Bitmap export problem with spiro lines

General discussions about Inkscape.
roblob
Posts: 4
Joined: Tue Oct 12, 2010 10:26 pm

Bitmap export problem with spiro lines

Postby roblob » Tue Oct 12, 2010 10:45 pm

Hi,

I just ran into a strange problem that I just can't seem to solve. I have two overlapping spiro paths which together should form a ridged spine on my pic. For some reason part of the ridged spine doesn't get a fill when I export the drawing to a bitmap (via File > Export Bitmap). If I export the parts by themselves the fills are ok, but when the two spiro paths are exported together the problem appears.

The problematic part of the image is attached below and I set varying stroke colors to highlight the parts. Any suggestions on what might be causing this and how to avoid the problem would be greatly appreciated. Thanks.

r.
Attachments
logo_problem.png
a part of the image showing the problem
logo_problem.png (45.06 KiB) Viewed 2144 times

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brynn
Posts: 10309
Joined: Wed Sep 26, 2007 4:34 pm
Location: western USA
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Re: Bitmap export problem with spiro lines

Postby brynn » Tue Oct 12, 2010 11:25 pm

Cool monster!
I can't explain your problem. Maybe it's a bug? But I wanted to suggest that you try grouping the 2 spiros, before exporting. I'm thinking maybe if it appears to the exporter to be one object????

roblob
Posts: 4
Joined: Tue Oct 12, 2010 10:26 pm

Re: Bitmap export problem with spiro lines

Postby roblob » Wed Oct 13, 2010 3:41 pm

Thanks, it's a part of an oriental dragon I'm working on for a site logo.

Anyway, grouping didn't change the behavior. It must be a bug, but I was hoping someone might have a workaround. It'll be a nuisance to manually fix that in gimp every time.

Should I report this bug to the project and how do I go about that if so?

r.

roblob
Posts: 4
Joined: Tue Oct 12, 2010 10:26 pm

Re: Bitmap export problem with spiro lines

Postby roblob » Wed Oct 13, 2010 4:00 pm

Ok, seems I'm quicker than the mods... =)

I found the bug on the launchpad and the workaround is to save the file as .png through the save dialog. The export seems to be the bugging part.

r.

vwanweb
Posts: 169
Joined: Sun Jun 06, 2010 1:48 pm

Re: Bitmap export problem with spiro lines

Postby vwanweb » Thu Oct 14, 2010 11:46 am

have you tried converting the spiro paths (2) to a regular paths (>path >object to path) then.
selecting both objects and either combine (>path >combine) or union (>path >union)?

~suv
Posts: 2272
Joined: Sun May 10, 2009 2:07 am

Re: Bitmap export problem with spiro lines

Postby ~suv » Thu Oct 14, 2010 2:58 pm

vwanweb wrote:have you tried converting the spiro paths (2) to a regular paths (>path >object to path) then.
selecting both objects and either combine (>path >combine) or union (>path >union)?
To avoid the (known) glitches of Inkscape's renderer when exporting to bitmap at certain dpis, I would recommend to test with different methods: a) break apart (and group as needed) the converted path effects and b) combine/union as many paths as possible after converting the path effects to regular paths. AFAIU paths with a huge number of nodes are more prone to be exported partially or with incorrect fills than grouped paths with fewer nodes.

A better workaround than saving as 'Cairo PNG' is to vary the dpi value in the 'Export bitmap…' dialog slightly, or - for partially rendered (small) curved paths with incorrect fills - to insert an additional node into the path before exporting to bitmap.

Some related reports:
Bug #189214 in Inkscape: “curve is exported badly (but displayed correctly)
Bug #381022 in Inkscape: “view rendering glitch for complex paths
Bug #428415 in Inkscape: “Portions of path not drawn on screen or exported

These issues will (hopefully) be fixed when Inkscape switches to cairo as internal renderer (for the canvas, and bitmap export), as planned for 0.49.

roblob
Posts: 4
Joined: Tue Oct 12, 2010 10:26 pm

Re: Bitmap export problem with spiro lines

Postby roblob » Thu Oct 14, 2010 8:18 pm

Hi,

Thanks for the tips. It seems the object -> path + union for the two spiro paths solved the problem and I can now export the whole image smoothly.


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