Android实现3D翻转动画效果

Android中并没有提供直接做3D翻转的动画，所以关于3D翻转的动画效果需要我们自己实现，那么我们首先来分析一下Animation 和 Transformation。

Animation动画的主要接口，其中主要定义了动画的一些属性比如开始时间，持续时间，是否重复播放等等。而Transformation中则包含一个矩阵和alpha值，矩阵是用来做平移，旋转和缩放动画的，而alpha值是用来做alpha动画的，要实现3D旋转动画我们需要继承自Animation类来实现，我们需要重载getTransformation和applyTransformation，在getTransformation中Animation会根据动画的属性来产生一系列的差值点，然后将这些差值点传给applyTransformation，这个函数将根据这些点来生成不同的Transformation。下面是

具体实现：

package com.example.textviewtest;

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

public class Rotate3dAnimation extends Animation {
  // 开始角度
  private final float mFromDegrees;
  // 结束角度
  private final float mToDegrees;
  // 中心点
  private final float mCenterX;
  private final float mCenterY;
  private final float mDepthZ;
  // 是否需要扭曲
  private final boolean mReverse;
  // 摄像头
  private Camera mCamera;

  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();
  }

  // 生成Transformation
  @Override
  protected void applyTransformation(float interpolatedTime, Transformation t) {
    final float fromDegrees = mFromDegrees;
    // 生成中间角度
    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);
    // 取得变换后的矩阵
    camera.getMatrix(matrix);
    camera.restore();

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

其中包括了旋转的开始和结束角度，中心点、是否扭曲、和一个Camera，这里我们主要分析applyTransformation函数，其中第一个参数就是通过getTransformation函数传递的差指点，然后我们根据这个差值通过线性差值算法计算出一个中间角度degrees，Camera类是用来实现绕Y轴旋转后透视投影的，因此我们首先通过t.getMatrix()取得当前的矩阵，然后通过camera.translate来对矩阵进行平移变换操作，camera.rotateY进行旋转。这样我们就可以很轻松的实现3D旋转效果了。

下面是布局文件main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@drawable/main_screen_bg"
  android:gravity="center_horizontal"
  android:orientation="vertical"
  tools:context=".MainActivity" >

  <Button
    android:id="@+id/next_btn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="20dip"
    android:drawableTop="@drawable/qiangpiao_dropdown"
    android:text="下一个" />

  <TextView
    android:id="@+id/tv"
    android:layout_width="300dip"
    android:layout_height="300dip"
    android:layout_gravity="center"
    android:background="@drawable/call_show_frame_safe"
    android:gravity="center"
    android:textColor="#ffffff"
    android:textSize="15sp" />

</LinearLayout>

MainActivity的代码如下：

package com.example.textviewtest;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.Animation;
import android.view.animation.DecelerateInterpolator;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity {
  private TextView tv;
  private Button btn;
  private int count = 1;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tv = (TextView) findViewById(R.id.tv);
    tv.setText(String.valueOf(count));
    btn = (Button) findViewById(R.id.next_btn);
    applyRotation(0, 90);

    btn.setOnClickListener(new View.OnClickListener() {

      @Override
      public void onClick(View v) {
        applyRotation(0, 90);
      }
    });

  }

  private void applyRotation(float start, float end) {
    // 计算中心点
    final float centerX = tv.getWidth() / 2.0f;
    final float centerY = tv.getHeight() / 2.0f;

    final Rotate3dAnimation rotation = new Rotate3dAnimation(start, end,
        centerX, centerY, 310.0f, true);
    rotation.setDuration(500);
    rotation.setFillAfter(true);
    rotation.setInterpolator(new AccelerateInterpolator());
    // 设置监听
    rotation.setAnimationListener(new DisplayNextView());

    tv.startAnimation(rotation);
  }

  private final class DisplayNextView implements Animation.AnimationListener {

    public void onAnimationStart(Animation animation) {
    }

    // 动画结束
    public void onAnimationEnd(Animation animation) {
      tv.post(new SwapViews());
    }

    public void onAnimationRepeat(Animation animation) {
    }
  }

  private final class SwapViews implements Runnable {

    public void run() {
      final float centerX = tv.getWidth() / 2.0f;
      final float centerY = tv.getHeight() / 2.0f;
      Rotate3dAnimation rotation = null;

      tv.requestFocus();

      rotation = new Rotate3dAnimation(90, 0, centerX, centerY, 310.0f,
          false);
      rotation.setDuration(500);
      rotation.setFillAfter(true);
      rotation.setInterpolator(new DecelerateInterpolator());
      // 开始动画
      tv.startAnimation(rotation);
      tv.setText(String.valueOf(count++));
    }
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
  }

} 

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。