Overlay Live video with paintbrush style drawings? - opencv

Question

I need some direction on whats the best programming approach to overlay a live video from a webcam (or a pre loaded video), with paintbrush. i.e, drawing lines , circles and such, to mark areas in the video while its playing.
right now using OpenCV + Tkinter, is there a better way to approach this?
Thanks
EDIT: trying to paint directly on the video window, but cant get it to work.. here is my code:
import cv2
import numpy as np
def interactive_drawing(event,x,y,flags,param):
global ix,iy,drawing, mode
if event==cv2.EVENT_LBUTTONDOWN:
drawing=True
ix,iy=x,y
elif event==cv2.EVENT_MOUSEMOVE:
if drawing==True:
if mode==True:
cv2.line(frame,(ix,iy),(x,y),(0,0,255),10)
ix=x
iy=y
print x,y
elif event==cv2.EVENT_LBUTTONUP:
drawing=False
if mode==True:
cv2.line(frame,(ix,iy),(x,y),(0,0,255),10)
ix=x
iy=y
return x,y
drawing=False # true if mouse is pressed
mode=True # if True, draw rectangle. Press 'm' to toggle to curve
cap = cv2.VideoCapture('track.avi')
while(cap.isOpened()):
ret, frame = cap.read()
if frame is None:
break
# cv2.namedWindow("frame", cv2.WND_PROP_FULLSCREEN)
# cv2.setWindowProperty("frame",cv2.WND_PROP_FULLSCREEN,cv2.WINDOW_FULLSCREEN)
cv2.setMouseCallback('frame',interactive_drawing)
cv2.imshow('frame',frame)
if cv2.waitKey(15) & 0xFF == ord('q'):
break
cap.release()
cv2.destroyAllWindows()
# mouse callback function
##img = np.zeros((512,512,3), np.uint8)
##
##cv2.namedWindow('begueradj')
##cv2.setMouseCallback('begueradj',interactive_drawing)
##while(1):
## cv2.imshow('begueradje',img)
## k=cv2.waitKey(1)&0xFF
## if k==27:
## break
##cv2.destroyAllWindows()

Answer 1

I would only use OpenCV for that purpose, as it already provides drawing functions such as :
Lines
Rectangles
Circles
Ellipses
Polygons
etc.
EDIT: This code snippet should help you get started. The important point here is that you have to save the drawing elements in a variable (curve_points in my case) and draw them on each new frames:
import cv2
import numpy as np
def interactive_drawing(event,x,y,flags,param):
global drawing, mode
if event==cv2.EVENT_LBUTTONDOWN:
drawing=True
elif event==cv2.EVENT_MOUSEMOVE:
if drawing==True:
if mode==True:
curves[len(curves)-1].append((x,y)) #append new points to the last list of curves
elif event==cv2.EVENT_LBUTTONUP:
drawing=False
if mode==True:
curves.append([]) #adding a new list to curves
return x,y
def draw_curves(myArray):
for j in range(0, len(myArray)):
for i in range(1, len(myArray[j])):
cv2.line(frame,myArray[j][i-1],myArray[j][i],(0,0,255),10)
drawing=False # true if mouse is pressed
mode=True # if True, draw rectangle. Press 'm' to toggle to curve
cap = cv2.VideoCapture(0) #cap = cv2.VideoCapture('track.avi')
curves = [[]] # initializing curves list with an empty list
cv2.namedWindow('frame')
cv2.setMouseCallback('frame',interactive_drawing)
while(cap.isOpened()):
ret, frame = cap.read()
if frame is None:
break
draw_curves(curves)
cv2.imshow('frame',frame)
if cv2.waitKey(15) & 0xFF == ord('q'):
break
cap.release()
cv2.destroyAllWindows()