Android动画处理——Tween动画

 通过一个Tween动画（补间动画，学过Flash的人应该很熟悉）实例学习。

首先，关于Tween动画有两种方法可以创建，先看第一种——在Java代码里编辑：

package com.android.tween;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.drawable.BitmapDrawable;
import android.view.KeyEvent;
import android.view.View;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.view.animation.ScaleAnimation;
import android.view.animation.TranslateAnimation;

public class GameView extends View
{
    /* 定义Alpha动画 */
    private Animation   mAnimationAlpha     = null;

    /* 定义Scale动画 */
    private Animation   mAnimationScale     = null;

    /* 定义Translate动画 */
    private Animation   mAnimationTranslate = null;

    /* 定义Rotate动画 */
    private Animation   mAnimationRotate    = null;

    /* 定义Bitmap对象 */
    Bitmap              mBitmap             = null;

    public GameView(Context context)
    {
        super(context);

        /* 装载资源 */
        mBitmap = ((BitmapDrawable) getResources().getDrawable(R.drawable.my)).getBitmap();
    }

    public void onDraw(Canvas canvas)
    {
        super.onDraw(canvas);

        /* 绘制图片 */
        canvas.drawBitmap(mBitmap, 0, 0, null);
    }

    public boolean onKeyUp(int keyCode, KeyEvent event)
    {
        switch ( keyCode )
        {
        case KeyEvent.KEYCODE_DPAD_UP:
            /* 创建Alpha动画 */
            mAnimationAlpha = new AlphaAnimation(0.1f, 1.0f);
            /* 设置动画的时间 */
            mAnimationAlpha.setDuration(3000);
            /* 开始播放动画 */
            this.startAnimation(mAnimationAlpha);
            break;
        case KeyEvent.KEYCODE_DPAD_DOWN:
            /* 创建Scale动画 */
            mAnimationScale =new ScaleAnimation(0.0f, 1.0f, 0.0f, 1.0f,
                                                Animation.RELATIVE_TO_SELF, 0.5f,
                                                Animation.RELATIVE_TO_SELF, 0.5f);
            /* 设置动画的时间 */
            mAnimationScale.setDuration(500);
            /* 开始播放动画 */
            this.startAnimation(mAnimationScale);
            break;
        case KeyEvent.KEYCODE_DPAD_LEFT:
            /* 创建Translate动画 */
            mAnimationTranslate = new TranslateAnimation(10, 100,10, 100);
            /* 设置动画的时间 */
            mAnimationTranslate.setDuration(1000);
            /* 开始播放动画 */
            this.startAnimation(mAnimationTranslate);
            break;
        case KeyEvent.KEYCODE_DPAD_RIGHT:
            /* 创建Rotate动画 */
            mAnimationRotate=new RotateAnimation(0.0f, +360.0f,
                                                 Animation.RELATIVE_TO_SELF,0.5f,
                                                 Animation.RELATIVE_TO_SELF, 0.5f);
            /* 设置动画的时间 */
            mAnimationRotate.setDuration(1000);
            /* 开始播放动画 */
            this.startAnimation(mAnimationRotate);
            break;
        }
        return true;
    }
}

 

mAnimationScale =new ScaleAnimation(0.0f, 1.0f, 0.0f, 1.0f,

Animation.RELATIVE_TO_SELF, 0.5f, 

Animation.RELATIVE_TO_SELF, 0.5f);关于这个构造方法的参数理解，可以利用Eclipse的提示功能一个一个的去理解这几个参数，我这里说一下，Animation.RELATIVE_TO_SELF这个参数是限定后面的参数的参照方式，是相对的还是绝对的，相对父界面，还是相对手机窗口，绝对的话你可以设置具体的数值了！

注意：别以为在GameView这个自定义的View里重写了onKeyUp()这个函数，就以为会自动监听键盘事件了，还必须在主Acitivity（HellloTween.java）里重写onKeyUp()方法，并且调用GameView里面的onKeyUp();这样才能做到监听键盘事件！

 

主Acitivity，HellloTween.java代码：

package com.android.tween;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;

public class HellloTween extends Activity
{
    private GameView    mGameView;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        mGameView = new GameView(this);

        setContentView(mGameView);
    }

    public boolean onKeyUp(int keyCode, KeyEvent event)
    {
        if ( mGameView == null )
        {
            return false;
        }
        mGameView.onKeyUp(keyCode,event);
        return true;
    }
    public boolean onKeyDown(int keyCode, KeyEvent event)
    {
        if ( mGameView == null )
        {
            return false;
        }
        if ( keyCode ==  KeyEvent.KEYCODE_BACK)
        {
            this.finish();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
}

再看第二种——在XML里设置：

先建res/anim文件夹，然后在里面分别建alpha_animation.xml、scale_animation.xml、translate_animation.xml、rotate_animation.xml四个文件（注意：文件的命名有规定的，must contain only [a-z0-9_.]）：

alpha_animation.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <alpha
        android:fromAlpha="0.1"
        android:toAlpha="1.0"
        android:duration="2000"
    />
</set>

scale_animation.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <scale
        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
        android:fromXScale="0.0"
        android:toXScale="1.0"
        android:fromYScale="0.0"
        android:toYScale="1.0"
        android:pivotX="80%"
        android:pivotY="50"
        android:fillAfter="true"
        android:duration="500"
    />
</set>

 

                android:pivotX="80%" 比例，经实验，应该是相对手机屏幕的长宽的比例。

android:pivotY="50" 具体像素

                 当然，这两个参数的具体含义是为了确定缩放时的起点，即图片右下角的位置。以这个位置为起点，然后向左上方向放大。

 

translate_animation.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <translate
        android:fromXDelta = "10"
        android:toXDelta = "100"
        android:fromYDelta = "10"
        android:toYDelta = "100"
        android:duration = "1000"
        />
</set>

rotate_animation.xm

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <rotate
        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
        android:fromDegrees="0"
        android:toDegrees="360"
        android:pivotX="0"
        android:pivotY="50%"
        android:duration="1000"
        />
</set>

android:pivotX="0"

android:pivotY="50%"

这两个属性和上面的基本上差不多，有区别的地方是，这里的作用主要是为了确定旋转的轴心。

GameView.java

package com.android.myAnimation;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.drawable.BitmapDrawable;
import android.view.KeyEvent;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;

public class GameView extends View
{
    Context mContext = null;
    private Animation mAnimationAlpha = null;
    private Animation mAnimationScale = null;
    private Animation mAnimationTranslate = null;
    private Animation mAnimationRotate = null;
    private Bitmap mBitmap = null;
    public GameView(Context context) {
        super(context);

        mContext = context;
        mBitmap = ((BitmapDrawable)getResources().getDrawable(R.drawable.my)).getBitmap();
    }

    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawBitmap(mBitmap, 0, 0, null);
    }

    public boolean onKeyUp(int keyCode, KeyEvent event) {
        switch(keyCode) {
            case KeyEvent.KEYCODE_DPAD_UP:
                mAnimationAlpha = AnimationUtils.loadAnimation(mContext, R.anim.alpha_animation);
                startAnimation(mAnimationAlpha);
                break;
            case KeyEvent.KEYCODE_DPAD_DOWN:
                mAnimationScale = AnimationUtils.loadAnimation(mContext, R.anim.scale_animation);
                startAnimation(mAnimationScale);
                break;
            case KeyEvent.KEYCODE_DPAD_LEFT:
                mAnimationTranslate = AnimationUtils.loadAnimation(mContext, R.anim.translate_animation);
                startAnimation(mAnimationTranslate);
                break;
            case KeyEvent.KEYCODE_DPAD_RIGHT:
                mAnimationRotate = AnimationUtils.loadAnimation(mContext, R.anim.rotate_animation);
                startAnimation(mAnimationRotate);
                break;
        }

        return true;
    }
}

AnimationXML.java(主Activity)：

package com.android.myAnimation;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;

public class AnimationXML extends Activity {
    private GameView mGameView = null;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mGameView = new GameView(this);

        setContentView(mGameView);
    }

    public boolean onKeyUp(int keyCode, KeyEvent event) {
        if(mGameView == null) {
            return false;
        }

        mGameView.onKeyUp(keyCode, event);
        return true;
    }

    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(mGameView == null) {
            return false;
        }

        if(keyCode == KeyEvent.KEYCODE_BACK) {
            this.finish();
            return true;
        }

        return super.onKeyDown(keyCode, event);
    }
}

最后看看效果图：

alpha_animation

scale_animation

rotate_animation

translate_animation

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