[转]《元件滚动条》

《元件滚动条》

/*
================================================================================

《元件滚动条》

更改了对文本滚动控制改为对元件的控制，并增加缓动效果。
代码借鉴了：火山动态文本滚动条 V5 ，特此注明！
------------------------------------------------------------

Copyright (c) 2011 [无空]

My web:
  闪耀空间
  http://www.flash-me.cn/
E-mail:
  flashme@live.cn

                                                  2011-3-4
================================================================================
*/
package {
	import flash.events.MouseEvent;
	import flash.events.Event;
	import flash.display.SimpleButton;
	import flash.text.TextField;
	import flash.display.Sprite;
	//import flash.display.MovieClip;
	import flash.utils.getTimer;
	import flash.geom.Rectangle;


	public class myScrollBar extends Sprite {

		//=============本类属性==============
		接口元件
		private var scrollCon:Sprite;
		private var scrollBar_sprite:Sprite;
		private var up_btn:SimpleButton;
		private var down_btn:SimpleButton;
		private var pole_sprite:Sprite;
		private var bg_sprite:Sprite;
		初始数据
		private var poleStartHeight:Number;
		private var poleStartY:Number;
		private var totalPixels:Number;
		private var areaY:int;
		private var areaBg:uint;
		private var easingSpeed:uint=7;
		上下滚动按钮按钮下时间
		private var putTime:Number;

		/**
		 * @param scrollCon_fc:被滚动的元件
		 * @param scrollBarMc_fc：舞台上与本类所代理的滚动条元件
		 * @param height_fc：滚动条高
		 * @param width_fc：滚动条宽
		 */
		public function myScrollBar(scrollCon_fc:Sprite, scrollBarMc_fc:Sprite, area_fc:uint=0, height_fc:uint=0, width_fc:uint=0) {
			//——————滚动条_sprite，滚动条按钮和滑块mc，被滚动的文本域初始化
			scrollCon=scrollCon_fc;
			scrollBar_sprite=scrollBarMc_fc;
			up_btn=SimpleButton(scrollBar_sprite.getChildByName("up_btn"));
			down_btn=SimpleButton(scrollBar_sprite.getChildByName("down_btn"));
			pole_sprite=Sprite(scrollBar_sprite.getChildByName("pole_mc"));
			bg_sprite=Sprite(scrollBar_sprite.getChildByName("bg_mc"));

			//——————可用性控制
			pole_sprite.visible=false;
			up_btn.enabled=false;
			down_btn.enabled=false;

			//——————其他属性初始化
			areaY = scrollCon.y;
			if(area_fc==0){
				//未接收到高度定义时默认让其上下距离相等
				area_fc=scrollCon.parent.stage.stageHeight-areaY*2;
			}
			areaBg = area_fc;
			bg_sprite.useHandCursor=false;

			//遮罩
			var maskSprite:Sprite=new Sprite();
			maskSprite.graphics.beginFill(0xff0000);
			maskSprite.graphics.drawRect(scrollCon.x,areaY,scrollCon.width,areaBg);
			maskSprite.graphics.endFill();
			//遮罩无需放入显示列表
			//***若需要控制遮罩位置等相关属性可将下面注释取消***
			//maskSprite.name="maskSprite";
			//scrollCon.parent.addChild(maskSprite);
			scrollCon.mask=maskSprite;

			if (height_fc==0) {
				bg_sprite.height=areaBg;
			} else {
				bg_sprite.height=height_fc;
			}
			if (width_fc!=0) {
				bg_sprite.width=width_fc+2;
				pole_sprite.width=width_fc;
				up_btn.width=up_btn.height=down_btn.width=down_btn.height=width_fc;
			}
			down_btn.y=bg_sprite.y+bg_sprite.height-down_btn.height;
			poleStartHeight=Math.floor(down_btn.y-up_btn.y-up_btn.height);
			poleStartY=pole_sprite.y=Math.floor(up_btn.y+up_btn.height);


			//——————注册侦听器

			//用鼠标接触元件的方式来更新高度数据，用这种方式侦听或许不太好，但没找到更好办法。
			scrollCon.addEventListener(MouseEvent.MOUSE_OVER, renew);
			scrollBar_sprite.addEventListener(MouseEvent.MOUSE_OVER, renew);
			//初始运行scrollBar_sprite侦听
			scrollBar_sprite.dispatchEvent(new MouseEvent(MouseEvent.MOUSE_OVER));

			//鼠标滚轮
			scrollCon.addEventListener(MouseEvent.MOUSE_WHEEL, mouseWheel);
			//上滚动按钮
			up_btn.addEventListener(MouseEvent.MOUSE_DOWN, upBtn);
			up_btn.stage.addEventListener(MouseEvent.MOUSE_UP, upBtnUp);
			//下滚动按钮
			down_btn.addEventListener(MouseEvent.MOUSE_DOWN, downBtn);
			down_btn.stage.addEventListener(MouseEvent.MOUSE_UP, downBtnUp);
			//滑块
			pole_sprite.addEventListener(MouseEvent.MOUSE_DOWN, poleSprite);
			pole_sprite.stage.addEventListener(MouseEvent.MOUSE_UP, poleUp);
			//滑块背景点击
			bg_sprite.addEventListener(MouseEvent.MOUSE_DOWN, bgDown);

		}

		private function renew(event : MouseEvent):void {
			//判断滑块儿是否显示，并根据元件高度定义滑块高度
			if (scrollCon.height>areaBg) {
				pole_sprite.visible=true;
				up_btn.enabled=true;
				down_btn.enabled=true;
				//定义一个高度因子
				var heightVar:Number=areaBg/scrollCon.height;
				//根据高度因子初始化滑块的高度
				pole_sprite.height=Math.floor(poleStartHeight*Math.pow(heightVar,1/3));
				//拖动条可响应的范围
				totalPixels=Math.floor(down_btn.y-up_btn.y-up_btn.height-pole_sprite.height);
				pole_sprite.y=PoleNewY(scrollCon.y);

			} else {
				pole_sprite.visible=false;
				up_btn.enabled=false;
				down_btn.enabled=false;
			}
		}

		/**
		 * 计算公式
		 */
		//以拖动条的位置计算来MC的位置，返回int值
		private function ConNewY(nowPosition:int):int {
			return -(scrollCon.height-areaBg)*(nowPosition-poleStartY)/totalPixels +areaY;
		}
		//以MC的位置来计算拖动条的位置，返回int值
		private function PoleNewY(nowPosition:int):int {
			return totalPixels*(areaY-nowPosition)/(scrollCon.height-areaBg) +poleStartY;
		}


		/**
		 * 滑块滚动
		 */
		private function poleSprite(event : MouseEvent):void {
			//监听舞台，这样可以保证拖动滑竿的时候，鼠标在舞台的任意位置松手，都会停止拖动
			scrollBar_sprite.stage.addEventListener(MouseEvent.MOUSE_UP, poleUp);
			//限定拖动范围
			var dragRect:Rectangle=new Rectangle(pole_sprite.x,poleStartY,0,totalPixels);
			pole_sprite.startDrag(false, dragRect);
			scrollBar_sprite.addEventListener(Event.ENTER_FRAME, poleDown);
		}

		private function poleDown(event : Event):void {
			//在滚动过程中及时获得滑块所处位置
			var nowPosition:int=pole_sprite.y;
			//新位置
			var newY:int=ConNewY(nowPosition);
			//缓动效果，scrollCon.y的位置： scrollCon.y += ((计算出的新位置)-scrollCon.y)/缓动值
			scrollCon.y += (newY - scrollCon.y)/easingSpeed;

		}

		private function poleUp(event : MouseEvent):void {
			var nowPosition:int=pole_sprite.y;
			//弹起在次计算的原因是当鼠标弹起时移除了poleDown函数里的缓动效果，导致scrollCon没有到达计算位置。
			scrollCon.y=ConNewY(nowPosition);

			pole_sprite.stopDrag();
			scrollBar_sprite.removeEventListener(Event.ENTER_FRAME, poleDown);
			scrollBar_sprite.stage.removeEventListener(MouseEvent.MOUSE_UP, poleUp);
			//scrollCon.addEventListener(Event.SCROLL, textScroll);
		}

		/**
		 * 滑块背景点击
		 */
		private function bgDown(event : MouseEvent):void {
			var nowPosition:int;
			if ((scrollBar_sprite.mouseY-up_btn.y-up_btn.height) < (pole_sprite.height / 2)) {
				nowPosition=Math.floor(up_btn.y+up_btn.height);
			} else if ((down_btn.y - scrollBar_sprite.mouseY) < pole_sprite.height / 2) {
				nowPosition=Math.floor(down_btn.y-pole_sprite.height);
			} else {
				nowPosition=scrollBar_sprite.mouseY-pole_sprite.height/2;
			}
			pole_sprite.y=nowPosition;
			scrollCon.y=ConNewY(nowPosition);

		}

		/**
		 * 下滚动按钮
		 */
		private function downBtn(event : MouseEvent):void {
			if (scrollCon.y>(areaY+areaBg-scrollCon.height)) {
				scrollCon.y-=10;
				var nowPosition:int=scrollCon.y;
				pole_sprite.y=PoleNewY(nowPosition);
			}
			//当鼠标在按钮上按下的时间大于设定时间时，连续滚动
			putTime=getTimer();
			scrollBar_sprite.addEventListener(Event.ENTER_FRAME, downBtnDown);
		}

		private function downBtnDown(event : Event):void {
			if (getTimer()-putTime>500) {
				if (scrollCon.y>(areaY+areaBg-scrollCon.height)) {
					scrollCon.y-=1;
					var nowPosition:int=scrollCon.y;
					pole_sprite.y=PoleNewY(nowPosition);
				}
			}
		}

		private function downBtnUp(event : MouseEvent):void {
			scrollBar_sprite.removeEventListener(Event.ENTER_FRAME, downBtnDown);
		}

		/**
		 * 上滚动按钮
		 */
		private function upBtn(event : MouseEvent):void {
			if (scrollCon.y<areaY) {
				scrollCon.y+=10;
				var nowPosition:int=scrollCon.y;
				pole_sprite.y=PoleNewY(nowPosition);
			}
			//当鼠标在按钮上按下的时间大于设定时间时，连续滚动
			putTime=getTimer();
			scrollBar_sprite.addEventListener(Event.ENTER_FRAME, upBtnDown);
		}

		private function upBtnDown(event : Event):void {
			if (getTimer()-putTime>500) {
				if (scrollCon.y<areaY) {
					scrollCon.y+=1;
					var nowPosition:int=scrollCon.y;
					pole_sprite.y=PoleNewY(nowPosition);
				}
			}
		}

		private function upBtnUp(event : MouseEvent):void {
			scrollBar_sprite.removeEventListener(Event.ENTER_FRAME, upBtnDown);
		}

		/**
		 * 鼠标滚轮事件
		 */
		private function mouseWheel(event : MouseEvent):void {

			var nowPosition:int;
			if (event.delta<0) {
				if (scrollCon.y>(areaY+areaBg-scrollCon.height)) {
					scrollCon.y+=Math.floor(event.delta*3);
					nowPosition=scrollCon.y;
					pole_sprite.y=PoleNewY(nowPosition);
				}
			} else if (event.delta>0) {
				if (scrollCon.y<areaY) {
					scrollCon.y+=Math.floor(event.delta*3);
					nowPosition=scrollCon.y;
					pole_sprite.y=PoleNewY(nowPosition);
				}
			}

		}
	}
}