why this code loop forever after a draw a rectangle

[meInvent bbird]

after succeed to draw lines in graph,

however,

https://drive.google.com/file/d/0Bxs_ao6uuBDUWVBFZzVIVGotRlk/view?usp=sharing

expected the blue line connect the bottom of red line graph

https://drive.google.com/file/d/0Bxs_ao6uuBDUNGZFS2F3WnJERzA/view?usp=sharing

how can convex hull be adjusted to do like second graph of sky blue line


On Saturday, September 17, 2016 at 7:48:46 AM UTC+8, meInvent bbird wrote:
> img is the image
> 
> im is a new memory of image using  img.copy()
> 
> 
> On Saturday, September 17, 2016 at 7:46:42 AM UTC+8, meInvent bbird wrote:
> > thank you very much,
> > it out of the loop now.
> > because drawLine function return things
> > 
> > i just change drawLine to rectangle,
> > have not thought that rectangle not return thing, just edit the parameter
> > 
> > 
> > 
> > On Saturday, September 17, 2016 at 5:26:53 AM UTC+8, MRAB wrote:
> > > On 2016-09-16 20:14, Gary Herron wrote:
> > > > On 09/16/2016 04:24 AM, meInvent bbird wrote:
> > > >> im = img.copy()
> > > >> cntcounter = 0
> > > >> for cnt in contours:
> > > >>          epsilon = 0.1*cv2.arcLength(cnt,True)
> > > >>          approx = cv2.approxPolyDP(cnt,epsilon,True)	
> > > >>          #peri = cv2.arcLength(cnt, True)
> > > >>          #approx = cv2.approxPolyDP(c, 0.5 * peri, True)
> > > >>          #print("len(approx)="+str(len(approx)))
> > > >>          if len(approx) == 4:
> > > >>              print("approx=" + str(approx))
> > > >>              cntcounter = cntcounter + 1
> > > >>              print("here1")
> > > >>              x,y,w,h = cv2.boundingRect(cnt)
> > > >>              print("here2")
> > > >>              while im is None:
> > > >>                  time.sleep(1)
> > > >>              if im is not None:
> > > >>                  print("here3")
> > > >>                  im = cv2.rectangle(im.copy(), (x,y), (x+w, y+h), (0,255,0), 2)
> > > >>                  #im = cv2.line(im,(x,y),(x+w,y),(0,255,0),2)
> > > >>                  #im = cv2.line(im,(x+w,y),(x+w,y+h),(0,255,0),2)
> > > >>                  #im = cv2.line(im,(x,y+h),(x+w,y+h),(0,255,0),2)
> > > >>                  #im = cv2.line(im,(x,y),(x,y+h),(0,255,0),2)
> > > >>
> > > >>
> > > >> cv2.imwrite(r'C:\Users\tester\Documents\masda.png',im)
> > > >
> > > >
> > > > These two lines:
> > > >
> > > >    while im is None:
> > > >      time.sleep(1)
> > > >
> > > > are an infinite loop if im is None;
> > > >
> > > >
> > > > Since you haven't told us what im (or img, contours, cv2) are, I can't
> > > > tell how im might become None, but it does look like you (confusingly)
> > > > use im for two different things:  an img.copy() and a cv2.rectangle,
> > > > whatever those may be.
> > > >
> > > > Pure guesswork:  if cv2.rectangle draws a rectangle, what does it
> > > > return?  If it doesn't return anything, the line
> > > >      im = cv2.rectangle(...)
> > > > is how im gets the value of None.
> > > >
> > > It looks like the OP is using OpenCV.
> > > 
> > > You're right about cv2.rectangle; it does return None.
> > > 
> > > The line:
> > > 
> > >      im = cv2.rectangle(im.copy(), (x,y), (x+w, y+h), (0,255,0), 2)
> > > 
> > > makes a copy of the image im, draws a rectangle on it, and then binds 
> > > None to im.
> > > 
> > > The copied rectangle is discarded because there's no reference to it, so 
> > > the entire line in pointless.
> > > 
> > > It basically does the same thing as:
> > > 
> > >      im = None
> > > 
> > > only slower!