Android使用Rotate3dAnimation实现3D旋转动画效果的实例代码

利用Android的ApiDemos的Rotate3dAnimation实现了个图片3D旋转的动画，围绕Y轴进行旋转，还可以实现Z轴的缩放。点击开始按钮开始旋转，点击结束按钮停止旋转。

代码如下：:

Rotate3dAnimation.java

public class Rotate3dAnimation extends Animation { 
 private final float mFromDegrees; 
 private final float mToDegrees; 
 private final float mCenterX; 
 private final float mCenterY; 
 private final float mDepthZ; 
 private final boolean mReverse; 
 private Camera mCamera; 
 /** 
 * Creates a new 3D rotation on the Y axis. The rotation is defined by its 
 * start angle and its end angle. Both angles are in degrees. The rotation 
 * is performed around a center point on the 2D space, definied by a pair 
 * of X and Y coordinates, called centerX and centerY. When the animation 
 * starts, a translation on the Z axis (depth) is performed. The length 
 * of the translation can be specified, as well as whether the translation 
 * should be reversed in time. 
 * 
 * @param fromDegrees the start angle of the 3D rotation 
 * @param toDegrees the end angle of the 3D rotation 
 * @param centerX the X center of the 3D rotation 
 * @param centerY the Y center of the 3D rotation 
 * @param reverse true if the translation should be reversed, false otherwise 
 */ 
 public Rotate3dAnimation(float fromDegrees, float toDegrees, 
 float centerX, float centerY, float depthZ, boolean reverse) { 
 mFromDegrees = fromDegrees; 
 mToDegrees = toDegrees; 
 mCenterX = centerX; 
 mCenterY = centerY; 
 mDepthZ = depthZ; 
 mReverse = reverse; 
 } 
 @Override 
 public void initialize(int width, int height, int parentWidth, int parentHeight) { 
 super.initialize(width, height, parentWidth, parentHeight); 
 mCamera = new Camera(); 
 } 
 @Override 
 protected void applyTransformation(float interpolatedTime, Transformation t) { 
 final float fromDegrees = mFromDegrees; 
 float degrees = fromDegrees + ((mToDegrees - fromDegrees) * interpolatedTime); 
 final float centerX = mCenterX; 
 final float centerY = mCenterY; 
 final Camera camera = mCamera; 
 final Matrix matrix = t.getMatrix(); 
 //保存一次camera初始状态，用于restore() 
 camera.save(); 
 if (mReverse) { 
 camera.translate(0.0f, 0.0f, mDepthZ * interpolatedTime); 
 } else { 
 camera.translate(0.0f, 0.0f, mDepthZ * (1.0f - interpolatedTime)); 
 } 
 //围绕Y轴旋转degrees度 
 camera.rotateY(degrees); 
 //行camera中取出矩阵，赋值给matrix 
 camera.getMatrix(matrix); 
 //camera恢复到初始状态，继续用于下次的计算 
 camera.restore(); 
 matrix.preTranslate(-centerX, -centerY); 
 matrix.postTranslate(centerX, centerY); 
 } 
} 

Test3DRotateActivity.java

public class Test3DRotateActivity extends Activity { 
 /** Called when the activity is first created. */ 
 private final String TAG="Test3DRotateActivity"; 
 private ImageView image; 
 private Button start ,stop; 
 private Rotate3dAnimation rotation; 
 private StartNextRotate startNext; 
 @Override 
 public void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 setContentView(R.layout.main); 
 image = (ImageView) findViewById(R.id.image); 
 start=(Button) findViewById(R.id.start); 
 stop = (Button) findViewById(R.id.stop); 
 start.setOnClickListener(new OnClickListener() { 
 public void onClick(View v) { 
 // TODO Auto-generated method stub 
 //进行360度的旋转 
 startRotation(0,360); 
 } 
 }); 
 stop.setOnClickListener(new OnClickListener() { 
 public void onClick(View v) { 
 // TODO Auto-generated method stub 
 image.clearAnimation(); 
 } 
 }); 
 } 
 private void startRotation(float start, float end) { 
 // 计算中心点 
 final float centerX = image.getWidth() / 2.0f; 
 final float centerY = image.getHeight() / 2.0f; 
 Log.d(TAG, "centerX="+centerX+", centerY="+centerY); 
 // Create a new 3D rotation with the supplied parameter 
 // The animation listener is used to trigger the next animation 
 //final Rotate3dAnimation rotation =new Rotate3dAnimation(start, end, centerX, centerY, 310.0f, true); 
 //Z轴的缩放为0 
 rotation =new Rotate3dAnimation(start, end, centerX, centerY, 0f, true); 
 rotation.setDuration(2000); 
 rotation.setFillAfter(true); 
 //rotation.setInterpolator(new AccelerateInterpolator()); 
 //匀速旋转 
 rotation.setInterpolator(new LinearInterpolator()); 
 //设置监听 
 startNext = new StartNextRotate(); 
 rotation.setAnimationListener(startNext); 
 image.startAnimation(rotation); 
 } 
 private class StartNextRotate implements AnimationListener{ 
 public void onAnimationEnd(Animation animation) { 
 // TODO Auto-generated method stub 
 Log.d(TAG, "onAnimationEnd......"); 
 image.startAnimation(rotation); 
 } 
 public void onAnimationRepeat(Animation animation) { 
 // TODO Auto-generated method stub 
 } 
 public void onAnimationStart(Animation animation) { 
 // TODO Auto-generated method stub 
 } 
 } 
} 

main.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 android:orientation="vertical" > 
 <Button 
 android:id="@+id/start" 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:text="开始" /> 
 <Button 
 android:id="@+id/stop" 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:text="结束" /> 
 <ImageView 
 android:id="@+id/image" 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:src="@drawable/t1" 
 /> 
</LinearLayout> 

代码中用Camera来实现动画，Camera就是一个摄像机，一个物体原地不动，我们带着摄像机按设定的角度进行移动，之后从Camera中取出完成该动画的Matrix，然后画我们的物体，这个就是这个3D动画实现的原理。
具体的解释见代码中注释部分，重点说一下Rotate3dAnimation.java中的

matrix.preTranslate(-centerX, -centerY); 
matrix.postTranslate(centerX, centerY); 

由于旋转是以(0,0)为中心的,所以为了把界面的中心与(0,0)对齐,就要preTranslate(-centerX, -centerY),旋转完成后,调用postTranslate(centerX, centerY),再把图片移回来,这样看到的动画效果就是activity的界面图片从在centerX为中心绕Y轴旋转了。
你还可以把上面代码改成

matrix.preTranslate(-centerX, 0); 
matrix.postTranslate(centerX, 0); 

看有什么不同效果。

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