Development Project Ideas

General

• Improve startup time and initialization performance (i.e. improve font cache).
• Improve icon cache: Convert the icon cache (widgets/icon.cpp) to create the PNGs with a directory structure and index file matching the icon theme specification. Use this to get rid of customized classes InkAction, SPIcon, and so on.
• Continue C++ migration:
  • Use Glib::ustring for UTF-8 data and std::string for filenames and raw byte strings instead of C-strings (char*).
  • Replace uses of GList and GSList with STL containers.
• Use a different data structure for Inkscape::Selection. Inkscape::Selection currently uses GSList as its data structure. This is suboptimal, since a very common operation is checking whether some object is selected. Change Inkscape::Selection so that its underlying structure is a boost::multi_index container which implements the same semantics as Java's LinkedHashSet.
• Extension system improvements: Refactor the extension API. Clean up the kludgy class hierarchy, possibly using multiple inheritance. Use GInputStream and GOutputStream as parameters instead of file paths, so that things like the clipboard can write data to memory without going through a temporary file.

XML tree

• SAX parser: Convert the current document parser from DOM to SAX, so that it creates our XML tree right away, instead of creating the libxml2 DOM tree, creating our tree to match it, then freeing the libxml2 tree. This should improve performance and allow more robust fixes for some problems.
• Typed XML tree: Improve XML tree so that it can store some attributes in parsed, binary form. The main target of this are the data URIs used to embed images, which could be stored as binary data only. This work should be done after completing the SAX parser, as this will make it easier.

2Geom geometry library

• Rewrite of Geom::PathVector and Geom::Path:
  • Change PathVector to be a real object instead of a std::vector of Path, so that it can have useful methods, similar to curves.
  • Move the copy-on-write idiom to the PathVector object, rather than using it in the Path.
  • Investigate whether it is possible to store subpath data in a more compact way and make the Curve objects only convenience facades. Right now, if the path has only linear segments, every point is stored twice.
  • Apply the following renames to match SVG terminology:
    • Path -> Subpath
    • PathVector -> Path
• Remove SPCurve: SPCurve is a thin wrapper around Geom::PathVector which exists for historical reasons. Its functionality should be added to PathVector, and SPCurve should be purged.
• Provide a quick bounding box routine for stroked paths.
• Boolean operations and stroking: Add methods to PathVector objects:
  • Set operators (& | - ^), which perform the relevant boolean operation on the paths. Use the algorithm from CGAL or devise a new robust algorithm.
  • stroke(double line_width, LineJoin join, LineCap cap, double miter_limit), which performs the stroke-to-path operation.
  • stroke(double line_width, LineJoin join, LineCap cap, double miter_limit, std::vector<double> const &dasharray), which performs stroke-to-path with dashing.

Object tree

• Improve the performance of layer visibility: Right now, toggling layer visibility causes massive changes in the display tree, because the entire toggled layer is invalidated at the XML level. This results in very bad performance for an action which should nearly instantaneous. Improve the control flow so that only the visibility of the object representing the layer is turned off, but the remainder of the display and object tree is leaved alone.
• Robust ID handling: Currently ID clash resolution is implemented as a giant switch over object types, listing every possible dependency. Replace this with virtual methods on objects, which provide information on what each object refers to. Improve behavior when a dependency of an object is deleted, and when IDs are changed / deleted from the XML editor.
• Replace the print functions in the SPxxx classes with a generic "Visitor" pattern and port at least one export type (e.g. EMF, PDF, PS) to the new routines.

User interface

• Shape manipulators: The idea here is to rewrite shape tools in the same paradigm as the node tool. Instead of storing all information about the shape in knots which differ only by their callbacks, allow to store information in a higher-level manipulator object. This would enable things like dragging the side of a rectangle, consistent outlining / update preferences for all shapes, and editing more than one shape at once.
• Transformation Anchors
• Extend the Symbols dialog to include generic objects.
• Connector tool improvements - Expose new libavoid functionality: orthogonal routing, connector ports, curved connectors. (Mentor: Michael Wybrow)
• Fillet/Chamfer tool
• Provide more actions in the context menu depending on the content of the selection, e.g. show "Put on Path", "Flow into Frame" etc. when the selection contains the appropriate objects.
• When right-clicking a control point, show a transient dialog which would allow one to key in its coordinates.
• Provide a way to resize the page directly on the canvas, instead of keying in numbers in the Document Properties dialog.

Project infrastructure and platform support

• Migrate argument parsing to GOption and remove the dependency on popt. Update the devlibs version of Glib to one where this bug is fixed: [1]. Once this is done, port argument parsing to GOption.
• Common build system for all platforms: Migrate the build system to CMake for all platforms and remove Autotools.
• GTK3 on Windows: Rebuild the Windows devlibs so that they contain GTK3. Make the Windows port work with them, possibly sending the appropriate patches to the GTK maintainers.

Rendering Improvements

• ICC Color Management for cairo outputs - Would allow Inkscape to produce CMYK PDFs and PSs with Cairo.
• Box blur: Currently we always use a very accurate method to compute the Gaussian blur filter. Add an alternate method which approximates Gaussian blur using three stacked box blurs (simple averages). This is detailed in the SVG 1.1 SE specification.
• Pluggable renderers - allow writing rendering backends which use something other than Cairo, e.g, OpenGL, Skia, Mozilla Azure or GEGL.
• OpenGL renderer - implement an OpenGL 3.x+ canvas which would render Beziers using this method: http://http.developer.nvidia.com/GPUGems3/gpugems3_ch25.html Investigate whether this generalizes to S-basis and circular arcs. Since the described method does not handle stroking, this work depends on implementing boolean operations and stroking. Also check how OpenGL path rendering is implemented in Qt, since apparently the performance there is very good. http://zrusin.blogspot.com/2011/09/nv-path-rendering.html

Better SVG standard coverage

• Full SVG viewbox support
• Multiple Page support
• Improve SVG compliance. Current status of W3C test suite compliance.

SVG 2 and CSS3

See: SVG2.

This includes providing suitable GUI and SVG 1.1 fallbacks.

• Filling and Stroking
  • Stroke position
  • Stroke dash adjustment
  • Multiple fills
  • Paint order (Rendering alread implemented, needs GUI and fallback.)
  • Marker color matching stroke.
  • Vector Effects (non-destructive boolean-ops would be a good start)
  • CSS3 color support
  • CSS3 blend modes

• Paint servers
  • Solid-color support (Named colors, would deprecate the single-stop gradient approach we currently use)
  • Mesh gradient (Basic implementation done, needs refinement and fallback.)
  • Hatched patterns

• Text
  • CSS based text flow

• Misc
  • CSS3 2d and 3d transforms

Note: Some of the above items are somewhat low hanging fruit and would need a few of them to make a good proposal, others alone are worthy of a full GSoC project.

Improve Inkscape SVG for use on Web

A proposal should fix most if not all of these problems:

• Fix "plain" SVG to not remove <script> section, etc.
• Add option to set viewbox attribute to Document Properties.
• Easily add/edit hyperlinks.
• Better CSS support.
• Option to add title to SVG (searchability and accessibility).
• Remove XML prolog/DOCTYPE.
• Move sodipodi namespace items to Inkscape namespace.

Improved Eraser tool

Example of result of the cut/eraser tool

The Eraser tool has some limitations in cut-out from objects mode:

• There is a minimum width of 1 unit in the line to cut, thus the resulting parts don't fit exactly (1 unit gap minimum).
• This mode does not work with groups.
• The cut is not constrained: no straight or parallel modes.

The goal is make an optional to produce a zero width cut that solves the above problems.
There are new Boolean operations, implemented but not used in trunk. We need to switch the division method from Livarot to these new operations.
Another feature interesting is a button to get the guides over the selected item and use it as cut-out.
We can make optional check to convert strokes to path previously to cut to avoid continuing with stroke thought cut-out item fills.

Live Path Effects related

• More Live Path Effects - There is a lengthy list of ideas to choose from here.

Import/export projects

• Importing of 3D scene files in 16 file formats using Open Asset Import Library
• xar-to-svg converter - Converter for Xara Xtreme to Inkscape
• KML SVG translation - For use of Inkscape with Google Earth or Maps

Generic ideas

• Font editing and creation features, e.g. designing SVG fonts using styles
• kidscape - Condensed version of Inkscape aimed at young kids and small form factor devices
• Cutter control - Enable Inkscape's use with vinyl cutters.