* KP Enter */
			case 36: /* Return */
				/*
				* Feature in the Macintosh.  The default behaviour when the return key is pressed is
				* to select the default button.  This is not the expected behaviour for Composite and
				* its subclasses.  The fix is to avoid calling the default handler.
				*/
				return OS.noErr;
		}
	}
	return result;
}

boolean hooksKeys () {
	return hooks (SWT.KeyDown) || hooks (SWT.KeyUp);
}

void invalidateChildrenVisibleRegion (int control) {
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
		Control child = children [i];
		child.resetVisibleRegion (control);
		child.invalidateChildrenVisibleRegion (control);
	}
}

/**
 * Returns <code>true</code> if the receiver or any ancestor 
 * up to and including the receiver's nearest ancestor shell
 * has deferred the performing of layouts.  Otherwise, <code>false</code>
 * is returned.
 *
 * @return the receiver's deferred layout state
 *
 * @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>
 * 
 * @see #setLayoutDeferred(boolean)
 * @see #getLayoutDeferred()
 * 
 * @since 3.1
 */
public boolean isLayoutDeferred () {
	checkWidget ();
	return findDeferredControl () != null;
}

boolean isTabGroup () {
	if ((state & CANVAS) != 0) return true;
	return super.isTabGroup ();
}

/**
 * If the receiver has a layout, asks the layout to <em>lay out</em>
 * (that is, set the size and location of) the receiver's children. 
 * If the receiver does not have a layout, do nothing.
 * <p>
 * This is equivalent to calling <code>layout(true)</code>.
 * </p>
 * <p>
 * Note: Layout is different from painting. If a child is
 * moved or resized such that an area in the parent is
 * exposed, then the parent will paint. If no child is
 * affected, the parent will not paint.
 * </p>
 * 
 * @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 layout () {
	checkWidget ();
	layout (true);
}

/**
 * If the receiver has a layout, asks the layout to <em>lay out</em>
 * (that is, set the size and location of) the receiver's children. 
 * If the argument is <code>true</code> the layout must not rely
 * on any information it has cached about the immediate children. If it
 * is <code>false</code> the layout may (potentially) optimize the
 * work it is doing by assuming that none of the receiver's 
 * children has changed state since the last layout.
 * If the receiver does not have a layout, do nothing.
 * <p>
 * If a child is resized as a result of a call to layout, the 
 * resize event will invoke the layout of the child.  The layout
 * will cascade down through all child widgets in the receiver's widget 
 * tree until a child is encountered that does not resize.  Note that 
 * a layout due to a resize will not flush any cached information 
 * (same as <code>layout(false)</code>).
 * </p>
 * <p>
 * Note: Layout is different from painting. If a child is
 * moved or resized such that an area in the parent is
 * exposed, then the parent will paint. If no child is
 * affected, the parent will not paint.
 * </p>
 *
 * @param changed <code>true</code> if the layout must flush its caches, 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 layout (boolean changed) {
	checkWidget ();
	if (layout == null) return;
	layout (changed, false);
}

/**
 * If the receiver has a layout, asks the layout to <em>lay out</em>
 * (that is, set the size and location of) the receiver's children. 
 * If the changed argument is <code>true</code> the layout must not rely
 * on any information it has cached about its children. If it
 * is <code>false</code> the layout may (potentially) optimize the
 * work it is doing by assuming that none of the receiver's 
 * children has changed state since the last layout.
 * If the all argument is <code>true</code> the layout will cascade down
 * through all child widgets in the receiver's widget tree, regardless of
 * whether the child has changed size.  The changed argument is applied to 
 * all layouts.  If the all argument is <code>false</code>, the layout will
 * <em>not</em> cascade down through all child widgets in the receiver's widget 
 * tree.  However, if a child is resized as a result of a call to layout, the 
 * resize event will invoke the layout of the child.  Note that 
 * a layout due to a resize will not flush any cached information 
 * (same as <code>layout(false)</code>).
 * </p>
 * <p>
 * Note: Layout is different from painting. If a child is
 * moved or resized such that an area in the parent is
 * exposed, then the parent will paint. If no child is
 * affected, the parent will not paint.
 * </p>
 *
 * @param changed <code>true</code> if the layout must flush its caches, and <code>false</code> otherwise
 * @param all <code>true</code> if all children in the receiver's widget tree should be laid out, 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>
 *
 * @since 3.1
 */
public void layout (boolean changed, boolean all) {
	checkWidget ();
	if (layout == null && !all) return;
	markLayout (changed, all);
	updateLayout (all);
}

/**
 * Forces a lay out (that is, sets the size and location) of all widgets that 
 * are in the parent hierarchy of the changed control up to and including the 
 * receiver.  The layouts in the hierarchy must not rely on any information 
 * cached about the changed control or any of its ancestors.  The layout may 
 * (potentially) optimize the work it is doing by assuming that none of the 
 * peers of the changed control have changed state since the last layout.
 * If an ancestor does not have a layout, skip it.
 * <p>
 * Note: Layout is different from painting. If a child is
 * moved or resized such that an area in the parent is
 * exposed, then the parent will paint. If no child is
 * affected, the parent will not paint.
 * </p>
 * 
 * @param changed a control that has had a state change which requires a recalculation of its size
 * 
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the changed array is null any of its controls are null or have been disposed</li> 
 *    <li>ERROR_INVALID_PARENT - if any control in changed is not in the widget tree of the receiver</li>
 * </ul>
 * @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>
 *
 * @since 3.1
 */
public void layout (Control [] changed) {
	checkWidget ();
	if (changed == null) error (SWT.ERROR_INVALID_ARGUMENT);
	for (int i=0; i<changed.length; i++) {
		Control control = changed [i];
		if (control == null) error (SWT.ERROR_INVALID_ARGUMENT);
		if (control.isDisposed ()) error (SWT.ERROR_INVALID_ARGUMENT);
		boolean ancestor = false;
		Composite composite = control.parent;
		while (composite != null) {
			ancestor = composite == this;
			if (ancestor) break;
			composite = composite.parent;
		}
		if (!ancestor) error (SWT.ERROR_INVALID_PARENT);
	}
	int updateCount = 0;
	Composite [] update = new Composite [16];
	for (int i=0; i<changed.length; i++) {
		Control child = changed [i];
		Composite composite = child.parent;
		while (child != this) {
			if (composite.layout != null) {
				composite.state |= LAYOUT_NEEDED;
				if (!composite.layout.flushCache (child)) {
					composite.state |= LAYOUT_CHANGED;
				}
			}
			if (updateCount == update.length) {
				Composite [] newUpdate = new Composite [update.length + 16];
				System.arraycopy (update, 0, newUpdate, 0, update.length);
				update = newUpdate;
			}
			child = update [updateCount++] = composite;
			composite = child.parent;
		}
	}
	for (int i=updateCount-1; i>=0; i--) {
		update [i].updateLayout (false);
	}
}

void markLayout (boolean changed, boolean all) {
	if (layout != null) {
		state |= LAYOUT_NEEDED;
		if (changed) state |= LAYOUT_CHANGED;
	}
	if (all) {
		Control [] children = _getChildren ();
		for (int i=0; i<children.length; i++) {
			children [i].markLayout (changed, all);
		}
	}
}

Point minimumSize (int wHint, int Hint, boolean changed) {
	Control [] children = _getChildren ();
	int width = 0, height = 0;
	for (int i=0; i<children.length; i++) {
		Rectangle rect = children [i].getBounds ();
		width = Math.max (width, rect.x + rect.width);
		height = Math.max (height, rect.y + rect.height);
	}
	return new Point (width, height);
}

void releaseChildren (boolean destroy) {
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
		Control child = children [i];
		if (child != null && !child.isDisposed ()) {
			child.release (false);
		}
	}
	super.releaseChildren (destroy);
}

void releaseWidget () {
	super.releaseWidget ();
	if (scrolledVisibleRgn != 0) OS.DisposeRgn (scrolledVisibleRgn);
	if (siblingsVisibleRgn != 0) OS.DisposeRgn (siblingsVisibleRgn);
	siblingsVisibleRgn = scrolledVisibleRgn = 0;
	layout = null;
	tabList = null;
}

void removeControl (Control control) {
	fixTabList (control);
}

void resetVisibleRegion (int control) {
	if (scrolledVisibleRgn != 0) {
		OS.DisposeRgn (scrolledVisibleRgn);
		scrolledVisibleRgn = 0;
	}
	if (siblingsVisibleRgn != 0) {
		OS.DisposeRgn (siblingsVisibleRgn);
		siblingsVisibleRgn = 0;
	}
	super.resetVisibleRegion (control);
}

/**
 * Sets the background drawing mode to the argument which should
 * be one of the following constants defined in class <code>SWT</code>:
 * <code>INHERIT_NONE</code>, <code>INHERIT_DEFAULT</code>,
 * <code>INHERIT_FORCE</code>.
 *
 * @param mode the new background mode
 *
 * @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>
 *
 * @see SWT
 * 
 * @since 3.2
 */
public void setBackgroundMode (int mode) {
	checkWidget ();
	backgroundMode = mode;
	Control [] children = _getChildren ();
	for (int i = 0; i < children.length; i++) {
		children [i].updateBackgroundMode ();
	}
}

int setBounds (int x, int y, int width, int height, boolean move, boolean resize, boolean events) {
	int result = super.setBounds (x, y, width, height, move, resize, events);
	if (layout != null && (result & RESIZED) != 0) {
		markLayout (false, false);
		updateLayout (false);
	}
	return result;
}

public boolean setFocus () {
	checkWidget ();
	Control [] children = _getChildren ();
	for (int i= 0; i < children.length; i++) {
		if (children [i].setFocus ()) return true;
	}
	return super.setFocus ();
}

/**
 * Sets the layout which is associated with the receiver to be
 * the argument which may be null.
 *
 * @param layout the receiver's new layout or null
 *
 * @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 setLayout (Layout layout) {
	checkWidget();
	this.layout = layout;
}

/**
 * If the argument is <code>true</code>, causes subsequent layout
 * operations in the receiver or any of its children to be ignored.
 * No layout of any kind can occur in the receiver or any of its
 * children until the flag is set to false.
 * Layout operations that occurred while the flag was
 * <code>true</code> are remembered and when the flag is set to 
 * <code>false</code>, the layout operations are performed in an
 * optimized manner.  Nested calls to this method are stacked.
 *
 * @param defer the new defer state
 *
 * @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>
 * 
 * @see #layout(boolean)
 * @see #layout(Control[])
 *
 * @since 3.1
 */
public void setLayoutDeferred (boolean defer) {
	if (!defer) {
		if (--layoutCount == 0) {
			if ((state & LAYOUT_CHILD) != 0 || (state & LAYOUT_NEEDED) != 0) {
				updateLayout (true);
			}
		}
	} else {
		layoutCount++;
	}
}

boolean setScrollBarVisible (ScrollBar bar, boolean visible) {
	boolean changed = super.setScrollBarVisible (bar, visible);
	if (changed && layout != null) {
		markLayout (false, false);
		updateLayout (false);
	}
	return changed;
}

boolean setTabGroupFocus () {
	if (isTabItem ()) return setTabItemFocus ();
	boolean takeFocus = (style & SWT.NO_FOCUS) == 0;
	if ((state & CANVAS) != 0) takeFocus = hooksKeys ();
	if (takeFocus && setTabItemFocus ()) return true;
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
		Control child = children [i];
		if (child.isTabItem () && child.setTabItemFocus ()) return true;
	}
	return false;
}

/**
 * Sets the tabbing order for the specified controls to
 * match the order that they occur in the argument list.
 *
 * @param tabList the ordered list of controls representing the tab order or null
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if a widget in the tabList is null or has been disposed</li> 
 *    <li>ERROR_INVALID_PARENT - if widget in the tabList is not in the same widget tree</li>
 * </ul>
 * @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 setTabList (Control [] tabList) {
	checkWidget ();
	if (tabList != null) {
		for (int i=0; i<tabList.length; i++) {
			Control control = tabList [i];
			if (control == null) error (SWT.ERROR_INVALID_ARGUMENT);
			if (control.isDisposed ()) error (SWT.ERROR_INVALID_ARGUMENT);
			if (control.parent != this) error (SWT.ERROR_INVALID_PARENT);
		}
		Control [] newList = new Control [tabList.length];
		System.arraycopy (tabList, 0, newList, 0, tabList.length);
		tabList = newList;
	} 
	this.tabList = tabList;
}

int traversalCode (int key, int theEvent) {
	if ((state & CANVAS) != 0) {
		if ((style & SWT.NO_FOCUS) != 0) return 0;
		if (hooksKeys ()) return 0;
	}
	return super.traversalCode (key, theEvent);
}

void updateBackgroundMode () {
	super.updateBackgroundMode ();
	Control [] children = _getChildren ();
	for (int i = 0; i < children.length; i++) {
		children [i].updateBackgroundMode ();
	}
}

void updateLayout (boolean all) {
	Composite parent = findDeferredControl ();
	if (parent != null) {
		parent.state |= LAYOUT_CHILD;
		return;
	}
	if ((state & LAYOUT_NEEDED) != 0) {
		boolean changed = (state & LAYOUT_CHANGED) != 0;
		state &= ~(LAYOUT_NEEDED | LAYOUT_CHANGED);
		layout.layout (this, changed);
	}
	if (all) {
		state &= ~LAYOUT_CHILD;
		Control [] children = _getChildren ();
		for (int i=0; i<children.length; i++) {
			children [i].updateLayout (all);
		}
	}
}

}