examples/api/lib/widgets/interactive_viewer/interactive_viewer.transformation_controller.0.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';

/// Flutter code sample for [InteractiveViewer.transformationController].

void main() => runApp(const TransformationControllerExampleApp());

class TransformationControllerExampleApp extends StatelessWidget {
  const TransformationControllerExampleApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: TransformationControllerExample(),
    );
  }
}

class TransformationControllerExample extends StatefulWidget {
  const TransformationControllerExample({super.key});

  @override
  State<TransformationControllerExample> createState() => _TransformationControllerExampleState();
}

/// [AnimationController]s can be created with `vsync: this` because of
/// [TickerProviderStateMixin].
class _TransformationControllerExampleState extends State<TransformationControllerExample>
    with TickerProviderStateMixin {
  final TransformationController _transformationController = TransformationController();
  Animation<Matrix4>? _animationReset;
  late final AnimationController _controllerReset;

  void _onAnimateReset() {
    _transformationController.value = _animationReset!.value;
    if (!_controllerReset.isAnimating) {
      _animationReset!.removeListener(_onAnimateReset);
      _animationReset = null;
      _controllerReset.reset();
    }
  }

  void _animateResetInitialize() {
    _controllerReset.reset();
    _animationReset = Matrix4Tween(
      begin: _transformationController.value,
      end: Matrix4.identity(),
    ).animate(_controllerReset);
    _animationReset!.addListener(_onAnimateReset);
    _controllerReset.forward();
  }

// Stop a running reset to home transform animation.
  void _animateResetStop() {
    _controllerReset.stop();
    _animationReset?.removeListener(_onAnimateReset);
    _animationReset = null;
    _controllerReset.reset();
  }

  void _onInteractionStart(ScaleStartDetails details) {
    // If the user tries to cause a transformation while the reset animation is
    // running, cancel the reset animation.
    if (_controllerReset.status == AnimationStatus.forward) {
      _animateResetStop();
    }
  }

  @override
  void initState() {
    super.initState();
    _controllerReset = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 400),
    );
  }

  @override
  void dispose() {
    _controllerReset.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Theme.of(context).colorScheme.primary,
      appBar: AppBar(
        automaticallyImplyLeading: false,
        title: const Text('Controller demo'),
      ),
      body: Center(
        child: InteractiveViewer(
          boundaryMargin: const EdgeInsets.all(double.infinity),
          transformationController: _transformationController,
          minScale: 0.1,
          maxScale: 1.0,
          onInteractionStart: _onInteractionStart,
          child: Container(
            decoration: const BoxDecoration(
              gradient: LinearGradient(
                begin: Alignment.topCenter,
                end: Alignment.bottomCenter,
                colors: <Color>[Colors.orange, Colors.red],
                stops: <double>[0.0, 1.0],
              ),
            ),
          ),
        ),
      ),
      persistentFooterButtons: <Widget>[
        IconButton(
          onPressed: _animateResetInitialize,
          tooltip: 'Reset',
          color: Theme.of(context).colorScheme.surface,
          icon: const Icon(Icons.replay),
        ),
      ],
    );
  }
}