June 2020 - Inkscape Devel - Inkscape Mailman

win32 build working again
by Bob Jamison 08 Apr '24

08 Apr '24

The win32 build, which was broken for the weekend, is working again. I just made a "manual autobuild" again, so that we can see how it looks on Windows: http://troi.titan-aeu.com/~rjamison/inkscape/builds/ Bob

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Regarding the serialization of Spiro control points
by Fred Brennan 28 Mar '22

28 Mar '22

Greetings, I write from the FontForge project. Of particular interest to me is the Spiro spline feature, which was originated around ten years ago by Raph Levien. One thing I'd like to add, (which would benefit both our projects,) is the ability of FontForge to understand the Inkscape Spiro serialization format. However, there are several things about the format which to me as an outsider appear to be defects serious enough that I have no idea how to even *import* these splines correctly, much less export our Spiro splines to this format. I would very much like to support the _de facto_ standard Inkscape has originated of supporting Spiro in SVG, but I am lost. George Williams, FontForge's original author, noticed this defect over eleven years ago.[1] Things are virtually unchanged since then, I checked `git blame`. Spiro has five point types, not including beginning and ending points. They are: * G4 curve (o) * G2 curve (c) * Corner (v) * Left Constraint ([) * Right Constraint (]) The ASCII single letters are the normal method of Spiro serialization, as championed by Raph Levien and by us in FontForge. Inkscape seems to create what I will call a "pseudo-SVG path". So, it is not really an SVG path, but rather is an SVG path which undergoes transformation into the typical Spiro format. Inkscape stores this in the "original-d" attribute. So, given a Bezier spline with control points defined as (x, y, c1, c2), Inkscape interprets a control point with only (x, y) to be a corner, meanwhile a control point with all four is a G4 curve, and (x, y, c1, NULL) is a left constraint while (x, y, NULL, c2) is a right constraint. I can probably overcome this, although George Williams was right to be skeptical of this format. There is no way I can see to define a G2 curve in this strange "original-d" format. Thus, this email. I write to ask a few things. I suppose first of all, what are the chances that we can convince you guys to store Spiro splines in plate[2] format, or another widely accepted Spiro serialization format? Second, if we cannot convince you to do that, how do I export FontForge spiros which contain G2 control points to Inkscape's original-d format? It's not possible, yes? So should I just silently fail and save them as G4? The curves will not be the same if I do that. Should I disallow export to SVG w/Spiro if glyph contains G2 control point? That seems a steep cost that will just confuse my users, so perhaps I should abandon the whole thing if it comes to that. Cordial regards, Fredrick Brennan (@ctrlcctrlv) [1]: https://narkive.com/63FADpG3.4 [2]: https://levien.com/garden/ppedit/README, section "Plate files"

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bit of an update on svg animation
by NASA Jeff 28 Jun '20

28 Jun '20

- hi everyone - I've been looking at animation support and evaluating the competition. also I found a javascript implementation of the web animations api which may be the animation engine to support as it's getting native support in browsers. that doesn't limit us by not allowing support for snap or GSAP on top of this. web animations API works with css and svg and provides interfaces to animation, keyframes and timelines. - - https://github.com/web-animations/web-animations-js <https://github.com/web-animations/web-animations-js> github.com *web-animations/web-animations-js* <https://github.com/web-animations/web-animations-js> JavaScript implementation of the Web Animations API - web-animations/web-animations-js - SVGator, a commercial svg animator supports javascript (using it's custom engine) or css - I still wouldn't suggest supporting any old javascript, but a cut down version of javascript where complex functions get replaced with stubs that return some default value and the code can be evaluated to get the animation (limited by what javascript functionality is implemented) and property settings for the animation can be traced. I would do this roughly by using the built in parser in the javascript engine to calculate animation settings to be presented in the UI. the commercial svg animation tool SVGator supports javascript and css. it doesn't allow the javascript to be modified in the application, I haven't tried importing and svg file with modified javascript. it may also be a good idea to support snap or GSAP ontop of this, on the other hand, they may become obsolete as web animation s API gets full support and people start writing functions for it such as the morph one found here https://coherent-labs.com/Documentation/cpp-gameface/d1/dea/shape_morphing.… - - for instance, simple loops may be supported, but more complex(that use the result of a function call to determine the loop[ conditions) ones may be too complex to support rationally - Doing this loses nothing as the animation will still run in a browser, but Inkscape may only support animations with complex functionality partitioning - Accurate animation playback can still be supported by executing the javascipt but I would limit imports to trusted javascript and not any old javascript for reasons of side effects and security. there are already shims that implement SMIL in javascript, and assuming they allow you to position the timeline and query keyframes and object attributes they should allow for a relatively straight forward SMIL implementation so long as javascript is supported. this proposal sees inkscape supporting SMIL, CSS and javascript. the Web Animations API implementation should allow for the support of CSS without any javascript but can still be used for the actual process of animating and setting the timeline position. at the moment I'm still working on importing text from pdf files in scribus. I have most of the functionality already implemented for this out just requires a bit of polish. to do that I'm going to refactor the code to use a simple framework that should make the code a lot cleaner, be faster and support all the features for the Polish needed to have a decent implementation.

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Suggestions documentation regarding "Getting Started with Inkscape Development"
by wiesi＠posteo.net 24 Jun '20

24 Jun '20

Hello, I recently filed a pull request and was pointed out to * increase the timeout in "Settings => CI/CD => General Pipelines => Timeout" to 3h * Check the "Allow commits from members who can merge to the target branch" in the pull request settings. I suggest to add a section in "Getting Started with Inkscape Development" on the homepage describing the correct settings and maybe also how to create a fork on gitlab (or just link the gitlab documentation). Cheers, Thomas

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Inkscape Hackfest 2020
by Martin Owens 23 Jun '20

23 Jun '20

Dear Inkscape developers and users, I've been thinking about how best we can host a hackfest for 2020 given all the restrictions. After talking with multiple people, I've decided that the best format for an online hackfest is to have one spread out over the summer. So may I present to everyone the Summer of Hackfest: https://gitlab.com/inkscape/vectors/general/-/issues/161 This gitlab issue is just for organising people's preferences, and thoughts. Once I have times confirmed, I'm going to write everything in the regular hackfest wiki page for everyone. So. The idea here is to take advantage of the online nature of this year's hackfest activity and allow people more breathing room between sessions. Each week I'll be hosting a video chat which you will be free to join and just hang out in and where hopefully some of the important topics will happen once per week. No grueling commitment, no big block of time, just a predictable schedule of lovely inkscape topics which will be publisised to get more people involved than ever before. Please join me on GitLab to proposed topics and set your preferred times. I'm looking for one topic per week, so that's six topics. And thanks for your participation. Best Regards, Martin Owens

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chrome's support for modifying web animations api in it's developers console.
by NASA Jeff 21 Jun '20

21 Jun '20

Chrome seems to do a reasonable job of capturing and modifying web animations API in JavaScript. Its not so hot, however, when it comes to elements that have animations that are programmatically generated, it doesn't even group them all together and identify the source of programmatic generation, which in many cases is just a simple trace of the code. I dare say it could do better than just passively listening out for animation events and actually infer many of the from the source documents.

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[GSoC Paths] Status update
by Moazin Khatri 18 Jun '20

18 Jun '20

Hi everyone, I would like to provide a status update on the Path Library Improvement project. Since this is my first report to the list (the last one wasn't public), I'd like to discuss everything done so far. This report is huge and quite technical, so if you want a short version, it is this: "I have successfully written a relatively short piece of code that creates simplification results totally identical to the livarot version. The algorithm is the same as livarot and is nearly as fast. I'm about to start cleaning it, documenting it and integrating it with simplify, lpe-simplify and pencil tool. This will be done within the next two days." Now the detailed version: According to the original schedule, I was supposed to work on the Path Simplification feature and that is what I have been doing. I started with writing some boilerplate code that will allow me to trigger my own Path Simplification code in Inkscape. This is so that I can compare its results with livarot based simplification quickly. I started exploring the simplification algorithm of lightvarot and wrote some path flattening (the process of approximating a path by line segments) myself. I integrated these in Inkscape and the algorithm produced pretty satisfying results but it was too slow. In a "Release" build, the performance might be okay for a "Path > Simplify" but would do pretty bad in live path effects. For what it's worth, I also created an animation explaining this algorithm. You can find it here: https://moazin.github.io/simplification-algos.html Disappointed by its performance, I replaced the main part of the algorithm with its equivalent from livarot (that's explained in the link attached under the title "Livarot / Simplifying the curve". The performance improved but there were significant differences between the results. I had a choice here, I could either just rewrite a cleaner version of livarot's code or understand what's causing the differences and fix those. I chose to do the latter. I started following the procedure "draw paths -> trigger both algorithms -> debug both simultaneously -> understand and fix the differences -> repeat". Going down this route, I understood almost all the parts of livarot and was even able to discover/fix bugs in both livarot and lightvarot. Here are the reasons behind the differences: 1. The codes for flattening the paths were different so obviously there were differences in the results. I simply implemented livarot's algorithm for splitting cubic beziers to solve this problem. 2. There is an iteration of Newton-Raphson method. (I'll probably add what this iteration is and what it does in the link attached above soon, it's mostly math stuff). I suspect that the code for this iteration in lightvarot is mathematically incorrect, so I fixed it. I will do the derivation again to be sure if it's really a bug though. Anyways, I fixed it by replacing the constants from my derivation (which are identical to the livarot version). 3. There is a special portion in livarot code which fixes what livarot calls the "splotch" problem. When the number of points you're fitting are few, you can sometimes get a fit which fits the points correctly but overall doesn't fit the polyline properly. There is some special code that calculates error differently to take into account this situation and thereby avoid bad fits. My code was missing this code, so I wrote it. 4. There is a slight optimization in livarot that reuses some calculations and I suspect it compromises on the accuracy of the fits. I need to investigate more to be sure. I fixed it in livarot by simply using the non-optimized version. (There are two `AttemptSimplify`) 5. There were some silly bugs in livarot's non-optimized `AttemptSimplify`. A minus was replaced by a plus and a weight factor was commented. Fixed both of those on the livarot side. After doing all of these changes, both versions are producing totally identical results. The computation time is also mostly identical. There is a very minor difference in the flattening part which I'm working on. The code can be found at: https://gitlab.com/moazin/inkscape/-/tree/integrating-livarot-low-redesign My code lives in `src/path/PathSimplifier(.h/.cpp)` and `src/path/PathFlattener(.h/.cpp)`. The temporary verb "Path > MyOperation" triggers code in `src/path/path-myoperation(.h/.cpp)`. The commit history is pretty much garbage since I have been experimenting a lot. Over the weekend I'll be cleaning this code, documenting it properly and integrating it in lpe-simplify and the pencil tool. I'll add the final resulting code "cleanly" on a fresh branch. An interesting part of this project is the "design" of whatever code I write. But I think it's too early for me to start thinking about it because as I move towards Boolean Operations, a lot of new things will be discovered and whatever "design" I decide on would change. So, IMHO, this can be discussed later once I am done with Boolean Operations. Please feel free to ask any questions that you may have or provide feedback. Thank you, Moazin

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C++ & Gtk dependencies
by Alex Valavanis 10 Jun '20

10 Jun '20

Hi All, I just wanted to follow up a couple of recent discussions on our build dependencies. 1. There was some talk of moving to C++17. Tav - I think you were going ahead with a dependency bump in master? Are we still doing this, or did we find any issues? 2. Are we OK to bump to Gtk+ 3.24? AFAIK this is the final Gtk+ 3 version so would be a good stable target for Inkscape 1.1. The only issue would be RHEL/CentOS/Debian LTS are stuck on an older version. My feeling about this kind of thing is that we keep Inkscape 1.0.* as our LTS and push ahead with a dependency bump in master. Best wishes, Alex

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Getting error status/messages for Inkscape actions (when called via activate_action)
by wiesi＠posteo.net 08 Jun '20

08 Jun '20

Hello everyone, is there a possibility to get some error status and/or error messages when executing actions via, e.g., activate_action()? I had a look at the glibmm documentation but couldn't find anything regarding this topic. I've just included executing Inkscape actions from the internal Python interpreter feature I'm porting to the current master branch (https://gitlab.com/wiesi/inkscape/-/tree/python-internal-1) and it would be nice (maybe even mandatory) for the Python user to get some feedback whether an action was successful and a meaningful error message if not. Can anyone point me in the right direction? Does glibmm have some infrastructure for this task that I'm just unable to find or does it really require some extended surgery? Thanks, Thomas

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Re: need help implementing command line args
by intricate machinations 06 Jun '20

06 Jun '20

Small bump. Any help would be appreciated. Should I just try to turn the args into STRING types and manually parse the INT values somewhere?

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