转自 http://blog.sina.com.cn/s/blog_6919c12201019o44.html
一牛人写的工具类，使透明图片转化为原件，原件继承了该类，就能使透明区域不接受鼠标事件，
package com.mosesSupposes.bitmap {
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.MovieClip;
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.geom.Matrix;
import flash.geom.Point;
import flash.geom.Rectangle;
public class InteractivePNG extends MovieClip {
// -== Public Properties ==-
public function get interactivePngActive() : Boolean {
return _interactivePngActive;
}
public function get alphaTolerance() : uint {
return _threshold;
}
public function set alphaTolerance(value : uint) : void {
_threshold = Math.min(255, value);
}
// Excluded from documentation for simplicity, a note is provided under disableInteractivePNG.
override public function set hitArea(value : Sprite) : void {
if (value!=null && super.hitArea==null) {
disableInteractivePNG();
}
else if (value==null && super.hitArea!=null) {
enableInteractivePNG();
}
super.hitArea = value;
}
// Excluded from documentation for simplicity, a note is provided under disableInteractivePNG.
override public function set mouseEnabled(enabled : Boolean) : void {
if (isNaN(_buttonModeCache)==false) { // indicates that mouse has entered clip bounds.
disableInteractivePNG();
}
super.mouseEnabled = enabled;
}
// -== Private Properties ==-
protected var _threshold : uint = 128;
protected var _transparentMode : Boolean = false;
protected var _interactivePngActive : Boolean = false;
protected var _bitmapHit : Boolean = false;
protected var _basePoint : Point;
protected var _mousePoint : Point;
protected var _bitmapForHitDetection : Bitmap;
protected var _buttonModeCache : Number = NaN;
// -== Public Methods ==-
public function InteractivePNG():void {
super();
_basePoint = new Point();
_mousePoint = new Point();
enableInteractivePNG();
}
public function drawBitmapHitArea(event:Event=null) : void
{
var isRedraw:Boolean = (_bitmapForHitDetection!=null);
if (isRedraw) {
try { removeChild(_bitmapForHitDetection); }catch(e:Error) { }
}
var bounds:Rectangle = getBounds(this);
var left:Number = bounds.left;
var top:Number = bounds.top;
var b:BitmapData = new BitmapData(bounds.width, bounds.height, true, 0);
_bitmapForHitDetection = new Bitmap(b);
_bitmapForHitDetection.name = "interactivePngHitMap"; // (So that it is not a mystery if the displaylist is being inspected!)
_bitmapForHitDetection.visible = false;
var mx:Matrix = new Matrix();
mx.translate(-left, -top);
b.draw(this, mx);
addChildAt(_bitmapForHitDetection, 0);
_bitmapForHitDetection.x = left;
_bitmapForHitDetection.y = top;
}
public function disableInteractivePNG(): void {
deactivateMouseTrap();
removeEventListener(Event.ENTER_FRAME, trackMouseWhileInBounds);
try { removeChild(_bitmapForHitDetection); }catch(e:Error) { }
_bitmapForHitDetection==null;
super.mouseEnabled = true;
_transparentMode = false;
setButtonModeCache(true);
_bitmapHit = false;
_interactivePngActive = false;
}
public function enableInteractivePNG(): void {
disableInteractivePNG();
if (hitArea!=null)
return;
activateMouseTrap();
_interactivePngActive = true;
}
// -== Private Methods ==-
protected function activateMouseTrap() : void {
addEventListener(MouseEvent.ROLL_OVER, captureMouseEvent, false, 10000, true); //useCapture=true, priority=high, weakRef=true
addEventListener(MouseEvent.MOUSE_OVER, captureMouseEvent, false, 10000, true);
addEventListener(MouseEvent.ROLL_OUT, captureMouseEvent, false, 10000, true);
addEventListener(MouseEvent.MOUSE_OUT, captureMouseEvent, false, 10000, true);
addEventListener(MouseEvent.MOUSE_MOVE, captureMouseEvent, false, 10000, true);
}
protected function deactivateMouseTrap() : void {
removeEventListener(MouseEvent.ROLL_OVER, captureMouseEvent);
removeEventListener(MouseEvent.MOUSE_OVER, captureMouseEvent);
removeEventListener(MouseEvent.ROLL_OUT, captureMouseEvent);
removeEventListener(MouseEvent.MOUSE_OUT, captureMouseEvent);
removeEventListener(MouseEvent.MOUSE_MOVE, captureMouseEvent);
}
protected function captureMouseEvent(event : Event) : void
{
if (!_transparentMode) {
if (event.type==MouseEvent.MOUSE_OVER || event.type==MouseEvent.ROLL_OVER) {
// The buttonMode state is cached then disabled to avoid a cursor flicker
// at the movieclip bounds. Reenabled when bitmap is hit.
setButtonModeCache();
_transparentMode = true;
super.mouseEnabled = false;
addEventListener(Event.ENTER_FRAME, trackMouseWhileInBounds, false, 10000, true); // activates bitmap hit & exit tracking
trackMouseWhileInBounds(); // important: Immediate response, and sets _bitmapHit to correct state for event suppression.
}
}
if (!_bitmapHit)
event.stopImmediatePropagation();
}
protected function trackMouseWhileInBounds(event:Event=null):void
{
if (bitmapHitTest() != _bitmapHit)
{
_bitmapHit = !_bitmapHit;
// Mouse is now on a nonclear pixel based on alphaTolerance. Reenable mouse events.
if (_bitmapHit) {
deactivateMouseTrap();
setButtonModeCache(true, true);
_transparentMode = false;
super.mouseEnabled = true; // This will trigger rollOver & mouseOver events
}
// Mouse is now on a clear pixel based on alphaTolerance. Disable mouse events but .
else if (!_bitmapHit) {
_transparentMode = true;
super.mouseEnabled = false; // This will trigger rollOut & mouseOut events
}
}
// When mouse exits this MovieClip's bounds, end tracking & restore all.
var localMouse:Point = _bitmapForHitDetection.localToGlobal(_mousePoint);
if (hitTestPoint( localMouse.x, localMouse.y)==false) {
removeEventListener(Event.ENTER_FRAME, trackMouseWhileInBounds);
_transparentMode = false;
setButtonModeCache(true);
super.mouseEnabled = true;
activateMouseTrap();
}
}
protected function bitmapHitTest():Boolean {
if (_bitmapForHitDetection==null)
drawBitmapHitArea();
_mousePoint.x = _bitmapForHitDetection.mouseX;
_mousePoint.y = _bitmapForHitDetection.mouseY;
return _bitmapForHitDetection.bitmapData.hitTest(_basePoint, _threshold, _mousePoint);
}
protected function setButtonModeCache(restore:Boolean=false, retain:Boolean=false) : void {
if (restore) {
if (_buttonModeCache==1)
buttonMode = true;
if (!retain)
_buttonModeCache = NaN;
return;
}
_buttonModeCache = (buttonMode==true ? 1 : 0);
buttonMode = false;
}
}
}