svg: Add Svg widget for static SVG rendering

[seobinpark]

ThorVG's Picture::load() already supports the SVG MIME type, but the Flutter plugin only exposed it through the Lottie-specific native binding and build configuration.

Add a new Svg widget (Svg.asset/file/memory/network) that renders static SVG through the same native pipeline as Lottie. Generalize the previously Lottie-only native class into a format-neutral one that accepts the MIME type as a parameter, and include the SVG loader in the iOS/Android build scripts, which had excluded it from the compiled engine.

issue: #38

[Copilot]

Pull request overview

This PR adds first-class Flutter support for static SVG rendering using ThorVG’s existing Picture::load() SVG support, reusing the same native rendering pipeline previously exposed only for Lottie. It also generalizes the native “Lottie animation” binding into a format-neutral animation/picture wrapper that accepts a MIME type at load time, and updates mobile build scripts to compile the SVG loader into the embedded ThorVG engine.

Changes:

• Introduces a new Svg widget (Svg.asset/file/memory/network) for static SVG rendering via the ThorVG native pipeline.
• Generalizes the native/Dart FFI API from Lottie-specific to format-neutral by adding a mimetype parameter to load and renaming the binding types.
• Enables the ThorVG SVG loader in iOS/Android build scripts so SVG parsing is available in the compiled engine.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/tvgFlutterAnimation.h	Renames/modernizes the exported C API type to a format-neutral FlutterAnimation.
src/tvgFlutterAnimation.cpp	Generalizes native load to accept a MIME type (e.g., lottie+json, svg).
lottie/meson.build	Switches the built source from the Lottie-specific native file to the generalized one.
lottie/flutter_build.ios.sh	Enables the svg loader in the iOS ThorVG build configuration.
lottie/flutter_build.android.sh	Enables the svg loader in the Android ThorVG build configuration.
lib/thorvg.dart	Exposes the new Svg widget from the public package entrypoint.
lib/src/thorvg.dart	Updates the Dart wrapper to use the generalized native binding and pass MIME types.
lib/src/thorvg_bindings_generated.dart	Updates generated FFI bindings to use FlutterAnimation instead of Lottie-specific types.
lib/src/svg.dart	Adds the new Svg widget implementation (async load + native render to ui.Image).
lib/src/lottie.dart	Updates Lottie to pass its MIME type (lottie+json) into the generalized loader.
ffigen.yaml	Points ffigen at the new generalized native header for binding generation.
CONTRIBUTORS.md	Adds a new contributor entry.

Comments suppressed due to low confidence (2)

lib/src/svg.dart:183

• Calling tvg.load(..., 0, 0, ...) propagates a 0x0 size into the native resize() path (via load()), which reallocates a 0-byte buffer and targets the canvas with a null/invalid buffer. Use a minimal non-zero size for the initial load (you can still resize later for the actual render).

  void _tvgLoad() {
    try {
      tvg!.load(data, 'svg', 0, 0, false, false, false);

lib/src/svg.dart:200

• _tvgRender() can attempt to resize/render/decode with a 0 width/height (e.g., before constraints are resolved), which will throw in decodeImageFromPixels and can also trigger native issues. Guard against non-positive dimensions and avoid calling setState after dispose (async decode).

  void _tvgRender() async {
    try {
      tvg!.resize(renderWidth.toInt(), renderHeight.toInt());
      final buffer = tvg!.render();
      if (buffer == null) return;

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[tinyjin]

Thanks please check comments

[tinyjin]

@seobinpark

Need 3 commits? Please clean up the commit history.

Plus, good to add SVG example