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
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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
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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
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<?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
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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
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matrix.preTranslate(-centerX, 0); matrix.postTranslate(centerX, 0); |
看有什么不同效果。
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原文链接：https://blog.csdn.net/heqiangflytosky/article/details/17042977
