Rotate camera preview to Portrait Android OpenCV Camera

Question

I am trying to use OpenCV 2.4.3.2 to create a camera app and do some opencv processing. I would like it to be able to have multiple UI orientations, not just Landscape.

The problem is that when I change the orientation to portrait, the image comes out sideways.

I understand that I could just rotate the input image before doing image processing (and thus leave the orientation as landscape only), which is fine and works, but doesn't solve the problem that the rest of my UI will be in the wrong orientation.

I have also tried using this code to rotate the camera 90deg, but it just doesn't seem to work.

mCamera.setDisplayOrientation(90);

It either has no effect, or sometimes just causes the preview to be blacked out

Has anyone done this successfully with OpenCV? My class extends from JavaCameraView.

Edit

I have made an improvement, which is that I have rotated the image inside of OpenCV as it is displayed in the CameraBridgeViewBase.java class.

In the deliver and draw frame method:

if (canvas != null) {
            canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);
            //canvas.drawBitmap(mCacheBitmap, (canvas.getWidth() - mCacheBitmap.getWidth()) / 2, (canvas.getHeight() - mCacheBitmap.getHeight()) / 2, null);
            //Change to support portrait view
            Matrix matrix = new Matrix();
            matrix.preTranslate((canvas.getWidth() - mCacheBitmap.getWidth()) / 2,(canvas.getHeight() - mCacheBitmap.getHeight()) / 2);

            if(getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT)
                matrix.postRotate(90f,(canvas.getWidth()) / 2,(canvas.getHeight()) / 2);
            canvas.drawBitmap(mCacheBitmap, matrix, new Paint());

... Basically, this just roatates the input image like so

This is better, but I obviously want this to be full screen.

question from:https://stackoverflow.com/questions/14816166/rotate-camera-preview-to-portrait-android-opencv-camera

Answer 1

I had the same problem trying to implement OpenCV. I was able to fix it by making the following changes to the deliverAndDrawFrame method.

1. Rotate the canvas object

   Canvas canvas = getHolder().lockCanvas();
   // Rotate canvas to 90 degrees
   canvas.rotate(90f, canvas.getWidth()/2, canvas.getHeight()/2);
   

2. Resize the bitmap to fit entire size of canvas before drawing

   // Resize
   Bitmap bitmap = Bitmap.createScaledBitmap(mCacheBitmap, canvas.getHeight(), canvas.getWidth(), true);
   // Use bitmap instead of mCacheBitmap
   canvas.drawBitmap(bitmap, new Rect(0,0,bitmap.getWidth(), bitmap.getHeight()), new Rect(
       (int)((canvas.getWidth() - mScale*bitmap.getWidth()) / 2),
       (int)((canvas.getHeight() - mScale*bitmap.getHeight()) / 2),
       (int)((canvas.getWidth() - mScale*bitmap.getWidth()) / 2 + mScale*bitmap.getWidth()),
       (int）((canvas.getHeight() - mScale*bitmap.getHeight()) / 2 + mScale*bitmap.getHeight()
     )), null);
   
   // Unlock canvas
   getHolder().unlockCanvasAndPost(canvas);