Android之动画3D旋转

本文主要记录一个坑

关于3D的旋转，三维空间有xyz轴，手机上x轴：手机的宽；y轴：手机的高;z轴：手机到人眼那个垂直于手机面的方向，3D旋转就是围绕y轴旋转。本文主要内容来自Google的官方demo。

不知道怎么下载google sample请看步骤（Android studio）

File --> New --> Import samlpe...（如果你被墙了，戳这里，只能帮你到这里了）

先说说这个坑是啥：在onCreate()里无法得到布局控件的宽和高，那就去onResume()里，那时视图都加载完了，不好意思，依旧获取不到，只能在onClick（listener是观察者模式）里使用时再得到值

看看3D效果



看看3D旋转的Util

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

/**
* <p>Description: 使用Camera来实现，Rotate3dAnimation使用的是绕Y轴旋转  </p>
* Created by slack on 2016/7/13 18:35 .
*
*  from : http://blog.163.com/benben_long/blog/static/19945824320141117443156/ */
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);
}
}

怎么使用的，我就两个button布局

<?xml version="1.0" encoding="utf-8"?>
<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:gravity="center"
android:id="@+id/layout"
tools:context="com.example.rotate3d.MainActivity">

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="rotate"
android:text="Hello World!" />

<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="buttonRotate"
android:text="Hello World!" />
</LinearLayout>

mainActivity里，基于上面的坑，只能使用时再获取控件宽和高了

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutCompat;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity {

LinearLayout layout;
Button button;
boolean isback = false;
Rotate3dAnimation animation;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
layout = (LinearLayout) findViewById(R.id.layout);
button = (Button)findViewById(R.id.button);
}

@Override
protected void onResume() {
super.onResume();
Log.i("slack",layout.getWidth()+","+layout.getHeight());
}

public void rotate(View view) {
float centerX = layout.getWidth() / 2f;
float centerY = layout.getHeight() / 2f;
Log.i("slack",layout.getWidth()+","+layout.getHeight());
Log.i("slack",centerX+","+centerY);
if(isback){
animation = new Rotate3dAnimation(180, 360,
centerX, centerY
, 100.0f, false);
}else{
animation = new Rotate3dAnimation(0, 180,
centerX, centerY
, 100.0f, false);
}
animation.setDuration(1000);//动画持续时间设为500毫秒
animation.setFillAfter(true);//动画完成后保持完成的状态
layout.startAnimation(animation);

isback = !isback;
}

public void buttonRotate(View view) {
/**
* 重点是两个参数 float centerX, float centerY
* 动画都是建立在某一个视图View上的，所以这个 坐标参数是
* 以要动画的view 为坐标系里的坐标
* 比如下面这个只是单个的view以中轴为中心旋转，关键是x轴
* 这里的x轴是这个button的坐标系里的中心 button.getWidth()/2f
*  y轴无所谓，因为是绕着Y轴旋转的 ,如下图
*    - - - - - - - - -
*   \      (x,y)       \
*   \        *         \
*   \                  \
*    - - - - - - - - - -
*/
Rotate3dAnimation  animation = new Rotate3dAnimation(0, 360,
( button.getWidth()/2f),
( button.getHeight()/2f)
, 100.0f, false);

animation.setDuration(1000);//动画持续时间设为500毫秒
animation.setFillAfter(true);//动画完成后保持完成的状态
button.startAnimation(animation);

}
}