Android Camera

1 Camera拍照

用Camera去拍照，将遵循以下几个步骤

• 获得一个Camera实例，通过open()方法：

Camera camera = Camera.open()

• 如果必要的画，可以修改一些默认参数：

Camera.Parameter parameter = camera.getParameters()

• 通过初始化SurfaceHolder去setPreviewDisplay(SurfaceHolder)，没有Surface不能开始预览：

SurfaceHolder holder = surfaceView.getHolder();
camera.setPreviewDisplay(holder);
一般在SurfaceHolder.Callback的onSurfaceCreate()设置预览和开启预览

• 调用startPreview()方法开始更新预览的Surface，在拍照前，预览（Preview）必须被开启：

camera.startPreview()

• 当你想开始拍照时，使用takePicture()方法，等待回调提供真实的图像数据：

（camera.takePicture(null, null, null, this),Camera.PictureCallback）

• 当拍完一张照片时，预览（Preview）将会停止，当你想要拍更多的照片时，需要再一次调用startPreview()方法
  （Camera.PictureCallback的onPictureTaken()回调中startPreview()重新开启预览）

• 当调用stopPreview()方法时，将停止更新预览的Surface

• 当调用release()方法时，将马上释放camera

1.1 使用Camera拍照

• Camera相关权限

<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />

1.1.1 Camera拍照

?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:orientation="vertical">

    <Button
        android:id="@+id/btn_take_picture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="拍照" />

    <ImageView
        android:id="@+id/iv_picture"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
        tools:ignore="contentDescription" />

</LinearLayout>

package com.example.media.camera;

import android.content.ContentValues;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;

import com.example.media.R;

import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class CameraActivity extends AppCompatActivity {
    private static final String TAG = CameraActivity.class.getSimpleName();
    private static final int REQUEST_CODE_TAKE_PICTURE = 10001;

    private static SimpleDateFormat sDateFormat = new SimpleDateFormat("yyyyMMddHHmmss", Locale.CHINA);

    private String mPicturePath;
    private ImageView mIvPicture;

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

        mIvPicture = findViewById(R.id.iv_picture);

        findViewById(R.id.btn_take_picture).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                doTakePicture();
            }
        });
    }

    private void doTakePicture() {
        // MediaStore：多媒体的内容提供者（ContentProvider是全局的提供者）
        // MediaStore.Images.Media.EXTERNAL_CONTENT_URI：保存在content://media/external/images/media/xxx（数据编号），外部存储SD卡等
        // MediaStore.Images.Media.INTERNAL_CONTENT_URI：保存在content://media/internal/images/media/xxx（数据编号），内存
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        Uri pictureUri;
        String picturePath = getPictureFilePath();
        if (picturePath != null && !TextUtils.isEmpty(picturePath)) {
            // 7.0以上不支持 file://path，只支持 content://path
            // 7.0以前路径：file://storage/emulated/0/Pictures/myPicture20180107xxx.jpg
            // 7.0以上：content://media/external/images/media/xxxx
            if (Build.VERSION.SDK_INT > Build.VERSION_CODES.N) {
                ContentValues contentValues = new ContentValues();
                contentValues.put(MediaStore.Images.Media.DATA, picturePath);
                pictureUri = getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, contentValues);
            } else {
                pictureUri = Uri.fromFile(new File(picturePath));
            }
            intent.putExtra(MediaStore.EXTRA_OUTPUT, pictureUri);
        }
        startActivityForResult(intent, REQUEST_CODE_TAKE_PICTURE);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        // 拍照前用户指定了拍照图片的Uri，则data将返回null，直接使用自己指定的图片路径即可
        if (requestCode == REQUEST_CODE_TAKE_PICTURE && resultCode == RESULT_OK) {
            Bitmap bitmap = getBitmap(mPicturePath);
            if (bitmap != null) {
                mIvPicture.setImageBitmap(bitmap);
            }
        }
    }

    private Bitmap getBitmap(String picturePath) {
        if (picturePath != null && !TextUtils.isEmpty(picturePath)) {
            return getThumbnailBitmap(picturePath);
        }
        return null;
    }

    private Bitmap getThumbnailBitmap(String path) {
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(path, options);
        options.inSampleSize = getThumbnailSampleSize(options);
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeFile(path, options);
    }

    private int getThumbnailSampleSize(BitmapFactory.Options options) {
        // 采样率需要调整一下
        int inSampleSize = 1;
        int imageWidth = options.outWidth;
        int imageHeight = options.outHeight;

        if (imageWidth > 512 || imageHeight > 512) {
            final int halfWidth = imageWidth / 2;
            final int halfHeight = imageHeight / 2;

            while ((halfWidth / inSampleSize) >= 512 && (halfHeight / inSampleSize) >= 512) {
                inSampleSize *= 2;
            }
        }

        return inSampleSize;
    }

    private String getPictureFilePath() {
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            File pictureDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
            if (!pictureDir.exists()) {
                if (pictureDir.mkdir()) {
                    mPicturePath = pictureDir.getAbsolutePath() + File.separator + "myPicture." + sDateFormat.format(new Date()) + ".jpg";
                    return mPicturePath;
                }
            }
            mPicturePath = pictureDir.getAbsolutePath() + File.separator + "myPicture." + sDateFormat.format(new Date()) + ".jpg";
            Log.v(TAG, "picture path = " + mPicturePath);
            return mPicturePath;
        }
        return null;
    }
}

1.2.2 Camera+SurfaceView预览拍照

<?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:orientation="vertical">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="300dp">

        <SurfaceView
            android:id="@+id/surface_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

        <TextView
            android:id="@+id/tv_delay_time"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:textColor="@android:color/white"
            android:textSize="25sp"
            android:visibility="gone"
            tools:text="10" />

    </RelativeLayout>


    <Button
        android:id="@+id/btn_delay_take_picture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_margin="10dp"
        android:text="延迟10s拍照" />

</LinearLayout>


/**
 * 1、Surface：Surface是Android的一个抽象类，表示绘制图形或图像的位置。
 * 获取Surface比较简单的方式是使用SurfaceView。
 *
 * 2、SurfaceHolder：Surface的监听器（即图形绘制监听器）；
 * 通过SurfaceHolder.Callback回调接口监听创建、销毁或更改Surface。
 *
 * 3、Camera.PictureCallback：图像捕获回调
 *
 * 其他Camera回调接口：
 * （1）Camera.PreviewCallback：
 * onPreviewFrame(byte[] data, Camera camera)方法，当存在预览帧（preview frame)时调用该方法。
 *
 * 在Camera对象上，有3中不同的方式使用这个回调：
 * [1]setPreviewCallback(Camera.PreviewCallback)：使用该方法注册Camera.PreviewCallback，
 * 这将确保在屏幕上显示一个新的预览帧时调用onPreviewFrame()方法。传递到onPreviewFrame()方法中的数据字节数组最有可能采用YUV格式。
 *
 * [2]setOneShotPreviewCallback(Camera.PreviewCallback)：使用该方法注册Camera.PreviewCallback，
 * 从而当下一幅预览图像可用时调用一次onPreviewFrame()方法。同样，传递到onPreviewFrame()方法的预览图像数据最有可能采用YUV格式。
 * 可以使用ImageFormat中的常量检查Camera.getParameters().getPreviewFormat()返回的结果确定这一点。
 *
 * [3]setPreviewCallbackWithBuffer(Camera.PreviewCallback)：与setPreviewCallback的工作方式相同，
 * 但要求指定一个字节数组作为缓冲区，用于预览图像数据。这时为了能够更好地管理处理预览图像时使用的内存。
 *
 * （2）Camera.AutoFocusCallback：
 * onAutoFocus(boolean success, Camera camera)方法，当完成一个自动聚焦活动时调用它。
 * 通过传入此回调接口的一个实例，在调用Camera对象上的autoFocus方法时会触发自动聚焦。
 *
 * （3）Camera.ErrorCallback：
 * onError(int error, Camera camera)方法，当发生一个Camera错误时调用它。
 * 有两个常量可用于与传入的错误代码进行比较：CAMERA.ERROR_UNKNOWN和CAMERA_ERROR_SERVER_DIED。
 *
 * （4）Camera.OnZoomChangeListener：
 * onZoomChange(int zoomValue, boolean stopped, Camera camera)方法，当正在进行或完成“平滑缩放”（慢慢缩小或放大）时调用它。
 *
 * （5）Camera.ShutterCallback：
 * onShutter()方法，当捕获图像时立刻调用它。
 */

public class CameraSurfaceViewActivity extends AppCompatActivity
        implements SurfaceHolder.Callback, Camera.PictureCallback, View.OnClickListener {

    // 预览图像最大显示宽度和高度
    private static final int LARGE_WIDTH = 2048;
    private static final int LARGE_HEIGHT = 2048;

    // 延迟拍照
    private int mDelayTime = 10;
    private boolean mIsTimerRunning = false;
    private TextView mTvDelayTime;

    private Camera mCamera;
    private SurfaceView mSurfaceView;

    @SuppressLint("HandlerLeak")
    private Handler sHandler = new Handler();
    private Runnable mTimerRunnable = new Runnable() {
        @Override
        public void run() {
            if (mDelayTime > 0) {
                if (mIsTimerRunning) {
                    mDelayTime--;
                    mTvDelayTime.setVisibility(View.VISIBLE);
                    mTvDelayTime.setText(String.valueOf(mDelayTime));
                    sHandler.postDelayed(mTimerRunnable, 1000);
                }
            } else {
                takePicture();
                mDelayTime = 10;
                mTvDelayTime.setVisibility(View.GONE);
                mIsTimerRunning = false;
            }
        }
    };

    @Override
    protected void onDestroy() {
        sHandler.removeCallbacksAndMessages(null);
        super.onDestroy();
    }

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

        Button btnTakePicture = findViewById(R.id.btn_delay_take_picture);
        mTvDelayTime = findViewById(R.id.tv_delay_time);
        btnTakePicture.setOnClickListener(this);

        mSurfaceView = findViewById(R.id.surface_view);
        mSurfaceView.setClickable(true);
        mSurfaceView.setFocusable(true);
        mSurfaceView.setFocusableInTouchMode(true); // 在触摸模式时设置可获取焦点
        mSurfaceView.setOnClickListener(this);
        SurfaceHolder surfaceHolder = mSurfaceView.getHolder();
        surfaceHolder.addCallback(this);
        // 推送类型的Surface，即在Surface本身的外部维持绘图缓冲区，该缓冲区由Camera管理
        // 推送类型的Surface是Camera预览所需的Surface
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    /**
     * Surface创建时回调
     */
    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mCamera = Camera.open();
        try {
            Camera.Parameters parameters = mCamera.getParameters();
//            mCamera.setDisplayOrientation(x); // 摄像头方向 仅支持0 90 180 270四个角度
            if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) {
                mCamera.setDisplayOrientation(0); // 设置预览时摄像头方向，默认是横向
                parameters.setRotation(0); // 拍摄后图片方向，不设置默认是竖屏90度
            } else {
                mCamera.setDisplayOrientation(90);
                parameters.setRotation(90);
            }

            // 获取支持的颜色
            List<String> colorEffects = parameters.getSupportedColorEffects();
            for (String colorEffect : colorEffects) {
                // Camera.Parameters.EFFECT_WHITEBOARD（白平衡效果）等等
                if (colorEffect.equals(Camera.Parameters.EFFECT_NONE)) {
                    parameters.setColorEffect(colorEffect);
                    break;
                }
            }

            // 设置预览大小
            int bestWidth = 0;
            int bestHeight = 0;
            List<Camera.Size> sizes = parameters.getSupportedPreviewSizes();
            for (Camera.Size size : sizes) {
                if (size.width > bestWidth && size.width <= LARGE_WIDTH
                        && size.height > bestHeight && size.height <= LARGE_HEIGHT) {
                    bestWidth = size.width;
                    bestHeight = size.height;
                }
            }
            if (bestWidth != 0 && bestHeight != 0) {
                Toast.makeText(this, "bestWidth = " + bestWidth + ",bestHeight = " + bestHeight, Toast.LENGTH_SHORT).show();
                parameters.setPreviewSize(bestWidth, bestHeight);
                // SurfaceView也要修改大小
                RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(bestWidth, bestHeight);
                lp.addRule(Gravity.CENTER);
                mSurfaceView.setLayoutParams(lp);
            }

            mCamera.setParameters(parameters);
            mCamera.setPreviewDisplay(holder);
        } catch (IOException e) {
            e.printStackTrace();
            mCamera.release(); // 抛出异常时，确保Camera能被释放
        }
        mCamera.startPreview();
    }

    /**
     *  Surface更改时回调
     */
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    /**
     *  Surface销毁时回调
     */
    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        if (mCamera != null) {
            mCamera.stopPreview(); // 先调用stopPreview()确保该释放的资源都被清理
            mCamera.release();
        }
    }

    /**
     *  拍照回调
     * @param data 拍照图片字节码
     * @param camera Camera引用
     */
    @Override
    public void onPictureTaken(byte[] data, Camera camera) {
        Uri pictureUri = getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new ContentValues());
        if (pictureUri != null) {
            OutputStream outputStream = null;
            try {
                outputStream = getContentResolver().openOutputStream(pictureUri);
                if (outputStream != null) {
                    outputStream.write(data);
                    outputStream.flush();
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                closeSilently(outputStream);
            }
        }

        Toast.makeText(this, "图片保存成功", Toast.LENGTH_SHORT).show();

        // 拍照完成并保存图片后，重新开启预览
        camera.startPreview();
    }

    private void closeSilently(Closeable closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.surface_view:
                // 设置点击SurfaceView时执行拍照操作
                takePicture();
                break;
            case R.id.btn_delay_take_picture:
                if (!mIsTimerRunning) {
                    mIsTimerRunning = true;
                    sHandler.post(mTimerRunnable);
                }
                break;
        }
    }

    private void takePicture() {
        if (mCamera != null) {
            mCamera.takePicture(null, null, null, CameraSurfaceViewActivity.this);
        }
    }
}

2 Camera录像

用Camera录像，将遵循以下几个步骤：

• 获取一个初始化Camera并开启预览

• 调用unlock()方法允许media进程去访问Camera

• 通过MediaRecorder.setCamera(camera)设置Camera

• 当完成录制时，调用reconnect()方法重新获取且重新lock camera

• 调用stopPreview()方法且release()方法释放Camera和MediaRecorder

2.1 使用Camera录像

?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn_start_camera_record"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="开始录像" />

    <Button
        android:id="@+id/btn_stop_camera_record"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="停止录像"/>

    <SurfaceView
        android:id="@+id/surface_view"
        android:layout_width="match_parent"
        android:layout_height="300dp" />

</LinearLayout>

package com.example.media.camera;

import android.hardware.Camera;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;

import com.example.media.R;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class CameraRecordActivity extends AppCompatActivity implements SurfaceHolder.Callback {
    private static final String TAG = CameraRecordActivity.class.getSimpleName();

    private Button mBtnStartCameraRecord;
    private Button mBtnStopCameraRecord;

    private SurfaceHolder mSurfaceHolder;
    private MediaRecorder mMediaRecorder;
    private Camera mCamera;

    private String mRecordFilePath;

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

        SurfaceView surfaceView = findViewById(R.id.surface_view);
        mSurfaceHolder = surfaceView.getHolder();
        mSurfaceHolder.addCallback(this);
        mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

        mBtnStartCameraRecord = findViewById(R.id.btn_start_camera_record);
        mBtnStartCameraRecord.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mBtnStartCameraRecord.setEnabled(false);
                mBtnStopCameraRecord.setEnabled(true);
                mBtnStartCameraRecord.setText("正在录像中.....");

                try {
                    mCamera.unlock();
                    mMediaRecorder = new MediaRecorder();
                    mMediaRecorder.setCamera(mCamera); // 需要在MediaRecorder.prepare()之前设置，否则抛异常
                    // 设置录像源（在setOutputFormat()之前设置）
                    mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER); // 音频源
                    mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA); // 视频源
                    // 设置录制视频格式
                    mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
                    // 设置录像编码（在setOutputFormat()之后设置）
                    mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
                    mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
                    // 设置录像参数（视频质量相关）
                    mMediaRecorder.setVideoSize(640, 480); // 设置视频分辨率
                    mMediaRecorder.setVideoFrameRate(30); // 设置视频帧率，1秒30帧
                    mMediaRecorder.setVideoEncodingBitRate(3 * 1024 * 1024); // 设置视频编码流，值越大，视频越清晰，当然视频越大
                    mMediaRecorder.setOrientationHint(90);
                    mMediaRecorder.setMaxDuration(30 * 1000); // 设置录制最大时长为30秒
                    mMediaRecorder.setPreviewDisplay(mSurfaceHolder.getSurface());

                    mRecordFilePath = getRecordFilePath();
                    if (mRecordFilePath != null) {
                        mMediaRecorder.setOutputFile(mRecordFilePath);
                        mMediaRecorder.prepare();
                        mMediaRecorder.start();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });

        mBtnStopCameraRecord = findViewById(R.id.btn_stop_camera_record);
        mBtnStopCameraRecord.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mBtnStartCameraRecord.setEnabled(true);
                mBtnStopCameraRecord.setEnabled(false);
                mBtnStartCameraRecord.setText("开始录像");

                try {
                    mCamera.reconnect();
                    mCamera.lock();
                    mMediaRecorder.stop();
                    mMediaRecorder.release();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });

        mBtnStartCameraRecord.setEnabled(true);
        mBtnStopCameraRecord.setEnabled(false);
    }

    private String getRecordFilePath() {
        if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            Log.v(TAG, "external storage no exists");
            return null;
        }

        String recordDirPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Android/data/" +
                getPackageName() + File.separator + "camera_record/";
        File recordDir = new File(recordDirPath);
        if (!recordDir.exists()) {
            if (!recordDir.mkdirs()) {
                Log.v(TAG, "record dir create failed");
                return null;
            }
        }
        mRecordFilePath = recordDirPath + new SimpleDateFormat("yyyyMMddHHmmss", Locale.CHINA).format(new Date())
                + "camera_record.mp4";
        return mRecordFilePath;
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        try {
            mCamera = Camera.open();
            mCamera.setDisplayOrientation(90);
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        if (mCamera != null) {
            try {
                mCamera.stopPreview();
                mCamera.setPreviewDisplay(holder);
                mCamera.startPreview();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        if (mCamera != null) {
            mCamera.stopPreview();
            mCamera.release();
            mCamera = null;
        }
    }
}