GridDelegateWithInOrderChildPlacement({double columnSpacing: 0.0, double rowSpacing: 0.0, EdgeInsets padding: EdgeInsets.zero })

Initializes columnSpacing, rowSpacing, and padding for subclasses.

By default, the columnSpacing, rowSpacing, and padding are zero.

Source 

GridDelegateWithInOrderChildPlacement({
  this.columnSpacing: 0.0,
  this.rowSpacing: 0.0,
  this.padding: EdgeInsets.zero
}) {
  assert(columnSpacing != null && columnSpacing >= 0.0);
  assert(rowSpacing != null && rowSpacing >= 0.0);
  assert(padding != null && padding.isNonNegative);
}