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# Points contained within a path

 P: n/a In my app the user can draw an arbitrary path onto an image. Now I need to determine all of the pixels that are contained within that path. Note that the path can intersect itself and I can always assume that the path is closed. Are there any articles, algorithms, tools, etc. that can assist with determining which pixels are contained within the path? Thanks, Lance Nov 21 '05 #1
6 Replies

 P: n/a LjLevend, Not that you should go there however there is maybe an interesting newsgroup for your question. microsof.public.dotnet.framework.drawing Maybe you find your answer there from more persons than here? Cor "ljlevend" In my app the user can draw an arbitrary path onto an image. Now I need to determine all of the pixels that are contained within that path. Note that the path can intersect itself and I can always assume that the path is closed. Are there any articles, algorithms, tools, etc. that can assist with determining which pixels are contained within the path? Thanks, Lance Nov 21 '05 #2

 P: n/a "ljlevend" wrote in message news:FC**********************************@microsof t.com... In my app the user can draw an arbitrary path onto an image. Now I need to determine all of the pixels that are contained within that path. Note that the path can intersect itself and I can always assume that the path is closed. Are there any articles, algorithms, tools, etc. that can assist with determining which pixels are contained within the path? Your closed path is a polygon. Filliing a polygon on the screen is an old and throughly solved problem. Here's some keywords to get you started on Google. polygon fill algorithm Scanline Fill Algorithm Boundary fill Algorithm Flood fill Algorithm David Nov 21 '05 #3

 P: n/a Hi, Take look at the graphicspath isvisible, pathdata, and pathpoints. http://msdn.microsoft.com/library/de...sibletopic.asp http://msdn.microsoft.com/library/de...hdatatopic.asp http://msdn.microsoft.com/library/de...ointstopic.asp Ken ------------------- "ljlevend" wrote in message news:FC**********************************@microsof t.com... In my app the user can draw an arbitrary path onto an image. Now I need to determine all of the pixels that are contained within that path. Note that the path can intersect itself and I can always assume that the path is closed. Are there any articles, algorithms, tools, etc. that can assist with determining which pixels are contained within the path? Thanks, Lance Nov 21 '05 #4

 P: n/a Thanks a lot for the topic ideas. I need to determine the points contained in the polygon in real-time (as the user moves the polygon with the mouse) so speed is a primary concern. The scanline algorithm sounds like the fastest, but I couldn't find any samples in VB or C#. Do you know of any? Thanks again, Lance Nov 21 '05 #5

 P: n/a Thanks. Nov 21 '05 #6

 P: n/a "ljlevend" wrote in message news:D1**********************************@microsof t.com... Thanks a lot for the topic ideas. I need to determine the points contained in the polygon in real-time (as the user moves the polygon with the mouse) so speed is a primary concern. The scanline algorithm sounds like the fastest, but I couldn't find any samples in VB or C#. Do you know of any? If speed is of the utmost importance you might not want to use a canned implementation anyway. Just hook the mouse move event and trace one scanline: from the mouse's current position to the edge. David Nov 21 '05 #7

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