android - 如何显示我的相机预览

Question

我写了一个相机预览类

public class CameraView extends SurfaceView implements SurfaceHolder.Callback{
    private Camera camera;

    public CameraView(Context context) {
        super(context);
        getHolder().addCallback(this);
        getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }


    public static void setCameraDisplayOrientation(Activity activity, int cameraId, Camera camera){
        Camera.CameraInfo info = new Camera.CameraInfo();
        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;
        }else{
            result = (info.orientation - degrees + 360) % 360;
        }

        camera.setDisplayOrientation(result);

    }

    @Override
    public void surfaceCreated(SurfaceHolder surfaceHolder) {
        camera = Camera.open();
    }

    @Override
    public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {
        setCameraDisplayOrientation((Activity)getContext(), Camera.CameraInfo.CAMERA_FACING_BACK, camera);
        Camera.Parameters parameters = camera.getParameters();
        Camera.Size bestSize = null;
        for (Camera.Size size : parameters.getSupportedPictureSizes()){
            if (size.width <= i1 && size.height <=i2) {
                if (bestSize == null) {
                    bestSize = size;
                } else {
                    int bestArea = bestSize.width * bestSize.height;
                    int newArea = size.width * size.height;

                    if (newArea > bestArea){
                        bestSize = size;
                    }
                }
            }
        }

        parameters.setPictureSize(bestSize.width, bestSize.height);
        parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
        camera.setParameters(parameters);

        try{
            camera.setPreviewDisplay(surfaceHolder);
        }catch (IOException e){
            e.printStackTrace();
        }

        camera.startPreview();


    }

    @Override
    public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
        camera.stopPreview();
        camera.release();
        camera = null;
    }


}

然后我写了一个布局文件，我想在“SurfaceView”中显示预览

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <SurfaceView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/camera_view" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:layout_alignParentBottom="true"
        android:weightSum="1">

        <Button
            android:id="@+id/stop_navigation"
            android:layout_weight="0.5"
            android:layout_height="32dp"
            android:layout_width="0dp"
            android:text="@string/stop_navigation"
            android:textColor="@color/colorWhite"
            android:textSize="12sp"
            android:background="@color/colorAccent" />
    </LinearLayout>

</RelativeLayout>

那么在main activity中应该怎么做呢？在我刚刚执行以下代码之前，一切都很好。

CameraView cameraView = new CameraView(this);
addContentView(cameraView, new ActionBar.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.WRAP_CONTENT));

但现在我需要将预览放入我设计的布局中。

Answer 1

Use FrameLayout and add CameraPreview to it.



// Create an instance of Camera
        mCamera = getCameraInstance();

        // Create our Preview view and set it as the content of our activity.
        mPreview = new CameraPreview(this, mCamera);
        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
        preview.addView(mPreview);


/** A basic Camera preview class */
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) {
            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.

        if (mHolder.getSurface() == null){
          // preview surface does not exist
          return;
        }

        // stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e){
          // ignore: tried to stop a non-existent preview
        }

        // 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){
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }
}


    <FrameLayout
        android:id="@+id/camera_preview"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_weight="1"
        />