FLASH加载外部图片实现淡入淡出的效果

建一个空的MC，将它放到舞台上，取实例名称为pic_mc
第1帧放入代码：

var i =0;
pic_mc.loadMovie("http://xueyou./attachment/201007/17/161247_1279370763nzNn.jpg.thumb.jpg")
pic_mc._xscale = pic_mc._yscale = 150;
pic_mc._alpha=0;
onEnterFrame = function(){
        if (i<20){
                pic_mc._alpha += 5;
                i++;
        } else {
                delete onEnterFrame;
}
}

第70帧插入关键帧放入代码：
onEnterFrame = function(){
        if (i>0){
                pic_mc._alpha -= 5;
                i--;
        } else {
                delete onEnterFrame;
}
}

第90帧插入帧