calculateAxisPositioning function

AxisPosition calculateAxisPositioning({ required double totalSize, required double objectSize, required double axisPosition, })

Given an axis (x or y) of totalSize, this will calculate how to position an object in the axis based on its objectSize and the axisPosition. If the object exceed the totalSize at the top or the bottom, it will be aligned at the start or at the end with _alignObject.

Implementation

AxisPosition calculateAxisPositioning({
  required double totalSize,
  required double objectSize,
  required double axisPosition,
}) {
  if (axisPosition < 0.0 || axisPosition > 1.0) {
    throw AssertionError('The axisPosition must be provided and must be a value'
        ' between 0.0 and 1.0 inclusive');
  }

  if (objectSize >= totalSize)
    return _alignObject(
      totalSize: totalSize,
      objectSize: objectSize,
      alignEnd: true,
      alignStart: true,
    );

  final objectCenter = totalSize * axisPosition;
  final objectHalfSize = objectSize / 2;

  final firstSize = objectCenter - objectHalfSize;
  if (firstSize < 0)
    return _alignObject(
      totalSize: totalSize,
      objectSize: objectSize,
      alignStart: true,
    );

  final secondSize = totalSize - objectCenter - objectHalfSize;
  if (secondSize < 0)
    return _alignObject(
      totalSize: totalSize,
      objectSize: objectSize,
      alignEnd: true,
    );

  return AxisPosition(
    firstSpace: AxisCoordinates(start: 0, end: firstSize),
    objectSpace: AxisCoordinates(start: firstSize, end: firstSize + objectSize),
    secondSpace: AxisCoordinates(start: firstSize + objectSize, end: totalSize),
  );
}