path segments are lost

[Frederik Elwert]

When cleaning up path data, the last segment is lost in special cases. This bug is introduced in scour 0.14, so I guess it’s related to the attempt to remove the last segment whith closed paths. But in some cases, the path isn’t closed after the cleanup.

I noticed this behaviour with a cairo generated file. Cairo creates a bit odd paths with a M command after the path is closed by Z. Maybe this causes the problem.

Original path:
M 601.441406 216 L 649.480469 216 L 649.480469 273.601562 L 601.441406 273.601562 Z M 601.441406 216

Cleaned path with lost segment:
M601.44,216h48.04v57.60h-48.04m0-57.60

[codedread (codedread)]

Hi Frederik,

I appreciate this bug - can you possibly send me a file where the path generated by scour actually causes a visual problem?

The example you have given shows the converted path as being identical except for missing the closepath ('Z') segment. Scour 0.14 was simply dropping the Z segment (closepath) and this didn't cause a problem in Firefox, Opera or Safari.

I have worked out a modified version of scour that no longer drops the closepath commands. I have checked this in as revision 105. Can you please test it?

Thanks,
Jeff

[codedread (codedread)]

Potential fix checked in as revision 105

[Frederik Elwert (frederik-elwert)]

> I appreciate this bug - can you possibly send me a file where the path generated by scour actually causes a visual problem?

I have attached an SVG file generated by R using cairo as its backend. When running scour 0.14 on it, rectangles (like the border around the legend) loose one edge.

> The example you have given shows the converted path as being identical except for missing the closepath ('Z') segment. Scour 0.14 was simply dropping the Z segment (closepath) and this didn't cause a problem in Firefox, Opera or Safari.

Ok, than I misunderstood what scour was trying to do. In many SVG files (e.g., generated by Inkscape) the Z segment can be omitted, since its redundant: The last segment of closed paths usually ends at the starting point. But in the example file, the Z segment is used in a propper and efficient way: Only three segments of a rectangle are drawn, and the Z segment closes the rectangle.

If one wanted to make use of the Z command in scour, one could rather drop the last segment if it ends where the first one starts, and keep the Z segment. But I don’t know how hard this would be to implement.

> I have worked out a modified version of scour that no longer drops the closepath commands. I have checked this in as revision 105. Can you please test it?

Yes, that revision fixes the problem for the attached file. Thanks a lot!

Cheers,
Frederik

[codedread (codedread)]

Fix checked in with revision 105

[codedread (codedread)]

Actually this was my fault. Removing Z segments have no effect on the fill but they DO have an effect on the stroke. I have added a unit test for this and release Scour 0.15 with this change.

Thanks a lot Frederick!

By the way, what is 'R' that you mention above?

[codedread (codedread)]

Ok, found it! http://www.r-project.org/

Talk about a hard thing to find using Google! :)