Android开发--Animation的应用

1.简介

Animation提供了一系列的动画效果，可以作用于大多数控件上。它有分为两大类：Tweened Animation，Frame-by-Frame Animation。

其中，前者提供旋转，缩放，移动，淡入淡出动画效果；后者可以创建Drawable序列，这些序列可以按照指定时间显示。

2.应用

Animations的使用可以归纳为以下五个步骤：

1.创建AnimationSet对象  

 AnimationSet(boolean shareInterpolator)                                         

2.创建Animation对象    

淡入淡出效果：        

AlphaAnimation(float fromAlpha, float toAlpha)        

fromAlpha - Starting alpha value for the animation, where 1.0 means fully opaque and 0.0 means fully transparent.

toAlpha - Ending alpha value for the animation.

注:区间(0,1)的0表示完全透明，1表示完全不透明     

 缩放效果：

ScaleAnimation(float fromX, float toX, float fromY, float toY)         

注:(fromX=1,fromY=1,toX=2,toY=2)       //从原始大小,放大到两倍.以左边为开始点
    (fromX=0,fromY=0,toX=2,toY=2)      //从零放大两倍

ScaleAnimation(float fromX, float toX, float fromY, float toY, float pivotX, float pivotY)

注:(pivotX,pivotY)为放大的中心点

ScaleAnimation(float fromX, float toX, float fromY, float toY, int pivotXType, float pivotXValue, int pivotYType, float pivotYValue)

pivotXType - Specifies how pivotXValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.

pivotXValue - The X coordinate of the point about which the object is being scaled, specified as an absolute number where 0 is the left edge.

pivotYType - Specifies how pivotYValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.

pivotYValue - The Y coordinate of the point about which the object is being scaled, specified as an absolute number where 0 is the top edge.

旋转效果：

RotateAnimation(float fromDegrees, float toDegrees)

fromDegrees - Rotation offset to apply at the start of the animation.

toDegrees - Rotation offset to apply at the end of the animation.

RotateAnimation(float fromDegrees, float toDegrees, float pivotX, float pivotY)

fromDegrees - Rotation offset to apply at the start of the animation.

toDegrees - Rotation offset to apply at the end of the animation.

pivotX - The X coordinate of the point about which the object is being rotated, specified as an absolute number where 0 is the left edge.

pivotY - The Y coordinate of the point about which the object is being rotated, specified as an absolute number where 0 is the top edge.

RotateAnimation(float fromDegrees, float toDegrees, int pivotXType, float pivotXValue, int pivotYType, float pivotYValue)

pivotXType - Specifies how pivotXValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.

pivotXValue - The X coordinate of the point about which the object is being rotated, specified as an absolute number where 0 is the left edge. This value can  either be an absolute number if pivotXType is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.

pivotYType - Specifies how pivotYValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.

pivotYValue - The Y coordinate of the point about which the object is being rotated, specified as an absolute number where 0 is the top edge. This value can either be an absolute number if pivotYType is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.

平移效果：

TranslateAnimation(float fromXDelta, float toXDelta, float fromYDelta, float toYDelta)

fromXDelta - Change in X coordinate to apply at the start of the animation

toXDelta - Change in X coordinate to apply at the end of the animation

fromYDelta - Change in Y coordinate to apply at the start of the animation

toYDelta - Change in Y coordinate to apply at the end of the animation

TranslateAnimation(int fromXType, float fromXValue, int toXType, float toXValue, int fromYType, float fromYValue, int toYType, float toYValue)

fromXType - Specifies how fromXValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.

fromXValue - Change in X coordinate to apply at the start of the animation. This value can either be an absolute number if fromXType is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.

toXType - Specifies how toXValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.

toXValue - Change in X coordinate to apply at the end of the animation. This value can either be an absolute number if toXType is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.

fromYType - Specifies how fromYValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.

fromYValue - Change in Y coordinate to apply at the start of the animation. This value can either be an absolute number if fromYType is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.

toYType - Specifies how toYValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.

toYValue - Change in Y coordinate to apply at the end of the animation. This value can either be an absolute number if toYType is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.

3.为Animation对象设置相应的数据

注：详情见API中Animation的方法摘要

4.将Animation对象放入AnimationSet中

addAnimation(Animation a)

5.使用控件加载动画

startAnimation(Animation a)

3.代码

以下代码以图片的淡入淡出为例：

public class Activity1 extends Activity implements OnClickListener{
    //声明对象
    private ImageView iv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.act1);
        //将对象与ID匹配
        iv=(ImageView) findViewById(R.id.imageView1);
        //显示图片
        iv.setBackgroundResource(R.drawable.i2);
        iv.setOnClickListener(this);
    }  
    @Override
    public void onClick(View v) {
        //创建AnimationSet对象
        AnimationSet animationset1 = new AnimationSet(true);
        //创建动画对象，此为但如淡出动画。其中，0表示完全透明，1表示完全不透明。
        AlphaAnimation alpha = new AlphaAnimation(0, 1);
        //设置动画时间
        alpha.setDuration(2000);
        //将动画放入AnimationSet对象中
        animationset1.addAnimation(alpha);
        //部件开始动画
        iv.startAnimation(animationset1);
    }

4.效果