精确选择识别png图片有像素的区域

/**
 *
 * *---------------------------------------*
 * |  ***精确选择识别png图片有像素的区域***  |
 * *---------------------------------------*
 **
 * 编辑修改收录：fengzi（疯子、wu341、wgq341）
 *
 * 不会写代码，我是代码搬运工。
 *
 * 联系方式：QQ（493712833）。
 *
 * 随   笔： https://www.cnblogs.com/fengziwu/
 *
 * 版权协议：请自觉遵守LGPL协议，欢迎修改、复制、转载、传播给更多需要的人。
 * 免责声明：任何因使用此软件导致的纠纷与软件/程序开发者无关。
 * 日   期： 2019.05.08
 *
 */

package fengzi.bmd
{
	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
		{
			// indicates that mouse has entered clip bounds.
			if (isNaN(_buttonModeCache)==false)
			{
				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);

			// (So that it is not a mystery if the displaylist is being inspected!)
			_bitmapForHitDetection.name = "interactivePngHitMap";
			_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
		{

			//useCapture=true, priority=high, weakRef=true
			addEventListener(MouseEvent.ROLL_OVER, captureMouseEvent, false, 10000, 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
					//buttonMode状态被缓存，然后被禁用以避免光标闪烁。
					// at the movieclip bounds. Reenabled when bitmap is hit.
					//在移动边界。点击位图时重新启用。
					setButtonModeCache();
					_transparentMode = true;
					super.mouseEnabled = false;
					// activates bitmap hit & exit tracking
					//激活位图命中和退出跟踪
					addEventListener(Event.ENTER_FRAME, trackMouseWhileInBounds, false, 10000, true);
					// important: Immediate response, and sets _bitmapHit to correct state for event suppression.
					//重要提示：立即响应，并将“位图命中”设置为事件抑制的正确状态。
					trackMouseWhileInBounds();
				}
			}

			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.
				//鼠标现在位于基于alphatolerance的非清晰像素上。重新启用鼠标事件。
				if (_bitmapHit)
				{
					deactivateMouseTrap();
					setButtonModeCache(true, true);
					_transparentMode = false;
					// This will trigger rollOver & mouseOver events
					//这将触发滚动和鼠标悬停事件
					super.mouseEnabled = true;
				}
				else if (!_bitmapHit)
				{
					// Mouse is now on a clear pixel based on alphaTolerance. Disable mouse events but .
					//鼠标现在位于基于alphatolerance的清晰像素上。禁用鼠标事件。
					_transparentMode = true;

					// This will trigger rollOut & mouseOut events
					//这将触发卷展栏和鼠标输出事件
					super.mouseEnabled = false;
				}
			}

			// When mouse exits this MovieClip's bounds, end tracking & restore all.
			//当鼠标退出movieclip的边界时，结束跟踪并全部恢复。
			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;
		}
	}
}