## resvg [![Build Status]](https://travis-ci.org/RazrFalcon/resvg)
[Build Status]: https://travis-ci.org/RazrFalcon/resvg.svg?branch=master
*resvg* is an [SVG](https://en.wikipedia.org/wiki/Scalable_Vector_Graphics) rendering library.
It can be used:
- As Rust library.
- As C library (see [capi](./capi)).
- As CLI application (see [tools/rendersvg](./tools/rendersvg)).
## Purpose
*resvg* can be used to render SVG files based on a
[static](http://www.w3.org/TR/SVG11/feature#SVG-static)
[SVG Full 1.1](https://www.w3.org/TR/SVG/Overview.html) subset, excluding
[fonts support](https://www.w3.org/TR/SVG11/feature#Font).
In simple terms: no animations, scripting and embedded fonts.
The core idea is to make a fast, portable, small, multiple backend library
designed for edge-cases.
It can be used as a simple SVG to PNG converter
and as an embeddable library to paint SVG on an application native canvas.
## Why a new library?
*resvg* is trying to compete with [librsvg], [QtSvg]
and [Inkscape] (only as a CLI SVG to PNG converter).
One of the main difference from other rendering libraries is that *resvg* does a lot
of preprocessing before rendering. It converts shapes to paths, resolves attributes,
removes groups, removes invisible elements, fixes a lot of issues in malformed SVG files
and only then starts the rendering. So it's very easy to implement a new rendering backend.
More details [here](https://github.com/RazrFalcon/usvg/blob/master/docs/usvg_spec.adoc).
### 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 [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*,
because it's still a complete SVG editor, not a tiny library.
Also, it's very slow.
But it has the best SVG support amongst other.
### 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.
## SVG support
Results of the static subset of the [SVG test suite](https://www.w3.org/Graphics/SVG/Test/20110816/):
Results of the [resvg test suite](https://github.com/RazrFalcon/resvg-test-suite):
You can find a complete table of supported features
[here](https://razrfalcon.github.io/resvg-test-suite/svg-support-table.html).
It also includes alternative libraries.
TL;DR
- no `filter`
- no `marker`
- no `symbol`
- no `view`
- CSS support is minimal
## Performance
- Oxygen Icon Theme 4.12
- Contains 4947 files.
- All images are converted from `.svgz` to `.svg`.
- In the `resvg` >80% of the time is spent during PNG generation.
- The `librsvg` is slower than `resvg` because those icons are using Gaussian blur heavily, which is expensive.
- QtSvg is suspiciously slow for no reasons. Source code can be found
[here](https://github.com/RazrFalcon/resvg-test-suite/tree/master/tools/qtsvgrender).
- ["Benchmark" source code](https://github.com/RazrFalcon/resvg-test-suite/tree/master/tools/perf).
## Backends
*resvg* supports [Qt] and [cairo] backends.
## Project structure
- `resvg` - rendering backends implementation
- [`usvg`](https://github.com/RazrFalcon/usvg) - an SVG simplification tool
- [`svgdom`](https://github.com/RazrFalcon/svgdom) - a DOM-like SVG tree
- [`svgtypes`](https://github.com/RazrFalcon/svgtypes) - SVG types parser and writer
- [`xmlparser`](https://github.com/RazrFalcon/xmlparser) - an XML parser
- [`rctree`](https://github.com/RazrFalcon/rctree) - a DOM-like tree
- [`resvg-qt`](https://github.com/RazrFalcon/resvg-qt) - a minimal bindings for [Qt]
All other dependencies aren't written by me for this project.
## Build
See [doc/build.md](doc/build.md) for details.
## License
*resvg* is licensed under the [MPLv2.0](https://www.mozilla.org/en-US/MPL/).
[Inkscape]: https://www.inkscape.org
[librsvg]: https://wiki.gnome.org/action/show/Projects/LibRsvg
[QtSvg]: https://doc.qt.io/qt-5/qtsvg-index.html
[cairo]: https://www.cairographics.org/
[Qt]: https://www.qt.io/
[Skia]: https://skia.org/
[GNOME]: https://www.gnome.org/