private void adjustLeftByAspectRatio(RectF rect, float aspectRatio) {
    rect.left = rect.right - rect.height() * aspectRatio;
  }
Adjust left edge by current crop window height and the given aspect ratio, the right edge
remains in possition while the left adjusts to keep aspect ratio to the height.
core/src/main/java/com/theartofdev/edmodo/cropper/CropWindowMoveHandler.java