c# - Limiting DataGridView cell multi selection to only column or row -

i have datagridview number of columns , rows. have mutliselect enabled, allows selection of cells.

i want limit selection vertically, horizontally, full row or full column, never mix of both. user can select dragging starting @ cell either vertically or horizontally.

here's small diagram clarify if helps @ all.

here's brute force method - when selection changes, de-select cells fall outside current row/column selection:

int _selectedrow = -1; int _selectedcolumn = -1; private void datagridview1_selectionchanged(object sender, eventargs e) {     switch (datagridview1.selectedcells.count)     {         case 0:             // store no current selection             _selectedrow = -1;             _selectedcolumn = -1;             return;         case 1:             // store starting point multi-select             _selectedrow = datagridview1.selectedcells[0].rowindex;             _selectedcolumn = datagridview1.selectedcells[0].columnindex;             return;     }      foreach (datagridviewcell cell in datagridview1.selectedcells)     {         if (cell.rowindex == _selectedrow)         {             if (cell.columnindex != _selectedcolumn)             {                 _selectedcolumn = -1;             }         }         else if (cell.columnindex == _selectedcolumn)         {             if (cell.rowindex != _selectedrow)             {                 _selectedrow = -1;             }         }         // otherwise cell selection illegal - de-select         else cell.selected = false;     } }