TRows

Grid band class that paints multiple rows of column cells

Overview

TRows is a grid band class that paints multiple rows of column cells. It includes support for hierarchical “rows-inside-rows” through the Children property, enabling master-detail row structures.

Key Properties

Height · TCoordinate

Default height for all rows in pixels. Individual row heights can be overridden using the Heights property.

Grid.Rows.Height.Value := 25; // 25 pixels per row

Heights[Index] · Single

Individual height for a specific row. Allows different rows to have different heights.

Grid.Rows.Heights[0] := 30;  // First row 30 pixels
Grid.Rows.Heights[1] := 20;  // Second row 20 pixels

Spacing · TCoordinate

Vertical spacing between rows in pixels.

Grid.Rows.Spacing.Value := 2; // 2 pixels between rows

Back · TFormat

Background formatting for all rows. Defines the default background color, gradient, and other visual properties.

Grid.Rows.Back.Brush.Color := clWhite;

Alternate · TAlternateFormat

Formatting properties for odd-numbered rows. Enables alternating row colors for better readability.

Grid.Rows.Alternate.Visible := True;
Grid.Rows.Alternate.Brush.Color := clSilver;

RowLines · TStroke

Stroke properties for horizontal lines between rows.

Grid.Rows.RowLines.Visible := True;
Grid.Rows.RowLines.Color := clGray;
Grid.Rows.RowLines.Width := 1;

Hover · TCellHover

Selection and formatting properties for the cell under the mouse cursor.

Grid.Rows.Hover.Visible := True;
Grid.Rows.Hover.Format.Brush.Color := clYellow;

Data · TVirtualData

The data source for the rows. Must be assigned to display data in the grid.

Grid.Rows.Data := MyVirtualData;

Children · TRowsBands

Collection of optional sub-rows for each row. Enables hierarchical row structures.

var
  SubRow: TGridBand;
begin
  SubRow := Grid.Rows.Children.Add;
  // Configure sub-row
end;

SubBands · TRowsBands

Collection of additional bands that can be displayed for each row.

VisibleColumns · TVisibleColumns

Internal property containing an array of all visible columns. Used for rendering.

YSpacing · Single

Calculated vertical spacing value used internally for rendering.

Key Methods

HeightOf(ARow) · Single

Returns the height of the specified row, taking into account custom heights or the default height.

var
  H: Single;
begin
  H := Grid.Rows.HeightOf(5); // Height of row 5
end;

TopOf(ARow) · Single

Returns the Y coordinate of the top edge of the specified row.

var
  Y: Single;
begin
  Y := Grid.Rows.TopOf(10); // Top position of row 10
end;

BottomOf(ARow) · Single

Returns the Y coordinate of the bottom edge of the specified row.

var
  Y: Single;
begin
  Y := Grid.Rows.BottomOf(10); // Bottom position of row 10
end;

RowAt(Y, AvailableHeight) · Integer

Returns the row index at the specified Y coordinate, or -1 if no row is found.

var
  RowIndex: Integer;
begin
  RowIndex := Grid.Rows.RowAt(100, Grid.Height);
end;

FirstVisible(AOffset) · Integer

Returns the index of the first visible row, optionally offset by the specified amount.

var
  FirstRow: Integer;
begin
  FirstRow := Grid.Rows.FirstVisible(Grid.Rows.Scroll.Y);
end;

AutoHeight(ARow) · Single

Calculates the automatic height for the specified row based on cell content.

var
  H: Single;
begin
  H := Grid.Rows.AutoHeight(5);
  Grid.Rows.Heights[5] := H;
end;

AllHeightsEqual · Boolean

Returns true if all rows have the same height.

Empty · Boolean

Returns true if there are no rows to display (data is empty).

MaxBottom · Single

Returns the Y coordinate of the bottom of the last row.

CalcDefaultHeight

Calculates and sets the default row height based on font size and cell formatting.

Grid.Rows.CalcDefaultHeight;

Clear

Clears all row-specific data and resets to initial state.

Grid.Rows.Clear;

Swap(A, B)

Swaps two rows at the specified indices.

Grid.Rows.Swap(0, 5); // Swap first and sixth rows

Usage Examples

Basic Row Configuration

begin
  // Set default row height
  Grid.Rows.Height.Value := 30;
  
  // Configure row spacing
  Grid.Rows.Spacing.Value := 1;
  
  // Enable row lines
  Grid.Rows.RowLines.Visible := True;
  Grid.Rows.RowLines.Color := clSilver;
end;

Alternating Row Colors

begin
  // Set default row background
  Grid.Rows.Back.Brush.Color := clWhite;
  
  // Configure alternate row formatting
  Grid.Rows.Alternate.Visible := True;
  Grid.Rows.Alternate.Brush.Color := RGB(240, 240, 240);
end;

Custom Row Heights

var
  i: Integer;
begin
  // Set individual row heights
  for i := 0 to Grid.Rows.Data.Count - 1 do
  begin
    if i mod 3 = 0 then
      Grid.Rows.Heights[i] := 40  // Every third row is taller
    else
      Grid.Rows.Heights[i] := 25;
  end;
end;

Auto-Height Rows

var
  i: Integer;
  H: Single;
begin
  // Calculate automatic height for each row
  for i := 0 to Grid.Rows.Data.Count - 1 do
  begin
    H := Grid.Rows.AutoHeight(i);
    Grid.Rows.Heights[i] := H;
  end;
end;

Row Hover Effect

begin
  // Enable hover highlighting
  Grid.Rows.Hover.Visible := True;
  Grid.Rows.Hover.Format.Brush.Color := clYellow;
  Grid.Rows.Hover.Format.Transparency := 128; // Semi-transparent
end;

Finding Rows

var
  RowIndex: Integer;
  Y: Single;
begin
  // Find row at mouse position
  RowIndex := Grid.Rows.RowAt(Mouse.Y, Grid.Height);
  if RowIndex >= 0 then
  begin
    // Get row position
    Y := Grid.Rows.TopOf(RowIndex);
    ShowMessage(Format('Row %d at Y=%g', [RowIndex, Y]));
  end;
end;

Hierarchical Rows

var
  DetailBand: TGridBand;
begin
  // Add sub-rows (detail rows)
  DetailBand := Grid.Rows.Children.Add;
  DetailBand.Height.Value := 20;
  
  // Check if children are visible for a specific row
  if Grid.Rows.IsChildrenVisible(nil, 5) then
    ShowMessage('Row 5 has visible children');
end;

Scrolling

The TRows class includes scroll support:

begin
  // Access scroll position
  ShowMessage('Vertical scroll: ' + FloatToStr(Grid.Rows.Scroll.Y));
  
  // Get first visible row after scrolling
  var FirstRow := Grid.Rows.FirstVisible(Grid.Rows.Scroll.Y);
end;

Related Classes

• TColumn - Column class
• TColumns - Columns collection
• TRowGroup - Row group with headers and footers