主要介绍一下如何实现View的3D旋转效果，实现的主要原理就是围绕Y轴旋转，同时在Z轴方面上有一个深入的缩放。
演示的demo主要有以下几个重点：
1，自定义旋转动画
2，动画做完后，重置ImageView
1，自定义动画类
这里实现了一个Rotate3dAnimation的类，它扩展了Animation类，重写applyTransformation()方法，提供指定时间的矩阵变换，我们在这个方法里，就可以利用Camera类得得到一个围绕Y轴旋转的matrix，把这个matrix设置到Transformation对象中。
@Overrideprotected 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(); camera.save(); if (mReverse) { camera.translate(0.0f, 0.0f, mDepthZ * interpolatedTime); } else { camera.translate(0.0f, 0.0f, mDepthZ * (1.0f - interpolatedTime)); } camera.rotateY(degrees); camera.getMatrix(matrix); camera.restore(); matrix.preTranslate(-centerX, -centerY); matrix.postTranslate(centerX, centerY);}
2，如何使用这个动画类
在Activity中，我们有两个大小一样的ImageView，它们都放在FrameLayout中，这样他们位置是重叠的，对最上面的ImageView做动画（旋转角度从0到90），当动画做完后，再对后面的ImageView做动画（旋转角度从90到180），在这里，要控制相应的ImageView隐藏或显示。
private final class DisplayNextView implements Animation.AnimationListener { public void onAnimationStart(Animation animation) { } public void onAnimationEnd(Animation animation) { mContainer.post(new SwapViews()); } public void onAnimationRepeat(Animation animation) { } }
动画做完后，执行的代码如下：
private final class SwapViews implements Runnable { @Override public void run() { mImageView1.setVisibility(View.GONE); mImageView2.setVisibility(View.GONE); mIndex++; if (0 == mIndex % 2) { mStartAnimView = mImageView1; } else { mStartAnimView = mImageView2; } mStartAnimView.setVisibility(View.VISIBLE); mStartAnimView.requestFocus(); Rotate3dAnimation rotation = new Rotate3dAnimation( -90, 0, mCenterX, mCenterY, mDepthZ, false); rotation.setDuration(mDuration); rotation.setFillAfter(true); rotation.setInterpolator(new DecelerateInterpolator()); mStartAnimView.startAnimation(rotation); } }
3，完整代码如下
Rotate3dAnimActivity.java
public class Rotate3dAnimActivity extends Activity{ ImageView mImageView1 = null; ImageView mImageView2 = null; ImageView mStartAnimView = null; View mContainer = null; int mDuration = 500; float mCenterX = 0.0f; float mCenterY = 0.0f; float mDepthZ = 0.0f; int mIndex = 0; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.rotate_anim); mImageView1 = (ImageView) findViewById(R.id.imageView1); mImageView2 = (ImageView) findViewById(R.id.imageView2); mContainer = findViewById(R.id.container); mStartAnimView = mImageView1; findViewById(R.id.button1).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { mCenterX = mContainer.getWidth() / 2; mCenterY = mContainer.getHeight() / 2; getDepthZ(); applyRotation(mStartAnimView, 0, 90); } }); InputMethodManager imm = (InputMethodManager)getSystemService(INPUT_METHOD_SERVICE); imm.hideSoftInputFromWindow(getWindow().getDecorView().getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS); } private void getDepthZ() { EditText editText = (EditText) findViewById(R.id.edit_depthz); String string = editText.getText().toString(); try { mDepthZ = (float)Integer.parseInt(string); //mDepthZ = Math.min(mDepthZ, 300.0f); } catch (Exception e) { e.printStackTrace(); } } private void applyRotation(View animView, float startAngle, float toAngle) { float centerX = mCenterX; float centerY = mCenterY; Rotate3dAnimation rotation = new Rotate3dAnimation( startAngle, toAngle, centerX, centerY, mDepthZ, true); rotation.setDuration(mDuration); rotation.setFillAfter(true); rotation.setInterpolator(new AccelerateInterpolator()); rotation.setAnimationListener(new DisplayNextView()); animView.startAnimation(rotation); } /** * This class listens for the end of the first half of the animation. * It then posts a new action that effectively swaps the views when the container * is rotated 90 degrees and thus invisible. */ private final class DisplayNextView implements Animation.AnimationListener { public void onAnimationStart(Animation animation) { } public void onAnimationEnd(Animation animation) { mContainer.post(new SwapViews()); } public void onAnimationRepeat(Animation animation) { } } private final class SwapViews implements Runnable { @Override public void run() { mImageView1.setVisibility(View.GONE); mImageView2.setVisibility(View.GONE); mIndex++; if (0 == mIndex % 2) { mStartAnimView = mImageView1; } else { mStartAnimView = mImageView2; } mStartAnimView.setVisibility(View.VISIBLE); mStartAnimView.requestFocus(); Rotate3dAnimation rotation = new Rotate3dAnimation( -90, 0, mCenterX, mCenterY, mDepthZ, false); rotation.setDuration(mDuration); rotation.setFillAfter(true); rotation.setInterpolator(new DecelerateInterpolator()); mStartAnimView.startAnimation(rotation); } }}
rotate_anim.xml
Rotate3dAnimation.java
package com.nj1s.lib.anim;import android.graphics.Camera;import android.graphics.Matrix;import android.view.animation.Animation;import android.view.animation.Transformation;/** * An animation that rotates the view on the Y axis between two specified angles. * This animation also adds a translation on the Z axis (depth) to improve the effect. */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(); camera.save(); if (mReverse) { camera.translate(0.0f, 0.0f, mDepthZ * interpolatedTime); } else { camera.translate(0.0f, 0.0f, mDepthZ * (1.0f - interpolatedTime)); } camera.rotateY(degrees); camera.getMatrix(matrix); camera.restore(); matrix.preTranslate(-centerX, -centerY); matrix.postTranslate(centerX, centerY); }}