不调用Android onPreviewFrame [英] Android onPreviewFrame is not called

问题描述

我的相机有问题.我想在onPreviewFrame中获取图片，但从未调用过.我打开相机，设置预览显示和预览回叫，但是什么也没有.我只想了解我错了.

I have a problem with camera. I want to get picture in onPreviewFrame but it's never called. I opened a camera, set preview Display and preview Callback but nothing. I just want to understand where I was wrong.

public class VideoCall extends Activity implements View.OnClickListener, Callback, PreviewCallback
{

    TabHost thVideoChat;
    Button btnVideoUp, btnVideoDown;
    Handler uiHandler;
    SurfaceView videoPrev;
    SurfaceHolder surfaceHolder;
    Camera camera;

    Timer timer;
    boolean getPic;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.a_video);
        initialize();

        Log.d("RAYZ", "onCreate");
    }

    private void initialize()
    {

        thVideoChat = (TabHost) findViewById(R.id.thVideoChat);
        thVideoChat.setup();

        TabSpec specs = thVideoChat.newTabSpec("1");
        specs.setContent(R.id.tabVideo);
        specs.setIndicator("Видео", getResources().getDrawable(R.drawable.mcam));
        thVideoChat.addTab(specs);

        specs = thVideoChat.newTabSpec("2");
        specs.setContent(R.id.tabChat);
        specs.setIndicator("Чат", getResources().getDrawable(R.drawable.mchat));
        thVideoChat.addTab(specs);

        btnVideoUp = (Button) findViewById(R.id.btnVideoUp);
        btnVideoDown = (Button) findViewById(R.id.btnVideoDown);
        btnVideoUp.setOnClickListener(this);
        btnVideoDown.setOnClickListener(this);

        videoPrev = (SurfaceView) findViewById(R.id.videoPrev);

        if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT)
        {

            LayoutParams lp = videoPrev.getLayoutParams();
            lp.height = 320;
            lp.width = 240;
            videoPrev.setLayoutParams(lp);

        }
        else
        {
            LayoutParams lp = videoPrev.getLayoutParams();
            lp.height = 240;
            lp.width = 320;
            videoPrev.setLayoutParams(lp);
        }

        surfaceHolder = videoPrev.getHolder();
        surfaceHolder.addCallback(this);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

        uiHandler = new Handler();
        getPic = false;
    }

    @Override
    protected void onPause()
    {
        Log.d("RAYZ", "onPause");
        if (camera != null)
        {
            camera.setPreviewCallback(null);
            camera.stopPreview();
            camera.release();
            camera = null;
        }
        if (timer != null)
        {
            timer.cancel();
        }
        super.onPause();
    }

    @Override
    protected void onResume()
    {
        super.onResume();
        camera = Camera.open();
    }

    @Override
    public void onClick(View v)
    {
        switch (v.getId())
        {
            case R.id.btnVideoUp:
            {
                btnVideoUp.setEnabled(false);
                btnVideoDown.setEnabled(true);

                timer = new Timer();

                Log.d("RAYZ", "G_BTN");

                timer.schedule(new TimerTask()
                {

                    @Override
                    public void run()
                    {
                        uiHandler.post(new Runnable()
                        {

                            @Override
                            public void run()
                            {
                                getPic = true;
                            }
                        });
                    }
                }, 0L, 1L * 500L);

                break;
            }
            case R.id.btnVideoDown:
            {
                btnVideoUp.setEnabled(true);
                btnVideoDown.setEnabled(false);
                Log.d("RAYZ", "R_BTN");
                timer.cancel();
                timer = null;
                break;
            }
            default:
                break;
        }

    }

    @Override
    public void onPreviewFrame(byte[] data, Camera camera)
    {
        Log.d("RAYZ", "getPic");
        // if (getPic)
        // {

        // }

    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
    {

    }

    @Override
    public void surfaceCreated(SurfaceHolder holder)
    {   

        try
        {

            camera.setPreviewDisplay(holder);
            camera.setPreviewCallback(this);
            camera.startPreview();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder)
    {

    }

}

在其他2台设备(手机HTS和Sony Xperia)上尝试了此代码，一切正常.但是在我的平板电脑上它不起作用.我很困惑.

Tried this code on 2 other devices (phones HTS and Sony Xperia) and everything worked fine. But on my tablet it does not work. I'm confused.

推荐答案

一段时间以来，我一直在努力解决这个问题，而我的解决方案是在SurfaceView.surfaceChanged中的Camera.setPreviewDisplay之后立即调用Camera.setPreviewCallback:

I have been struggling with this problem for sometime and the solution for me was to call Camera.setPreviewCallback just after Camera.setPreviewDisplay in SurfaceView.surfaceChanged:

public void onCreate(Bundle state) { log("onCreate");
    try {
        super.onCreate(state);
        setContentView(R.layout.main);
        text = (TextView) findViewById(R.id.text);
        surface = (SurfaceView) findViewById(R.id.surface);
        int type = SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS;
        surface.getHolder().setType(type);//REQUIRED:API10
        surface.getHolder().addCallback(this);
        camera = Camera.open();
        camera.setDisplayOrientation(90); // portrait mode only
    } catch (Exception e) {
        showException(e);
    }
}


public void surfaceChanged(SurfaceHolder sh, int format, int w, int h) { log("surfaceChanged");
    try {
        camera.stopPreview();
        Size s = camera.getParameters().getPreviewSize();
        LayoutParams params = surface.getLayoutParams();
        params.height = w*s.width/s.height; // portrait mode only
        surface.setLayoutParams(params);
        camera.setPreviewDisplay(sh);
        camera.setPreviewCallback(this);
        camera.startPreview();
    } catch (Exception ex) {
        showException(ex);
    }
}

阅读大量文章后，我意识到如果相机没有完全初始化的SurfaceHolder，则setPreviewCallback可能会失败.

Reading numerous article I realized the setPreviewCallback may fail if the camera does not have a fully initialized SurfaceHolder.

我希望这对您有帮助...

I hope this helps ...

这篇关于不调用Android onPreviewFrame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！