camera_button_controller.dart

import 'dart:math';

import 'package:flare_dart/math/mat2d.dart';
import 'package:flare_flutter/flare.dart';
import 'package:flare_flutter/flare_controller.dart';
import 'package:flutter/animation.dart';

enum CameraButtonState { closed, camera, accept, upload, cancel }

const double _mixIconTime = 0.4;
const double _interpolateProgressTime = 0.1;

class CameraButtonController extends FlareController {
  ActorAnimation _open;
  ActorAnimation _progress;
  ActorAnimation _showProgress;
  ActorAnimation _showIcons;
  ActorAnimation _showCancel;
  ActorAnimation _iconEmpty;
  ActorAnimation _iconAccept;
  ActorAnimation _iconCamera;

  ActorAnimation _iconAnimation;

  double _openTime = 0.0;
  double _iconMix = 0.0;
  double _showProgressTime = 0.0;
  double _showCancelTime = 0.0;
  double _showIconsTime = 0.0;

  CameraButtonState _state;
  CameraButtonState get state => _state;
  set state(CameraButtonState value) {
    if (value == _state) {
      return;
    }
    _state = value;
    // reset icon mix
    _iconMix = 0;
    switch (_state) {
      case CameraButtonState.camera:
        _iconAnimation = _iconCamera;
        break;
      case CameraButtonState.accept:
        _iconAnimation = _iconAccept;
        break;
      case CameraButtonState.cancel:
      case CameraButtonState.upload:
        _iconAnimation = _iconEmpty;
        break;
      default:
        _iconAnimation = null;
        break;
    }
    isActive.value = true;
  }

  double _progressValue = 0.0;
  double _targetProgress = 0.0;
  double get progress => _targetProgress;
  set progress(double value) {
    isActive.value = true;
    _targetProgress = value.clamp(0, 1);
  }

  @override
  bool advance(FlutterActorArtboard artboard, double elapsed) {
    double displayProgress = 0;

    bool keepRunning = false;
    switch (_state) {
      case CameraButtonState.closed:
        _openTime = max(0, _openTime - elapsed);
        if (_openTime == 0) {
          // reset progress visibility to 0 once fully closed.
          _showProgressTime = 0;
          _showCancelTime = 0;
          _showIconsTime = 0;
        }

        if (_openTime > 0) {
          keepRunning = true;
        }
        break;
      case CameraButtonState.camera:
      case CameraButtonState.accept:
        _openTime = min(_open.duration, _openTime + elapsed);
        _showProgressTime = max(0, _showProgressTime - elapsed);
        _showIconsTime = min(_showIcons.duration, _showIconsTime + elapsed);
        _showCancelTime = max(0, _showCancelTime - elapsed);
        if (_openTime < _open.duration ||
            _showProgressTime > 0 ||
            _showIconsTime < _showIcons.duration ||
            _showCancelTime > 0) {
          keepRunning = true;
        }
        break;

      case CameraButtonState.cancel:
        displayProgress = _targetProgress;
        _showIconsTime = min(_showIcons.duration, _showIconsTime + elapsed);
        _showCancelTime = min(_showCancel.duration, _showCancelTime + elapsed);
        _openTime = min(_open.duration, _openTime + elapsed);
        _showProgressTime =
            min(_showProgress.duration, _showProgressTime + elapsed);
        if (_showIconsTime < _showIcons.duration ||
            _showCancelTime < _showCancel.duration ||
            _openTime < _open.duration ||
            _showProgressTime < _showProgress.duration) {
          keepRunning = true;
        }
        break;

      case CameraButtonState.upload:
        displayProgress = _targetProgress;
        _openTime = min(_open.duration, _openTime + elapsed);
        _showCancelTime = max(0, _showCancelTime - elapsed);
        _showProgressTime =
            min(_showProgress.duration, _showProgressTime + elapsed);

        if (_openTime < _open.duration ||
            _showCancelTime > 0 ||
            _showProgressTime < _showProgress.duration) {
          keepRunning = true;
        }
        break;
    }
    _progressValue += (displayProgress - _progressValue) *
        min(1.0, elapsed / _interpolateProgressTime);
    if ((_progressValue - displayProgress).abs() > 0.01) {
      keepRunning = true;
    }

    // finally apply animations
    _showIcons.apply(_showIconsTime, artboard, 1.0);
    _showProgress.apply(_showProgressTime, artboard, 1.0);
    _showCancel.apply(_showCancelTime, artboard, 1.0);
    _open.apply(_openTime, artboard, 1.0);
    // interpolate towards icon
    if (_iconAnimation != null) {
      _iconMix = min(1, _iconMix + (elapsed / _mixIconTime));
      _iconAnimation.apply(0.0, artboard, Curves.easeInOut.transform(_iconMix));
      if ((_iconMix - 1).abs() > 0.01) {
        keepRunning = true;
      }
    }
    _progress.apply(_progressValue * _progress.duration, artboard, 1.0);

    return keepRunning;
  }

  @override
  void initialize(FlutterActorArtboard artboard) {
    _open = artboard.getAnimation("open");
    _progress = artboard.getAnimation("progress");
    _showProgress = artboard.getAnimation("show-progress");
    _showCancel = artboard.getAnimation("show-cancel");
    _showIcons = artboard.getAnimation("show-icons");
    _iconEmpty = artboard.getAnimation("icon-none");
    _iconAccept = artboard.getAnimation("icon-check");
    _iconCamera = artboard.getAnimation("icon-camera");
    state = CameraButtonState.closed;
  }

  @override
  void setViewTransform(Mat2D viewTransform) {
    // intentionally empty, we don't need the view transform.
  }
}