/*******************************************************************************
 * Copyright (c) 2000, 2020 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.widgets;


import org.eclipse.swt.*;
import org.eclipse.swt.accessibility.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.internal.ExceptionStash;
import org.eclipse.swt.internal.cocoa.*;

/**
 * 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), 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="https://eclipse.dev/eclipse/swt/snippets/#composite">Composite snippets</a>
 * @see <a href="https://eclipse.dev/eclipse/swt/">Sample code and further information</a>
 */
public class Composite extends Scrollable {
	Layout layout;
	Control[] tabList;
	int layoutCount, backgroundMode;
	private boolean isStyledText; // This field is set to true if Object is StyledText

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 () {
	NSView nsClipView = contentView();
	if (nsClipView == null) return new Control [0];
	NSArray views = nsClipView.subviews();
	int count = (int)views.count();
	Control [] children = new Control [count];
	if (count == 0) return children;
	int j = 0;
	for (int i=0; i<count; i++){
		Widget widget = display.getWidget (views.objectAtIndex (count - i - 1).id);
		if (widget != null && widget != this && widget instanceof Control) {
			children [j++] = (Control) widget;
		}
	}
	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;
}

@Override
boolean acceptsFirstMouse (long id, long sel, long theEvent) {
	if ((state & CANVAS) != 0) {
		return true;
	}
	return super.acceptsFirstMouse (id, sel, theEvent);
}

@Override
boolean acceptsFirstResponder (long id, long sel) {
	if ((state & CANVAS) != 0) {
		if ((style & SWT.NO_FOCUS) == 0 && hooksKeys ()) {
			if (contentView().subviews().count() == 0) return true;
		}
		return false;
	}
	return super.acceptsFirstResponder (id, sel);
}

@Override
long accessibilityAttributeValue (long id, long sel, long arg0) {
	NSString nsAttributeName = new NSString(arg0);
	long superValue = super.accessibilityAttributeValue(id, sel, arg0);

	if ((state & CANVAS) != 0) {
		// If this Composite has an Accessible that defined a role, return that, unless the
		// supplied role was NSAccessibilityUnknownRole.  In that case, return an SWT-specific constant.
		// This lets the accessibility hierarchy know there's a container here.
		if (id == accessibleHandle()) {
			if (nsAttributeName.isEqualToString (OS.NSAccessibilityRoleAttribute)) {
				if (superValue != 0) {
					NSString role = new NSString(superValue);
					if (!role.isEqualToString(OS.NSAccessibilityUnknownRole)) return superValue;
				}

				NSString role = NSString.stringWith("SWTComposite");
				return role.id;
			} else if (nsAttributeName.isEqualToString (OS.NSAccessibilityRoleDescriptionAttribute)) {
				if (superValue != 0) {
					NSString role = new NSString(superValue);
					if (!role.isEqualToString(OS.NSAccessibilityUnknownSubrole)) return superValue;
				}

				NSString roleDescription = NSString.stringWith("generic container view");
				return roleDescription.id;
			}
		}
	}

	return superValue;
}


@Override
boolean accessibilityIsIgnored(long id, long sel) {
	if (id == accessibleHandle()) {
		// If a Composite or subclass has an Accessible it should not be ignored.
		if (accessible != null) return accessible.internal_accessibilityIsIgnored(ACC.CHILDID_SELF);
	}

	return super.accessibilityIsIgnored(id, sel);
}

/**
 * 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>
 *
 * @deprecated use {@link Composite#layout(Control[], int)} instead
 * @since 3.1
 */
@Deprecated
public void changed (Control[] changed) {
	layout(changed, SWT.DEFER);
}

@Override
public Point computeSize (int wHint, int hHint, boolean changed) {
	checkWidget();
	display.runSkin ();
	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);
}

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

@Override
Widget [] computeTabList () {
	Widget 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];
		Widget [] childList = child.computeTabList ();
		if (childList.length != 0) {
			Widget [] newResult = new Widget [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;
}

@Override
void createHandle () {
	state |= CANVAS;
	boolean scrolled = (style & (SWT.V_SCROLL | SWT.H_SCROLL)) != 0;
	if (!scrolled)  state |= THEME_BACKGROUND;
	NSRect rect = new NSRect();
	if (scrolled || hasBorder ()) {
		NSScrollView scrollWidget = (NSScrollView)new SWTScrollView().alloc();
		scrollWidget.initWithFrame (rect);
		scrollWidget.setDrawsBackground(false);
		if ((style & SWT.H_SCROLL) != 0) scrollWidget.setHasHorizontalScroller(true);
		if ((style & SWT.V_SCROLL) != 0) scrollWidget.setHasVerticalScroller(true);
		scrollWidget.setBorderType(hasBorder() ? OS.NSBezelBorder : OS.NSNoBorder);
		scrollView = scrollWidget;
	}
	NSView widget = (NSView)new SWTCanvasView().alloc();
	widget.initWithFrame (rect);
//	widget.setFocusRingType(OS.NSFocusRingTypeExterior);
	view = widget;
	if (scrollView != null) {
		NSClipView contentView = scrollView.contentView();
		contentView.setAutoresizesSubviews(true);
		view.setAutoresizingMask(OS.NSViewWidthSizable | OS.NSViewHeightSizable);
	}
}

/**
 * Fills the interior of the rectangle specified by the arguments,
 * with the receiver's background.
 *
 * <p>The <code>offsetX</code> and <code>offsetY</code> are used to map from
 * the <code>gc</code> origin to the origin of the parent image background. This is useful
 * to ensure proper alignment of the image background.</p>
 *
 * @param gc the gc where the rectangle is to be filled
 * @param x the x coordinate of the rectangle to be filled
 * @param y the y coordinate of the rectangle to be filled
 * @param width the width of the rectangle to be filled
 * @param height the height of the rectangle to be filled
 * @param offsetX the image background x offset
 * @param offsetY the image background y offset
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the gc is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the gc has been disposed</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 3.6
 */
public void drawBackground(GC gc, int x, int y, int width, int height, int offsetX, int offsetY) {
	checkWidget ();
	if (gc == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (gc.isDisposed ()) error (SWT.ERROR_INVALID_ARGUMENT);
	Control control = findBackgroundControl ();
	if (control != null) {
		NSRect rect = new NSRect();
		rect.x = x;
		rect.y = y;
		rect.width = width;
		rect.height = height;
		int imgHeight = -1;
		GCData data = gc.getGCData();
		if (data.image != null) imgHeight =  data.image.getBounds().height;
		NSGraphicsContext context = gc.handle;
		if (data.flippedContext != null) {
			NSGraphicsContext.static_saveGraphicsState();
			NSGraphicsContext.setCurrentContext(context);
		}
		control.fillBackground (view, context, rect, imgHeight, data.view, offsetX, offsetY);
		if (data.flippedContext != null) {
			NSGraphicsContext.static_restoreGraphicsState();
		}
	} else {
		gc.fillRectangle (x, y, width, height);
	}
}

@Override
void drawBackground (long id, NSGraphicsContext context, NSRect rect) {
	if (id != view.id) return;
	if ((state & CANVAS) != 0) {
		if ((style & SWT.NO_BACKGROUND) == 0) {
			fillBackground (view, context, rect, -1);
		}
	}
}

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

@Override
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;
}

@Override
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>INHERIT_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 ();
}

/**
 * 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;
}

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

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

/**
 * 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;
}

@Override
boolean isOpaque (long id, long sel) {
	if ((state & CANVAS) != 0) {
		if (id == view.id) {
			return region == null && isOpaque();
		}
	}
	return super.isOpaque (id, sel);
}

boolean isOpaque() {
	if (isStyledText) {
		/*
		 * When overlay scroll bars are used, Control.isObscured() always returns true,
		 * causing isOpaque to return false. This causes performance problems while
		 * redraw/scrolling. To workaround this, don't check for isObscured() here if the
		 * object is StyledText.
		 */
		return background == null || backgroundAlpha == 255;
	}
	return background != null && background[3] == 1 && !isObscured ();
}

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

@Override
void keyDown (long id, long sel, long theEvent) {
	if (hasFocus()) {
		if ((state & CANVAS) != 0) {
			Shell s = this.getShell();
			s.deferFlushing();
			NSArray array = NSArray.arrayWithObject (new NSEvent (theEvent));
			s.keyInputHappened = false;
			view.interpretKeyEvents (array);
			if (imeInComposition ()) return;
			if (!s.keyInputHappened) {
				NSEvent nsEvent = new NSEvent (theEvent);
				boolean [] consume = new boolean [1];
				if (translateTraversal (nsEvent.keyCode (), nsEvent, consume)) return;
				if (isDisposed ()) return;
				if (!sendKeyEvent (nsEvent, SWT.KeyDown)) return;
				if (consume [0]) return;
			}
			return;
		}
	}
	super.keyDown (id, sel, theEvent);
}

/**
 * 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>
 * Use of this method is discouraged since it is the least-efficient
 * way to trigger a layout. The use of <code>layout(true)</code>
 * discards all cached layout information, even from controls which
 * have not changed. It is much more efficient to invoke
 * {@link Control#requestLayout()} on every control which has changed
 * in the layout than it is to invoke this method on the layout itself.
 * </p>
 * <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>
 * It is normally more efficient to invoke {@link Control#requestLayout()}
 * on every control which has changed in the layout than it is to invoke
 * this method on the layout itself. Clients are encouraged to use
 * {@link Control#requestLayout()} where possible instead of calling
 * this method.
 * </p>
 * <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>
 * It is normally more efficient to invoke {@link Control#requestLayout()}
 * on every control which has changed in the layout than it is to invoke
 * this method on the layout itself. Clients are encouraged to use
 * {@link Control#requestLayout()} where possible instead of calling
 * this method.
 * </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>
 * It is normally more efficient to invoke {@link Control#requestLayout()}
 * on every control which has changed in the layout than it is to invoke
 * this method on the layout itself. Clients are encouraged to use
 * {@link Control#requestLayout()} where possible instead of calling
 * this method.
 * </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 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);
	layout (changed, SWT.NONE);
}

/**
 * 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.
 * <p>
 * The parameter <code>flags</code> may be a combination of:
 * </p>
 * <dl>
 * <dt><b>SWT.ALL</b></dt>
 * <dd>all children in the receiver's widget tree should be laid out</dd>
 * <dt><b>SWT.CHANGED</b></dt>
 * <dd>the layout must flush its caches</dd>
 * <dt><b>SWT.DEFER</b></dt>
 * <dd>layout will be deferred</dd>
 * </dl>
 * <p>
 * When the <code>changed</code> array is specified, the flags <code>SWT.ALL</code>
 * and <code>SWT.CHANGED</code> have no effect. In this case, 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>
 * <p>
 * When the <code>changed</code> array is not specified, the flag <code>SWT.ALL</code>
 * indicates that the whole widget tree should be laid out. And the flag
 * <code>SWT.CHANGED</code> indicates that the layouts should flush any cached
 * information for all controls that are laid out.
 * </p>
 * <p>
 * The <code>SWT.DEFER</code> flag always causes the layout to be deferred by
 * calling <code>Composite.setLayoutDeferred(true)</code> and scheduling a call
 * to <code>Composite.setLayoutDeferred(false)</code>, which will happen when
 * appropriate (usually before the next event is handled). When this flag is set,
 * the application should not call <code>Composite.setLayoutDeferred(boolean)</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 a control that has had a state change which requires a recalculation of its size
 * @param flags the flags specifying how the layout should happen
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if any of the controls in changed is null or has 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 3.6
 */
public void layout (Control [] changed, int flags) {
	checkWidget ();
	if (changed != null) {
		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;
			// Update layout when the list of children has changed.
			// See bug 497812.
			child.markLayout(false, false);
			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;
			}
		}
		if ((flags & SWT.DEFER) != 0) {
			setLayoutDeferred (true);
			display.addLayoutDeferred (this);
		}
		for (int i=updateCount-1; i>=0; i--) {
			update [i].updateLayout (false);
		}
	} else {
		if (layout == null && (flags & SWT.ALL) == 0) return;
		markLayout ((flags & SWT.CHANGED) != 0, (flags & SWT.ALL) != 0);
		if ((flags & SWT.DEFER) != 0) {
			setLayoutDeferred (true);
			display.addLayoutDeferred (this);
		}
		updateLayout ((flags & SWT.ALL) != 0);
	}
}

@Override
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 ();
	Rectangle clientArea = getClientArea();
	int width = 0, height = 0;
	for (int i=0; i<children.length; i++) {
		Rectangle rect = children [i].getBounds ();
		width = Math.max (width, rect.x - clientArea.x + rect.width);
		height = Math.max (height, rect.y - clientArea.y + rect.height);
	}
	return new Point (width, height);
}

@Override
boolean mouseEvent (long id, long sel, long theEvent, int type) {
	boolean result = super.mouseEvent (id, sel, theEvent, type);
	return (state & CANVAS) == 0 ? result : new NSEvent (theEvent).type () != OS.NSLeftMouseDown;
}

@Override
void pageDown(long id, long sel, long sender) {
	if ((state & CANVAS) != 0) return;
	super.pageDown(id, sel, sender);
}

@Override
void pageUp(long id, long sel, long sender) {
	if ((state & CANVAS) != 0) return;
	super.pageUp(id, sel, sender);
}

@Override
void redrawWidget(NSView view, boolean redrawChildren) {
	super.redrawWidget(view, redrawChildren);
	if (redrawChildren) {
		Control[] _getChildren = _getChildren();
		for (Control child : _getChildren) {
			if (child != null && !child.isDisposed () && child.isVisible()) {
				child.redrawWidget(child.view, redrawChildren);
			}
		}
	}
}

@Override
public void redraw(int x, int y, int width, int height, boolean all) {
	super.redraw(x, y, width, height, all);
	if (all) {
		Control[] children = _getChildren();
		for (Control child : children) {
			if (child != null && !child.isDisposed () && child.isVisible()) {
				NSRect rect = new NSRect();
				rect.x = x;
				rect.y = y;
				rect.width = width;
				rect.height = height;
				rect = view.convertRect_toView_(rect, child.view);
				child.redraw((int)rect.x, (int)rect.y, (int)rect.width, (int)rect.height, all);
			}
		}
	}
}

@Override
void reflectScrolledClipView (long id, long sel, long aClipView) {
	if ((state & CANVAS) != 0) return;
	super.reflectScrolledClipView (id, sel, aClipView);
}

@Override
void releaseChildren (boolean destroy) {
	try (ExceptionStash exceptions = new ExceptionStash ()) {
		for (Control child : _getChildren ()) {
			if (child == null || child.isDisposed ())
				continue;

			try {
				child.release (false);
			} catch (Error | RuntimeException ex) {
				exceptions.stash (ex);
			}
		}
		super.releaseChildren (destroy);
	}
}

@Override
void releaseWidget () {
	super.releaseWidget ();
	layout = null;
	tabList = null;
}

void removeControl (Control control) {
	if (control.hasFocus()) redrawWidget(view, true);
	fixTabList (control);
}

@Override
void reskinChildren (int flags) {
	super.reskinChildren (flags);
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
		Control child = children [i];
		if (child != null) child.reskin (flags);
	}
}

@Override
void resized () {
	super.resized ();
	if (layout != null) {
		markLayout (false, false);
		updateLayout (false);
	}
}

@Override
void scrollWheel (long id, long sel, long theEvent) {
	if ((state & CANVAS) != 0) {
		NSView view = scrollView != null ? scrollView : this.view;
		if (id == view.id) {
			getShell().deferFlushing();
			NSEvent nsEvent = new NSEvent(theEvent);
			boolean handled = false;
			double deltaY = nsEvent.deltaY();
			double deltaX = nsEvent.deltaX ();
			if ((hooks(SWT.Gesture) || filters (SWT.Gesture))) {
				if (!gestureEvent(id, theEvent, SWT.GESTURE_PAN)) {
					handled = true;
				}
			}
			if (!handled) {
				if (deltaY != 0) {
					boolean doit = true;
					if (hooks (SWT.MouseWheel) || filters (SWT.MouseWheel)) {
						doit = sendMouseEvent(nsEvent, SWT.MouseWheel, true);
					}
					ScrollBar bar = verticalBar;
					if (doit && bar != null && bar.getEnabled ()) {
						if (-1 < deltaY && deltaY < 0) deltaY = -1;
						if (0 < deltaY && deltaY < 1) deltaY = 1;
						int selection = Math.max (0, (int)(0.5f + bar.getSelection () - bar.getIncrement () * deltaY));
						bar.setSelection (selection);
						Event event = new Event ();
						event.detail = deltaY > 0 ? SWT.PAGE_UP : SWT.PAGE_DOWN;
						bar.sendSelectionEvent (SWT.Selection, event, true);
						handled = true;
					}
					if (!doit) handled = true;
				}
				if (deltaX != 0) {
					boolean doit = true;
					if (hooks (SWT.MouseHorizontalWheel) || filters (SWT.MouseHorizontalWheel)) {
						doit = sendMouseEvent(nsEvent, SWT.MouseHorizontalWheel, true);
					}
					ScrollBar bar = horizontalBar;
					if (doit && bar != null && bar.getEnabled ()) {
						if (-1 < deltaX && deltaX < 0) deltaX = -1;
						if (0 < deltaX && deltaX < 1) deltaX = 1;
						int selection = Math.max (0, (int)(0.5f + bar.getSelection () - bar.getIncrement () * deltaX));
						bar.setSelection (selection);
						Event event = new Event ();
						event.detail = deltaX > 0 ? SWT.PAGE_UP : SWT.PAGE_DOWN;
						bar.sendSelectionEvent (SWT.Selection, event, true);
						handled = true;
					}
					if (!doit) handled = true;
				}
				if (!handled) view.superview().scrollWheel(nsEvent);
			}
			return;
		}
		callSuper(id, sel, theEvent);
		return;
	}
	super.scrollWheel (id, sel, theEvent);
}

/**
 * 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 ();
	}
}

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

@Override
void setIsStyledText() {
	isStyledText = true;
}

/**
 * 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) {
	checkWidget();
	if (!defer) {
		if (--layoutCount == 0) {
			if ((state & LAYOUT_CHILD) != 0 || (state & LAYOUT_NEEDED) != 0) {
				updateLayout (true);
			}
		}
	} else {
		layoutCount++;
	}
}

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

@Override
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];
		/*
		 * It is unlikely but possible that a child is disposed at this point, for more
		 * details refer bug 381668.
		 */
		if (!child.isDisposed() && 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;
}

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

@Override
void updateBackgroundColor () {
	super.updateBackgroundColor ();
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
		if ((children [i].state & PARENT_BACKGROUND) != 0) {
			children [i].updateBackgroundColor ();
		}
	}
}

@Override
void updateBackgroundImage () {
	super.updateBackgroundImage ();
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
		if ((children [i].state & PARENT_BACKGROUND) != 0) {
			children [i].updateBackgroundImage ();
		}
	}
}

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

@Override
void updateCursorRects (boolean enabled) {
	super.updateCursorRects (enabled);
	Control [] children = _getChildren ();
	for (int i = 0; i < children.length; i++) {
		Control control = children [i];
		control.updateCursorRects (enabled && control.isEnabled ());
	}
}

@Override
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);
		display.runSkin ();
		layout.layout (this, changed);
	}
	if (all) {
		state &= ~LAYOUT_CHILD;
		Control [] children = _getChildren ();
		for (int i=0; i<children.length; i++) {
			children [i].updateLayout (all);
		}
	}
}

@Override
public String toString() {
	return super.toString() + " [layout=" + layout + "]";
}

}
