Android 4.4沒有預覽/ UI的攝像頭捕獲

Question

我試圖觸發Nexus 5（Android 4.4.3，股票）上的圖片捕獲，而不觸發任何UI或預覽。我已經在這個網站和其他網站上看到了幾種方法，但它們似乎是設備特定的，或者與最新版本的Android不兼容。我對Android開發相當陌生，所以我可能會錯過一些相當基本的東西，我非常感謝所提供的幫助。

這裏是我的代碼：

package com.example.omnisense; 

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

import android.content.Context; 
import android.content.Intent; 
import android.graphics.ImageFormat; 
import android.hardware.Camera; 
import android.hardware.Camera.CameraInfo; 
import android.hardware.Camera.Parameters; 
import android.hardware.Camera.Size; 
import android.os.Environment; 
import android.support.v4.content.LocalBroadcastManager; 
import android.util.Log; 
import android.view.SurfaceHolder; 
import android.view.SurfaceView; 

public class Sensor_Camera { 
    private Camera mCamera; 
    private Context context; 
    private SurfaceView sv; 
    private Parameters parameters; 

    private int width; 
    private int height; 
    private Size size; 

    public Sensor_Camera(Context c_){ 
     context = c_; 
     sv = new SurfaceView(context); 
     if (Camera.getNumberOfCameras() >= 2) { 
      mCamera = Camera.open(CameraInfo.CAMERA_FACING_FRONT); 
     } else { 
      mCamera = Camera.open(); 
     }  


    } 

    public void takePicture() { 
     try { 
      mCamera.setPreviewDisplay(sv.getHolder()); 
      parameters = mCamera.getParameters(); 
      size = parameters.getPictureSize(); 
      width = size.width; 
      height = size.height; 
      // Default picture format is NV21 
      mCamera.setParameters(parameters); 

      mCamera.startPreview(); 

      mCamera.takePicture(null, null, mCall); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 

    private Camera.PictureCallback mCall = new Camera.PictureCallback() { 

     @Override 
     public void onPictureTaken(final byte[] data, Camera camera) { 
       // Do Stuff 
       mCamera.stopPreview(); 
       mCamera.release(); 
       mCamera = null; 
     } 
    };  

} 

這裏有問題/答案/博客文章，我發現引用此：

Invisible SurfaceView for Camera Preview

http://cell0907.blogspot.com/2014/01/android-camera-capture-without.html

Android: Take Photo Without User Interface

一個d這裏的相關logcat的輸出：

06-09 01:25:22.831: D/Main(20056): onClick 
06-09 01:25:22.831: D/Main(20056): testButton Click 
06-09 01:25:23.111: D/Camera(20056): app passed NULL surface 
06-09 01:25:23.121: D/AndroidRuntime(20056): Shutting down VM 
06-09 01:25:23.121: W/dalvikvm(20056): threadid=1: thread exiting with uncaught exception (group=0x41d2bba8) 
06-09 01:25:23.121: E/AndroidRuntime(20056): FATAL EXCEPTION: main 
06-09 01:25:23.121: E/AndroidRuntime(20056): Process: com.example.omnisense, PID: 20056 
06-09 01:25:23.121: E/AndroidRuntime(20056): java.lang.RuntimeException: takePicture failed 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.hardware.Camera.native_takePicture(Native Method) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.hardware.Camera.takePicture(Camera.java:1244) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.hardware.Camera.takePicture(Camera.java:1189) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at com.example.omnisense.Sensor_Camera.takePicture(Sensor_Camera.java:60) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at com.example.omnisense.MainActivity.testButtonPress(MainActivity.java:172) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at com.example.omnisense.MainActivity$2.onClick(MainActivity.java:235) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.view.View.performClick(View.java:4438) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.view.View$PerformClick.run(View.java:18422) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.os.Handler.handleCallback(Handler.java:733) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.os.Handler.dispatchMessage(Handler.java:95) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.os.Looper.loop(Looper.java:136) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at android.app.ActivityThread.main(ActivityThread.java:5017) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at java.lang.reflect.Method.invokeNative(Native Method) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at java.lang.reflect.Method.invoke(Method.java:515) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:133) 
06-09 01:25:23.121: E/AndroidRuntime(20056): at dalvik.system.NativeStart.main(Native Method) 

在我的主要活動這個類是使用下面的代碼：

Sensor_Camera sense_camera = new Sensor_Camera(this); 
sense_camera.takePicture(); 

我已經添加了使用許可權和使用特徵的相機好。我不確定問題是什麼，雖然我認爲它與使用空的SurfaceView有關。是否有任何解決方法，或者在4.4中是不可能的？

如果還有其他事情我應該發佈我的代碼，請讓我知道！預先感謝任何和所有幫助。

Answer 1

看着the documentation，您使用的覽回調，他們注意

當縮放，完全處理覽 圖像可用（注意：不是所有的硬件支持）時發生覽回調。

聽起來好像您的設備可能不支持，所以您可能需要使用jpeg回調（第4個可選參數）。