ViewportModel class

A viewport widget for scrollable content.

The viewport manages a scrollable view of content that may be larger than the available display area. It supports vertical and horizontal scrolling with keyboard and mouse input.

Example

class DocViewerModel implements Model {
  final ViewportModel viewport;
  final String content;

  DocViewerModel({ViewportModel? viewport, this.content = ''})
      : viewport = (viewport ?? ViewportModel(width: 80, height: 24))
          ..setContent(content);

  @override
  (Model, Cmd?) update(Msg msg) {
    // Handle window resize
    if (msg is WindowSizeMsg) {
      return (
        DocViewerModel(
          viewport: viewport.copyWith(
            width: msg.width,
            height: msg.height - 2, // Leave room for status
          ),
          content: content,
        ),
        null,
      );
    }

    final (newViewport, cmd) = viewport.update(msg);
    return (
      DocViewerModel(viewport: newViewport as ViewportModel, content: content),
      cmd,
    );
  }

  @override
  String view() => '''
${viewport.view()}
${(viewport.scrollPercent * 100).toInt()}%
''';
}