如何在flutter中使用rive的状态机？

Posted 2023-02-23

【中文标题】如何在flutter中使用rive的状态机？

【英文标题】：How to use rive's state machine in flutter?

【发布时间】：2021-07-08 12:37:16

【问题描述】：

我创建了一个 .riv 文件，其中包含 3 个状态动画：开始、处理、结束，它们位于“状态机”中。 Rive 团队最近宣布了一项具有动态变化动画的新功能，它是“状态机”。不确定，如何在颤振项目中使用它，即如何动态改变动画的值。如果有人需要一些代码，没问题，我可以提供。此外，链接到 rive 的“状态机”https://www.youtube.com/watch?v=0ihqZANziCk。我没有找到与此新功能相关的任何示例。请帮忙！谢谢。

【参考方案1】：

rives pub 包站点上有示例。这是状态机的一个。 example_state_machine.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter/widgets.dart';
import 'package:rive/rive.dart';

/// An example showing how to drive two boolean state machine inputs.
class ExampleStateMachine extends StatefulWidget 
  const ExampleStateMachine(Key? key) : super(key: key);

  @override
  _ExampleStateMachineState createState() => _ExampleStateMachineState();


class _ExampleStateMachineState extends State<ExampleStateMachine> 
  /// Tracks if the animation is playing by whether controller is running.
  bool get isPlaying => _controller?.isActive ?? false;

  Artboard? _riveArtboard;
  StateMachineController? _controller;
  SMIInput<bool>? _hoverInput;
  SMIInput<bool>? _pressInput;

  @override
  void initState() 
    super.initState();

    // Load the animation file from the bundle, note that you could also
    // download this. The RiveFile just expects a list of bytes.
    rootBundle.load('assets/rocket.riv').then(
      (data) async 
        // Load the RiveFile from the binary data.
        final file = RiveFile.import(data);

        // The artboard is the root of the animation and gets drawn in the
        // Rive widget.
        final artboard = file.mainArtboard;
        var controller =
            StateMachineController.fromArtboard(artboard, 'Button');
        if (controller != null) 
          artboard.addController(controller);
          _hoverInput = controller.findInput('Hover');
          _pressInput = controller.findInput('Press');
        
        setState(() => _riveArtboard = artboard);
      ,
    );
  

  @override
  Widget build(BuildContext context) 
    return Scaffold(
      backgroundColor: Colors.grey,
      appBar: AppBar(
        title: const Text('Button State Machine'),
      ),
      body: Center(
        child: _riveArtboard == null
            ? const SizedBox()
            : MouseRegion(
                onEnter: (_) => _hoverInput?.value = true,
                onExit: (_) => _hoverInput?.value = false,
                child: GestureDetector(
                  onTapDown: (_) => _pressInput?.value = true,
                  onTapCancel: () => _pressInput?.value = false,
                  onTapUp: (_) => _pressInput?.value = false,
                  child: SizedBox(
                    width: 250,
                    height: 250,
                    child: Rive(
                      artboard: _riveArtboard!,
                    ),
                  ),
                ),
              ),
      ),
    );
  

【参考方案2】：

另一个答案已经过时了。

class SimpleStateMachine extends StatefulWidget 
  const SimpleStateMachine(Key? key) : super(key: key);

  @override
  _SimpleStateMachineState createState() => _SimpleStateMachineState();


class _SimpleStateMachineState extends State<SimpleStateMachine> 
  SMITrigger? _bump;

  void _onRiveInit(Artboard artboard) 
    final controller = StateMachineController.fromArtboard(artboard, 'bumpy');
    artboard.addController(controller!);
    _bump = controller.findInput<bool>('bump') as SMITrigger;
  

  void _hitBump() => _bump?.fire();

  @override
  Widget build(BuildContext context) 
    return Scaffold(
      appBar: AppBar(
        title: const Text('Simple Animation'),
      ),
      body: Center(
        child: GestureDetector(
          child: RiveAnimation.network(
            'https://cdn.rive.app/animations/vehicles.riv',
            fit: BoxFit.cover,
            onInit: _onRiveInit,
          ),
          onTap: _hitBump,
        ),
      ),
    );
  

查看 RIVE 指南：

https://help.rive.app/runtimes/state-machines