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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.apis.animation;
     18 
     19 import android.view.animation.Animation;
     20 import android.view.animation.Transformation;
     21 import android.graphics.Camera;
     22 import android.graphics.Matrix;
     23 
     24 /**
     25  * An animation that rotates the view on the Y axis between two specified angles.
     26  * This animation also adds a translation on the Z axis (depth) to improve the effect.
     27  */
     28 public class Rotate3dAnimation extends Animation {
     29     private final float mFromDegrees;
     30     private final float mToDegrees;
     31     private final float mCenterX;
     32     private final float mCenterY;
     33     private final float mDepthZ;
     34     private final boolean mReverse;
     35     private Camera mCamera;
     36 
     37     /**
     38      * Creates a new 3D rotation on the Y axis. The rotation is defined by its
     39      * start angle and its end angle. Both angles are in degrees. The rotation
     40      * is performed around a center point on the 2D space, definied by a pair
     41      * of X and Y coordinates, called centerX and centerY. When the animation
     42      * starts, a translation on the Z axis (depth) is performed. The length
     43      * of the translation can be specified, as well as whether the translation
     44      * should be reversed in time.
     45      *
     46      * @param fromDegrees the start angle of the 3D rotation
     47      * @param toDegrees the end angle of the 3D rotation
     48      * @param centerX the X center of the 3D rotation
     49      * @param centerY the Y center of the 3D rotation
     50      * @param reverse true if the translation should be reversed, false otherwise
     51      */
     52     public Rotate3dAnimation(float fromDegrees, float toDegrees,
     53             float centerX, float centerY, float depthZ, boolean reverse) {
     54         mFromDegrees = fromDegrees;
     55         mToDegrees = toDegrees;
     56         mCenterX = centerX;
     57         mCenterY = centerY;
     58         mDepthZ = depthZ;
     59         mReverse = reverse;
     60     }
     61 
     62     @Override
     63     public void initialize(int width, int height, int parentWidth, int parentHeight) {
     64         super.initialize(width, height, parentWidth, parentHeight);
     65         mCamera = new Camera();
     66     }
     67 
     68     @Override
     69     protected void applyTransformation(float interpolatedTime, Transformation t) {
     70         final float fromDegrees = mFromDegrees;
     71         float degrees = fromDegrees + ((mToDegrees - fromDegrees) * interpolatedTime);
     72 
     73         final float centerX = mCenterX;
     74         final float centerY = mCenterY;
     75         final Camera camera = mCamera;
     76 
     77         final Matrix matrix = t.getMatrix();
     78 
     79         camera.save();
     80         if (mReverse) {
     81             camera.translate(0.0f, 0.0f, mDepthZ * interpolatedTime);
     82         } else {
     83             camera.translate(0.0f, 0.0f, mDepthZ * (1.0f - interpolatedTime));
     84         }
     85         camera.rotateY(degrees);
     86         camera.getMatrix(matrix);
     87         camera.restore();
     88 
     89         matrix.preTranslate(-centerX, -centerY);
     90         matrix.postTranslate(centerX, centerY);
     91     }
     92 }
     93