resvg

resvg is an SVG rendering library.

Purpose

resvg can be used as:

• a Rust library
• a C library (see capi)
• a CLI application (see tools/rendersvg)

to render SVG files based on a static SVG Full 1.1 subset to raster images or to a backend's canvas (e.g. to a QWidget via QPainter).

The core idea is to make a fast, small, portable, multiple-backend SVG library designed for edge-cases.

Another major difference from other SVG rendering libraries is that resvg does a lot of preprocessing before rendering. It converts an input SVG into a simplified one called Micro SVG and only then it begins rendering. So it's very easy to implement a new rendering backend. And you can also access Micro SVG as XML directly via usvg tool.

SVG support

resvg is aiming to support only the static SVG subset; e.g. no a, script, view or cursor elements, no events and no animations.

A list of unsupported features can be found here.

SVG Tiny 1.2 and SVG 2.0 are not supported and not planned.

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.

Performance

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 QRasterPaintEngine is slow.

• The Oxygen icon theme contains 4947 files.
• All images were converted from .svgz to .svg beforehand.
• resvg is slower than librsvg because the Oxygen icon theme uses Gaussian blur heavily, and librsvg has a faster blur implementation. Also, librsvg uses native cairo clipping, which is incorrect but faster.
• QtSvg doesn't support filter, clipPath, mask and pattern that are heavily used in the Oxygen icon theme. So it's actually very slow.

For more details checkout benches/README.md

Project structure

• resvg – rendering backends implementation
  • usvg – an SVG simplification tool
    • roxmltree – a DOM-like XML tree
      • xmlparser – an XML parser
    • svgtypes – SVG types parser and writer
    • simplecss – a simple CSS2 parser
    • ttf-parser – a TrueType/OpenType parser
    • xmlwriter – a simple XML writer
    • rctree – a DOM-like tree
  • resvg-qt – minimal bindings to Qt
  • resvg-skia – minimal bindings to Skia

All other dependencies aren't written by me for this project.

Directory structure

• benches - basic benchmarks for rendering operations
• bindings – minimal bindings to Qt and Skia used by resvg
• capi – C interface for resvg
• docs – basic documentation
• examples – usage examples for resvg as a library
• src – source code
• testing-tools – scripts used for testing
• tools – useful tools
• usvg – an SVG simplification library used by resvg

Safety

• The library must not panic. Any panic should be considered a critical bug and should be reported. There are only a 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 unsafe anyway. Also, usvg uses unsafe for fonts memory mapping.

License

resvg is licensed under the MPLv2.0.