相机预览显示在android中受到挤压

Question

My intent is to have a square Camera Preview.

I do not have a 1:1 ratio Camera preview available (I am in an Nexus 5 emulator), so my optimal size available is 640 x 480, so to accommodate a square preview I am setting the SurfaceView size to be equal to the aspect ratio but offsetting the margin offscreen by half the difference to leave only the cropped square on screen. The surface view itself is correctly sized and offset, but the camera preview itself is still displaying the squeezed preview within the square instead of displaying partially offscreen in the correct aspect ratio.

Any thoughts? Or better yet, call me stupid and point me in the direction of a better solution.

Code to set the size of the SurfaceView

Camera.Parameters parameters = camera.getParameters();
List<Size> sizes = parameters.getSupportedPreviewSizes();
Size optimalSize = getOptimalPreviewSize(sizes, imageHolder.getMeasuredWidth(), imageHolder.getMeasuredHeight());

parameters.setPreviewSize(optimalSize.width, optimalSize.height);

int screenWidth = imageHolder.getMeasuredWidth();
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(surfaceView.getMeasuredWidth(), surfaceView.getMeasuredHeight());

int ratio = screenWidth / optimalSize.height;

params.width = optimalSize.width * ratio;
int offset = params.width - screenWidth;
if(offset > 0) {
   offset = offset/2;
}

params.setMargins(-offset,0,0,0);
surfaceView.setLayoutParams(params);
camera.setParameters(parameters);

camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();

This is how the preview looks currently

This is how the photo looks in the same sized square after its captured

Answer 1

I think the easiest solution is just to mask out those parts of the camera preview which you don't want to see. Just put a view on top. Other way would be to do some realtime image processing, which will require you to deal with the NDK.