Limiting the range about flutter-circular-slider HOT 3 OPEN

var angle = coordinatesToRadians(_painter.center, position);
var percentage = radiansToPercentage(angle);
// Int value on the slider representing the new value of the handler.
var newValue = percentageToValue(percentage, widget.divisions);

if (isBothHandlersSelected) {
  // The user is dragging a section between two handlers.
  if (_isSecondHandlerSelected && _isFirstHandlerSelected) {
    // The user is moving the section between handler #1 and #2.
    // Calculates new value for handler #1.
    var newFirstValue =
        (newValue - _differenceFromInitPoint) % widget.divisions;
    if (newFirstValue != widget.firstValue) {
      // Handler #1 is at a different position so update all the values.
      var newSecondValue =
          (widget.secondValue + (newFirstValue - widget.firstValue)) % widget.divisions;
      var newThirdValue =
          (widget.thirdValue + (newFirstValue - widget.firstValue)) % widget.divisions;
      var newFourthValue =
          (widget.fourthValue + (newFirstValue - widget.firstValue)) % widget.divisions;
      widget.onSelectionChange(
          newFirstValue, newSecondValue, newThirdValue, newFourthValue);
      if (isPanEnd) {
        widget.onSelectionEnd(
            newFirstValue, newSecondValue, newThirdValue, newFourthValue);
      }
    }
  } else if (_isThirdHandlerSelected && _isSecondHandlerSelected) {
    // The user is moving the section between handler #2 and #3.
    var newValueEnd =
        (newValue - _differenceFromInitPoint) % widget.divisions;
    if (newValueEnd != widget.secondValue) {
      var diff = newValueEnd - widget.secondValue;
      var newValueInit_2 = (widget.thirdValue + diff) % widget.divisions;
      var newValueEnd_2 = (widget.fourthValue + diff) % widget.divisions;
      var newValueInit = (widget.firstValue + diff) % widget.divisions;
      widget.onSelectionChange(
          newValueInit, newValueEnd, newValueInit_2, newValueEnd_2);
      if (isPanEnd) {
        widget.onSelectionEnd(
            newValueInit, newValueEnd, newValueInit_2, newValueEnd_2);
      }
    }
  } else if (_isFourthHandlerSelected && _isThirdHandlerSelected) {
    // The user is moving the section between handler #3 and #4.
    var newValueInit_2 =
        (newValue - _differenceFromInitPoint) % widget.divisions;
    if (newValueInit_2 != widget.thirdValue) {
      var diff = newValueInit_2 - widget.thirdValue;
      var newValueEnd_2 = (widget.fourthValue + diff) % widget.divisions;
      var newValueInit = (widget.firstValue + diff) % widget.divisions;
      var newValueEnd = (widget.secondValue + diff) % widget.divisions;
      widget.onSelectionChange(
          newValueInit, newValueEnd, newValueInit_2, newValueEnd_2);
      if (isPanEnd) {
        widget.onSelectionEnd(
            newValueInit, newValueEnd, newValueInit_2, newValueEnd_2);
      }
    }
  } else {
    // The user is moving the section between handler #4 and #1.
    var newValueEnd_2 =
        (newValue - _differenceFromInitPoint) % widget.divisions;
    if (newValueEnd_2 != widget.fourthValue) {
      var diff = newValueEnd_2 - widget.fourthValue;
      var newValueInit = (widget.firstValue + diff) % widget.divisions;
      var newValueEnd = (widget.secondValue + diff) % widget.divisions;
      var newValueInit_2 = (widget.thirdValue + diff) % widget.divisions;
      widget.onSelectionChange(
          newValueInit, newValueEnd, newValueInit_2, newValueEnd_2);
      if (isPanEnd) {
        widget.onSelectionEnd(
            newValueInit, newValueEnd, newValueInit_2, newValueEnd_2);
      }
    }
  }
  // No need to manage single handlers.
  return;
}

// isDoubleHandler but one handler was selected
if (_isFirstHandlerSelected) {
  // prec = end_2 succ = end
  if (!_isInRange(newValue, widget.fourthValue, widget.secondValue)) {
    newValue = widget.firstValue;
  }
  widget.onSelectionChange(
      newValue, widget.secondValue, widget.thirdValue, widget.fourthValue);
  if (isPanEnd) {
    widget.onSelectionEnd(
        newValue, widget.secondValue, widget.thirdValue, widget.fourthValue);
  }
} else if (_isSecondHandlerSelected) {
  // prec = init e succ = init_2
  if (!_isInRange(newValue, widget.firstValue, widget.thirdValue)) {
    newValue = widget.secondValue;
  }
  widget.onSelectionChange(
      widget.firstValue, newValue, widget.thirdValue, widget.fourthValue);
  if (isPanEnd) {
    widget.onSelectionEnd(
        widget.firstValue, newValue, widget.thirdValue, widget.fourthValue);
  }
} else if (_isThirdHandlerSelected) {
  // prec = end e succ = end_2
  if (!_isInRange(newValue, widget.secondValue, widget.fourthValue)) {
    newValue = widget.thirdValue;
  }
  widget.onSelectionChange(widget.firstValue, widget.secondValue, newValue, widget.fourthValue);
  if (isPanEnd) {
    widget.onSelectionEnd(widget.firstValue, widget.secondValue, newValue, widget.fourthValue);
  }
} else {
  //_isEnd_2HandlerSelected
  // prec = init_2 e succ = init
  if (!_isInRange(newValue, widget.thirdValue, widget.firstValue)) {
    newValue = widget.fourthValue;
  }
  widget.onSelectionChange(
      widget.firstValue, widget.secondValue, widget.thirdValue, newValue);
  if (isPanEnd) {
    widget.onSelectionEnd(widget.firstValue, widget.secondValue, widget.thirdValue, newValue);
  }
}