Android 3D旋转动画——Rotate3dAnimation

在Android中如果想要实现3D效果一般有两种选择，一是使用Open GL ES，二是使用Camera。Open GL ES使用起来太过复杂，一般是用于比较高级的3D特效或游戏，像比较简单的一些3D效果，使用Camera就足够了。

Camera中提供了三种旋转方法，分别是rotateX()、rotateY()和rotateZ，调用这三个方法，并传入相应的角度，就可以让视图围绕这三个轴进行旋转，而今天我们要做的中轴旋转效果其实就是让视图围绕Y轴进行旋转。使用Camera让视图进行旋转的示意图，如下所示：

package com.example.rotate3danimation;

import android.graphics.Camera;
import android.graphics.Matrix;
import android.view.animation.Animation;
import android.view.animation.Transformation;

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();
        // 将当前的摄像头位置保存下来，以便变换进行完成后恢复成原位，
        camera.save();
        // camera.translate，这个方法接受3个参数，分别是x,y,z三个轴的偏移量，我们这里只将z轴进行了偏移，
        if (mReverse) {
            // z的偏移会越来越大。这就会形成这样一个效果，view从近到远
            camera.translate(0.0f, 0.0f, mDepthZ * interpolatedTime);
        } else {
            // z的偏移会越来越小。这就会形成这样一个效果，我们的View从一个很远的地方向我们移过来，越来越近，最终移到了我们的窗口上面～
            camera.translate(0.0f, 0.0f, mDepthZ * (1.0f - interpolatedTime));
        }

        // 是给我们的View加上旋转效果，在移动的过程中，视图还会移Y轴为中心进行旋转。
        camera.rotateY(degrees);
        // 是给我们的View加上旋转效果，在移动的过程中，视图还会移X轴为中心进行旋转。
        // camera.rotateX(degrees);

        // 这个是将我们刚才定义的一系列变换应用到变换矩阵上面，调用完这句之后，我们就可以将camera的位置恢复了，以便下一次再使用。
        camera.getMatrix(matrix);
        // camera位置恢复
        camera.restore();

        // 以View的中心点为旋转中心,如果不加这两句，就是以（0,0）点为旋转中心
        matrix.preTranslate(-centerX, -centerY);
        matrix.postTranslate(centerX, centerY);
    }
}

 

使用：

final Rotate3dAnimation rotation = new Rotate3dAnimation(360, 270, windowWidth/2, 0,  
                                    0, false);  
                            // 动画持续时间500毫秒  
                            rotation.setDuration(250);  
                            // 动画完成后保持完成的状态  
                            rotation.setFillAfter(true);  
                          //  rotation.setInterpolator(new AccelerateInterpolator());  
                            scanCouponIV.startAnimation(rotation);
                            rotation.setAnimationListener(new AnimationListener() {
                                
                                @Override
                                public void onAnimationStart(Animation animation) {
                                    // TODO Auto-generated method stub
                                    
                                }
                                
                                @Override
                                public void onAnimationRepeat(Animation animation) {
                                    // TODO Auto-generated method stub
                                    
                                }
                                
                                @Override
                                public void onAnimationEnd(Animation animation) {
                                    scanCouponIV.setVisibility(View.INVISIBLE);
                                    scanCouponIV.setOnClickListener(null);
                                }
                            });