May 2013 - Inkscape Devel - Inkscape Mailman

GSoC 2013: Implement a new raster-to-vector algorithm...
by Vinícius dos Santos Oliveira 02 Jul '13

02 Jul '13

I'll be coding for this project very soon and I created a repository for it at https://github.com/vinipsmaker/kopf2011 . When we decide where is the best place to keep the project during the WIP phase, I'll move it. I'll be using the namespace *Kopf2011* for this library. If you don't like the namespace, let me know and I can change that. I'll publish updates of the project at my personal blog at http://vinipsmaker.wordpress.com/category/computacao/gsoc2013-inkscape/ . Let me know if you need anything else. -- Vinícius dos Santos Oliveira https://about.me/vinipsmaker

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Tentative patch for downscaling in Cairo
by Krzysztof Kosiński 30 Jun '13

30 Jun '13

Hello I had a look at how complex would it be to add correct downscaling to Cairo now that Pixman supports convolution filters. It turns out it this is rather easy. Here is an initial, minimal attempt. It uses convolution filters only if the image is being downscaled by more than half a pixel in at least one dimension. Some discussion: 1. The sampling and reconstruction kernels are picked in a way that gives comparable quality when upscaling and downscaling. I paired box sampling with bilinear reconstruction and impulse (point) sampling with box reconstruction. This gives the expected result for NEAREST filter. BEST filter uses Lanczos3 for both kernels. 2. Subsampling bits are always set to 1, since this doesn't seem to affect quality at all. 3. I am not sure whether this code works correctly for matrices with a skew component. It should be OK for any combination of scale, rotation and translation. 4. This patch causes new failures in the test suite: - recording-surface*: possibly an effect of improved quality. - surface-pattern-scale-down*, surface-pattern-big-scale-down: the reference images should be updated. - pthread-same-source: I have no idea why this is failing, since this test shouldn't even trigger the new code. - large-source-roi: this test attempts to downscale an image which is 30000 pixels wide down to 7 pixels. The filter parameters seem to be created correctly, but they might trigger an overflow somewhere in the convolution code; the output rectangle is white instead of red, as if nothing was drawn. - device-offset-scale: there are subtle differences which look like convolution-related smoothing; I'm not sure whether this is OK or not. Note that master currently fails many more tests, I only listed new failures cause by this patch. Regards, Krzysztof Kosiński

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Safely mixing C/C++ bindings for GNOME libraries
by Alex Valavanis 07 Jun '13

07 Jun '13

Hi All, Just a quick note about a common source of build failures (e.g., bug #112274) [1]. Basically, we disable the use of deprecated GNOME library symbols wherever possible so that we can avoid big API migration projects in future. A common problem, however, is that some of the C++ bindings (e.g., glibmm and gtkmm) use some of those deprecated symbols! In other words: Inkscape ----> glibmm ----> deprecated stuff in glib \---> glib \---> gtkmm ----> deprecated stuff in gtk+ \---> gtk+ So, even though we don't use deprecated stuff ourselves, we still need to take a little care with this! The solution is to ** Ensure that high-level dependencies are included in our source before low-level dependencies ** For example, the Glib::Thread API in glibmm depends on deprecated GThread stuff in glib. We will get a build failure if we do the following... #include <glib.h> #include <glibmm/threads.h> This is because the deprecated GThread stuff in <glib.h> will be hidden by the C++ preprocessor. When <glibmm/threads.h> is subsequently included, GThread stuff will therefore appear to be undeclared and we get an error like this: /usr/include/glibmm-2.4/threads.h:142:11: error: field ‘gobject_’ has incomplete type /usr/include/glibmm-2.4/glibmm/threads.h: In member function ‘GThread* Glib::Threads::Thread::gobj()’: The solution is to do the inclusions in this order: #include <glibmm/threads.h> #include <glib.h> This now compiles correctly because when <glibmm/threads.h> itself includes <glib.h>, it temporarily re-enables the deprecated stuff, uses it, and then disables it again. A couple of additional notes: 1. There's actually no need to #include <glib.h> after one of the <glibmm/*.h> headers... it is already pulled into our source by the glibmm header! 2. Remember that you have to avoid *any* inclusion on <glib.h> before using a <glibmm/*.h> header. As such, it's safest to just put the C++ headers at the top of any source file: i.e., // Gtkmm/Glibmm headers first... #include <gtkmm/aaa.h> #include <gtkmm/bbb.h> #include <glibmm/ccc.h> #include <glibmm/ddd.h> // Now include Inkscape stuff... #include "ui/dialog/wibble.h" #include "ui/dialog/wobble.h" 3. Ultimately, we can probably get rid of all direct usage of <glib.h> and Gtk+ headers and replace them with their respective C++ binding headers. Cheers, AV [1] https://bugs.launchpad.net/inkscape/+bug/1122774

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[Units] Unit Refactor
by Matthew Petroff 05 Jun '13

05 Jun '13

I am going to working on refactoring and then improving Inkscape's unit handling this summer for Google Summer of Code. I plan on posting regular progress updates on my blog [1] and summaries of the updates here. I have branched the repository for the first phase of my project [2] and will merge the changes back into the trunk once it is done and create a new branch for the second phase. I look forward to working with the Inkscape community this summer. -Matthew [1] http://www.mpetroff.net/archives/category/programming/gsoc/ [2] https://code.launchpad.net/~matthewpetroff/inkscape/gsoc-2013-unit-refactor

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Re: [Inkscape-devel] GSoC 2013: Implement a new raster-to-vector algorithm...
by Vinícius dos Santos Oliveira 31 May '13

31 May '13

2013/5/31 Martin Sucha <martin.sucha-inkscape@...2313...> > What about something like libdepixelize? Although the name does not > exactly mention pixel art, it seems it does not yield any hits in google > yet. My concern was about the name of the symbols/variables/classes/..., not the library per se. The library could implement (as you stated) other algorithms in future and should use a generic name. The potrace tool ( http://potrace.sourceforge.net/ ) uses the name tracing to refer to this technique. I like both names (libtracer, libdepixelize) and other names also (libvectorizer) and whatever you guys choose is fine to me. -- Vinícius dos Santos Oliveira https://about.me/vinipsmaker

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Re: [Inkscape-devel] New Inkscape Website (Staging)
by Martin Owens 31 May '13

31 May '13

Nicolas, Thanks for getting back to me with some fantastic questions. I've pushed the conversation to the inkscape developer mailing list so others can stay up to date and offer their ideas. ... On Fri, 2013-05-31 at 14:34 +0100, Nicolas Dufour wrote: > I've started to work on translating pages and parts of the UI. > Django-CMS is a bit complex and its website documentation somewhat > cryptic, but it looks very interesting, and quite convenient for a > translator. It can take one like that. The template formula for including blocks of CMSable widgets is something that may require refinement as we go forwards. Especially for the front page. For now, we're using the most basic formulations. > I've just added a bug report about translated menus that are split in > two lines and cause some issues > (https://bugs.launchpad.net/inkscape-web/+bug/1186235). It's a very > annoying problem, but I'm sure it won't be too difficult to solve. I > also have some questions: I saw the problem with the french menu and have already contacted the designer and some other people to help solve the issue. There has been no response as of yet, partly because of classes/exams. If anyone else wishes to help solve the bug, please see the developers link below. > * Regarding static content, we currently have some pages (tutorials > and keys and mouse references) that are generated externally (see > https://launchpad.net/inkscape-docs). How should we handle them? Note > that the keys and mouse references are linked directly in the > application and thus should be accessible from exactly the same > localized URL (for French: http://inkscape.org/doc/keys048.fr.html). I didn't know about the generative content, that's quite interesting. We could either insert the generated content into the right cms widget items, or do something else. It depends if we want the content committed to bzr or just in the database with other content. > * How will the news be managed? I see nothing about it on the website, > but I guess that's something that won't be abandoned. The news module is operational, but it has two big caveats: 1. English only, 2. No on-site editing. Thus as the technical lead, I intend to replace the news module with a newly written one which has both multi-language and onsite editing. > * The French menu is exactly as defined in > http://staging.inkscape.org/fr/admin/cms/page/, but it's not the case > with the other languages. Is the menu order language-dependent? The CMS seems to order the menu according to how much has been translated and which menu was edited last. It is not idea, but a fix would require patching upstream. > * Apparently, the website is synchronized to the LP code manually > (I've ported images for the books page, but they are not on-line yet). > Do you plan to give update access to someone else, or do you prefer > that we ask you every time we something is committed. The cron jobs are not complete, there is a bug report assigned to me. Images should actually be uploaded via the CMS unless they are non-content images for use in the style/theme of the website. I may have to reverse your commit for now. If you get stuck adding images, let me know and we'll figure it out together. > Apart from it, I'd like to run a local version of the website for > testing purposes. SQLite, Django, Django CMS and the dependencies are > installed on my computer, but I still have difficulties with the CMS > modules (Error: No module named cmsplugin_news, or Error: No module > named cms.plugins.twitter if I comment the cmsplugin_news line). Do > you have some documentation on how to run it (the README file didn't > help)? I'm new to Django CMS, and not very experienced with Django and > I've probably missed something obvious... If not, I'll try to search > the web, there should be some tips somewhere. Absolutely, at the bottom of the website there's a link "Website development guide:" to this wiki page: http://wiki.inkscape.org/wiki/index.php/WebSite and by following this guide we hope, the website should work locally for development. This also includes bringing in the data from the staging website, since the cms would be empty otherwise. Please continue to report bugs and press the website further :-) Best Regards, Martin Owens

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I have a faster, SIMD IIR filter implementation, but have accuracy problems
by Yale Zhang 29 May '13

29 May '13

All, I have ported the IIR filter implementation to use SSE intrinsics and have achieved a 2.5x speedup so far. But I'm having accuracy problems for large blurs due to using single precision instead of double. I've attached examples outputs that blurs a box with several sizes. For sigma=120, the annoying mach bands start getting noticeable. At sigma=200, it looks very bad, and at 350, you might as well use it as a sharpen filter :) This is the first graphics application I've seen where single precision isn't enough. Is the reason due to the recursive behavior of IIR (more accumulation of error) ? Basically, for large blurs (stdev > 100), 24 bits of precision isn't sufficient and you end up getting very annoying mach bands. For sigma = 100, the filter coefficients are: b[0] = 0.00000387430191040 b[1] = 2.96391582489013672 b[2] = -2.92843437194824219 b[3] = 0.96451467275619507 If I add b[0] to the other terms last (b[1] + b[2] + b[3]) + b[0], (earlier, when I added the b[0] term to b[1], the accuracy was even worse as expected), the alignment of the operands in binary is approximately: 1.00000000000000000000000 0.00000000000000000100000 meaning the addition loses a lot of the b[0] term's precision. Can anyone suggest how to proceed next and how useful you think this speedup is? (for me it's a moderate improvement because in my comic, I use marble and brick textures for the walls and floors - I also vectorized the turbulence generator). I would like to avoid using double precision since SSE supports only 2 doubles per operation instead of 4 floats. The things I thought about of trying next are: 1. Use int32 arithmetic (that would add 9 extra bits of precision) 2. Use 4 taps instead of 3. Would this really help? I don't know much about IIR filter design. Can someone give me the coefficient formula for 4 taps? Thanks for helping, Yale

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[CAD] Connectors and Symbols
by Martin Owens 29 May '13

29 May '13

Dear Sebastian Götte and Tavmjong Bah, I'm working on these two items most keenly too, I would like to participate in code review as well as design review for the blueprints etc. The codebases for both items are not super big so I'd like to make sure we don't start committing over each other since the GSoC projects are nominally forked. I have a UI change for symbols which is waiting merge. I'm also interested in the design of the connectors since I know we all have different ideas about how it should be done (elements vs attributes, children vs groups). I'm not sure of the scope yet of the CAD work for 2013, can someone link me to the blueprint? Best Regards, Martin Owens

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Reports with patches pending code review (two-patch-rule / GSoC 2013)
by ~suv 29 May '13

29 May '13

Reports with patches pending code review (two-patch-rule / GSoC 2013) Status 2013-04-30 19:00 +0100: ============================== - Bug #181493: Locked layers not completely locked https://bugs.launchpad.net/inkscape/+bug/181493 - Bug #388684: auto-name duplicate objects https://bugs.launchpad.net/inkscape/+bug/388684 (no patch yet) - Bug #525508: Rotation step 22.5 https://bugs.launchpad.net/inkscape/+bug/525508 (committed) - Bug #830663: default window size too small https://bugs.launchpad.net/inkscape/+bug/830663 - Bug #448728: default preferences window size too small https://bugs.launchpad.net/inkscape/+bug/448728 - Bug #587729: Missing tweak tool cursor symbols https://bugs.launchpad.net/inkscape/+bug/587729 - Bug #180912: Dropper tool overrides keyboard shortcut https://bugs.launchpad.net/inkscape/+bug/180912 - Bug #773288: Document Properties > Page Border https://bugs.launchpad.net/inkscape/+bug/773288 (committed) - Bug #448872: Update selection based on bounding box https://bugs.launchpad.net/inkscape/+bug/448872 (merge proposal) - Bug #669748: Add a command-line switch to specify EPS Export level https://bugs.launchpad.net/inkscape/+bug/669748 - Bug #1173776: (E)PS export crashes when running from command-line https://bugs.launchpad.net/inkscape/+bug/1173776 (merge proposal) - updates the incredibly old Doxyfile file to use newer config values https://code.launchpad.net/~vinipsmaker/inkscape/doxygen - Bug #503712: Personal default template not used https://bugs.launchpad.net/inkscape/+bug/503712 (committed) - Bug #1023797: Scrollbars in Swatches dialog https://bugs.launchpad.net/inkscape/+bug/1023797 (committed) - Bug #257223: 'Object to path' for connectors https://bugs.launchpad.net/inkscape/+bug/257223 - Bug #629081: Spiro and path operations fails https://bugs.launchpad.net/inkscape/+bug/629081 Help for the bug team with getting code-related questions answered, patches reviewed, tested and committed in a timely manner would be appreciated.

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[GSoC -Templates]
by Jan Darowski 29 May '13

29 May '13

Hi! Thanks for accepting my proposal, I hope to be up to your expectations. First of all, I would like to know few technical details: Do you guys prefer mailing most of my questions to this list or directly to the mentor? If the second option, which address? What do you expect me to do during this period before official coding start? I mean except google formal requirements and preparing everything for the fast start. Thanks, Jan Darowski, Slagvi

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