Android 相机预览看起来很奇怪 [英] Android camera preview look strange

问题描述

我正在实施一个相机应用程序，当我查看预览(尤其是使用前置摄像头)时，图像非常胖.看起来图像被水平拉伸.我使用优化的相机尺寸遵循 sdk 示例，但它没有帮助.如何调整我的相机设置，使其像其他相机应用程序一样预览?

I am implementing a camera app and when I look at the preview (especially with front camera), the image is very fat. It looks like the image get stretched horizontally. I follow the sdk sample with the optimzed camera size but it doesn't help. How can I adjust my camera setting so that it will preview like the other camera app?

谢谢.

我的代码如下.

public class CameraActivity extends Activity implements SurfaceHolder.Callback, Camera.ShutterCallback, Camera.PictureCallback {

Camera m_camera;
SurfaceView m_surfaceView;
int m_numOfCamera;
int m_defaultCameraId;
int m_currentCamera;
int m_surfaceWidth;
int m_surfaceHeight;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_camera);
    getActionBar().setDisplayHomeAsUpEnabled(true);


    m_surfaceView = (SurfaceView)findViewById(R.id.cameraPreview);
    m_surfaceView.getHolder().addCallback(this);

    m_camera = Camera.open();

    m_numOfCamera = Camera.getNumberOfCameras();

    CameraInfo cameraInfo = new CameraInfo();
    for (int i = 0; i < m_numOfCamera; ++i) {
        Camera.getCameraInfo(i, cameraInfo);
        if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) {
            m_defaultCameraId = i;
            m_currentCamera = m_defaultCameraId;
        }       
    }

    if (m_numOfCamera < 1) {
        MenuItem switchCam = (MenuItem)findViewById(R.id.menu_switch_camera);
        switchCam.setVisible(false);
    }
}

@Override
public void onPause() {
    super.onPause();
    m_camera.stopPreview();
}

@Override
public void onDestroy() {
    super.onDestroy();
    m_camera.release();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_camera, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(final MenuItem item) 
{
    if (item.getItemId() == android.R.id.home) 
    {
        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(intent);

        return true;
    } 
    else if (item.getItemId() == R.id.menu_switch_camera)
    {
        if (m_camera != null) {
            m_camera.stopPreview();
            m_camera.release();
            m_camera = null;
        }   

        m_camera = Camera.open((m_currentCamera + 1) % m_numOfCamera);
        m_currentCamera = (m_currentCamera + 1) % m_numOfCamera;

        Camera.Parameters params = m_camera.getParameters();
        List<Camera.Size> sizes = params.getSupportedPreviewSizes();
        Camera.Size size = getOptimalPreviewSize(sizes, m_surfaceWidth, m_surfaceHeight);

        params.setPreviewSize(size.width,  size.height);

        m_camera.setParameters(params);
        setCameraDisplayOrientation(this, m_currentCamera, m_camera);
        m_camera.startPreview();
        try {
            m_camera.setPreviewDisplay(m_surfaceView.getHolder());
        } catch (Exception e) {
            e.printStackTrace();
        }   
        return true;
    }
    return true;
}

public void onPictureTaken(byte[] arg0, Camera arg1) {
    // TODO Auto-generated method stub

}

public void onShutter() {
    // TODO Auto-generated method stub

}

public void surfaceChanged(SurfaceHolder arg0, int format, int w, int h) {
    m_surfaceWidth = w;
    m_surfaceHeight = h;
    Camera.Parameters params = m_camera.getParameters();
    List<Camera.Size> sizes = params.getSupportedPreviewSizes();
    Camera.Size selected = getOptimalPreviewSize(sizes, w, h);

    params.setPreviewSize(selected.width,  selected.height);


    m_camera.setParameters(params);
    setCameraDisplayOrientation(this, m_currentCamera, m_camera);
    m_camera.startPreview();    
}

private static void setCameraDisplayOrientation(Activity activity,
         int cameraId, android.hardware.Camera camera) {
     android.hardware.Camera.CameraInfo info =
             new android.hardware.Camera.CameraInfo();
     android.hardware.Camera.getCameraInfo(cameraId, info);
     int rotation = activity.getWindowManager().getDefaultDisplay()
             .getRotation();
     int degrees = 0;
     switch (rotation) {
         case Surface.ROTATION_0: degrees = 0; break;
         case Surface.ROTATION_90: degrees = 90; break;
         case Surface.ROTATION_180: degrees = 180; break;
         case Surface.ROTATION_270: degrees = 270; break;
     }

     int result;
     if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
         result = (info.orientation + degrees) % 360;
         result = (360 - result) % 360;  // compensate the mirror
     } else {  // back-facing
         result = (info.orientation - degrees + 360) % 360;
     }
     camera.setDisplayOrientation(result);
 }


public void surfaceCreated(SurfaceHolder arg0) {
    try {
        m_camera.setPreviewDisplay(m_surfaceView.getHolder());
    } catch (Exception e) {
        e.printStackTrace();
    }   
}

public void surfaceDestroyed(SurfaceHolder arg0) {
    // TODO Auto-generated method stub

}

private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {


    final double ASPECT_TOLERANCE = 0.1;
    double targetRatio = (double) w / h;
    if (sizes == null)
        return null;

    Size optimalSize = null;
    double minDiff = Double.MAX_VALUE;

    int targetHeight = h;

    // Try to find an size match aspect ratio and size
    for (Size size : sizes) {
        double ratio = (double) size.width / size.height;
        if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
            continue;
        if (Math.abs(size.height - targetHeight) < minDiff) {
            optimalSize = size;
            minDiff = Math.abs(size.height - targetHeight);
        }
    }

    // Cannot find the one match the aspect ratio, ignore the requirement
    if (optimalSize == null) {
        minDiff = Double.MAX_VALUE;
        for (Size size : sizes) {
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }
    }

    return optimalSize;
}

}

推荐答案

相机预览总是填满显示它的 SurfaceView.如果 m_surfaceView 的纵横比与相机的纵横比不匹配，预览将被拉伸.

The camera preview always fills up the SurfaceView showing it. If the aspect ratio of m_surfaceView doesn't match with the camera's aspect ratio, the preview will be stretched.

您需要创建与纵横比匹配的 m_surfaceView.这意味着，您需要从代码中创建它，而不是从布局 XML 文件中创建.

You'll need to create m_surfaceView matching the aspect ratio. That means, you'll need to create it from code, not from layout XML file.

您可以在 android 示例项目中找到一个示例项目 APIDemos.在项目中有一个名为CameraPreview 的东西.这个有一个很好的演示，用于在 SurfaceView 中设置相机预览.它有一个 extends ViewGroup 的类，并从代码中添加 SurfaceView 作为其子项.onMeasure() 方法已被覆盖以确定 SurfaceView 的高度和宽度，因此保留纵横比.看一下项目，我希望它会清楚.

There is a sample project APIDemos that you'll find in android sample projects. In the project there is a thing named CameraPreview. This one has a good demonstration for setting up camera preview in a SurfaceView. It has a class that extends ViewGroup, and adds the SurfaceView as its child from the code. The onMeasure() method has been overridden to determine the height and width of the SurfaceView, so the aspect ratio is preserved. Take a look on the project, and I hope it will be clear.

[抱歉，我无法在此处发布链接 - this 应该是链接，但我发现它坏了.但是如果您已经安装了带有Android SDK 的示例项目，您可以在示例中找到该项目.打开一个新的 Android 示例项目，选择 APIDemos，然后查找名为 CameraPreview 的类.据我所知，它应该在 com.example.android.apis.graphics 包中.]

[Sorry I couldn't post the link here - this is supposed to be the link, but I found it broken. But if you have installed the sample projects with the Android SDK, you can find the project in the samples. Open a new Android Sample Project, select APIDemos, then look for a class named CameraPreview. It should be in the package com.example.android.apis.graphics, as far as I remember.]

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