我可以在没有预览的情况下在服务中使用Android相机吗? [英] Can I use Android Camera in service without preview?

问题描述

我已经在Android中创建了一个应用程序，可以使用摄像头测量出用户面部与手机屏幕之间的距离.

I have create a application in Android that using a camera I can measure out the distance between user's face to the phone screen.

问题描述:

现在，我要使其在后台运行，以便在使用其他应用程序时可以使用该功能.这表示我应该在没有预览的情况下打开相机，并在使用中对其进行处理

我做了什么

我在这里提到了一些问题

I referred some questions here

如何从应用程序背景录制视频:Android

​​如何在后台使用Android相机?

从没有预览的相机拍摄图片

API级别16

我的服务文件

import android.app.Service;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.media.MediaRecorder;
import android.os.IBinder;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.Toast;
import java.io.File;
import java.io.IOException;
import java.util.List;

public class RecorderService extends Service {
private static final String TAG = "RecorderService";
private SurfaceView mSurfaceView;
private SurfaceHolder mSurfaceHolder;
private static Camera mServiceCamera;
private boolean mRecordingStatus;
private MediaRecorder mMediaRecorder;
File path = android.os.Environment.getExternalStorageDirectory();


@Override
public void onCreate() {
    Log.i(TAG,"onCreate");
    mRecordingStatus = false;
    //mServiceCamera = CameraRecorder.mCamera;
    mServiceCamera = Camera.open(1);
    mSurfaceView = MainActivity.mSurfaceView;
    mSurfaceHolder = MainActivity.mSurfaceHolder;

    super.onCreate();
    if (mRecordingStatus == false)
        startRecording();
}

@Override
public IBinder onBind(Intent intent) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void onDestroy() {
    Log.i(TAG,"onDestroy");

    stopRecording();
    mRecordingStatus = false;

    super.onDestroy();
}

public boolean startRecording(){
    Log.i(TAG,"startRecording");

    try {
        Toast.makeText(getBaseContext(), "Recording Started", Toast.LENGTH_SHORT).show();

        //mServiceCamera = Camera.open();
        Camera.Parameters params = mServiceCamera.getParameters();
        mServiceCamera.setParameters(params);
        Camera.Parameters p = mServiceCamera.getParameters();

        final List<Size> listSize = p.getSupportedPreviewSizes();
        Size mPreviewSize = listSize.get(2);
        Log.v(TAG, "use: width = " + mPreviewSize.width
                + " height = " + mPreviewSize.height);
        p.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
        p.setPreviewFormat(PixelFormat.YCbCr_420_SP);
        mServiceCamera.setParameters(p);

        try {
            mServiceCamera.setPreviewDisplay(mSurfaceHolder);
            mServiceCamera.startPreview();
        }
        catch (IOException e) {
            Log.e(TAG, e.getMessage());
            e.printStackTrace();
        }

        mServiceCamera.unlock();

        mMediaRecorder = new MediaRecorder();
        mMediaRecorder.setCamera(mServiceCamera);
        mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
        mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.DEFAULT);
        mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.DEFAULT);
        mMediaRecorder.setOutputFile(path+"/outputVideo.mp4");
        mMediaRecorder.setVideoFrameRate(30);
        mMediaRecorder.setVideoSize(mPreviewSize.width, mPreviewSize.height);
        mMediaRecorder.setPreviewDisplay(mSurfaceHolder.getSurface());

        mMediaRecorder.prepare();
        mMediaRecorder.start();

        mRecordingStatus = true;

        return true;
    } catch (IllegalStateException e) {
        Log.d(TAG, e.getMessage());
        e.printStackTrace();
        return false;
    } catch (IOException e) {
        Log.d(TAG, e.getMessage());
        e.printStackTrace();
        return false;
    }
}

public void stopRecording() {
    Log.i(TAG,"stopRecording");

    Toast.makeText(getBaseContext(), "Recording Stopped", Toast.LENGTH_SHORT).show();
    try {
        mServiceCamera.reconnect();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    try{
        mMediaRecorder.stop();
    }catch (Exception ignored)
    {

    }
    mMediaRecorder.reset();
    mMediaRecorder.release();
    mServiceCamera.stopPreview();
    mServiceCamera.release();
    mServiceCamera = null;
}
}

推荐答案

您可以参考

You can refer this Question, which discuss how to do video record in the service. The steps to capture image is same as it.

要满足您的要求，您可能需要:

To achieve your requirement, you may need:

1. 在您的服务中获取相机实例.检查此官方指南.
2. 设置相机参数.使用Camera.getParameters()，Camera.setParameters()，Camera.Parameters.setPictureSize(int with, int height)和Camera.Parameters.setPictureFormat(int format)之类的API来做到这一点.
3. 准备用于存储图像的文件.您需要实现Camera.PictureCallback来实现.
4. 拍照前请致电Camera.startPreview().如果您未在拍照前调用此功能，则会出现异常. (注意:您无需先执行Camera.setPreviewdisplay(SurfaceHolder display).)
5. 在您的服务中致电camera.takePicture().然后，您可以将捕获的图像存储在指定的文件中.

1. Get camera instance in your service. Check this Official Guideline.
2. Setup your camera parameters. Use the APIs like Camera.getParameters(), Camera.setParameters(), Camera.Parameters.setPictureSize(int with, int height) and Camera.Parameters.setPictureFormat(int format) to do so.
3. Prepare a file used to store the image. You need to implement Camera.PictureCallback to do so.
4. Call Camera.startPreview() before you takeing picutre. If you don't call this function before taking picture, you will get exception. (Note: You don't need to do Camera.setPreviewdisplay(SurfaceHolder display) first.)
5. Call camera.takePicture() in your service. Then you can get the captured image stored on the file you specified.

工作后，请不要忘记维护资源消耗生命周期，以正确获取/释放摄像机.

After it work, don forget to maintain the resource durning lifecycle to acquire/release camera correctly.

这是我在Github上的示例代码，在评论中也有提及.

Here is my sample code on Github, it is also mentioned in the comment.

这篇关于我可以在没有预览的情况下在服务中使用Android相机吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！