package

{

/*

*@ ClassName : package::backGround

*@ INTRO : the continuously scroll background

*@ Author : feiruo

*@ LanguageVersion : 3.0

*@ SDKVersion : Flash Player 9.0

*@ Date : 2015.09.09

*/

import flash.display.MovieClip;

import flash.events.Event;

import flash.events.MouseEvent;

dynamic public class backGround extends MovieClip //dynamic表示可以向该类进行动态的添加属性

{

public var myAcc:Number=20; //缓动系数

public var mouseAcc:Number=10; //鼠标缓动系数

public var autoPlay_speed:Number=3; //自动滚动速度初始值

public var mouseOverPlay_speed:Number=-3; //鼠标经过时背景播放的速度，正数向右，负数向左

private var autoPlay:Boolean=false;

private var mouseF:Number=0;

private var mouseover:Boolean=false;

private var isDrag:Boolean;

private var speed:Number=0;

private var startX2:Number=0;

private var startX:Number=0;

private var memory_x:Number=0;

private var _width:Number;

public function backGround()

{

addFrameScript(0, frame1); //在影片剪辑backGround元件中时间轴第一帧添加代码

this._width=this.width/3;

return;

}

public function frame1():void

{

isDrag=false;

speed=5; //设定初始滚动速度

addEventListener(Event.ENTER_FRAME, update);//添加帧事件

this.addEventListener(MouseEvent.MOUSE_OVER,function(e:MouseEvent):void{mouseover=true;});

this.addEventListener(MouseEvent.MOUSE_OUT,function(e:MouseEvent):void{mouseover=false;});

if (autoPlay == false) //如果没有自动滚动，添加鼠标事件

{

this.addEventListener(MouseEvent.MOUSE_DOWN, mouseHandler);

stage.addEventListener(MouseEvent.MOUSE_UP, mouseHandler);

}

return;

}//end function

private function mouseUpdate()

{

startX2 = startX2 + (mouseX - startX - startX2) / 3;

//计算鼠标位置差值

bg_mc.x = memory_x + startX2;

//计算当前背景图应该所在的新位置

if (bg_mc.x > 0)

{

bg_mc.x = bg_mc.x - this._width;

//返回到第一张图或第二张图之间，所显示画面与当前的位置其实一样

}

if (bg_mc.x <= -this._width)

{

bg_mc.x = bg_mc.x + this._width;

//返回到第二张图或第三张图之间

}

return;

}//end function

private function mouseHandler(e:MouseEvent):void

{

if (e.type == MouseEvent.MOUSE_DOWN)

{

memory_x = bg_mc.x; //临时存储当前背景图的x坐标

startX = mouseX; //鼠标按下，临时存储鼠标x坐标

startX2 = mouseX - startX; //按下移动后，计算移动距离

mouseF = mouseX; //记录当前鼠标位置

isDrag = true; //拖动属性设置为true，可以拖动

mouseUpdate();

}

else if (e.type == MouseEvent.MOUSE_UP)

{

if (isDrag)

{

speed = (-(mouseF - mouseX)) / mouseAcc; //计算鼠标弹起是背景图应该滚动的速度

isDrag = false; //拖动为false

}

}

return;

}//end function

private function update(e:Event):void

{

mouseover ? bg_mc.x+=mouseOverPlay_speed : bg_mc.x+=0;

if (autoPlay == false) //如果背景图没有自己滚动，并且速度不为0，计算当前位置

{

if (Math.abs(speed) >= 0)

{

bg_mc.x = bg_mc.x + speed;

}

}

else

{

bg_mc.x = bg_mc.x + autoPlay_speed; //否则自动滚动

}

if (bg_mc.x > 0)

{

bg_mc.x = -this._width + speed;

}

if (bg_mc.x <= -this._width)

{

bg_mc.x = speed;

}

mouseF = mouseF + (mouseX - mouseF) / mouseAcc;

//计算非拖动与拖动情况下的速度

if (!isDrag)

{

speed = speed + (-speed) / myAcc;

}

else

{

speed = speed + (-speed) / myAcc;

mouseUpdate();

}

if (Math.abs(speed) < 0.5)

//如果速度绝对值小于0.5，可以默认为0

{

speed = 0;

}

return;

}

}

}