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Android相机基础基于camera2API
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前言
最近，在使用Android做一个照相机的开发。因为不能使用系统提供的相机应用，所以只能自己写一个。Android以前提供相机的api叫camera，不过在level 21被Google抛弃了。网上的教程，还有很多都是使用camera的，为了好好学习一下camera2，就去扒了Google提供的官方示例。下面给一个github的连接，可以找到全部的源码。
Camera2Basic Sample
源码分析
下述的例子主要提供的功能是：相机预览、拍照、照片保存。具体如下：进入该应用后，可以看到相机的预览画面，提供一个按钮用于拍照，拍完照片后照片会保存在SD卡的根目录下。
架构分析
首先来了解一下camera2的整体结构：
图1 camera2整体架构图
如上所示，整个camera2由一个CameraManager来进行统一管理，通过Context的getSystemService方法可以实例化CameraManager，然后该类主要通过三个类来对Camera进行操作。下面分别介绍一下：
- CameraDevice：描述一个照相机设备，一个Android设备可能会有多个摄像头，通过CameraId可以进行区别。它最主要有一个相机状态的回调函数，当下达打开相机的命令后，若相机正确的打开便会回调该函数。
- CameraCharacteristic：某个照相机设备的具体参数。本例主要用到它提供的输出格式（即输出数据的格式）。
- CameraCaptureSession：相机捕获会话，通过这个类可以和相机进行对话（预览还是单张拍照还是录像等）。这里有两个回调函数，捕获状态的回调，和捕获数据的回调（后文会有详述）。
上图左上部分所示的时Android设备和camera设备的通信情况，两者之间通过pipeline（管道）进行数据交换。当需要尽心不同的操作时，将CameraCaptureRequest通过管道传给camera，接收到请求后，camera做出相应的反应，将获取到得数据CmaeraMetadata通过管道传回给Android设备。
注意事项
本例，需要使用比较多的权限，请参看源码AndroidManifest.xml。
Android设备的屏幕方向，与摄像头的原始方向并不一致，需要做方向转换。一般而言，当Android设备横着放时，与摄像头的方向是一致的。
为了避免照片失真（照片被拉长或者压扁），需要保证预览的长宽比例、照片的长宽比例和相机输出格式的长宽比例三者保持一致。
代码流转
本例当中，用一个activity承载一个fragment。所有的代码都写在fragment里面，重写了fragment的几个生命周期函数:
- onCreateView：加载fragment的布局文件；
- onViewCreated：实例化布局控件；
- onActivityCreated：在SD卡的目录下建立jpg文件等待待将拍到的照片写进去；
- onResume：开始照相机线程，执行一些逻辑判断；
- onPause：关闭照相机，停止照相机线程；
图2 代码整体流程
正常来说，代码的整体流程如图2所示，activity将需要的fragment加载进来后，开始加载显示预览的控件texture，当控件加载完毕会执行一个回调函数
onSurfaceTextureAvailable()
，在这个回调函数里面，打开摄像头（即执行
openCamera()
）。
openCamera()
里面，首先要配置相机的输出，预览图像和拍照的图片要作不同的处理，然后根据当前的设备屏幕环境，判断是否需要进行数据的转换，最后通过cameraManager打开摄像头（调用
cameraManager.openCamera()
方法）。
更详细的方法请看后面的源码，图2当中，中间是判断屏幕方向的逻辑，右边是自动选择最合适的显示逻辑。
源码
// 代码比较长，请耐心查看，注释可能有不正确的地方，请提出
// 注意，下面代码为了配合我的使用，已经去掉了按钮，但是拍照的方法仍然保留，通过调用方法可以完成拍照
package com.eric_lai.weeding_robot.fragment;
/**
* Created by ERIC_LAI on 16/3/18.
*/
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.Fragment;
import android.content.Context;
import android.content.DialogInterface;
import android.content.res.Configuration;
import android.graphics.ImageFormat;
import android.graphics.Matrix;
import android.graphics.Point;
import android.graphics.RectF;
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.CaptureResult;
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.Handler;
import android.os.HandlerThread;
import android.support.annotation.NonNull;
import android.util.Log;
import android.util.Size;
import android.util.SparseIntArray;
import android.view.LayoutInflater;
import android.view.Surface;
import android.view.TextureView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
import com.eric_lai.weeding_robot.R;
import com.eric_lai.weeding_robot.view.AutoFitTextureView;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
public class CameraFragment extends Fragment {
/**
* Conversion from screen rotation to JPEG orientation.
*/
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
private static final String FRAGMENT_DIALOG = "dialog";
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);
}
/**
* 调试用TAG
*/
private static final String TAG = "CameraFragment";
/**
* 相机状态:
* 0: 预览
* 1: 等待上锁(拍照片前将预览锁上保证图像不在变化)
* 2: 等待预拍照(对焦, 曝光等操作)
* 3: 等待非预拍照(闪光灯等操作)
* 4: 已经获取照片
*/
private static final int STATE_PREVIEW = 0;
private static final int STATE_WAITING_LOCK = 1;
private static final int STATE_WAITING_PRECAPTURE = 2;
private static final int STATE_WAITING_NON_PRECAPTURE = 3;
private static final int STATE_PICTURE_TAKEN = 4;
/**
* Camera2 API提供的最大预览宽度和高度
*/
private static final int MAX_PREVIEW_WIDTH = 1920;
private static final int MAX_PREVIEW_HEIGHT = 1080;
/**
* SurfaceTexture监听器
*/
private final TextureView.SurfaceTextureListener mSurfaceTextureListener
= new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture texture, int width, int height) {
// SurfaceTexture就绪后回调执行打开相机操作
openCamera(width, height);
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture texture, int width, int height) {
// 预览方向改变时, 执行转换操作
configureTransform(width, height);
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) {
return true;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture texture) {
}
};
/**
* 正在使用的相机id
*/
private String mCameraId;
/**
* 预览使用的自定义TextureView控件
*/
private AutoFitTextureView mTextureView;
/**
* 预览用的获取会话
*/
private CameraCaptureSession mCaptureSession;
/**
* 正在使用的相机
*/
private CameraDevice mCameraDevice;
/**
* 预览数据的尺寸
*/
private Size mPreviewSize;
/**
* 相机状态改变的回调函数
*/
private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice cameraDevice) {
// 当相机打开执行以下操作:
// 1. 释放访问许可
// 2. 将正在使用的相机指向将打开的相机
// 3. 创建相机预览会话
mCameraOpenCloseLock.release();
mCameraDevice = cameraDevice;
createCameraPreviewSession();
}
@Override
public void onDisconnected(@NonNull CameraDevice cameraDevice) {
// 当相机失去连接时执行以下操作:
// 1. 释放访问许可
// 2. 关闭相机
// 3. 将正在使用的相机指向null
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
}
@Override
public void onError(@NonNull CameraDevice cameraDevice, int error) {
// 当相机发生错误时执行以下操作:
// 1. 释放访问许可
// 2. 关闭相机
// 3, 将正在使用的相机指向null
// 4. 获取当前的活动, 并结束它
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
Activity activity = getActivity();
if (null != activity) {
activity.finish();
}
}
};
/**
* 处理拍照等工作的子线程
*/
private HandlerThread mBackgroundThread;
/**
* 上面定义的子线程的处理器
*/
private Handler mBackgroundHandler;
/**
* 静止页面捕获(拍照)处理器
*/
private ImageReader mImageReader;
/**
* 输出照片的文件
*/
private File mFile;
/**
* ImageReader的回调函数, 其中的onImageAvailable会在照片准备好可以被保存时调用
*/
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
= new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
mBackgroundHandler.post(new ImageSaver(reader.acquireNextImage(), mFile));
}
};
/**
* 预览请求构建器, 用来构建"预览请求"(下面定义的)通过pipeline发送到Camera device
*/
private CaptureRequest.Builder mPreviewRequestBuilder;
/**
* 预览请求, 由上面的构建器构建出来
*/
private CaptureRequest mPreviewRequest;
/**
* 当前的相机状态, 这里初始化为预览, 因为刚载入这个fragment时应显示预览
*/
private int mState = STATE_PREVIEW;
/**
* 信号量控制器, 防止相机没有关闭时退出本应用(若没有关闭就退出, 会造成其他应用无法调用相机)
* 当某处获得这个许可时, 其他需要许可才能执行的代码需要等待许可被释放才能获取
*/
private Semaphore mCameraOpenCloseLock = new Semaphore(1);
/**
* 捕获会话回调函数
*
*/
private CameraCaptureSession.CaptureCallback mCaptureCallback
= new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureProgressed(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull CaptureResult partialResult) {
process(partialResult);
}
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
process(result);
}
// 自定义的一个处理方法
private void process(CaptureResult result) {
switch (mState) {
case STATE_PREVIEW: {
// 状态是预览时, 不需要做任何事情
break;
}
case STATE_WAITING_LOCK: {
// 等待锁定的状态, 某些设备完成锁定后CONTROL_AF_STATE可能为null
Integer afState = result.get(CaptureResult.CONTROL_AF_STATE);
if (afState == null) {
captureStillPicture();
} else if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState ||
CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState) {
// 如果焦点已经锁定(不管自动对焦是否成功), 检查AE的返回, 注意某些设备CONTROL_AE_STATE可
// 能为空
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null ||
aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
// 如果自动曝光(AE)设定良好, 将状态置为已经拍照, 执行拍照
mState = STATE_PICTURE_TAKEN;
captureStillPicture();
} else {
// 以上条件都不满足, 执行预拍照系列操作
runPrecaptureSequence();
}
}
break;
}
case STATE_WAITING_PRECAPTURE: {
// 等待预处理状态, 某些设备CONTROL_AE_STATE可能为null
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null ||
aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE ||
aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED) {
// 如果AE需要做于拍照或者需要闪光灯, 将状态置为"非等待预拍照"(翻译得有点勉强)
mState = STATE_WAITING_NON_PRECAPTURE;
}
break;
}
case STATE_WAITING_NON_PRECAPTURE: {
// 某些设备CONTROL_AE_STATE可能为null
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
// 如果AE做完"非等待预拍照", 将状态置为已经拍照, 并执行拍照操作
mState = STATE_PICTURE_TAKEN;
captureStillPicture();
}
break;
}
}
}
};
/**
* 在UI上显示Toast的方法
*/
private void showToast(final String text) {
final Activity activity = getActivity();
if (activity != null) {
activity.runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(activity, text, Toast.LENGTH_SHORT).show();
}
});
}
}
/**
* 返回最合适的预览尺寸
*
* @param choices 相机希望输出类支持的尺寸list
* @param textureViewWidth texture view 宽度
* @param textureViewHeight texture view 高度
* @param maxWidth 能够选择的最大宽度
* @param maxHeight 能够选择的醉倒高度
* @param aspectRatio 图像的比例(pictureSize, 只有当pictureSize和textureSize保持一致, 才不会失真)
* @return 最合适的预览尺寸
*/
private static Size chooseOptimalSize(Size[] choices, int textureViewWidth,
int textureViewHeight, int maxWidth, int maxHeight, Size aspectRatio) {
// 存放小于等于限定尺寸, 大于等于texture控件尺寸的Size
List<Size> bigEnough = new ArrayList<>();
// 存放小于限定尺寸, 小于texture控件尺寸的Size
List<Size> notBigEnough = new ArrayList<>();
int w = aspectRatio.getWidth();
int h = aspectRatio.getHeight();
for (Size option : choices) {
if (option.getWidth() <= maxWidth && option.getHeight() <= maxHeight &&
option.getHeight() == option.getWidth() * h / w) {
// option.getHeight() == option.getWidth() * h / w 用来保证
// pictureSize的 w / h 和 textureSize的 w / h 一致
if (option.getWidth() >= textureViewWidth &&
option.getHeight() >= textureViewHeight) {
bigEnough.add(option);
} else {
notBigEnough.add(option);
}
}
}
// 1. 若存在bigEnough数据, 则返回最大里面最小的
// 2. 若不存bigEnough数据, 但是存在notBigEnough数据, 则返回在最小里面最大的
// 3. 上述两种数据都没有时, 返回空, 并在日志上显示错误信息
if (bigEnough.size() > 0) {
return Collections.min(bigEnough, new CompareSizesByArea());
} else if (notBigEnough.size() > 0) {
return Collections.max(notBigEnough, new CompareSizesByArea());
} else {
Log.e(TAG, "Couldn't find any suitable preview size");
return choices[0];
}
}
public static CameraFragment newInstance() {
return new CameraFragment();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_camera, container, false);
}
@Override
public void onViewCreated(final View view, Bundle savedInstanceState) {
mTextureView = (AutoFitTextureView) view.findViewById(R.id.texture);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mFile = new File(getActivity().getExternalFilesDir(null), "pic.jpg");
}
@Override
public void onResume() {
super.onResume();
startBackgroundThread();
// 当屏幕关闭后重新打开, 若SurfaceTexture已经就绪, 此时onSurfaceTextureAvailable不会被回调, 这种情况下
// 如果SurfaceTexture已经就绪, 则直接打开相机, 否则等待SurfaceTexture已经就绪的回调
if (mTextureView.isAvailable()) {
openCamera(mTextureView.getWidth(), mTextureView.getHeight());
} else {
mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);
}
}
@Override
public void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
/**
* 设置相机的输出, 包括预览和拍照
*
* 处理流程如下:
* 1. 获取当前的摄像头, 并将拍照输出设置为最高画质
* 2. 判断显示方向和摄像头传感器方向是否一致, 是否需要旋转画面
* 3. 获取当前显示尺寸和相机的输出尺寸, 选择最合适的预览尺寸
*
* @param width 预览宽度
* @param height 预览高度
*/
private void setUpCameraOutputs(int width, int height) {
// 获取当前活动
Activity activity = getActivity();
// 获取CameraManager实例
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
// 遍历运行本应用的设备的所有摄像头
for (String cameraId : manager.getCameraIdList()) {
CameraCharacteristics characteristics
= manager.getCameraCharacteristics(cameraId);
// 如果该摄像头是前置摄像头, 则看下一个摄像头(本应用不使用前置摄像头)
Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
continue;
}
StreamConfigurationMap map = characteristics.get(
CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
if (map == null) {
continue;
}
// 选用最高画质
// maxImages是ImageReader一次可以访问的最大图片数量
Size largest = Collections.max(
Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
new CompareSizesByArea());
Log.d(TAG, "largest.width: " + largest.getWidth());
Log.d(TAG, "largest.height: " + largest.getHeight());
mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
ImageFormat.JPEG, /*maxImages*/2);
mImageReader.setOnImageAvailableListener(
mOnImageAvailableListener, mBackgroundHandler);
// 获取手机目前的旋转方向(横屏还是竖屏, 对于"自然"状态下高度大于宽度的设备来说横屏是ROTATION_90
// 或者ROTATION_270,竖屏是ROTATION_0或者ROTATION_180)
int displayRotation = activity.getWindowManager().getDefaultDisplay().getRotation();
// 获取相机传感器的方向("自然"状态下垂直放置为0, 顺时针算起, 每次加90读)
// 注意, 这个参数, 是由设备的生产商来决定的, 大多数情况下, 该值为90, 以下的switch这么写
// 是为了配适某些特殊的手机
int sensorOrientation =
characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
boolean swappedDimensions = false;
Log.d(TAG, "displayRotation: " + displayRotation);
Log.d(TAG, "sensorOritentation: " + sensorOrientation);
switch (displayRotation) {
// ROTATION_0和ROTATION_180都是竖屏只需做同样的处理操作
// 显示为竖屏时, 若传感器方向为90或者270, 则需要进行转换(标志位置true)
case Surface.ROTATION_0:
case Surface.ROTATION_180:
if (sensorOrientation == 90 || sensorOrientation == 270) {
Log.d(TAG, "swappedDimensions set true !");
swappedDimensions = true;
}
break;
// ROTATION_90和ROTATION_270都是横屏只需做同样的处理操作
// 显示为横屏时, 若传感器方向为0或者180, 则需要进行转换(标志位置true)
case Surface.ROTATION_90:
case Surface.ROTATION_270:
if (sensorOrientation == 0 || sensorOrientation == 180) {
swappedDimensions = true;
}
break;
default:
Log.e(TAG, "Display rotation is invalid: " + displayRotation);
}
// 获取当前的屏幕尺寸, 放到一个点对象里
Point displaySize = new Point();
activity.getWindowManager().getDefaultDisplay().getSize(displaySize);
// 旋转前的预览宽度(相机给出的), 通过传进来的参数获得
int rotatedPreviewWidth = width;
// 旋转前的预览高度(相机给出的), 通过传进来的参数获得
int rotatedPreviewHeight = height;
// 将当前的显示尺寸赋给最大的预览尺寸(能够显示的尺寸, 用来计算用的(texture可能比它小需要配适))
int maxPreviewWidth = displaySize.x;
int maxPreviewHeight = displaySize.y;
// 如果需要进行画面旋转, 将宽度和高度对调
if (swappedDimensions) {
rotatedPreviewWidth = height;
rotatedPreviewHeight = width;
maxPreviewWidth = displaySize.y;
maxPreviewHeight = displaySize.x;
}
// 尺寸太大时的极端处理
if (maxPreviewWidth > MAX_PREVIEW_WIDTH) {
maxPreviewWidth = MAX_PREVIEW_WIDTH;
}
if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
maxPreviewHeight = MAX_PREVIEW_HEIGHT;
}
// 自动计算出最适合的预览尺寸
// 第一个参数:map.getOutputSizes(SurfaceTexture.class)表示SurfaceTexture支持的尺寸List
mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
maxPreviewHeight, largest);
// 获取当前的屏幕方向
int orientation = getResources().getConfiguration().orientation;
if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
// 如果方向是横向(landscape)
mTextureView.setAspectRatio(
mPreviewSize.getWidth(), mPreviewSize.getHeight());
} else {
// 方向不是横向(即竖向)
mTextureView.setAspectRatio(
mPreviewSize.getHeight(), mPreviewSize.getWidth());
}
Log.d(TAG, "real preview width: " + rotatedPreviewWidth);
Log.d(TAG, "real preview height: " + rotatedPreviewHeight);
// Log.d(TAG, "max preview width: " + maxPreviewWidth);
// Log.d(TAG, "max preview width: : " + maxPreviewHeight);
// 下面这两个是计算后的previewSize=======================================
Log.d(TAG, "mPreviewSize.getWidth: " + mPreviewSize.getWidth());
Log.d(TAG, "mPreviewSize.getHeight: " + mPreviewSize.getHeight());
// =================================================================
mCameraId = cameraId;
return;
}
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (NullPointerException e) {
// 对话框显示错误
ErrorDialog.newInstance(getString(R.string.camera_error))
.show(getChildFragmentManager(), FRAGMENT_DIALOG);
}
}
/**
* 通过cameraId打开特定的相机
*/
private void openCamera(int width, int height) {
// 设置相机输出
setUpCameraOutputs(width, height);
// 配置格式转换
configureTransform(width, height);
// 获取当前活动和CameraManager的实例
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
// 尝试获得相机开打关闭许可, 等待2500时间仍没有获得则排除异常
if (!mCameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
throw new RuntimeException("Time out waiting to lock camera opening.");
}
// 打开相机, 参数是: 相机id, 相机状态回调, 子线程处理器
manager.openCamera(mCameraId, mStateCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
}
}
/**
* 关闭正在使用的相机
*/
private void closeCamera() {
try {
// 获得相机开打关闭许可
mCameraOpenCloseLock.acquire();
// 关闭捕获会话
if (null != mCaptureSession) {
mCaptureSession.close();
mCaptureSession = null;
}
// 关闭当前相机
if (null != mCameraDevice) {
mCameraDevice.close();
mCameraDevice = null;
}
// 关闭拍照处理器
if (null != mImageReader) {
mImageReader.close();
mImageReader = null;
}
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera closing.", e);
} finally {
// 释放相机开打关闭许可
mCameraOpenCloseLock.release();
}
}
/**
* 开启子线程
*/
private void startBackgroundThread() {
mBackgroundThread = new HandlerThread("CameraBackground");
mBackgroundThread.start();
mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
}
/**
* 停止子线程
*/
private void stopBackgroundThread() {
mBackgroundThread.quitSafely();
try {
mBackgroundThread.join();
mBackgroundThread = null;
mBackgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 创建预览对话
*/
private void createCameraPreviewSession() {
try {
// 获取texture实例
SurfaceTexture texture = mTextureView.getSurfaceTexture();
assert texture != null;
// 设置宽度和高度
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
// 用来开始预览的输出surface
Surface surface = new Surface(texture);
// 预览请求构建
mPreviewRequestBuilder
= mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
// 创建预览的捕获会话
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
// 相机关闭时, 直接返回
if (null == mCameraDevice) {
return;
}
// 会话可行时, 将构建的会话赋给field
mCaptureSession = cameraCaptureSession;
try {
// 自动对焦
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// 自动闪光
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// 构建上述的请求
mPreviewRequest = mPreviewRequestBuilder.build();
// 重复进行上面构建的请求, 以便显示预览
mCaptureSession.setRepeatingRequest(mPreviewRequest,
mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(
@NonNull CameraCaptureSession cameraCaptureSession) {
showToast("Failed");
}
}, null
);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 屏幕方向发生改变时调用转换数据方法
*
* @param viewWidth mTextureView 的宽度
* @param viewHeight mTextureView 的高度
*/
private void configureTransform(int viewWidth, int viewHeight) {
Activity activity = getActivity();
if (null == mTextureView || null == mPreviewSize || null == activity) {
return;
}
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
Matrix matrix = new Matrix();
RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
RectF bufferRect = new RectF(0, 0, mPreviewSize.getHeight(), mPreviewSize.getWidth());
float centerX = viewRect.centerX();
float centerY = viewRect.centerY();
if (Surface.ROTATION_90 == rotation || Surface.ROTATION_270 == rotation) {
bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
matrix.setRectToRect(viewRect, bufferRect, Matrix.ScaleToFit.FILL);
float scale = Math.max(
(float) viewHeight / mPreviewSize.getHeight(),
(float) viewWidth / mPreviewSize.getWidth());
matrix.postScale(scale, scale, centerX, centerY);
matrix.postRotate(90 * (rotation - 2), centerX, centerY);
} else if (Surface.ROTATION_180 == rotation) {
matrix.postRotate(180, centerX, centerY);
}
mTextureView.setTransform(matrix);
}
/**
* 实现拍照的方法
*/
private void takePicture() {
lockFocus();
}
/**
* 锁定焦点(拍照的第一步)
*/
private void lockFocus() {
try {
// 构建自动对焦请求
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CameraMetadata.CONTROL_AF_TRIGGER_START);
// 告诉mCaptureCallback回调状态
mState = STATE_WAITING_LOCK;
// 提交一个捕获单一图片的请求个相机
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 执行预拍照操作
*/
private void runPrecaptureSequence() {
try {
// 构建预拍照请求
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER,
CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER_START);
// 告诉mCaptureCallback回调状态
mState = STATE_WAITING_PRECAPTURE;
// 提交一个捕获单一图片的请求个相机
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 拍照操作
*/
private void captureStillPicture() {
try {
final Activity activity = getActivity();
if (null == activity || null == mCameraDevice) {
return;
}
// This is the CaptureRequest.Builder that we use to take a picture.
final CaptureRequest.Builder captureBuilder =
mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(mImageReader.getSurface());
// Use the same AE and AF modes as the preview.
captureBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
captureBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// Orientation
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
CameraCaptureSession.CaptureCallback CaptureCallback
= new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
showToast("Saved: " + mFile);
Log.d(TAG, mFile.toString());
unlockFocus();
}
};
mCaptureSession.stopRepeating();
mCaptureSession.capture(captureBuilder.build(), CaptureCallback, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 解开锁定的焦点
*/
private void unlockFocus() {
try {
// 构建失能AF的请求
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
// 构建自动闪光请求(之前拍照前会构建为需要或者不需要闪光灯, 这里重新设回自动)
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// 提交以上构建的请求
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
// 拍完照后, 设置成预览状态, 并重复预览请求
mState = STATE_PREVIEW;
mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 保存jpeg到指定的文件夹下, 开启子线程执行保存操作
*/
private static class ImageSaver implements Runnable {
/**
* jpeg格式的文件
*/
private final Image mImage;
/**
* 保存的文件
*/
private final File mFile;
public ImageSaver(Image image, File file) {
mImage = image;
mFile = file;
}
@Override
public void run() {
ByteBuffer buffer = mImage.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.remaining()];
buffer.get(bytes);
FileOutputStream output = null;
try {
output = new FileOutputStream(mFile);
output.write(bytes);
} catch (IOException e) {
e.printStackTrace();
} finally {
mImage.close();
if (null != output) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
/**
* 比较两个Size的大小基于它们的area
*/
static class CompareSizesByArea implements Comparator<Size> {
@Override
public int compare(Size lhs, Size rhs) {
// We cast here to ensure the multiplications won't overflow
return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
(long) rhs.getWidth() * rhs.getHeight());
}
}
/**
* 显示错误信息的对话框
*/
public static class ErrorDialog extends DialogFragment {
private static final String ARG_MESSAGE = "message";
public static ErrorDialog newInstance(String message) {
ErrorDialog dialog = new ErrorDialog();
Bundle args = new Bundle();
args.putString(ARG_MESSAGE, message);
dialog.setArguments(args);
return dialog;
}
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Activity activity = getActivity();
return new AlertDialog.Builder(activity)
.setMessage(getArguments().getString(ARG_MESSAGE))
.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
activity.finish();
}
})
.create();
}
}
}
// 代码比较长，请耐心查看，注释可能有不正确的地方，请提出
// 注意，下面代码为了配合我的使用，已经去掉了按钮，但是拍照的方法仍然保留，通过调用方法可以完成拍照
package com.eric_lai.weeding_robot.fragment;
/**
* Created by ERIC_LAI on 16/3/18.
*/
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.Fragment;
import android.content.Context;
import android.content.DialogInterface;
import android.content.res.Configuration;
import android.graphics.ImageFormat;
import android.graphics.Matrix;
import android.graphics.Point;
import android.graphics.RectF;
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.CaptureResult;
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.Handler;
import android.os.HandlerThread;
import android.support.annotation.NonNull;
import android.util.Log;
import android.util.Size;
import android.util.SparseIntArray;
import android.view.LayoutInflater;
import android.view.Surface;
import android.view.TextureView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
import com.eric_lai.weeding_robot.R;
import com.eric_lai.weeding_robot.view.AutoFitTextureView;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
public class CameraFragment extends Fragment {
/**
* Conversion from screen rotation to JPEG orientation.
*/
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
private static final String FRAGMENT_DIALOG = "dialog";
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);
}
/**
* 调试用TAG
*/
private static final String TAG = "CameraFragment";
/**
* 相机状态:
* 0: 预览
* 1: 等待上锁(拍照片前将预览锁上保证图像不在变化)
* 2: 等待预拍照(对焦, 曝光等操作)
* 3: 等待非预拍照(闪光灯等操作)
* 4: 已经获取照片
*/
private static final int STATE_PREVIEW = 0;
private static final int STATE_WAITING_LOCK = 1;
private static final int STATE_WAITING_PRECAPTURE = 2;
private static final int STATE_WAITING_NON_PRECAPTURE = 3;
private static final int STATE_PICTURE_TAKEN = 4;
/**
* Camera2 API提供的最大预览宽度和高度
*/
private static final int MAX_PREVIEW_WIDTH = 1920;
private static final int MAX_PREVIEW_HEIGHT = 1080;
/**
* SurfaceTexture监听器
*/
private final TextureView.SurfaceTextureListener mSurfaceTextureListener
= new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture texture, int width, int height) {
// SurfaceTexture就绪后回调执行打开相机操作
openCamera(width, height);
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture texture, int width, int height) {
// 预览方向改变时, 执行转换操作
configureTransform(width, height);
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) {
return true;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture texture) {
}
};
/**
* 正在使用的相机id
*/
private String mCameraId;
/**
* 预览使用的自定义TextureView控件
*/
private AutoFitTextureView mTextureView;
/**
* 预览用的获取会话
*/
private CameraCaptureSession mCaptureSession;
/**
* 正在使用的相机
*/
private CameraDevice mCameraDevice;
/**
* 预览数据的尺寸
*/
private Size mPreviewSize;
/**
* 相机状态改变的回调函数
*/
private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice cameraDevice) {
// 当相机打开执行以下操作:
// 1. 释放访问许可
// 2. 将正在使用的相机指向将打开的相机
// 3. 创建相机预览会话
mCameraOpenCloseLock.release();
mCameraDevice = cameraDevice;
createCameraPreviewSession();
}
@Override
public void onDisconnected(@NonNull CameraDevice cameraDevice) {
// 当相机失去连接时执行以下操作:
// 1. 释放访问许可
// 2. 关闭相机
// 3. 将正在使用的相机指向null
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
}
@Override
public void onError(@NonNull CameraDevice cameraDevice, int error) {
// 当相机发生错误时执行以下操作:
// 1. 释放访问许可
// 2. 关闭相机
// 3, 将正在使用的相机指向null
// 4. 获取当前的活动, 并结束它
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
Activity activity = getActivity();
if (null != activity) {
activity.finish();
}
}
};
/**
* 处理拍照等工作的子线程
*/
private HandlerThread mBackgroundThread;
/**
* 上面定义的子线程的处理器
*/
private Handler mBackgroundHandler;
/**
* 静止页面捕获(拍照)处理器
*/
private ImageReader mImageReader;
/**
* 输出照片的文件
*/
private File mFile;
/**
* ImageReader的回调函数, 其中的onImageAvailable会在照片准备好可以被保存时调用
*/
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
= new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
mBackgroundHandler.post(new ImageSaver(reader.acquireNextImage(), mFile));
}
};
/**
* 预览请求构建器, 用来构建"预览请求"(下面定义的)通过pipeline发送到Camera device
*/
private CaptureRequest.Builder mPreviewRequestBuilder;
/**
* 预览请求, 由上面的构建器构建出来
*/
private CaptureRequest mPreviewRequest;
/**
* 当前的相机状态, 这里初始化为预览, 因为刚载入这个fragment时应显示预览
*/
private int mState = STATE_PREVIEW;
/**
* 信号量控制器, 防止相机没有关闭时退出本应用(若没有关闭就退出, 会造成其他应用无法调用相机)
* 当某处获得这个许可时, 其他需要许可才能执行的代码需要等待许可被释放才能获取
*/
private Semaphore mCameraOpenCloseLock = new Semaphore(1);
/**
* 捕获会话回调函数
*
*/
private CameraCaptureSession.CaptureCallback mCaptureCallback
= new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureProgressed(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull CaptureResult partialResult) {
process(partialResult);
}
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
process(result);
}
// 自定义的一个处理方法
private void process(CaptureResult result) {
switch (mState) {
case STATE_PREVIEW: {
// 状态是预览时, 不需要做任何事情
break;
}
case STATE_WAITING_LOCK: {
// 等待锁定的状态, 某些设备完成锁定后CONTROL_AF_STATE可能为null
Integer afState = result.get(CaptureResult.CONTROL_AF_STATE);
if (afState == null) {
captureStillPicture();
} else if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState ||
CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState) {
// 如果焦点已经锁定(不管自动对焦是否成功), 检查AE的返回, 注意某些设备CONTROL_AE_STATE可
// 能为空
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null ||
aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
// 如果自动曝光(AE)设定良好, 将状态置为已经拍照, 执行拍照
mState = STATE_PICTURE_TAKEN;
captureStillPicture();
} else {
// 以上条件都不满足, 执行预拍照系列操作
runPrecaptureSequence();
}
}
break;
}
case STATE_WAITING_PRECAPTURE: {
// 等待预处理状态, 某些设备CONTROL_AE_STATE可能为null
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null ||
aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE ||
aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED) {
// 如果AE需要做于拍照或者需要闪光灯, 将状态置为"非等待预拍照"(翻译得有点勉强)
mState = STATE_WAITING_NON_PRECAPTURE;
}
break;
}
case STATE_WAITING_NON_PRECAPTURE: {
// 某些设备CONTROL_AE_STATE可能为null
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
// 如果AE做完"非等待预拍照", 将状态置为已经拍照, 并执行拍照操作
mState = STATE_PICTURE_TAKEN;
captureStillPicture();
}
break;
}
}
}
};
/**
* 在UI上显示Toast的方法
*/
private void showToast(final String text) {
final Activity activity = getActivity();
if (activity != null) {
activity.runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(activity, text, Toast.LENGTH_SHORT).show();
}
});
}
}
/**
* 返回最合适的预览尺寸
*
* @param choices 相机希望输出类支持的尺寸list
* @param textureViewWidth texture view 宽度
* @param textureViewHeight texture view 高度
* @param maxWidth 能够选择的最大宽度
* @param maxHeight 能够选择的醉倒高度
* @param aspectRatio 图像的比例(pictureSize, 只有当pictureSize和textureSize保持一致, 才不会失真)
* @return 最合适的预览尺寸
*/
private static Size chooseOptimalSize(Size[] choices, int textureViewWidth,
int textureViewHeight, int maxWidth, int maxHeight, Size aspectRatio) {
// 存放小于等于限定尺寸, 大于等于texture控件尺寸的Size
List<Size> bigEnough = new ArrayList<>();
// 存放小于限定尺寸, 小于texture控件尺寸的Size
List<Size> notBigEnough = new ArrayList<>();
int w = aspectRatio.getWidth();
int h = aspectRatio.getHeight();
for (Size option : choices) {
if (option.getWidth() <= maxWidth && option.getHeight() <= maxHeight &&
option.getHeight() == option.getWidth() * h / w) {
// option.getHeight() == option.getWidth() * h / w 用来保证
// pictureSize的 w / h 和 textureSize的 w / h 一致
if (option.getWidth() >= textureViewWidth &&
option.getHeight() >= textureViewHeight) {
bigEnough.add(option);
} else {
notBigEnough.add(option);
}
}
}
// 1. 若存在bigEnough数据, 则返回最大里面最小的
// 2. 若不存bigEnough数据, 但是存在notBigEnough数据, 则返回在最小里面最大的
// 3. 上述两种数据都没有时, 返回空, 并在日志上显示错误信息
if (bigEnough.size() > 0) {
return Collections.min(bigEnough, new CompareSizesByArea());
} else if (notBigEnough.size() > 0) {
return Collections.max(notBigEnough, new CompareSizesByArea());
} else {
Log.e(TAG, "Couldn't find any suitable preview size");
return choices[0];
}
}
public static CameraFragment newInstance() {
return new CameraFragment();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_camera, container, false);
}
@Override
public void onViewCreated(final View view, Bundle savedInstanceState) {
mTextureView = (AutoFitTextureView) view.findViewById(R.id.texture);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mFile = new File(getActivity().getExternalFilesDir(null), "pic.jpg");
}
@Override
public void onResume() {
super.onResume();
startBackgroundThread();
// 当屏幕关闭后重新打开, 若SurfaceTexture已经就绪, 此时onSurfaceTextureAvailable不会被回调, 这种情况下
// 如果SurfaceTexture已经就绪, 则直接打开相机, 否则等待SurfaceTexture已经就绪的回调
if (mTextureView.isAvailable()) {
openCamera(mTextureView.getWidth(), mTextureView.getHeight());
} else {
mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);
}
}
@Override
public void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
/**
* 设置相机的输出, 包括预览和拍照
*
* 处理流程如下:
* 1. 获取当前的摄像头, 并将拍照输出设置为最高画质
* 2. 判断显示方向和摄像头传感器方向是否一致, 是否需要旋转画面
* 3. 获取当前显示尺寸和相机的输出尺寸, 选择最合适的预览尺寸
*
* @param width 预览宽度
* @param height 预览高度
*/
private void setUpCameraOutputs(int width, int height) {
// 获取当前活动
Activity activity = getActivity();
// 获取CameraManager实例
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
// 遍历运行本应用的设备的所有摄像头
for (String cameraId : manager.getCameraIdList()) {
CameraCharacteristics characteristics
= manager.getCameraCharacteristics(cameraId);
// 如果该摄像头是前置摄像头, 则看下一个摄像头(本应用不使用前置摄像头)
Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
continue;
}
StreamConfigurationMap map = characteristics.get(
CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
if (map == null) {
continue;
}
// 选用最高画质
// maxImages是ImageReader一次可以访问的最大图片数量
Size largest = Collections.max(
Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
new CompareSizesByArea());
Log.d(TAG, "largest.width: " + largest.getWidth());
Log.d(TAG, "largest.height: " + largest.getHeight());
mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
ImageFormat.JPEG, /*maxImages*/2);
mImageReader.setOnImageAvailableListener(
mOnImageAvailableListener, mBackgroundHandler);
// 获取手机目前的旋转方向(横屏还是竖屏, 对于"自然"状态下高度大于宽度的设备来说横屏是ROTATION_90
// 或者ROTATION_270,竖屏是ROTATION_0或者ROTATION_180)
int displayRotation = activity.getWindowManager().getDefaultDisplay().getRotation();
// 获取相机传感器的方向("自然"状态下垂直放置为0, 顺时针算起, 每次加90读)
// 注意, 这个参数, 是由设备的生产商来决定的, 大多数情况下, 该值为90, 以下的switch这么写
// 是为了配适某些特殊的手机
int sensorOrientation =
characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
boolean swappedDimensions = false;
Log.d(TAG, "displayRotation: " + displayRotation);
Log.d(TAG, "sensorOritentation: " + sensorOrientation);
switch (displayRotation) {
// ROTATION_0和ROTATION_180都是竖屏只需做同样的处理操作
// 显示为竖屏时, 若传感器方向为90或者270, 则需要进行转换(标志位置true)
case Surface.ROTATION_0:
case Surface.ROTATION_180:
if (sensorOrientation == 90 || sensorOrientation == 270) {
Log.d(TAG, "swappedDimensions set true !");
swappedDimensions = true;
}
break;
// ROTATION_90和ROTATION_270都是横屏只需做同样的处理操作
// 显示为横屏时, 若传感器方向为0或者180, 则需要进行转换(标志位置true)
case Surface.ROTATION_90:
case Surface.ROTATION_270:
if (sensorOrientation == 0 || sensorOrientation == 180) {
swappedDimensions = true;
}
break;
default:
Log.e(TAG, "Display rotation is invalid: " + displayRotation);
}
// 获取当前的屏幕尺寸, 放到一个点对象里
Point displaySize = new Point();
activity.getWindowManager().getDefaultDisplay().getSize(displaySize);
// 旋转前的预览宽度(相机给出的), 通过传进来的参数获得
int rotatedPreviewWidth = width;
// 旋转前的预览高度(相机给出的), 通过传进来的参数获得
int rotatedPreviewHeight = height;
// 将当前的显示尺寸赋给最大的预览尺寸(能够显示的尺寸, 用来计算用的(texture可能比它小需要配适))
int maxPreviewWidth = displaySize.x;
int maxPreviewHeight = displaySize.y;
// 如果需要进行画面旋转, 将宽度和高度对调
if (swappedDimensions) {
rotatedPreviewWidth = height;
rotatedPreviewHeight = width;
maxPreviewWidth = displaySize.y;
maxPreviewHeight = displaySize.x;
}
// 尺寸太大时的极端处理
if (maxPreviewWidth > MAX_PREVIEW_WIDTH) {
maxPreviewWidth = MAX_PREVIEW_WIDTH;
}
if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
maxPreviewHeight = MAX_PREVIEW_HEIGHT;
}
// 自动计算出最适合的预览尺寸
// 第一个参数:map.getOutputSizes(SurfaceTexture.class)表示SurfaceTexture支持的尺寸List
mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
maxPreviewHeight, largest);
// 获取当前的屏幕方向
int orientation = getResources().getConfiguration().orientation;
if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
// 如果方向是横向(landscape)
mTextureView.setAspectRatio(
mPreviewSize.getWidth(), mPreviewSize.getHeight());
} else {
// 方向不是横向(即竖向)
mTextureView.setAspectRatio(
mPreviewSize.getHeight(), mPreviewSize.getWidth());
}
Log.d(TAG, "real preview width: " + rotatedPreviewWidth);
Log.d(TAG, "real preview height: " + rotatedPreviewHeight);
// Log.d(TAG, "max preview width: " + maxPreviewWidth);
// Log.d(TAG, "max preview width: : " + maxPreviewHeight);
// 下面这两个是计算后的previewSize=======================================
Log.d(TAG, "mPreviewSize.getWidth: " + mPreviewSize.getWidth());
Log.d(TAG, "mPreviewSize.getHeight: " + mPreviewSize.getHeight());
// =================================================================
mCameraId = cameraId;
return;
}
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (NullPointerException e) {
// 对话框显示错误
ErrorDialog.newInstance(getString(R.string.camera_error))
.show(getChildFragmentManager(), FRAGMENT_DIALOG);
}
}
/**
* 通过cameraId打开特定的相机
*/
private void openCamera(int width, int height) {
// 设置相机输出
setUpCameraOutputs(width, height);
// 配置格式转换
configureTransform(width, height);
// 获取当前活动和CameraManager的实例
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
// 尝试获得相机开打关闭许可, 等待2500时间仍没有获得则排除异常
if (!mCameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
throw new RuntimeException("Time out waiting to lock camera opening.");
}
// 打开相机, 参数是: 相机id, 相机状态回调, 子线程处理器
manager.openCamera(mCameraId, mStateCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
}
}
/**
* 关闭正在使用的相机
*/
private void closeCamera() {
try {
// 获得相机开打关闭许可
mCameraOpenCloseLock.acquire();
// 关闭捕获会话
if (null != mCaptureSession) {
mCaptureSession.close();
mCaptureSession = null;
}
// 关闭当前相机
if (null != mCameraDevice) {
mCameraDevice.close();
mCameraDevice = null;
}
// 关闭拍照处理器
if (null != mImageReader) {
mImageReader.close();
mImageReader = null;
}
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera closing.", e);
} finally {
// 释放相机开打关闭许可
mCameraOpenCloseLock.release();
}
}
/**
* 开启子线程
*/
private void startBackgroundThread() {
mBackgroundThread = new HandlerThread("CameraBackground");
mBackgroundThread.start();
mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
}
/**
* 停止子线程
*/
private void stopBackgroundThread() {
mBackgroundThread.quitSafely();
try {
mBackgroundThread.join();
mBackgroundThread = null;
mBackgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 创建预览对话
*/
private void createCameraPreviewSession() {
try {
// 获取texture实例
SurfaceTexture texture = mTextureView.getSurfaceTexture();
assert texture != null;
// 设置宽度和高度
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
// 用来开始预览的输出surface
Surface surface = new Surface(texture);
// 预览请求构建
mPreviewRequestBuilder
= mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
// 创建预览的捕获会话
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
// 相机关闭时, 直接返回
if (null == mCameraDevice) {
return;
}
// 会话可行时, 将构建的会话赋给field
mCaptureSession = cameraCaptureSession;
try {
// 自动对焦
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// 自动闪光
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// 构建上述的请求
mPreviewRequest = mPreviewRequestBuilder.build();
// 重复进行上面构建的请求, 以便显示预览
mCaptureSession.setRepeatingRequest(mPreviewRequest,
mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(
@NonNull CameraCaptureSession cameraCaptureSession) {
showToast("Failed");
}
}, null
);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 屏幕方向发生改变时调用转换数据方法
*
* @param viewWidth mTextureView 的宽度
* @param viewHeight mTextureView 的高度
*/
private void configureTransform(int viewWidth, int viewHeight) {
Activity activity = getActivity();
if (null == mTextureView || null == mPreviewSize || null == activity) {
return;
}
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
Matrix matrix = new Matrix();
RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
RectF bufferRect = new RectF(0, 0, mPreviewSize.getHeight(), mPreviewSize.getWidth());
float centerX = viewRect.centerX();
float centerY = viewRect.centerY();
if (Surface.ROTATION_90 == rotation || Surface.ROTATION_270 == rotation) {
bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
matrix.setRectToRect(viewRect, bufferRect, Matrix.ScaleToFit.FILL);
float scale = Math.max(
(float) viewHeight / mPreviewSize.getHeight(),
(float) viewWidth / mPreviewSize.getWidth());
matrix.postScale(scale, scale, centerX, centerY);
matrix.postRotate(90 * (rotation - 2), centerX, centerY);
} else if (Surface.ROTATION_180 == rotation) {
matrix.postRotate(180, centerX, centerY);
}
mTextureView.setTransform(matrix);
}
/**
* 实现拍照的方法
*/
private void takePicture() {
lockFocus();
}
/**
* 锁定焦点(拍照的第一步)
*/
private void lockFocus() {
try {
// 构建自动对焦请求
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CameraMetadata.CONTROL_AF_TRIGGER_START);
// 告诉mCaptureCallback回调状态
mState = STATE_WAITING_LOCK;
// 提交一个捕获单一图片的请求个相机
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 执行预拍照操作
*/
private void runPrecaptureSequence() {
try {
// 构建预拍照请求
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER,
CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER_START);
// 告诉mCaptureCallback回调状态
mState = STATE_WAITING_PRECAPTURE;
// 提交一个捕获单一图片的请求个相机
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 拍照操作
*/
private void captureStillPicture() {
try {
final Activity activity = getActivity();
if (null == activity || null == mCameraDevice) {
return;
}
// This is the CaptureRequest.Builder that we use to take a picture.
final CaptureRequest.Builder captureBuilder =
mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(mImageReader.getSurface());
// Use the same AE and AF modes as the preview.
captureBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
captureBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// Orientation
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
CameraCaptureSession.CaptureCallback CaptureCallback
= new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
showToast("Saved: " + mFile);
Log.d(TAG, mFile.toString());
unlockFocus();
}
};
mCaptureSession.stopRepeating();
mCaptureSession.capture(captureBuilder.build(), CaptureCallback, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 解开锁定的焦点
*/
private void unlockFocus() {
try {
// 构建失能AF的请求
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
// 构建自动闪光请求(之前拍照前会构建为需要或者不需要闪光灯, 这里重新设回自动)
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// 提交以上构建的请求
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
// 拍完照后, 设置成预览状态, 并重复预览请求
mState = STATE_PREVIEW;
mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 保存jpeg到指定的文件夹下, 开启子线程执行保存操作
*/
private static class ImageSaver implements Runnable {
/**
* jpeg格式的文件
*/
private final Image mImage;
/**
* 保存的文件
*/
private final File mFile;
public ImageSaver(Image image, File file) {
mImage = image;
mFile = file;
}
@Override
public void run() {
ByteBuffer buffer = mImage.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.remaining()];
buffer.get(bytes);
FileOutputStream output = null;
try {
output = new FileOutputStream(mFile);
output.write(bytes);
} catch (IOException e) {
e.printStackTrace();
} finally {
mImage.close();
if (null != output) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
/**
* 比较两个Size的大小基于它们的area
*/
static class CompareSizesByArea implements Comparator<Size> {
@Override
public int compare(Size lhs, Size rhs) {
// We cast here to ensure the multiplications won't overflow
return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
(long) rhs.getWidth() * rhs.getHeight());
}
}
/**
* 显示错误信息的对话框
*/
public static class ErrorDialog extends DialogFragment {
private static final String ARG_MESSAGE = "message";
public static ErrorDialog newInstance(String message) {
ErrorDialog dialog = new ErrorDialog();
Bundle args = new Bundle();
args.putString(ARG_MESSAGE, message);
dialog.setArguments(args);
return dialog;
}
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Activity activity = getActivity();
return new AlertDialog.Builder(activity)
.setMessage(getArguments().getString(ARG_MESSAGE))
.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
activity.finish();
}
})
.create();
}
}
}
