sizeOf static method

Rect sizeOf({
  1. required int index,
  2. required int length,
  3. required BoxConstraints constraints,
})

Returns a Rect of an element at the provided index in a FitView with the specified length and constraints.

Implementation

static Rect sizeOf({
  required int index,
  required int length,
  required BoxConstraints constraints,
}) {
  final columns = calculate(constraints: constraints, length: length);
  final rows = (length / columns).ceil();
  final outside = length % columns;

  for (int rowIndex = 0; rowIndex < rows; rowIndex++) {
    for (int columnIndex = 0; columnIndex < columns; columnIndex++) {
      final cellIndex = rowIndex * columns + columnIndex;

      if (cellIndex == index) {
        int inThisRow = columns;

        if (rows != 1 && columns != 1 && rowIndex == rows - 1) {
          inThisRow = outside;
        }

        final double width = constraints.maxWidth / inThisRow;
        final double height = constraints.maxHeight / rows;

        return Rect.fromLTWH(
          columnIndex * width,
          rowIndex * height,
          width,
          height,
        );
      }
    }
  }

  return Rect.zero;
}