trackoffical_app/lib/widget/matrix_gesture_detector.dart

import 'dart:math';
import 'package:flutter/widgets.dart';
import 'package:trackoffical_app/logger.dart';

typedef MatrixGestureDetectorCallback = void Function(
    Matrix4 matrix,
    Matrix4 translationDeltaMatrix,
    Matrix4 scaleDeltaMatrix,
    Matrix4 rotationDeltaMatrix,
    );

/// [MatrixGestureDetector] detects translation, scale and rotation gestures
/// and combines them into [Matrix4] object that can be used by [Transform] widget
/// or by low level [CustomPainter] code. You can customize types of reported
/// gestures by passing [shouldTranslate], [shouldScale] and [shouldRotate]
/// parameters.
///
class MatrixGestureDetector extends StatefulWidget {
  /// [Matrix4] change notification callback
  ///
  final MatrixGestureDetectorCallback onMatrixUpdate;

  /// The [child] contained by this detector.
  ///
  /// {@macro flutter.widgets.child}
  ///
  final Widget child;

  /// Whether to detect translation gestures during the event processing.
  ///
  /// Defaults to true.
  ///
  final bool shouldTranslate;

  /// Whether to detect scale gestures during the event processing.
  ///
  /// Defaults to true.
  ///
  final bool shouldScale;

  /// Whether to detect rotation gestures during the event processing.
  ///
  /// Defaults to true.
  ///
  final bool shouldRotate;

  /// Whether [ClipRect] widget should clip [child] widget.
  ///
  /// Defaults to true.
  ///
  final bool clipChild;

  final GlobalKey? childKey;

  /// When set, it will be used for computing a "fixed" focal point
  /// aligned relative to the size of this widget.
  final Alignment? focalPointAlignment;

  const MatrixGestureDetector({
    Key? key,
    required this.onMatrixUpdate,
    required this.child,
    this.shouldTranslate = true,
    this.shouldScale = true,
    this.shouldRotate = true,
    this.clipChild = true,
    this.focalPointAlignment,
    this.childKey,
  }) : super(key: key);

  @override
  _MatrixGestureDetectorState createState() => _MatrixGestureDetectorState(childKey);

  ///
  /// Compose the matrix from translation, scale and rotation matrices - you can
  /// pass a null to skip any matrix from composition.
  ///
  /// If [matrix] is not null the result of the composing will be concatenated
  /// to that [matrix], otherwise the identity matrix will be used.
  ///
  static Matrix4  compose(Matrix4 matrix, Matrix4? translationMatrix,
      Matrix4? scaleMatrix, Matrix4? rotationMatrix) {

    if (translationMatrix != null) matrix = translationMatrix * matrix;
    if (scaleMatrix != null) matrix = scaleMatrix * matrix;
    if (rotationMatrix != null) matrix = rotationMatrix * matrix;
    return matrix;
  }

  ///
  /// Decomposes [matrix] into [MatrixDecomposedValues.translation],
  /// [MatrixDecomposedValues.scale] and [MatrixDecomposedValues.rotation] components.
  ///
  static MatrixDecomposedValues decomposeToValues(Matrix4 matrix) {
    var array = matrix.applyToVector3Array([0, 0, 0, 1, 0, 0]);
    Offset translation = Offset(array[0], array[1]);
    Offset delta = Offset(array[3] - array[0], array[4] - array[1]);
    double scale = delta.distance;
    double rotation = delta.direction;
    return MatrixDecomposedValues(translation, scale, rotation);
  }
}

class _MatrixGestureDetectorState extends State<MatrixGestureDetector> {
  Matrix4 translationDeltaMatrix = Matrix4.identity();
  Matrix4 scaleDeltaMatrix = Matrix4.identity();
  Matrix4 rotationDeltaMatrix = Matrix4.identity();
  Matrix4 matrix = Matrix4.identity();
  final GlobalKey? childKey;
  _MatrixGestureDetectorState(this.childKey);

  @override
  Widget build(BuildContext context) {
    Widget child =
    widget.clipChild ? ClipRect(child: widget.child) : widget.child;
    return GestureDetector(
      onScaleStart: onScaleStart,
      onScaleUpdate: onScaleUpdate,
      child: child,
    );
  }

  _ValueUpdater<Offset> translationUpdater = _ValueUpdater(
    onUpdate: (oldVal, newVal) => newVal - (oldVal ?? Offset.zero),
  );
  _ValueUpdater<double> rotationUpdater = _ValueUpdater(
    onUpdate: (oldVal, newVal) => newVal - (oldVal ?? 0),
  );
  _ValueUpdater<double> scaleUpdater = _ValueUpdater(
    onUpdate: (oldVal, newVal) => newVal / (oldVal ?? 1),
  );

  void onScaleStart(ScaleStartDetails details) {
    translationUpdater.value = details.focalPoint;
    rotationUpdater.value = double.nan;
    scaleUpdater.value = 1.0;
  }

  void onScaleUpdate(ScaleUpdateDetails details) {
    translationDeltaMatrix = Matrix4.identity();
    scaleDeltaMatrix = Matrix4.identity();
    rotationDeltaMatrix = Matrix4.identity();

    // handle matrix translating
    if (widget.shouldTranslate) {
      Offset translationDelta = translationUpdater.update(details.focalPoint);
      translationDeltaMatrix = _translate(translationDelta);
      matrix = translationDeltaMatrix * matrix;
    }

    Offset? focalPoint;

    if (widget.focalPointAlignment != null && context.size != null) {
      focalPoint = widget.focalPointAlignment!.alongSize(context.size!);
    } else {
      RenderObject? renderObject;
      if (childKey != null ){
        renderObject = childKey?.currentContext?.findRenderObject();
      }else{
        renderObject = context.findRenderObject();
      }

      if (renderObject != null) {
        RenderBox renderBox = renderObject as RenderBox;
        focalPoint = renderBox.globalToLocal(details.focalPoint);
      }
    }

    // handle matrix scaling
    if (widget.shouldScale && details.scale != 1.0 && focalPoint != null) {
      double scaleDelta = scaleUpdater.update(details.scale);
      scaleDeltaMatrix = _scale(scaleDelta, focalPoint);
      matrix = scaleDeltaMatrix * matrix;
    }

    // handle matrix rotating
    if (widget.shouldRotate && details.rotation != 0.0) {
      if (rotationUpdater.value == null || rotationUpdater.value!.isNaN) {
        rotationUpdater.value = details.rotation;
      } else {
        if (focalPoint != null) {
          double rotationDelta = rotationUpdater.update(details.rotation);
          rotationDeltaMatrix = _rotate(rotationDelta, focalPoint);
          matrix = rotationDeltaMatrix * matrix;
        }
      }
    }

    widget.onMatrixUpdate(
        matrix, translationDeltaMatrix, scaleDeltaMatrix, rotationDeltaMatrix);
  }

  Matrix4 _translate(Offset translation) {
    var dx = translation.dx;
    var dy = translation.dy;

    //  ..[0]  = 1       # x scale
    //  ..[5]  = 1       # y scale
    //  ..[10] = 1       # diagonal "one"
    //  ..[12] = dx      # x translation
    //  ..[13] = dy      # y translation
    //  ..[15] = 1       # diagonal "one"
    return Matrix4(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, dx, dy, 0, 1);
  }

  Matrix4 _scale(double scale, Offset focalPoint) {
    var dx = (1 - scale) * focalPoint.dx;
    var dy = (1 - scale) * focalPoint.dy;

    //  ..[0]  = scale   # x scale
    //  ..[5]  = scale   # y scale
    //  ..[10] = 1       # diagonal "one"
    //  ..[12] = dx      # x translation
    //  ..[13] = dy      # y translation
    //  ..[15] = 1       # diagonal "one"
    return Matrix4(
        scale, 0, 0, 0,
        0, scale, 0, 0,
        0, 0, 1, 0,
        0, 0, 0, 1);
        // dx, dy, 0, 1);
  }

  Matrix4 _rotate(double angle, Offset focalPoint) {
    var c = cos(angle);
    var s = sin(angle);
    var dx = (1 - c) * focalPoint.dx + s * focalPoint.dy;
    var dy = (1 - c) * focalPoint.dy - s * focalPoint.dx;

    //  ..[0]  = c       # x scale
    //  ..[1]  = s       # y skew
    //  ..[4]  = -s      # x skew
    //  ..[5]  = c       # y scale
    //  ..[10] = 1       # diagonal "one"
    //  ..[12] = dx      # x translation
    //  ..[13] = dy      # y translation
    //  ..[15] = 1       # diagonal "one"
    return Matrix4(
          c,  s,  0,  0,
          -s, c,  0,  0,
          0,  0,  1,  0,
        0, 0, 0, 1);
          // dx, dy, 0,  1);
  }
}

typedef _OnUpdate<T> = T Function(T? oldValue, T newValue);

class _ValueUpdater<T> {
  final _OnUpdate<T> onUpdate;
  T? value;

  _ValueUpdater({required this.onUpdate});

  T update(T newValue) {
    T updated = onUpdate(value, newValue);
    value = newValue;
    return updated;
  }
}

class MatrixDecomposedValues {
  /// Translation, in most cases useful only for matrices that are nothing but
  /// a translation (no scale and no rotation).
  final Offset translation;

  /// Scaling factor.
  final double scale;

  /// Rotation in radians, (-pi..pi) range.
  final double rotation;

  MatrixDecomposedValues(this.translation, this.scale, this.rotation);

  @override
  String toString() {
    return 'MatrixDecomposedValues(translation: $translation, scale: ${scale.toStringAsFixed(3)}, rotation: ${rotation.toStringAsFixed(3)})';
  }
}