ExportedIDLookup class Widget

Used to look up what part of a ScalableImage is clicked on within a ScalableImageWidget.

An SVG node can have a name in its id attribute. When an SVG is read, or converted to an SI, these ID values can be marked as exported. This can be done by listing the IDs, or by using a regular expression. For example, to build an SI where all ID values are exported, you can specify -x '.*' to svg_to_si. Each exported ID does add some overhead, so in production, it's best to only export the ones you need.

A ScalableImageWidget can have an ExportedIDLookup instance associated with it. This can be used, for example, to determine which node(s) are under a mouse click (or other tap event).

Usage:

class _GlorpState extends State<GlorpWidget> {
    final ExportedIDLookup _idLookup = ExportedIDLookup();
    ...
    @override
    Widget build() => ...
        GestureDetector(
          onTapDown: _handleTapDown,
          child: ScalableImageWidget(
            ...
            lookup: _idLookup))
      ...;

  void _handleTapDown(TapDownDetails event) {
    final Set<String> hits = _idLookup.hits(event.localPosition);
    print('Tap down at ${event.localPosition}:  $hits');
  }
}

See demo/lib/main.dart for a more complete example.