在Android中使用SurfaceTexture实现相机预览的示例

Question

我正在尝试使用SurfaceTexture来呈现相机预览。我已经阅读了文档，但无法理解其工作原理。

请问是否有人能提供一个使用SurfaceTexture来预览相机的示例（非常基础的）或链接？我在谷歌上搜寻，但没有找到我需要的内容。

先感谢各位。

- AndroDev

Answer 1

如果您想要在纹理表面上使用相机功能，可以实现SurfaceTextureListener接口。您需要实现 4 个方法：

1）onSurfaceTextureAvailable - 在此处设置相机。

2）onSurfaceTextureSizeChanged - 在您的情况下，Android 相机会处理此方法。

3）onSurfaceTextureDestroyed - 在此处销毁所有相机内容。

4）onSurfaceTextureUpdated - 当您有需要更改的内容时，请在此处更新您的纹理！

请参考以下示例：

    public class MainActivity extends Activity implements SurfaceTextureListener{

    private Camera mCamera;
    private TextureView mTextureView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mTextureView = new TextureView(this);
        mTextureView.setSurfaceTextureListener(this);

        setContentView(mTextureView);
    }

    @Override
    public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
        mCamera = Camera.open();

        Camera.Size previewSize = mCamera.getParameters().getPreviewSize();
        mTextureView.setLayoutParams(new FrameLayout.LayoutParams(
                previewSize.width, previewSize.height, Gravity.CENTER));

        try {
            mCamera.setPreviewTexture(surface);
        } catch (IOException t) {
        }

        mCamera.startPreview();

    }

    @Override
    public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
        // Ignored, the Camera does all the work for us
    }

    @Override
    public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
        mCamera.stopPreview();
        mCamera.release();
        return true;
    }

    @Override
    public void onSurfaceTextureUpdated(SurfaceTexture surface) {
        // Update your view here!
    }
}

还有两件事情：不要忘记在您的项目清单中添加相机权限，SurfaceTexture是从API 11开始提供的。

- Thiago M Rocha

---

@Rhth，你使用“这是服务”是什么意思？ - Thiago M Rocha

这非常有帮助，谢谢！不过我有一个问题，您如何使整个surfaceTexture在用户看不见的情况下变得不可见，以便完全看不到它？ - PGMacDesign

@Thiago，我正在尝试这样做：这是正确的方法吗？"mTextureView.setVisibility(0);" - PGMacDesign

@Silmarilos 是的。尝试使用自己的Android常量来提高代码可读性。例如："mTextureView.setVisibility(View.GONE);" 或者 "mTextureView.setVisibility(View.VISIBLE);" - Thiago M Rocha

非常好，谢谢。最有效的代码似乎是：mTextureView.setVisibility(View.GONE); - PGMacDesign

Answer 2

public class VideoCapture extends Activity implements OnClickListener, SurfaceHolder.Callback {
MediaRecorder recorder;
SurfaceHolder holder;
boolean recording = false;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
        WindowManager.LayoutParams.FLAG_FULLSCREEN);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

recorder = new MediaRecorder();
initRecorder();

SurfaceView cameraView = new SurfaceView(this);
holder = cameraView.getHolder();
holder.addCallback(this);
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

cameraView.setClickable(true);
cameraView.setOnClickListener(this);
}

private void initRecorder() {
recorder.setAudioSource(MediaRecorder.AudioSource.DEFAULT);
recorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);

CamcorderProfile cpHigh = CamcorderProfile
        .get(CamcorderProfile.QUALITY_HIGH);
recorder.setProfile(cpHigh);
recorder.setOutputFile("/sdcard/videocapture_example.mp4");
recorder.setMaxDuration(50000); // 50 seconds
recorder.setMaxFileSize(5000000); // Approximately 5 megabytes
}

private void prepareRecorder() {
recorder.setPreviewDisplay(holder.getSurface());

try {
    recorder.prepare();
} catch (IllegalStateException e) {
    e.printStackTrace();
    finish();
} catch (IOException e) {
    e.printStackTrace();
    finish();
}
}

public void onClick(View v) {
if (recording) {
    recorder.stop();
    recording = false;

    // Let's initRecorder so we can record again
    initRecorder();
    prepareRecorder();
} else {
    recording = true;
    recorder.start();
}
}

public void surfaceCreated(SurfaceHolder holder) {
prepareRecorder();
}

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

public void surfaceDestroyed(SurfaceHolder holder) {
if (recording) {
    recorder.stop();
    recording = false;
}
recorder.release();
finish();
}
}

- Kamal

---

谢谢您的回答，但这不是我要找的。这个示例已经在API演示中提供了。我想使用SurfaceTexture做同样的事情。 - AndroDev