vyuh_diagram_core 3.2.0

Headless diagram engine for Dart: create shapes and connectors, edit through transactions with undo and redo, and extend with plugins. No Flutter needed.

example/main.dart

import 'package:vyuh_diagram_codec_json/vyuh_diagram_codec_json.dart';
import 'package:vyuh_diagram_core/vyuh_diagram_core.dart';

/// Run on the Dart VM. The same content commands work in the Flutter kit.
void main() {
  final controller = DiagramController();
  try {
    late final String tasks;
    controller.edits.batch('Plan the idea', () {
      // Every verb returns a decision; creations carry the new identity.
      final idea = controller.edits
          .createShape(
            Shapes.rectangle,
            text: 'An idea',
            at: const DiagramPoint(120, 120),
            style: const ShapeStyle(fill: DiagramColor(0xffd9f99d)),
          )
          .id!;
      tasks = controller.edits
          .createText(
            at: const DiagramPoint(400, 120),
            text: 'Sketch an idea\nBuild it together',
          )
          .id!;
      controller.edits
          .setTextAlignment(tasks, ParagraphAlignment.center)
          .requireAllowed();
      final connection = controller.edits.connect(idea, tasks).id!;
      controller.edits.addConnectorLabel(connection, text: 'Next step');
      controller.edits
          .setText(connection, 'Next step\nReview together')
          .requireAllowed();
      controller.edits
          .setConnectorStyle(connection, strokeStyle: StrokeStyle.dashed)
          .requireAllowed();
    }).requireAllowed();

    controller.edits
        .move(const DiagramPoint(0, 40), ids: [tasks])
        .requireAllowed();
    controller.edits.undo().requireAllowed();
    controller.edits.redo().requireAllowed();

    // Installed extensions persist the content and text they own.
    final saved = controller.save(DiagramJsonCodec.new);
    final reopened = DiagramController.open(
      saved,
      format: DiagramJsonCodec.new,
    );
    try {
      // Send this JSON to your application's file or persistence layer.
      // This command-line example writes it to standard output.
      // ignore: avoid_print
      print(reopened.save(DiagramJsonCodec.new));
    } finally {
      reopened.dispose();
    }
  } finally {
    controller.dispose();
  }
}