guiOpencv.py

import cv2
import numpy as np


class GUI(object):

	def __init__(self, res, rectCallback, windowName='vid'):
		w, h = res
		self.windowName = windowName
		cv2.imshow(windowName, np.zeros((h, w)))
		self.rs = RectSelector(windowName, rectCallback)

	def display(self, frame):
		if self.rs.dragging:
			self.rs.draw(frame)
		cv2.imshow(self.windowName, frame)
		self.key = chr(cv2.waitKey(1) & 0xFF)

	def close(self):
		cv2.destroyAllWindows()


class RectSelector:

	def __init__(self, win, callback):
		self.win = win
		self.callback = callback
		cv2.setMouseCallback(win, self.onmouse)
		self.drag_start = None
		self.drag_rect = None

	def onmouse(self, event, x, y, flags, param):
		x, y = np.int16([x, y]) # BUG
		if event == cv2.EVENT_LBUTTONDOWN:
			self.drag_start = (x, y)
			return
		if self.drag_start:
			if flags & cv2.EVENT_FLAG_LBUTTON:
				xo, yo = self.drag_start
				x0, y0 = np.minimum([xo, yo], [x, y])
				x1, y1 = np.maximum([xo, yo], [x, y])
				self.drag_rect = None
				if (x1 - x0) > 0 and (y1 - y0) > 0:
					self.drag_rect = (x0, y0, x1, y1)
			else:
				rect = self.drag_rect
				self.drag_start = None
				self.drag_rect = None
				if rect:
					self.callback(rect)

	def draw(self, vis):
		if not self.drag_rect:
			return False
		x0, y0, x1, y1 = self.drag_rect
		cv2.rectangle(vis, (x0, y0), (x1, y1), (0, 255, 0), 2)
		return True

	@property
	def dragging(self):
		return self.drag_rect is not None