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Overview

The TGridBands class is a collection that manages multiple TGridBand objects. Grid bands are rectangular areas within a TeeGrid that can display headers, footers, totals, or custom content. Each band supports mouse interaction, custom height, and click events.

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Class Hierarchy

TCollectionChange
  └── TGridBands

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Properties

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Visible

property Visible: Boolean read FVisible write SetVisible default True;
Controls whether the band collection is visible in the grid. Default: True Example: 
TeeGrid1.Header.Bands.Visible := False; // Hide all header bands

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Items

property Items[Index: Integer]: TGridBand read Get write Put; default;
Provides indexed access to individual TGridBand objects in the collection. Parameters:
  • Index: Zero-based integer index
Example: 
var
  Band: TGridBand;
begin
  Band := TeeGrid1.Header.Bands[0];
  Band.Height.Pixels := 40;
end;

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Floating

var Floating: Boolean;
Determines whether bands float over grid content or occupy fixed space.

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Height

var Height: Single;
The total calculated height of all bands in the collection.

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Methods

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Constructor Create

Constructor Create(AOwner: TPersistent; const AChanged: TNotifyEvent);
Creates a new TGridBands collection. Parameters:
  • AOwner: The persistent object that owns this collection
  • AChanged: Event handler called when the collection changes

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Assign

procedure Assign(Source: TPersistent); override;
Copies properties from another persistent object. Parameters:
  • Source: The source object to copy from
Example: 
TeeGrid2.Header.Bands.Assign(TeeGrid1.Header.Bands);

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AddText

function AddText(const AText: String): TTextBand;
Adds a new text band to the collection with the specified text. Parameters:
  • AText: The text to display in the band
Returns: The newly created TTextBand object Example: 
var
  Band: TTextBand;
begin
  Band := TeeGrid1.Header.Bands.AddText('Monthly Report');
  Band.Height.Pixels := 30;
  Band.TextRender.Font.Size := 14;
  Band.TextRender.Font.Style := [fsBold];
end;

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CalcHeight

procedure CalcHeight(const APainter: TPainter; const ATotal: Single);
Calculates the total height required for all bands in the collection. Parameters:
  • APainter: The painter object used for measurement calculations
  • ATotal: The total available height

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CanDisplay

function CanDisplay: Boolean; inline;
Returns True if the band collection can be displayed (is visible and contains items). Returns: Boolean indicating if bands should be painted

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Mouse

procedure Mouse(var AState: TMouseState; const AWidth, AHeight: Single);
Handles mouse events for all bands in the collection. Parameters:
  • AState: The current mouse state (position, button, event type)
  • AWidth: The width of the band area
  • AHeight: The height of the band area

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Paint

procedure Paint(var AData: TRenderData);
Paints all visible bands in the collection. Parameters:
  • AData: Rendering data containing painter and bounds information

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TGridBand

Base class for individual bands with the following key properties:
  • Height: TBandHeight - The height of the band
  • OnClick: TNotifyEvent - Event triggered when the band is clicked
  • Visible: Boolean - Controls band visibility
  • Hover: Inherited hover support for mouse interaction

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TTextBand

Specialized band for displaying text, inherits from TGridBand:
  • Text: String - The text to display
  • TextRender: TCellRender - Formatting options for the text

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Usage Examples

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Creating a Custom Header

procedure SetupCustomHeader(Grid: TTeeGrid);
var
  TitleBand: TTextBand;
begin
  Grid.Headers.Visible := True;
  
  // Add title band
  TitleBand := Grid.Headers.AddText('Sales Dashboard');
  TitleBand.Height.Pixels := 40;
  TitleBand.TextRender.Font.Size := 16;
  TitleBand.TextRender.Font.Style := [fsBold];
  TitleBand.Format.Brush.Color := clNavy;
  TitleBand.TextRender.Font.Color := clWhite;
end;

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Adding Multiple Bands

procedure AddMultipleBands(Grid: TTeeGrid);
var
  Band1, Band2: TTextBand;
begin
  // Add header bands
  Band1 := Grid.Headers.AddText('Company Name');
  Band1.Height.Pixels := 30;
  
  Band2 := Grid.Headers.AddText('Report Date: ' + DateToStr(Now));
  Band2.Height.Pixels := 25;
  Band2.TextRender.Font.Size := 10;
end;

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Handling Band Click Events

procedure TForm1.CreateBandWithClick;
var
  Band: TTextBand;
begin
  Band := TeeGrid1.Headers.AddText('Click Me');
  Band.OnClick := BandClickHandler;
end;

procedure TForm1.BandClickHandler(Sender: TObject);
begin
  ShowMessage('Band clicked!');
end;

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Constants

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Spacing

const Spacing = 0;
The spacing between bands (currently fixed at 0 pixels).

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See Also

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