System.StackOverflowException

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Dark Kai

Freshman
Joined
Sep 3, 2003
Messages
48
I've written a program to fill up a polygon(like in MSPaint). It worked fine in a small area but if i enlarge the area to fill then this error pops out during run time.
An unhandled exception of type 'System.StackOverflowException' occurred in mscorlib.dll
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Why can't my recursive function run ??

here is part of my program

Code: 
public function fill (byval x as integer,byval y as integer,byval colour as integer, byref imagearray(,) as integer)


      if imagearray(x,y)=colour then

            exit function

      else

            imagearray(x,y)=colour
            fill(x-1,y,colour,imagearray)
            fill(x+1,y,colour,imagearray)
            fill(x,y-1,colour,imagearray)
            fill(x,y+1,colour,imagearray)

      end if

end function
 
You are recursing too many times and therefore running out of space on the stack. A recursive function is not suitable to solve a problem like this because of the potential number of pixels involved. You could rewrite using a queue, or use the FloodFill API though.
 
uhh...Can I expend or increase the stack size ?? I don't understand what you meant by using a queue...Floodfill API might work but my imagebuffer is a User Defined Type (a structure of pixels). Thanks in advance.
 
No, you can't increase the stack size. At least, not for something like this - recursion just isn't appropriate.

You could investigate other means of maintaining context, using an array or collection-based class. Is there some reason you're using your own type for image data?
 
hmmmm....I'm using my own data type couze there are other info that i would like to bound with the image(I'm actually building a class). the reason i need this fill algorithm to work is couze i would like to select a region of interest in my image(ROI). meaning i will get this binary region(a frame with a filled polygon) and then further i will be able to process my image according to this binary region.

Attach with this is a illustration of the problem.
 
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