Question

I am developing an Android application that relies on the camera API, using an HTC EVO as my testing device. No matter what I’ve tried so far, the only time the camera preview looks right is in landscape mode (90 degrees rotation, to be specific). It seems as though there is no way to orient the preview correctly when in portrait mode (0 degrees rotation).

The default camera application on the device (for HTC Sense) allows for any kind of rotation without any problem, so I know that there is no hardware limitation. I even downloaded some source code from HTC’s developer site, but it’s all in C – kernel stuff, apparently.

Can anyone point me in the right direction for solving this problem? Is there a way to rotate the preview correctly in Android 2.1 or 2.2?

Thank you.

P.S. Here is the code I’m using, in case it helps…

package spikes.cameraSpike03;

import java.util.List;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;

public class MainActivity extends Activity implements SurfaceHolder.Callback {
 private static final String LOG_TAG = "spikes.cameraSpike03 - MainActivity";

 private Camera _camera;
 private boolean _previewIsRunning = false;

 private SurfaceView _svCameraView;
 private SurfaceHolder _surfaceHolder;

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

        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.main);

        _svCameraView = (SurfaceView)findViewById(R.id.svCameraView);

        _surfaceHolder = _svCameraView.getHolder();
        _surfaceHolder.addCallback(this);
        _surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
  if(_previewIsRunning){
   _camera.stopPreview();
  }

  try{
   Camera.Parameters parameters = _camera.getParameters();

   //Get the optimal preview size so we don't get an exception when setting the parameters 
   List<Size> supportedPreviewSizes = parameters.getSupportedPreviewSizes();
   Size optimalPreviewSize = getOptimalPreviewSize(supportedPreviewSizes, width, height);
   parameters.setPreviewSize(optimalPreviewSize.width, optimalPreviewSize.height);

   _camera.setParameters(parameters);

   _camera.setPreviewDisplay(holder);
  }
  catch(Exception ex){
   ex.printStackTrace();
   Log.e(LOG_TAG, ex.toString());
  }

  _camera.startPreview();
  _previewIsRunning = true;
 }

 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  _camera = Camera.open();
 }

 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  _camera.stopPreview();
  _previewIsRunning = false;
  _camera.release();
 }

 private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.05;
        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;
    }

}

Answer 1

Try locking the orientation of the Activity in horizontal if that fits with your design, or have a play with these:

private android.hardware.Camera mCamera;

…

mCamera.setDisplayOrientation(90);
params.setRotation(90);
mCamera.setParameters(params);

But I think setDisplayOrientation might be 2.2 only…