Why NovaSVG

• Nothing to link. Drop in novasvg.h (or the include/ folder) and you are done. No submodules, no system libraries, no fontconfig.
• Renders what real diagrams contain. Gradients, patterns, clip paths, masks, markers, a full SVG filter pipeline, CSS styling, embedded fonts, and <foreignObject> text, which is what Mermaid uses for every label.
• Close to a browser. Compared against Chromium on a 60-sample corpus, including 49 Mermaid diagrams. See how it stacks up.
• More than a renderer. Query elements with CSS selectors, rewrite styles, read bounding boxes and matrices, and render a single element on its own.
• Three ways in. C++ library, a novasvg command-line tool, and Python bindings with no dependencies.
• Portable. Windows, Linux and macOS, with the same text layout on every platform.

Quick start

C++

#include <novasvg/novasvg.h>
#include <iostream>

int main() {
    auto doc = novasvg::Document::loadFromFile("artwork.svg");
    if (!doc) return 1;

    // 640 px wide, height follows the aspect ratio, white background
    auto bitmap = doc->renderToBitmap(640, -1, novasvg::Color::white());
    bitmap.writeToPng("artwork.png");        // also writeToJpg / writeToBmp / writeToTga

    // Query it like a DOM
    for (auto& rect : doc->querySelectorAll("rect"))
        std::cout << rect.getAttribute("id") << '\n';

    std::cout << doc->width() << " x " << doc->height() << '\n';
}

g++ -std=c++17 -O2 -Iinclude main.cpp -o main

Command line

novasvg input.svg                                  # -> input.png
novasvg input.svg -o out.png -w 800 -b FFFFFF      # width 800, white background
novasvg input.svg --style "rect { fill: tomato; }" # restyle before rendering
novasvg info input.svg                             # size, bounding box, element count
novasvg query "circle" input.svg --json            # CSS-selector search
novasvg batch svg_dir/ png_dir/                    # convert a whole folder

Python

pip install novasvg        # no dependencies; NumPy is only needed for Bitmap.numpy()

import novasvg

novasvg.svg2png("artwork.svg", "artwork.png", width=800)     # one call

doc = novasvg.Document.load_from_file("artwork.svg")         # or keep the document
bitmap = doc.render_to_bitmap(width=800)
bitmap.write_to_png("artwork.png")

More in README_PYTHON.md.

Installation

Single header. Download novasvg.h and include it. Every function is inline, so it is safe to include from any number of translation units.

Copy the headers. Put include/novasvg/ in your project and #include <novasvg/novasvg.h>.

CMake FetchContent.

include(FetchContent)
FetchContent_Declare(novasvg
    GIT_REPOSITORY https://github.com/MohammadRaziei/novasvg.git
    GIT_TAG        master)
FetchContent_MakeAvailable(novasvg)

target_link_libraries(my_app PRIVATE novasvg::novasvg)

Installed package.

cmake -B build && cmake --build build -j
sudo cmake --install build

find_package(novasvg REQUIRED)
target_link_libraries(my_app PRIVATE novasvg::novasvg)   # or novasvg::noflag for no extra compile flags

Building from source also produces the novasvg command-line tool at build/novasvg.

How it compares

The same SVGs rendered by each engine, with Chromium as the reference. These samples were picked because the engines disagree on them.

Sample	Chromium	novasvg	resvg	lunasvg	cairosvg	thorvg	nanosvg
clip-mask
mermaid-02-flowchart
css-use-symbol
mermaid-47-flowchart-br-bold-label
mermaid-33-treemap
gradient-filter
mermaid-40-erd-relations
mermaid-01-venn
filter-primitives
mermaid-32-radar

Want the numbers behind the pictures? The full benchmark page lists every one of the 60 samples with its RMSE against Chromium and its render time in ms for every engine. You can click any render to zoom in.

👉 mohammadraziei.github.io/novasvg/benchmarks

You can also rebuild all of it yourself; see benchmarks/README.md.

What it renders

Not implemented yet: per-primitive filter regions, feColorMatrix / feTurbulence / feDisplacementMap, WOFF/WOFF2 fonts, and full HTML/CSS layout inside <foreignObject>. See checklist.md and COMPARISON.md for details.

Fonts

Font lookup works like a browser, with no OS font library involved. A font-family stack is walked name by name: an installed or registered font first, then a metric-compatible stand-in (arial → Liberation Sans / Arimo, times new roman → Liberation Serif / Tinos, calibri → Carlito, ...), then the generic keywords. A ~40 KB Latin subset of DejaVu Sans is compiled in as the last resort, so text renders even on a machine with no fonts installed. For the best fidelity, install a metric-compatible family such as fonts-liberation.

novasvg::addFontFaceFromFile("Inter", /*bold=*/false, /*italic=*/false, "Inter-Regular.ttf");

Disable the embedded font with -DNOVASVG_EMBED_DEFAULT_FONT=OFF or by defining NOVASVG_DISABLE_EMBEDDED_FONT.

API overview

Full reference: mohammadraziei.github.io/novasvg, or build it locally with -DNOVASVG_BUILD_DOCS=ON.

Command-line reference

novasvg --help and novasvg <subcommand> --help always list the current options.

Build options

Repository layout

include/novasvg/    the library (novasvg.h + detail/)
src/                command-line tool and Python bindings
examples/cpp/       small runnable samples
tests/              C++ (doctest) and Python (pytest) tests
benchmarks/         comparison against resvg, lunasvg, thorvg, nanosvg, cairosvg and Chromium
data/               sample SVGs, Mermaid corpus, bundled fonts
docs/               documentation site sources

Contributing

Issues and pull requests are welcome. Please fork, work on a feature branch, add a test when you change behaviour, and open a PR.

cmake -B build -DNOVASVG_BUILD_TESTS=ON && cmake --build build -j
ctest --test-dir build

License

MIT

Acknowledgments

NovaSVG grew out of the architecture of lunasvg, restructured as a flat, dependency-free, single-header library. The story is in docs/about.md.