resolveSvgInPayload function

Future resolveSvgInPayload(dynamic node, { int size = defaultSvgRasterSize, })

Recursively walks a method-channel node (maps/lists), rasterizing any Flutter asset SVG referenced by an image-bearing key (see svgImageDataKeys) and attaching the PNG bytes to a sibling <key>Data key.

Behavior:

• A single-image key (e.g. image, imageUrl) whose value is an SVG asset -> sibling <key>Data (Uint8List).
• A list-image key (e.g. gridImages) -> sibling <key>Data (List<Uint8List?>, null for non-SVG entries).
• Keys in svgIgnoredKeys are skipped entirely (never rasterized, never recursed into).
• Original image strings are preserved for native fallback / back-compat.

The node is mutated in place and also returned for convenience.

Implementation

Future<dynamic> resolveSvgInPayload(
  dynamic node, {
  int size = defaultSvgRasterSize,
}) async {
  if (node is Map) {
    for (final entry in svgImageDataKeys.entries) {
      final value = node[entry.key];
      if (svgListImageKeys.contains(entry.key)) {
        if (value is! List) continue;
        var hasSvg = false;
        final data = <Uint8List?>[];
        for (final item in value) {
          final bytes = await _rasterizeIfSvg(item, size);
          data.add(bytes);
          if (bytes != null) hasSvg = true;
        }
        if (hasSvg) node[entry.value] = data;
      } else {
        final bytes = await _rasterizeIfSvg(value, size);
        if (bytes != null) node[entry.value] = bytes;
      }
    }

    // Recurse into all values, skipping ignored keys and the byte payloads we
    // just attached. The latter are raster bytes ([Uint8List], which is itself
    // a `List<int>`) or lists of them; descending into those would needlessly
    // walk every individual byte.
    for (final key in node.keys.toList()) {
      if (svgIgnoredKeys.contains(key)) continue;
      if (_svgDataKeys.contains(key)) continue;
      final value = node[key];
      if (value is Uint8List) continue;
      await resolveSvgInPayload(value, size: size);
    }
  } else if (node is List) {
    for (final item in node) {
      if (item is Uint8List) continue;
      await resolveSvgInPayload(item, size: size);
    }
  }

  return node;
}