September 2020 - Inkscape Devel

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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Board Meeting this week!
by Ted Gould 02 Oct '20

02 Oct '20

Howdy Inkscapers, We have a board meeting this Friday, October 2nd at high noon Texas time and you're invited! In your time that is: https://www.timeanddate.com/worldclock/fixedtime.html?iso=20201002T10&p1=202 There is also a list of things we plan to discuss: https://wiki.inkscape.org/wiki/index.php?title=Board_Meetings If your name is next to one of those items, and you can't make it, please make sure to designate someone in your place. It'll make the meeting flow more smoothly. See you there! Ted

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Vectors Meeting, October 2020
by Maren Hachmann 30 Sep '20

30 Sep '20

Hi everyone! There's going to be the monthly Vectors (marketing and outreach group of Inkscape) meeting on Saturday. Time and date: https://inkscape.org/*inkscape-vectors/calendar/ Please add your agenda items to the agenda: https://gitlab.com/inkscape/vectors/general/-/issues/173 Hope that many of you can join :) Maren

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Help adding support for dxf arc on dxf_outlines.py
by Sandro Duarte 29 Sep '20

29 Sep '20

Hi, I'm trying to add dxf arc to the dxf_outlines extension but I'm having some problems: At first I'm using only the arcs that have the same radius, basically the code goes like this def dxf_arc(self,arc_info): """Draw an arc in the DXF format""" self.handle += 1 self.dxf_add(" 0\nARC\n 5\n%x\n100\nAcDbEntity\n 8\n%s\n 62\n%d\n100\nAcDbCircle\n" % (self.handle, self.layer, self.color)) self.dxf_add(" 10\n%f\n 20\n%f\n 30\n0.0\n 40\n%f\n100\nAcDbArc\n 50\n%f\n 51\n%f\n" % (arc_info[0],arc_info[1], arc_info[2], arc_info[3], arc_info[4]) def arc_info(previous_end_point, arc_path): Ax = previous_end_point[0] Ay = previous_end_point[1] radius = arc_path[1] Bx = arc_path[-2] By = arc_path[-1] ... return [center_point_x, centerpoint_y, radius, start_angle, end_angle] The problem is for this to work it must be before converting the path to superpath or all the svg arc information will be lost as it will become a curves but somewhere in the code there's the information that there is some issues when transforming(matrix) the path before converting it to superpath. So I'm thinking if it would be possible to use something like simplepath (but now it's decrepted) and convert the path into segments and then the segments to curve as they go into the process_shape loop and separating the arcs that fulfill the conditions(same radius) from the others that should be converted to curves and then to dxf spline. It would go like this: path -> transform matrix -> simplepath -> separate the arcs from the others (M L C etc) -> arcs goes to arc_info and the others goes to either dxf line or dxf spline as opposed to what it is now path -> superpath -> transform matrix -> separed lines from curves to go to dxf line and dxf spline respectively So my questions are : How to convert the path to some sort of superpath but without converting it curves? Does a command to do this exist or should I write a function to do it? And if I should write one, what's the format of a superpath so it could match with my function? What was the issues of having the transform matrix before converting it to a superpath? It is possible to do it the way i intend? Any help would be appreciated

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notes on Inkscape's canvas performance and caching, with GPU summary.
by NASA Jeff 23 Sep '20

23 Sep '20

There was some discussion on dev-chat about using SVG for rendering rotation handles and performance and bitmaps came up in discussion. This should provide a thinking point for talking about canvas performance at Fridays meeting. That led me onto some investigation into Inkscapes canvas performance when rendering bitmaps and vectors and how chrome handles it. This is about the only benefit of running on an old laptop. Anyhow, the notes cover the whole file and subfile (z-order sandwich) caching for all possible dynamic transforms of objects (that is excluding node, filter, style modification etc...) which should dramatically improve the performance of inkscape in anything to do with dynamic transformation where perfect fidelity isn't so critical because it's blurred to the eye. It's also very practical on the GPU which has enough fast memory and image filtering technologies to offer good support and high fidelity with no noticeable artifacts in the rendering. oliverthered 9:48 PM I just had a bit of a look at image drawing performance and there is lag when I'm dragging the image. That means the image position is being updated with intermediary points when the mouse has long left that point. scrolling the view point doesn't seem to have these issues, the performance is still slower than my web browser. That may be because the browser renders to over-view-size bitmaps, or a composite of bitmaps and caches them, so all scrolling involves is translating the cached bitmap. oliverthered 10:00 PM vector performance doesn't seem too bad, it's still not great though. does it use intermediary bitmaps with an alpha channel that are cached so that translating and scaling etc.. operations operate with optimum performance? in a similar way to how true type font rendering works in most applications, except with layers. so say when you select something the objects with z-orders above and below the selection are cached to bitmaps as layers so they don't have to be rendered for every update. obviously you get a sandwich effect if the selected objects aren't in a z-order group. oliverthered 11:16 PM me running out of memory/swapping or whatever causes chrome to show it's caching system for rendering and it uses square tiles (deciles) when rendering this svg file. with square tiles it's easy to clip the vectors so you can minimize redraw because in addition they over size the view. oliverthered 11:45 PM looking at inkscape, when the canvas size is larger than the view area +-42? inkscape resorts to redrawing the portions of the svg file that are out of view when they come back into view. where as chrome uses deciles so that at most the content of the squares are redrawn if they move back into view and are no longer in cache and at least the squares cache the content once it's been drawn once (in an over sized view that is square by square proportioned) it's cached and doesn't have to be drawn again for translation exercises. with decent filtering square caching can also be used for scale, rotate and skew with the svg file only being needed to be redrawn when it's enlarged beyond the cache size. There's a possibility that this may produce some unwelcome artifacts in studio production though so it may only be workable during dynamic operations with the svg file having to be redrawn once the dynamic (and so blurred by the eye) operation is complete to give production quality fidelity again. oliverthered 11:50 PM so all dynamic transforms of svg objects can use bitmap caching deciles as mentioned about along with the sandwich caching I mentioned earlier when a fraction of the svg file is modified, nodes, transform, properties, filters etc... This should work very well on the GPU too as it's ideal for this kind of compositing. That should cover animated transforms and path movement (esp in CSS) and with clipping changes to styles and filters and possibly node movement. It should be possible to parse this information out of the file so caching can be optimized with advanced knowledge and not have to be done with "on the fly" optimization for the various fragments which would get messy.

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Discussion for the next developers meeting
by NASA Jeff 23 Sep '20

23 Sep '20

I missed the last developers meeting but intend to make the next one. I'm still in Istanbul and I've had a good chance to think things through more thoroughly and simplify things, still I'll have to be briefer that I otherwise would be as I don't have access to all my resources and am working on a very old laptop. Points: -Pitfalls of CSS and Javascript and indeed SIML, which is now deprecated. *I have some examples of CSS and Javascript I've put together, I'll make sure all the examples are in both CSS and Javascript so the pitfalls can be seen. -Possibility of a dual implementation model, both CSS and Javascript. CSS being limited to just CSS and fully editable in the GUI, Javascript only limited by way of features available (re security etc...) but not being fully editable in the GUI, inkscape isn't an IDE. -Performance issues with Firefox ECMA scripting engine on older machines. -Options for implementing security beyond that provided by the ECMA engine by default. -Modular design, allowing the ECMA engine and APIs to more easily be integrated with other open source applications. *Engine integration, *API modules providing and API view with module availability restricted based on use. i.e. Runtime tool extensions need APIs that should not be available to SVG documents. -Lightly cover extra tools and GUI changes required for animation and interactivity etc... This will require some mockups to have a proper discussion about. -Possibility of assistance from Universities by way of taking on some of the work as elements of research projects. -Potential for revenue generation in a souped up version. -Discuss a Python2/3 implementation written in Javascript that I've used via University. This would allow for existing Python plugins that are apparently quite broken at the moment to be ported to javascript should the time come -Potential for macro recording and real-time extensions, e.g. new drawing tools like the shape recognition extension I've been working on. Finally, -Canvas performance, options available and discuss the current implementation and bottlenecks and how this can be moved forward into the up and coming OpenGL, Vulkan etc.. implementation.

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c++17 usage
by René de Hesselle 21 Sep '20

21 Sep '20

Developers, in our next meeting I'd like to discuss c++17 usage - specifically new std library features (https://wiki.inkscape.org/wiki/index.php?title=C%2B%2B17). Allow me to be blunt: so far we've achieved nothing but to increase complexity. For the introduction of 'filesystem' alone we already had to introduce three different strategies: - use std::filesystem as default for up-to-date gcc toolchains - use boost::filesystem on macOS to not break support for older OS releases - add -lstdc++fs linker flag for gcc 8.x I propose to refrain from using std c++17 library features and go for boost on all platforms where applicable (e.g. boost::filesystem). This way we avoid introducing new platform/compiler specific code paths that don't bring any benefit. René

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tuning the canvas
by NASA Jeff 18 Sep '20

18 Sep '20

I missed the dev meet up, I'm on holiday in Istanbul at the moment, here's some additional thoughts i had nodding off last night: I don't know what the performance bottle necks in the canvas are but i had a think about vector graphics performance and this is what I identified: caching of objects and image sections, reducing the fidelity when an object is being modified dynamically, improved drawing algorithms (integer) ... that's a no brainier (fits in with fidelity), clipping (which also fits in with caching), and finally JIT compiling drawing operations with dynamic elements in their inner loops so that they can be properly optimized out, vectorized and unrolled etc...

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canvas performance
by NASA Jeff 10 Sep '20

10 Sep '20

at the very least it should be podssijble to switch over to almost pure integer rendering with AA disabled to get enough performance to preview animations in real time.

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