why this code loop forever after a draw a rectangle
meInvent bbird
jobmattcon at gmail.com
Fri Sep 16 19:48:09 EDT 2016
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!
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