java - 如何从 java android 中的相机预览中获取字节数组？

Question

我是个彻头彻尾的菜鸟。阅读此 http://developer.android.com/guide/topics/media/camera.html 后，我设法编写并理解了这段代码.但现在我想获取字节数组进行预览，然后将其转换为位图。但我想实时执行此操作而不必被迫在存储中保存图片文件。请帮忙!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

    }
};

}

主要 Activity :

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

详细in the Android Developer docs here (您可能已经阅读过)，将 PictureCallback 接口(interface)的实现(参见下面的示例)添加到您的 Activity。您也可以使用 BitmapFactory 将返回的字节数组转换为 Bitmap。然后您可以根据需要使用它。

注意:我也会阅读 the docs here关于有效处理与内存相关的位图，因为如果您正在操作位图，您可能会遇到 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
    }
};

然后您需要将其传递给相机实例的 takePicture() 方法，例如

// 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);
        }
    }
);

希望对您有所帮助! :-)