如何在java android中从摄像机预览中获取字节数组？

Question

我是个十足的菜鸟。在阅读了这个http://developer.android.com/guide/topics/media/camera.html之后，我成功地编写和理解了这段代码。但是现在我想要获得预览的字节数组，然后将其转换为位图。但是，我想要实时地做到这一点，而不必被迫将图片文件保存在存储中。求你了救命！这是我的程序代码。

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
public CameraPreview(Context context, Camera camera) {
    super(context);
    mCamera = camera;

    // Install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    mHolder = getHolder();
    mHolder.addCallback(this);
    // deprecated setting, but required on Android versions prior to 3.0
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public void surfaceCreated(SurfaceHolder holder) {
    // The Surface has been created, now tell the camera where to draw the preview.
    try {
        mCamera.setPreviewDisplay(holder);

        mCamera.startPreview();
    } catch (IOException e) {
        String TAG = null;
        Log.d(TAG, "Error setting camera preview: " + e.getMessage());
    }
}

public void surfaceDestroyed(SurfaceHolder holder) {
    // empty. Take care of releasing the Camera preview in your activity.
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    // If your preview can change or rotate, take care of those events here.
    // Make sure to stop the preview before resizing or reformatting it.


    mCamera.setDisplayOrientation(90);
    // set preview size and make any resize, rotate or
    // reformatting changes here

    // start preview with new settings
    try {

        mCamera.setPreviewDisplay(mHolder);
        mCamera.startPreview();

    } catch (Exception e){
        String TAG = null;
        Log.d(TAG, "Error starting camera preview: " + e.getMessage());
    }
}
private PictureCallback mPicture = new PictureCallback(){

    @Override
    public void onPictureTaken(byte[] data, Camera camera)

    {
        // TODO: Implement this method

    }
};

}

和主要活动：

public class MainActivity extends Activity
{   private Camera mCamera;
private CameraPreview mPreview; 
int i;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);  
    mCamera = getCameraInstance();
    mPreview = new CameraPreview(this, mCamera);

    FrameLayout preview = (FrameLayout) findViewById(R.id.frame);
    preview.addView(mPreview);



} 
public static Camera getCameraInstance()
{
    Camera c = null;
    try
    {
        c = Camera.open();}
    catch (Exception e)
    { System.out.println("blamjjjh");}
    return c;
}
public void releasec(){
    mCamera.release();
}

@Override
protected void onStop()
{

    super.onStop();
    releasec();
}
}

Answer 1

作为详细的在这里的Android开发人员文档中 (您可能已经读过)，将PictureCallback接口的实现(参见下面的示例)添加到您的活动中。此外，您还可以使用BitmapFactory来转换被传递回Bitmap的字节数组。然后您可以根据需要使用这个。

注意:我还会阅读这里的医生关于有效处理位图与内存相关的内容，因为如果您正在操作位图，您可能会得到OutOfMemory错误。

private PictureCallback mPicture = new PictureCallback() {

    @Override
    public void onPictureTaken(byte[] data, Camera camera) {

       //create a Bitmap from the byte array
       Bitmap bitmap = BitmapFactory.decodeByteArray(data , 0, data.length);

       //use your Bitmap
    }
};

然后，您需要将它传递给针对相机实例的takePicture()方法。

// Add a listener to the Capture button
Button captureButton = (Button) findViewById(id.button_capture);
captureButton.setOnClickListener(
    new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // get an image from the camera
            mCamera.takePicture(null, null, mPicture);
        }
    }
);

希望这会有帮助！