Table of Contents

Selection

Pick the right selection mode, set selections programmatically, query what the user has selected, and react to selection changes.

Overview

Selection in TTMSFNCDataGrid is governed by Options.Selection.Mode — a single setting that determines whether one cell, one row, a range of cells, multiple disjoint rows, or anything in between is selectable. On top of the mode, RangeType selects between standard range expansion and Excel-style anchored selection.

DataGrid with a rectangular cell-range selection highlighted DataGrid with a rectangular cell-range selection highlighted (dark theme)

Quick example

Grid.Options.Selection.Mode := gsmCellRange;
Grid.Selection := MakeCellRange(0, 1, 3, 4);   // L=0, T=1, R=3, B=4

Selection modes

Mode Behaviour
gsmNone Selection disabled. Other interactions still work.
gsmSingleCell Exactly one cell at a time.
gsmSingleRow One whole row.
gsmSingleColumn One whole column.
gsmCellRange A contiguous rectangle. Shift+Click extends.
gsmRowRange Multiple contiguous rows.
gsmColumnRange Multiple contiguous columns.
gsmDisjunctRow Non-contiguous rows. Ctrl+Click to add.
gsmDisjunctColumn Non-contiguous columns.
gsmDisjunctCell Non-contiguous individual cells.
gsmDisjunctCellRange Disjoint ranges, like Windows Explorer. 
Grid.Options.Selection.Mode := gsmDisjunctRow;   // user can Ctrl+Click rows

Programmatic selection

Single cell

Grid.FocusedCell := MakeCell(2, 5);

A rectangular range

Grid.Selection := MakeCellRange(2, 1, 5, 10);    // L=2, T=1, R=5, B=10

A whole row or column (in matching mode)

Grid.Options.Selection.Mode := gsmSingleRow;
Grid.SelectedRows[5] := True;

Grid.Options.Selection.Mode := gsmSingleColumn;
Grid.SelectedColumns[2] := True;
DataGrid with a whole column selected — the Year column highlighted across every row DataGrid with a whole column selected — the Year column highlighted across every row (dark theme)

Multiple disjoint rows

Grid.Options.Selection.Mode := gsmDisjunctRow;
Grid.SelectedRows[2] := True;
Grid.SelectedRows[5] := True;
Grid.SelectedRows[8] := True;
DataGrid in disjoint-row mode with three non-contiguous rows selected DataGrid in disjoint-row mode with three non-contiguous rows selected (dark theme)

Reading the selection

API Returns
Grid.Selection Current rectangular range (always set, even in single-cell mode).
Grid.FocusedCell The cell with keyboard focus.
Grid.SelectedCells[col, row] True if (col, row) is part of the selection.
Grid.SelectedRows[row] True if the row is selected.
Grid.SelectedColumns[col] True if the column is selected.
Grid.SelectedCellCount Number of selected cells (any mode).
Grid.SelectedRowCount Number of selected rows.
Grid.SelectedColumnCount Number of selected columns. 
for var i := 0 to Grid.RowCount - 1 do
  if Grid.SelectedRows[i] then
    ProcessRow(i);

Excel-style range selection

Grid.Options.Selection.RangeType := gsrtKeepFocusedCell;

In this mode the grid behaves like Excel — the anchor cell stays put while Shift+Arrow expands the active end of the selection:

Keys Behaviour
Arrow Move active cell; resets the anchor.
Shift+Arrow Expand selection one cell from the anchor.
Ctrl+Arrow Jump to the next data boundary; selection unchanged.
Ctrl+Shift+Arrow Expand selection to the next data boundary.
Click Set new anchor.
Shift+Click Expand from anchor to clicked cell.

Selection on fixed cells

Options.Mouse.FixedCellSelection lets the fixed corner / row / column act as a selection trigger:

Value Effect
gfcsAll Top-left fixed cell selects every cell (with gsmCellRange).
gfcsRow Click a fixed-column cell to select its row (with gsmSingleRow).
gfcsColumn Click a fixed-row cell to select its column (with gsmSingleColumn).
gfcsRowRange / gfcsColumnRange Same, but supporting drag-extend with gsmRowRange / gsmColumnRange.

Fixed-cell selection is automatically suppressed when column-dragging, row-dragging, or sorting is enabled, since they need the click for their own behaviour.

Visual highlight on fixed cells

Set Options.Selection.ShowSelectionInFixedCells := True to highlight the row's fixed cell (and the column's fixed header) for the current selection — a row-number / header glow that follows the selection.

Events

Event When it fires
OnSelectingCell Before the selection changes; you can cancel.
OnSelectCell After the selection has moved.
OnSelectingCells / OnSelectCells Range equivalents. 
procedure TForm1.GridSelectCell(Sender: TObject; AColumn, ARow: Integer);
begin
  StatusBar1.SimpleText :=
    Format('Selected (%d, %d)', [AColumn, ARow]);
end;

Clearing selection

Grid.ClearSelection;        // clears every form of selection
Grid.SelectedRows[5] := False;
Grid.Selection := MakeCellRange(-1, -1, -1, -1);
  • Grid.Options.Selection.Mode — selection mode (see table above).
  • Grid.Options.Selection.RangeType — gsrtNormal or gsrtKeepFocusedCell (Excel-style).
  • Grid.Options.Selection.ShowSelectionInFixedCells — highlight fixed header.
  • Grid.Options.Mouse.FixedCellSelection — fixed-cell click behaviour.
  • Grid.Selection, Grid.FocusedCell
  • Grid.SelectedCells[col, row], SelectedRows[row], SelectedColumns[col]
  • Grid.SelectedCellCount, SelectedRowCount, SelectedColumnCount
  • Grid.ClearSelection
  • OnSelectingCell / OnSelectCell

See also