resvg is an SVG rendering library.
resvg can be used as:
The core idea is to make a fast, small, portable, multiple backend SVG library designed for edge-cases.
SVG can be rendered to a raster image or to a backend's canvas (e.g. to a QWidget via QPainter).
Why a new library?
One of the major differences from other rendering libraries is that resvg does a lot of preprocessing before rendering. It converts shapes to paths, resolves attributes, removes groups and invisible elements, fixes a lot of issues in malformed SVG files. Then it creates a simple render tree with all elements and attributes resolved. And only then it starts to render. So it's very easy to implement a new rendering backend.
More details here.
resvg vs librsvg
librsvg is the main competitor to the resvg. And even though that librsvg itself is being rewritten in Rust, as resvg, the architecture of the library is completely different:
- librsvg, currently, is heavily tied to the cairo library, unlike resvg
- librsvg is heavily tied to GNOME which makes it painful to distribute outside the Linux ecosystem
- librsvg doesn't really preprocess input files, rendering them as is
- librsvg has a minimal support of the edge-cases, which leads to rendering errors
resvg vs Inkscape
Inkscape is often used to convert SVG to PNG, but it's not an actual competitor to resvg, since it's still a complete vector editor, not a tiny library. Also, it's very slow. But it has the best SVG support amongst others.
resvg vs QtSvg
Without a doubt, QtSvg is heavily used in Qt applications. But QtSvg itself is very limited. It officially supports only a tiny portion of the SVG Tiny 1.2 subset. In simple terms - it correctly renders only primitive SVG images.
resvg is aiming to support only the static
SVG subset. E.g. no
cursor elements, no events and no animations.
Results of the static subset of the SVG test suite:
Results of the resvg test suite:
You can find a complete table of supported features here. It also includes alternative libraries.
Note that all tested applications have a different SVG support, which impacts the performance.
Also, we do not test against Chrome, Firefox, Inkscape and Batik because they have a huge startup time.
- Elementary Icon Theme contains 3417 files.
- Qt backend is slow because
- Oxygen Icon Theme contains 4947 files.
- All images were converted from
resvgis slower than
librsvgbecause Oxygen Icon Theme is using Gaussian blur heavily, which is expensive. And
librsvguses box blur optimization and multithreading, while
resvgalways uses a single-threaded IIR blur (at least for now).
- QtSvg doesn't support
patternthat are heavily used in the Oxygen Icon Theme. So it's actually very slow.
resvg- rendering backends implementation
All other dependencies aren't written by me for this project.
capi- C/FFI interface for resvg
docs- basic documentation
examples- resvg as a library usage examples
resvg-qt- a minimal bindings to Qt used by resvg
src- source code
testing_tools- scripts used for testing
tools- useful tools
usvg- an SVG simplification library used by resvg
- The library must not panic. Any panic should be considered a critical bug and reported. There are only few methods that can produce a panic.
- The core library structure (see above) does not use any
unsafe, but since all backends are implemented via FFI, we are stuck with
resvg is licensed under the MPLv2.0.