android camera移动方向_Android利用Camera实现中轴3D卡牌翻转效果

ゝ一纸荒年。 2023-01-09 14:19 165阅读 0赞

在Android系统API中，有两个Camera类：

android.graphics.Camera

android.hardware.Camera

第二个应用于手机硬件中的相机相关的操作，本文讲述的是利用第一个Camera类实现中轴3D转换的卡牌翻转效果，开始之前，先看一下Android系统中的坐标系：

![Image 1][]

对应于三维坐标系中的三个方向，Camera提供了三种旋转方法：

rotateX()

rotateY()

rotateX()

调用这三种方法，传入旋转角度参数，即可实现视图沿着坐标轴旋转的功能。本文的中轴3D旋转效果就是让视图沿着Y轴旋转的。

系统API Demos中已经为我们提供了一个非常好用的3D旋转动画的工具类：

Rotate3dAnimation.java：

package com.feng.androidtest;

import android.graphics.Camera;

import android.graphics.Matrix;

import android.util.Log;

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();

Log.i("interpolatedTime", interpolatedTime+"");

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);

可以看出， Rotate3dAnimation 总共做了两件事：在构造函数中赋值了旋转动画所需要的参数，以及重写(override)父类Animation中的applyTransformation()方法，下面分类阐述一下：

fromDegrees与toDegrees

视图旋转的开始角度和结束角度，当toDegree处于90倍数时，视图将变得不可见。

centerX与centerY

视图旋转的中心点。

depthZ

Z轴移动基数，用于计算Camera在Z轴移动距离

reverse

boolean类型，控制Z轴移动方向，达到视觉远近移动导致的视图放大缩小效果。

applyTransformation()

根据动画播放的时间 interpolatedTime (动画start到end的过程，interpolatedTime从0.0变化到1.0)，让Camera在Z轴方向上进行相应距离的移动，实现视觉上远近移动的效果。然后调用 rotateX()方法，让视图围绕Y轴进行旋转，产生3D立体旋转效果。最后再通过Matrix来确定旋转的中心点的位置。

activity\_main.xml布局文件：

xmlns:tools="http://schemas.android.com/tools"

android:layout\_width="fill\_parent"

android:layout\_height="fill\_parent"

android:background="@android:color/white" >

android:id="@+id/btn\_open"

android:layout\_width="match\_parent"

android:layout\_height="wrap\_content"

android:layout\_margin="16dp"

android:onClick="onClickView"

android:text="打开"

android:textColor="@android:color/black"

android:textSize="16sp" />

android:id="@+id/rl\_content"

android:layout\_width="match\_parent"

android:layout\_height="match\_parent"

android:layout\_below="@id/btn\_open"

android:layout\_marginTop="16dp"

android:background="@android:color/black">

android:id="@+id/iv\_logo"

android:layout\_width="match\_parent"

android:layout\_height="match\_parent"

android:contentDescription="@null"

android:src="@drawable/ic\_qrcode"

android:scaleType="centerInside"/>

android:id="@+id/tv\_desc"

android:layout\_width="wrap\_content"

android:layout\_height="wrap\_content"

android:padding="16dp"

android:text="脚本之家。"

android:textColor="@android:color/white"

android:textSize="18sp"

android:visibility="gone"/>

布局中配置了卡牌正面的图片控件，卡牌背面的文本控件，以及他们的parent容器，也就是本文中的旋转动画的执行对象。

MainActivity.java文件：

package com.feng.androidtest;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.animation.AccelerateInterpolator;

import android.view.animation.Animation;

import android.view.animation.Animation.AnimationListener;

import android.view.animation.DecelerateInterpolator;

import android.widget.Button;

import android.widget.ImageView;

import android.widget.RelativeLayout;

import android.widget.TextView;

import com.example.androidtest.R;

public class MainActivity extends Activity \{

private RelativeLayout mContentRl;

private ImageView mLogoIv;

private TextView mDescTv;

private Button mOpenBtn;

private int centerX;

private int centerY;

private int depthZ = 400;

private int duration = 600;

private Rotate3dAnimation openAnimation;

private Rotate3dAnimation closeAnimation;

private boolean isOpen = false;

@Override

protected void onCreate(Bundle savedInstanceState) \{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity\_main);

mContentRl = (RelativeLayout) findViewById(R.id.rl\_content);

mLogoIv = (ImageView) findViewById(R.id.iv\_logo);

mDescTv = (TextView) findViewById(R.id.tv\_desc);

mOpenBtn = (Button) findViewById(R.id.btn\_open);

/\*\*

\* 卡牌文本介绍打开效果：注意旋转角度

\*/

private void initOpenAnim() \{

//从0到90度，顺时针旋转视图，此时reverse参数为true，达到90度时动画结束时视图变得不可见，

openAnimation = new Rotate3dAnimation(0, 90, centerX, centerY, depthZ, true);

openAnimation.setDuration(duration);

openAnimation.setFillAfter(true);

openAnimation.setInterpolator(new AccelerateInterpolator());

openAnimation.setAnimationListener(new AnimationListener() \{

@Override

public void onAnimationStart(Animation animation) \{

@Override

public void onAnimationRepeat(Animation animation) \{

@Override

public void onAnimationEnd(Animation animation) \{

mLogoIv.setVisibility(View.GONE);

mDescTv.setVisibility(View.VISIBLE);

//从270到360度，顺时针旋转视图，此时reverse参数为false，达到360度动画结束时视图变得可见

Rotate3dAnimation rotateAnimation = new Rotate3dAnimation(270, 360, centerX, centerY, depthZ, false);

rotateAnimation.setDuration(duration);

rotateAnimation.setFillAfter(true);

rotateAnimation.setInterpolator(new DecelerateInterpolator());

mContentRl.startAnimation(rotateAnimation);

\});

/\*\*

\* 卡牌文本介绍关闭效果：旋转角度与打开时逆行即可

\*/

private void initCloseAnim() \{

closeAnimation = new Rotate3dAnimation(360, 270, centerX, centerY, depthZ, true);

closeAnimation.setDuration(duration);

closeAnimation.setFillAfter(true);

closeAnimation.setInterpolator(new AccelerateInterpolator());

closeAnimation.setAnimationListener(new AnimationListener() \{

@Override

public void onAnimationStart(Animation animation) \{

@Override

public void onAnimationRepeat(Animation animation) \{

@Override

public void onAnimationEnd(Animation animation) \{

mLogoIv.setVisibility(View.VISIBLE);

mDescTv.setVisibility(View.GONE);

Rotate3dAnimation rotateAnimation = new Rotate3dAnimation(90, 0, centerX, centerY, depthZ, false);

rotateAnimation.setDuration(duration);

rotateAnimation.setFillAfter(true);

rotateAnimation.setInterpolator(new DecelerateInterpolator());

mContentRl.startAnimation(rotateAnimation);

\});

public void onClickView(View v) \{

//以旋转对象的中心点为旋转中心点，这里主要不要再onCreate方法中获取，因为视图初始绘制时，获取的宽高为0

centerX = mContentRl.getWidth()/2;

centerY = mContentRl.getHeight()/2;

if (openAnimation == null) \{

initOpenAnim();

initCloseAnim();

//用作判断当前点击事件发生时动画是否正在执行

if (openAnimation.hasStarted() && !openAnimation.hasEnded()) \{

return;

if (closeAnimation.hasStarted() && !closeAnimation.hasEnded()) \{

return;

//判断动画执行

if (isOpen) \{

mContentRl.startAnimation(closeAnimation);

\}else \{

mContentRl.startAnimation(openAnimation);

isOpen = !isOpen;

mOpenBtn.setText(isOpen ? "关闭" : "打开");

代码中已对核心的地方做了注释解释，主要弄清楚 rotate3dAnimation构造参数中的 fromDegrees和toDegrees、depthZ、reverse参数，同时在动画中设置了速度插播器，如动画的前半程使用加速器 AccelerateInterpolator，后半程使用减速器 DecelerateInterpolator，使动画体验更加人性化。

以上就是本文的全部内容，希望对大家的学习Android软件编程有所帮助。

[Image 1]: