protected void refreshSizes() {
        if (cameraPreview == null) {
            return;
        }
        Rect framingRect = cameraPreview.getFramingRect();
        Size previewSize = cameraPreview.getPreviewSize();
        if (framingRect != null && previewSize != null) {
            this.framingRect = framingRect;
            this.previewSize = previewSize;
        }
    }
This view is overlaid on top of the camera preview. It adds the viewfinder rectangle and partial
transparency outside it, as well as the laser scanner animation and result points.

@author dswitkin@google.com (Daniel Switkin)
zxing-android-embedded/src/com/journeyapps/barcodescanner/ViewfinderView.java