There was no new release of Inkscape at Libre
Graphics Meeting 2012 in Vienna, but the SVG vector editor still made
a significant impact. One session showcased a new extension that
enables drawing with variable-width strokes, but several others showed
off independent applications that leverage Inkscape's extensibility to build
other tools, including an interactive mock-up creator for UI design
and a font editor.
Libre Graphics Meeting is the annual workshop and conference of the
open source graphics community; there are presentations from developers and
artists alike, as well as workshops and team meetings. 2012 was the
event's seventh year. LGM mainstays include GIMP, Blender, Inkscape,
Krita, and Scribus, among other projects, but the exact makeup varies
each year due to the moving venue and the irregular release schedules
kept by the various teams. Inkscape is nearing its next major
release, but its presence was felt in other sessions this year.
The variable-width stroke feature is named Powerstroke,
and was authored by presenter Johan Engelen. The implementation is
based on Inkscape's Live Path Effects (LPE) technique, which allows the user
to attach a non-destructive effect to any path object. These effects
are functions that manipulate the path data itself — meaning its
points and control points, not "stylistic" features like color or
opacity. LPEs can deform paths, map text or images along a path, and
many other tricks. LPEs produce a valid SVG path as output, so
they are preserved in other SVG viewers, but the original data is also
saved in an Inkscape-specific attribute, which makes them reversible.
Without Powerstroke, each path has a fixed stroke width along its
entire length (which is the default in almost every vector editor).
The new feature adds "width points" along the path; each contains the
location along the path and the width at that point —
where they change, the effect interpolates smoothly between them. In
the user interface, each width is shown as a line perpendicular to the
curve of the path, and has "handles" that allow you to directly adjust the
For the stroke width itself, there is very little else to it. The
interpolation between widths is performed by the lib2geom library, and
width control points have special purple handles to distinguish them
from regular points. There is an "advanced" option which allows you
to rearrange the order of the stroke-width points, which creates some
zany effects, and an auxiliary LPE called "Clone original path" was
created to enable filling Powerstroked shapes.
What is more complicated is how to handle sharp corners. The
SVG specification defines three possibilities: rounded, mitered
(pointed), or beveled (flattened). Powerstroke adds two of its own:
extrapolated and "spiro." The extrapolated corner is a variant on the
miter, but it is designed to more smoothly follow the shape that a pen
might take on paper. The spiro corner is more rounded, based on the Spiro curve type created by
Engelen hinted at several improvements for Powerstroke in future
releases. He would like to make Powerstroke output an option for
Inkscape's calligraphy tool rather than a stand-alone LPE, as well as
tackle asymmetric stroke widths. Calligraphy tool support might make
Powerstroke usable with pressure-sensitive pen tablets, which artists
would like. There are also pathological cases where the math
currently breaks down, such as coupling extremely sharp corners
with extremely large widths; fixing those is something mathematicians
Mocking the user interface
Red Hat's Máirín Duffy and Emily Dirsh presented a session entitled
"An awesome FLOSS design collaboration workflow," covering a range of
projects developed to support the Fedora Design Team. Duffy explained
that working as a user experience (UX) designer, she found the
existing collaboration tools frustrating when compared to Git and
other tools made for developers. Designers need to collaborate with
each other and with developers, she said, but often had little choice beyond
shared-folder synchronization and email attachments. The first
product of her campaign to create better design tools was
SparkleShare, a Git-backed storage service that functions like
Dropbox, but with the full power of commit, forking, and revision
SparkleShare helps developers share and iterate designs via flat files, but
it does not help when creating interactive UX mock-ups. For that, Duffy said,
most designers are stuck with unfavorable options like proprietary
tools, Adobe Flash, and web services that may or may not be around in
years to come. Her solution to this dilemma is Magic Mockup, a
utility for creating clickable, interactive mock-ups with Inkscape.
The nexus of the idea came from Sozi, which makes animated
presentations using SVG. Just as Sozi uses SVG's
designers draw interactive buttons, dialogs, and other widgets that respond to mouse
events. Clicks trigger a simple "change frames" action, which lets designers
mimic application state-changes, user input, or animations. Duffy wrote
Still in development is a way for designers to share their Magic Mockup work
with the public. Dirsh demonstrated her project, Glitter Gallery, which is
built primarily for sharing and commenting on Magic Mockup SVG files, but
supports other file types, too. Glitter Gallery is a Ruby application and is designed to run on Red Hat's OpenShift platform.
I presented another Inkscape-built utility in my talk about new
open font development tools. The Inkscape typography extensions are a collection
of related extensions that let font designers use Inkscape as the glyph-drawing
canvas. The workflow allows the designer to draw each glyph on a separate layer,
keeping the entire font in a single file (both because SVG does not have the concept of
"pages," and to make comparing glyphs simpler). The first extension sets up a blank
glyph-creation document, with guides set for baseline, x-height, cap-height, ascenders,
and descenders. The second is a "new layer" function, which creates a new layer named
for whichever letter of the alphabet the user specifies. The third extension cycles through
the layers and builds an SVG font file, mapping each layer to the
appropriate encoding slot. The extensions can also open and edit existing SVG
SVG fonts are not nearly as prevalent as TrueType or PostScript fonts, but the extensions
make for a good start. FontForge is the application of choice for open source font
crafting, but it does not offer a particularly pleasant editing experience. Inkscape
has better and more flexible tools, plus an easier to work with canvas (for example,
FontForge's glyph editor does not support on-canvas transformations). Is is also less
crash-prone than FontForge, and has better essential application features (such as a
More with SVG
In addition to the Inkscape-specific talks, there were several sessions about SVG itself.
Jeroen Dijkmeijer presented his iScriptDesign project, a web-based application that lets you construct
CAD-like blueprints suitable for laser cutting or CNC milling. Dijkmeijer uses iScriptDesign
to create and build wooden furniture, but it is suitable for any project made of flat parts that can be cut with a 2-D tool.
What makes iScriptDesign an improvement over bare SVG drawings is that it supports dynamic, adjustable
"JSVG." The list includes named-variable substitution, mathematical expressions
that are evaluated when the image is rendered, and user input methods like text-entry boxes
and adjustment sliders. He demonstrated a JSVG plan for a sofa table that incorporated adjustable
measurements for height, width, and depth. On-page sliders allow the user to scale various
dimensions of the design, and the application rearranges the resulting pieces to fit them onto the
smallest total area, to minimize production cost.
Dijkmeijer explained that the application also took steps to transform complex paths in the image
so that they were optimized for a laser-cutter's computer-controlled motion. For example, a
shape might include reflected segments, but it needs to have all of its paths oriented in the same
direction so that the cutting head can trace it with one continuous pass.
Chris Lilley from the World Wide Web Consortium (W3C)'s SVG working group was on hand at LGM as well, and provided feedback
to several of the SVG-oriented talks. He also presented an update on the ongoing development
of the SVG 2.0 specification, which will sport several enhancements of interest to artists. First, it
will allow images to specify colors in more precise terms than the generic 8-bit RGB triples common
in HTML. The initial plan was to use the Lab color space and specify a white point, but thanks to a
Q&A exchange on that subject with Kai-Uwe Behrmann of Oyranos and Richard Hughes of colord, the standard may
soon use the more abstract (but simpler) XYZ color space instead. It will also support attaching ICC
color profiles to documents, and will use them for embedded raster images, both ensuring better color matching.
I spoke to Lilley later about Dijkmeijer's JSVG effort, and he confirmed that the SVG Working Group is interested
in eventually adding mathematical expression, dynamic variables, and other such constructs to the
specification, although it will probably not make 2.0. The Q&A exchange with the color management
developers was not the only point in the week where the SVG specification took hints from the artists
and developers at the event; Lilley asked questions of many of the speakers, and called their feedback
to the process valuable — such as Magic Markup's interest in having layers become part
of the core format. Likewise, he was able to point some of the projects to helpful-if-not-well-known
options that could simplify development.
The last few Inkscape releases have added more and more via the application's extensions mechanism,
and they are increasingly specialized. For example, although she did not present an update on it this
year, Susan Spencer's Sew Brilliant uses Inkscape extensions to assist textile-makers, implementing
dynamic pattern-changing options akin to what iScriptDesign does with furniture designs. There may
not be many projects that combine font development, UI mock-ups, and textile making, so it is impressive
to see that Inkscape has evolved — under the radar — into a tool that so many
people are using in such diverse tasks. Likewise, although at times standards bodies seem like remote and unapproachable entities, it is interesting to see a specification like SVG evolve in real-time as developers and artists give their feedback. That sort of frank back-and-forth between developers and end users is also one of the facets of LGM that makes it worth attending, whether your favorite application has a new release to unveil or not.
[Thanks to the Libre Graphics Meeting for assistance with travel to Vienna.]
Comments (2 posted)
I'm sure things like trackstick emulation mode will be thouroughly
missed, but I've heard Linux is all about choice and I choose not
to maintain this any longer.
— Peter Hutterer
- Assume you have 2 pastures, with a gate between them, and a flock
of sheep. Your flock is in one pasture, and you want to get them to
the other pasture through the gate.
- Sheep are, to use the terms we have been using, 'unbreakable', and
'atomic'. (If you slice them into pieces to try to get them to fit
through the gate, you will end up with non-functioning sheep on the other
- If your gate is narrow, you will have to serialise your sheep, and
have them pass through one at a time.
- If it is wider then parts of different sheep will pass through the
gate intermingled from the perspective of a camera mounted on the
gate. "Nose of sheep 1, nose of sheep 2, head of sheep 1, nose of
sheep 3, head of sheep 3, body of sheep 3, tail of sheep 3, body of
sheep 2, body of sheep 1, tail of sheep 2, tail of sheep 1" is what
the camera might report as 'having gone passed', and we might conclude
that sheep 3 is a small lamb, and that sheep 1 is its mother who
slowed down going through the gate so that the lamb could keep up with
her -- but all of this doesn't matter because, as long as you do not
try to break them, the flock will function perfectly on the other side
of the gate without any attention being paid to them by you.
— Laura Creighton
on the PyPy transaction model
Comments (3 posted)
The first release of Apache OpenOffice, 3.4, has been announced. The version
numbering picks up from the last OpenOffice.org major release, which was
3.3. New features include improved ODF support, better pivot table support
in Calc, native support for SVG, enhanced graphics, and more. "'With the donation of OpenOffice.org to the ASF, the Foundation, and especially the podling project, was given a daunting task: re-energize a community and transform OpenOffice from a codebase of unknown Intellectual Property heritage, to a vetted and Apache Licensed software suite,' said Jim Jagielski, ASF President and an Apache OpenOffice project mentor. 'The release of Apache OpenOffice 3.4 shows just how successful the project has been: pulling in developers from over 21 corporate affiliations, while avoiding undue influence which is the death-knell of true open source communities; building a solid and stable codebase, with significant improvement and enhancements over other variants; and, of course, creating a healthy, vibrant and diverse user and developer community.'"
Comments (23 posted)
The long-awaited release of version 2.8 of the GIMP image editor is out.
There are lots of new features, many of which were previewed in this article
last November. See the release
for lots of details.
Comments (23 posted)
For those looking for some advanced git tricks: this
has a lot to offer, especially with regard to
difficult merges. Much of it comes from Linus himself: "You didn't
know about ORIG_HEAD? That's literally a 'Day One' feature of git, exactly
because it's so incredibly useful (especially to a maintainer). We had
ORIG_HEAD back when you had to script your stuff manually and bang two
rocks together to make git do anything at all.
Comments (none posted)
The "GNU nPth" library project, under development as part of GnuPG, has
decloaked and made its first release available. "nPth is a
non-preemptive threads implementation using an API very similar to the one
known from GNU Pth. It has been designed as a replacement of GNU Pth for
non-ancient operating systems. In contrast to GNU Pth is is based on the
system's standard threads implementation. Thus nPth allows the use of
libraries which are not compatible to GNU Pth.
" It is dual-licensed
under LGPLv3 and GPLv2.
Full Story (comments: 24)
Version 2.3 of the Open Build Service is out. New features include a
number of improvements around release maintenance, an improved web
interface, better cross-build support, and issue tracking support.
Full Story (comments: none)
Newsletters and articles
Comments (none posted)
The H has a
four page article
by Lennart Poettering, Kay Sievers and Thorsten
Leemhuis on systemd. From the third page: "The unit files that are associated with systemd and the services are located in the /lib/systemd/system/ directory; if an identically named file exists in /etc/systemd/system/, systemd will ignore the one in the lib directory. This allows administrators to copy and customise a systemd unit file without running the risk that it could be overwritten during the next update – this can happen in SysVinit distributions if one of the init scripts stored in /etc/rc.d/init.d/ has been modified.
Comments (22 posted)
Over at ars technica Ryan Paul takes
the GNU Image Manipulation Program
(GIMP) 2.8 release for a spin and
looks at the future plans for the project, including a full transition to
the Generic Graphics Library (GEGL) in the 2.10 release. "After the 2.10 release arrives, the next major version will be 3.0. According to the roadmap, the goal for 3.0 will be delivering support for Gtk+ 3, a major new version of the underlying widget toolkit that is used to build the GIMP’s interface. The other major feature item included in the roadmap for version 3.0 is pervasive high bit-depth support, a major feature that will made possible by the GEGL transition.
Comments (17 posted)
On his blog, Uwe Hermann writes
about the free logic analyzer software that he and Bert Vermeulen have been working on. "I originally started working on an open-source logic analyzer software named "flosslogic" in 2010, because I grew tired of almost all devices having a proprietary and Windows-only software, often with limited features, limited input/output file formats, limited usability, limited protocol decoder support, and so on. Thus, the goal was to write a portable, GPL'd, software that can talk to many different logic analyzers via modules/plugins, supports many input/output formats, and many different protocol decoders.
The advantage being, that every time we add a new driver for another logic analyzer it automatically supports all the input/output formats we already have, you can use all the protocol decoders we already wrote, etc. It also works the other way around: If someone writes a new protocol decoder or file format driver, it can automatically be used with any of the supported logic analyzers out of the box.
(Thanks to Paul Wise.)
Comments (10 posted)
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