android - 使用Android，如何将控制权传递回主线程？

Question

我使用OpenCV教程3代码(摄像机控制)(请参阅OpenCV4Android samples)作为我的代码的基础，并且一旦将图像保存在onPictureTaken()方法中，就需要能够打开和操作该图像。在操作期间，我希望能够显示图像的更改并使用Toast发布消息，这两者都要求我位于主线程中。

根据迄今为止收到的建议，我正在尝试在BroadcastReceiver中使用Activity，这是由sendBroadcast()中的JavaCameraView触发的。

我已经将Activity更新为包括BroadcastReceiver，并按如下所示进行注册和注销:

public class Tutorial3Activity extends Activity implements CvCameraViewListener2, OnTouchListener {
    :
    private ActivityReceiver activityReceiver;
    :
    @Override
    public void onCreate(Bundle savedInstanceState) {
        :
        IntentFilter intentFilter = new IntentFilter();
        this.registerReceiver(activityReceiver, intentFilter);
        :
    }
    :
    public void onDestroy() {
        :
        this.unregisterReceiver(activityReceiver);
        :
    }
    :
    private class ActivityReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            Log.i(TAG, "BroadcastReceiver triggered");
            if (intent.getAction().equals(Tutorial3View.IMAGE_READY)) {
                Log.i(TAG, "BroadcastReceiver received");
            }
        }
    }    
}

sendBroadcast()在 JavaCameraView中被调用，如下所示:

public class Tutorial3View extends JavaCameraView {
    :
    public static final String IMAGE_READY = "IMAGE_READY";
    private Context context;
    :
    public Tutorial3View(Context context, AttributeSet attrs) {
        :
        this.context = context;
        :
    }
    :
    public void takePicture(final String fileName) {
        PictureCallback callback = new PictureCallback() {
            private String mPictureFileName = fileName;
            @Override
            public void onPictureTaken(byte[] data, Camera camera) {
                :
                image_read();
                :
            }
        };
        mCamera.takePicture(null, null, callback);
    }
    :
    public void image_read() {
        Log.i(TAG, "BroadcastReceiver - send");
        Intent i = new Intent();
        i.setAction(IMAGE_READY);
        context.sendBroadcast(i);
        Log.i(TAG, "BroadcastReceiver - sent");
    }
}

Manifest包含 BroadcastReceiver，如下所示:

<receiver android:name="ActivityReceiver">
    <intent-filter android:label="IMAGE_READY"></intent-filter>
</receiver>

当我拍照时，LogCat会显示:

03-30 17:22:53.410: I/Sample::Tutorial3View(3174): BroadcastReceiver - send
03-30 17:22:53.410: I/Sample::Tutorial3View(3174): BroadcastReceiver - sent

但没有 BroadcastReceiver triggered或 BroadcastReceiver received的日志。

有人可以建议为什么不接收广播吗？

谢谢

Answer 1

您需要调用 runOnUiThread() 方法:

runOnUiThread(new Runnable() {
    @Override
    public void run() {
        // stuff to be done on UI Thread
    }
});