MVG Draw/Path and Larger strokewidths produces extra lines.

[richerm]

I had posted an issue over in Users with regards to polyline but based on my reading this seems to have been an issue for quite some time with no resolution in sight. Having said that there is an issue with draw and path (SVG) with higher stroke widths.

This draws properly.

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convert.exe -size 300x300 xc:#CCCCCC -stroke red -fill none -strokewidth 1 -draw "path 'M 252,168 L 254,156 254,148 254,138'" "D:\Output.png"

This draws the same thing but introduces a long trailing line.

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convert.exe -size 300x300 xc:#CCCCCC -stroke red -fill none -strokewidth 3 -draw "path 'M 252,168 L 254,156 254,148 254,138'" "D:\Output.png"

Note this seems to happen for any strokewidth bigger then 3. Any suggestions on the issue, fix or possible workarounds?

[richerm]

here is an even more trivial example:

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convert.exe -size 100x100 xc:#CCCCCC -stroke red -fill none -strokewidth 3 -draw "path 'M 20,56 L 20,48 20,38'" "Output.png"

I must be doing something fundamentally wrong(?)

[snibgo]

Seems like a bug to me. These two commands with v6.9.0-0 give different results, both wrong:

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convert.exe -size 100x100 xc:#CCCCCC -stroke red -fill none -strokewidth 3 -draw "path 'M20,56 L20,48 20,38'" "p1.png"

convert.exe -size 100x100 xc:#CCCCCC -stroke red -fill none -strokewidth 3 -draw "path 'M20,56 L20,48, 20,38'" "p2.png"

The second command contains an extra comma.

[richerm]

So does this mean it is acknowledged as a bug by the developers, or just that you, as a moderator agree? Is there a typical timeline for when the devs reply with anything? Just not sure of the process.

Thanks.

Matt

[snibgo]

I'm not a developer. I just remove spam, make the coffee, and so on.

It looks like a bug, and not just a single bug, but the code is too complex for me to easily figure out what it should do, let alone what it actually does.

I expect the developers have seen this thread. They may have put it on the "Eek! Difficult!" pile.

[richerm]

I was afraid of that (the difficulty) based on some reading with strokewidths here and their 'weird' behavior.
http://www.imagemagick.org/Usage/draw/#strokewidth

I originally tried to draw with regular polyline but met with similar results. Are you aware of any workaround I can do to draw random path (i.e. user was drawing with a pen type tool on the screen) with specified line width? Interestingly enough it get fixes when strokewidth < 3. I have a feeling this is no as well but just checking.

Thanks.

[snibgo]

You might draw each segment seperately, eg (Windows BAT syntax):

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%IM%convert.exe ^
  -size 100x100 xc:#CCCCCC -stroke red -fill none -strokewidth 3 ^
  -draw "path 'M20,56 L20,48, M20,48 L20,38'" ^
  "p3.png"

%IM%convert.exe ^
  -size 100x100 xc:#CCCCCC -stroke red -fill none -strokewidth 3 ^
  -draw "path 'M20,56 L20,48'" ^
  -draw "path 'M20,48 L20,38'" ^
  "p4.png"

%IM%convert.exe ^
  -size 100x100 xc:#CCCCCC -stroke red -fill none -strokewidth 3 ^
  -draw "line 20,56,20,48" ^
  -draw "line 20,48,20,38" ^
  "p5.png"

I mostly use the method as in p5.png, and have never noticed any problems with it.

EDIT: My p5.png version had superfluous single-quotes.

[richerm]

Thanks! That'll do in the short-term, even if it is quite verbose .

[snibgo]

I forgot to mention another possibility, slightly less verbose:

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%IM%convert.exe ^
  -size 100x100 xc:#CCCCCC -stroke red -fill none -strokewidth 3 ^
  -draw "line 20,56,20,48 line 20,48,20,38" ^
  "p6.png"

The draw commands can be put in a file:
pline.txt:

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line 20,56,20,48 line 20,48,20,38

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%IM%convert.exe ^
  -size 100x100 xc:#CCCCCC -stroke red -fill none -strokewidth 3 ^
  -draw "@pline.txt" ^
  "p7.png"