setColumn method
Sets the active column for subsequent operations.
This method is called before getLength and buildItem to specify which column is being processed. The index is typically 0-based.
Parameters:
index
- The column index to activate
Implementation
@override
void setColumn(int index) {
//print("setColumn index: $index");
_col = index + 1;
if (_col < 0) _col = 0;
}