android studio for android learning (十五) Camera2界面定制与保存到外部存储

1.使用android 5.0的Camera V2来控制手机拍照，5.0以后对拍照的API进行了全新的设计，这些API不仅大幅度提高了android的拍照功能，还支持RAW照片输出，还可以程序调整相机的对焦模式，曝光模式，快门等。

2.关键API简介

CameraManager:摄像头管理器

CameraCharacteristics:摄像头特性

CameraDevice:代表系统摄像头

CameraCaptureSession:创建会话的API，是一个非常重要的API，当程序不管是拍照还是预览都需要通过该API来创建会话，其中控制预览的方法为setRepeatingRequest();控制拍照的方法为capture()

为了监听cameraCaptureSession的创建过程和CameraCaptureSession的拍照过程API为CameraCaptureSession提供了stateCallback,CaptureCallback等内部类

CameraRequest代表一次捕获请求，CameraRequest.Builder则负责后成CameraRequest对象。

3.本示例演示打开摄像头通过camera2的API，将拍好的照片保存到外部存储器SD中，其中控制拍照的大致步骤如下：

调用CameraManager的openCamera()方法，该方法有三个参数，第一个是代表要打开的摄像头，第二个参数用于监听摄像头的状态，第三个参数代表要执行的callback的Hander,如果在当前执行，可以设置为NULL

当调用上面的openCamera后，就可以获取指定的系统摄像头CameraDevice,然后调用指定的CameraDevice的createCaptureSession()来创建CameraCaptureSession,该方法有三个参数，第一个是一个LIST集合，封装了所有需要从该摄像头获取图片的surface,第二个参数用来监听CameraCaptureSession的创建过程。第三个参数代表执行callback的handler.设置为null就是在本线程中执行。

调用cameraDevice中的createCaptureRequest()方法，该方法支持的请求参数包括预览，拍摄视频，拍照等

根据上面的方式来设置各种参数，这里是设置各种拍照参数

调用captureRequest.Builder的build方法，即可得打为CaptureRequest对象，接下来可通过CameraCaptureSession的setRepeatingRuest()方法来开始预览和拍照。

4示例代码和相关文件

androidMainfest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.dragon.camera"
android:versionCode="1"
android:versionName="1.0"
>

<user-sdk
android:minSdkVersion="21"
android:targetSdkVersion="21"/>

<!--添加必要的用户权限-->
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera2.full" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".Main">
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

</manifest>

strings.xml

<resources>
<string name="app_name">Camera</string>
<string name="take_picture">take picture</string>
</resources>

布局文件main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:orientation="vertical"
tools:context="com.dragon.camera.Main">
<TextureView
android:id="@+id/texture"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_above="@+id/btn_takepicture" />
<Button
android:id="@+id/btn_takepicture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="16dp"
android:layout_marginTop="16dp"
android:text="@string/take_picture" />
</RelativeLayout>

代码文件Main.java，核心代码文件，以加注释，大家可以慢慢看

package com.dragon.camera;

import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.ImageFormat;
import android.graphics.SurfaceTexture;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCaptureSession;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraDevice;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CameraMetadata;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.TotalCaptureResult;
import android.hardware.camera2.params.StreamConfigurationMap;
import android.media.Image;
import android.media.ImageReader;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.HandlerThread;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.util.Size;
import android.util.SparseIntArray;
import android.view.Surface;
import android.view.TextureView;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Main extends Activity {
private static final String TAG = " dragon camera test";
//    两个组件
private Button takePictureButton;
private TextureView textureView;
//用SparseIntArray来代替hashMap,进行性能优化
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
static {
ORIENTATIONS.append(Surface.ROTATION_0, 90);
ORIENTATIONS.append(Surface.ROTATION_90, 0);
ORIENTATIONS.append(Surface.ROTATION_180, 270);
ORIENTATIONS.append(Surface.ROTATION_270, 180);
}
//    摄像头ID，一般0是后视，1是前视
private String cameraId;
//定义代表摄像头的成员变量，代表系统摄像头，该类的功能类似早期的Camera类。
protected CameraDevice cameraDevice;
//    定义CameraCaptureSession成员变量，是一个拍摄绘话的类，用来从摄像头拍摄图像或是重新拍摄图像,这是一个重要的API.
protected CameraCaptureSession cameraCaptureSessions;
//    当程序调用setRepeatingRequest()方法进行预览时，或调用capture()进行拍照时，都需要传入CaptureRequest参数时
//    captureRequest代表一次捕获请求，用于描述捕获图片的各种参数设置。比如对焦模式，曝光模式...等，程序对照片所做的各种控制，都通过CaptureRequest参数来进行设置
//    CaptureRequest.Builder 负责生成captureRequest对象
protected CaptureRequest.Builder captureRequestBuilder;
//预览尺寸
private Size imageDimension;
//   ImageReader allow direct application access to image data rendered into a Surface.
private ImageReader imageReader;
//请求码常量，可以自定义
private static final int REQUEST_CAMERA_PERMISSION = 300;
private Handler mBackgroundHandler;
private HandlerThread mBackgroundThread;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

textureView = (TextureView) findViewById(R.id.texture);
assert textureView != null;
//        设置监听
textureView.setSurfaceTextureListener(textureListener);
takePictureButton = (Button) findViewById(R.id.btn_takepicture);
//        为空时抛出异常
assert takePictureButton != null;
class takePictureBtn implements View.OnClickListener{
public void onClick(View v) {
takePicture();
}
}
takePictureButton.setOnClickListener(new takePictureBtn());
}

//    定义了一个独立的监听类
TextureView.SurfaceTextureListener textureListener = new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
//open your camera here
openCamera();
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
// Transform you image captured size according to the surface width and height
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
return true;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture surface) {
}
};

private final CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
@Override
//        摄像头打开激发该方法
public void onOpened(CameraDevice camera) {

Log.e(TAG, "onOpened");
cameraDevice = camera;
//            开始预览
createCameraPreview();
}
//        摄像头断开连接时的方法
@Override
public void onDisconnected(CameraDevice camera) {
cameraDevice.close();
Main.this.cameraDevice = null;
}
//        打开摄像头出现错误时激发方法
@Override
public void onError(CameraDevice camera, int error) {
cameraDevice.close();
Main.this.cameraDevice = null;
}
};

protected void startBackgroundThread() {
mBackgroundThread = new HandlerThread("Camera Background");
mBackgroundThread.start();
mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
}
protected void stopBackgroundThread() {
mBackgroundThread.quitSafely();
try {
mBackgroundThread.join();
mBackgroundThread = null;
mBackgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
protected void takePicture() {
if(null == cameraDevice) {
Log.e(TAG, "cameraDevice is null");
//            如果没打开则返回
return;
}
//        摄像头管理器，专门用于检测、打开系统摄像头，并连接CameraDevices.
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
Log.e(TAG,"cameraDevice.getId "+cameraDevice.getId());//查看选中的摄像头ID
//            获取指定摄像头的相关特性（此处摄像头已经打开）
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraDevice.getId());

//            定义图像尺寸
Size[] jpegSizes = null;
if (characteristics != null) {
//                获取摄像头支持的最大尺寸
jpegSizes = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP).getOutputSizes(ImageFormat.JPEG);
}
int width = 640;
int height = 480;
if (jpegSizes != null && 0 < jpegSizes.length) {
width = jpegSizes[0].getWidth();
height = jpegSizes[0].getHeight();
}
//            创建一个ImageReader对象，用于获得摄像头的图像数据
ImageReader reader = ImageReader.newInstance(width, height, ImageFormat.JPEG, 1);
//动态数组
List<Surface> outputSurfaces = new ArrayList<Surface>(2);

outputSurfaces.add(reader.getSurface());
outputSurfaces.add(new Surface(textureView.getSurfaceTexture()));
//生成请求对象（TEMPLATE_STILL_CAPTURE此处请求是拍照）
final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
//            将ImageReader的surface作为captureBuilder的输出目标
captureBuilder.addTarget(reader.getSurface());
////设置自动对焦模式
//            captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
////            设置自动曝光模式
//            captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
captureBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);//推荐采用这种最简单的设置请求模式
// 获取设备方向
int rotation = getWindowManager().getDefaultDisplay().getRotation();
//            根据设置方向设置照片显示的方向
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
//            设置图片的存储位置
final File file = new File(Environment.getExternalStorageDirectory()+"/pic.jpg");
//ImageReader监听函数
ImageReader.OnImageAvailableListener readerListener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
Image image = null;
//                    读取图像并保存
try {
image = reader.acquireLatestImage();
ByteBuffer buffer = image.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.capacity()];
buffer.get(bytes);
save(bytes);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (image != null) {
image.close();
}
}
}
private void save(byte[] bytes) throws IOException {
OutputStream output = null;
try {
output = new FileOutputStream(file);
output.write(bytes);
} finally {
if (null != output) {
output.close();
}
}
}
};

reader.setOnImageAvailableListener(readerListener, mBackgroundHandler);
//拍照开始或是完成时调用，用来监听CameraCaptureSession的创建过程
final CameraCaptureSession.CaptureCallback captureListener = new CameraCaptureSession.CaptureCallback() {
@Override
//                拍照完成后提示图片的保存位置
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
Toast.makeText(Main.this, "Saved:" + file, Toast.LENGTH_SHORT).show();
createCameraPreview();
}
};

cameraDevice.createCaptureSession(outputSurfaces, new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
try {
session.capture(captureBuilder.build(), captureListener, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession session) {
}
}, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}

protected void createCameraPreview() {
try {
SurfaceTexture texture = textureView.getSurfaceTexture();
assert texture != null;
//            设置默认的预览大小
texture.setDefaultBufferSize(imageDimension.getWidth(), imageDimension.getHeight());
Surface surface = new Surface(texture);
//            请求预览
captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);

captureRequestBuilder.addTarget(surface);
//            创建cameraCaptureSession,第一个参数是图片集合，封装了所有图片surface,第二个参数用来监听这处创建过程
cameraDevice.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback(){
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
//The camera is already closed
if (null == cameraDevice) {
return;
}
// When the session is ready, we start displaying the preview.
cameraCaptureSessions = cameraCaptureSession;
updatePreview();
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
Toast.makeText(Main.this, "Configuration change", Toast.LENGTH_SHORT).show();
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void openCamera() {
//        实例化摄像头
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
Log.e(TAG, "is camera open");
try {
//            指定要打开的摄像头
cameraId = manager.getCameraIdList()[0];
//            获取打开摄像头的属性
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
//The available stream configurations that this camera device supports; also includes the minimum frame durations and the stall durations for each format/size combination.
StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
assert map != null;
imageDimension = map.getOutputSizes(SurfaceTexture.class)[0];
// Add permission for camera and let user grant the permission
//            权限检查
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(Main.this, new String[]{Manifest.permission.CAMERA, Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CAMERA_PERMISSION);
return;
}
//            打开摄像头，第一个参数代表要打开的摄像头，第二个参数用于监测打开摄像头的当前状态，第三个参数表示执行callback的Handler,
//            如果程序希望在当前线程中执行callback，像下面的设置为null即可。
manager.openCamera(cameraId, stateCallback, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
Log.e(TAG, "openCamera 1");
}
protected void updatePreview() {
if(null == cameraDevice) {
Log.e(TAG, "updatePreview error, return");
}
//        设置模式为自动
captureRequestBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
try {

cameraCaptureSessions.setRepeatingRequest(captureRequestBuilder.build(), null, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void closeCamera() {
if (null != cameraDevice) {
cameraDevice.close();
cameraDevice = null;
}
if (null != imageReader) {
imageReader.close();
imageReader = null;
}
}
//    如果没有相应的权限测关闭APP
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == REQUEST_CAMERA_PERMISSION) {
if (grantResults[0] == PackageManager.PERMISSION_DENIED) {
// close the app
Toast.makeText(Main.this, "Sorry!!!, you can't use this app without granting permission", Toast.LENGTH_LONG).show();
finish();
}
}
}
@Override
protected void onResume() {
super.onResume();
Log.e(TAG, "onResume");
startBackgroundThread();
if (textureView.isAvailable()) {
Log.e(TAG, "textureViewAvailable");
//            openCamera();
takePicture();
} else {
textureView.setSurfaceTextureListener(textureListener);
}
}
@Override
protected void onPause() {
Log.e(TAG, "onPause");
closeCamera();
stopBackgroundThread();
super.onPause();
}
}

//        takePictureButton.setOnClickListener(new View.OnClickListener() {
//            @Override
//            public void onClick(View v) {
//                takePicture();
//            }
//        });

整个工程或是项目源码下载地址：githubCamera2

另欢迎大家加入AR/VR交流群，后面将会有基于手机摄像头增强现实的实现讨论和实例：

Reference:

1./article/10529272.html

2.http://wiki.jikexueyuan.com/project/android-actual-combat-skills/android-hardware-camera2-operating-guide.html

3.https://developer.android.com/samples/Camera2Basic/src/com.example.android.camera2basic/Camera2BasicFragment.html

4.https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html