Thorvg.NET

This repository contains low-level bindings for ThorVG used in Evergine. This binding is generated from the ThorVG release: https://github.com/thorvg/thorvg/releases/tag/v1.1.0

Purpose

ThorVG is a lightweight vector graphics engine: it rasterises SVG, Lottie animations, text and shapes into a plain memory buffer, with no windowing system and no GPU required.

These bindings expose ThorVG's C API to .NET so that Evergine — and any other .NET application — can rasterise vector content directly, with no marshalling layer in between. See the upstream repository and the official documentation for what the engine itself can do.

Features

• Complete C API — 165 entry points covering the engine, canvases, shapes, gradients, pictures, text, animations and savers
• Names match the C API — tvg_engine_init, Tvg_Paint, TVG_RESULT_SUCCESS read exactly as they do in the ThorVG documentation, so upstream examples translate line by line
• Zero-overhead interop — opaque handles are plain IntPtr, value types are blittable structs; no wrapper allocations
• Renders anywhere — the software rasteriser writes straight into a buffer you own, so there is no window, context or GPU to set up
• Generated, not hand-written — regenerating for a new ThorVG release is a single command

Supported Platforms

• Windows x64, ARM64
• Linux x64, ARM64
• MacOS ARM64
• Android ARM64, x64
• iOS ARM64 and the ARM64 simulator — static archives, linked by buildTransitive/
• MacOS x64, browser-wasm — not built yet; each is one more leg in the native build

Android needs nothing special: the .so files sit under runtimes/android-*/native/ and .NET probes them by RID. iOS has no dynamic loader for third-party code, so it ships a static archive and buildTransitive/Evergine.Bindings.ThorVG.targets tells the consuming build to link it. The iOS link has not been verified against a real application — ThorVG bundles its own PNG, JPEG and WebP decoders, so -force_load could surface duplicate symbols in an app that also links those libraries.

Usage

usingEvergine.Bindings.ThorVG;
unsafe
{ThorVG.tvg_engine_init(0);IntPtrcanvas=ThorVG.tvg_swcanvas_create(Tvg_Engine_Option.TVG_ENGINE_OPTION_DEFAULT);varbuffer=newuint[512*512];
fixed (uint*pixels=buffer){ThorVG.tvg_swcanvas_set_target(canvas,pixels,512,512,512,Tvg_Colorspace.TVG_COLORSPACE_ARGB8888);IntPtrpicture=ThorVG.tvg_picture_new();ThorVG.tvg_picture_load(picture,"logo.svg");ThorVG.tvg_canvas_add(canvas,picture);ThorVG.tvg_canvas_draw(canvas,true);ThorVG.tvg_canvas_sync(canvas);}// `buffer` now holds the rasterised image.ThorVG.tvg_canvas_destroy(canvas);ThorVG.tvg_engine_term();}

Test/Program.cs is a runnable version of the above that also checks the native library against the header the bindings were generated from.

Demo

LowLevelDemo/ drives the binding the way an application would: ThorVG rasterises an animated vector scene — a breathing radial gradient, a ring of rotating petals, a star built from raw path commands, a dashed stroked arc and a looping Lottie loaded from memory — into a CPU buffer every frame, and the Evergine low-level graphics API uploads that buffer to a texture and presents it with a fullscreen triangle. The rasteriser is CPU-only, so no GPU features beyond a textured triangle are involved.

dotnet run --project LowLevelDemo/LowLevelDemo.csproj

Strings and buffers

const char* arguments — paths, mimetypes, names — are marshalled as UTF-8. The two payload arguments, on tvg_picture_load_data and tvg_font_load_data, take a byte* instead: they carry an explicit size and are bytes, not text, so marshalling them as a string would mangle PNG, WebP, TTF and compressed Lottie. Version strings come back as byte* pointing at library-owned memory — read them with Marshal.PtrToStringUTF8 and never free them.

Engines

The shipped libraries are built with the CPU rasteriser only. thorvg_capi.h declares the GL and WebGPU canvas functions unconditionally, so they are part of the binding surface and return TVG_RESULT_NOT_SUPPORTED at run time. Enabling those engines is a build-flag change and does not alter the managed API.

Building

dotnet build ThorvgGen.sln

To regenerate the bindings after changing the header:

dotnet run --project ThorvgGen/ThorvgGen.csproj

The generator parses ThorvgGen/Headers/thorvg_capi.h with CppAst and writes Evergine.Bindings.ThorVG/Generated/. ThorvgGen/Headers/libc-stubs/ stands in for the two system headers ThorVG includes, so parsing does not depend on the host's libc and Windows and Linux produce identical output.

Native libraries

ThorVG publishes no binaries — every release carries a single source tarball — so this repository compiles its own. .github/workflows/thorvg-meson.yml builds all four RIDs with meson from a given tag and stages each library at its final path; CD runs it automatically whenever the tracked release moves, so the header and the libraries always come from one revision.

The build uses -Dbindings=capi, which is off by default and without which the library builds perfectly and exports not one tvg_* symbol. The workflow checks the output for tvg_engine_init rather than trusting a green build.

Related Evergine Bindings

• WebGPU.NET — Bindings for WebGPU
• Meshoptimizer.NET — Bindings for meshoptimizer
• RenderDoc.NET — Bindings for RenderDoc
• XAtlas.NET — Bindings for xatlas
• MuJoCo.NET — Bindings for MuJoCo