> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/Steema/TeeGrid-VCL-FMX-Samples/llms.txt
> Use this file to discover all available pages before exploring further.

# TColumn

> Column class that defines properties for painting rows in a TeeGrid column

## Overview

`TColumn` defines the properties used to paint rows of a TeeGrid column. It includes support for hierarchical columns through the `Items` property, which can contain sub-columns.

## Key Properties

<ParamField path="Width" type="TColumnWidth">
  Column width. Can be set to automatic (default) or a custom value in pixels or percentage.
</ParamField>

<ParamField path="Header" type="TColumnHeader">
  Text and formatting properties to display the column name at TeeGrid headers. Contains the column's display text and visual styling.
</ParamField>

<ParamField path="Items" type="TColumns">
  Optional collection of sub-columns. Enables hierarchical column structures where columns can contain nested columns.
</ParamField>

<ParamField path="Expanded" type="Boolean" default="true">
  Controls visibility of column sub-columns. When `true`, displays the column's sub-columns if they exist.
</ParamField>

<ParamField path="Visible" type="Boolean" default="true">
  Controls column visibility. When `false`, the column is not displayed in the grid.
</ParamField>

<ParamField path="ReadOnly" type="Boolean" default="false">
  Enables or disables editing of grid cell content using the keyboard. When `true`, cells cannot be edited.
</ParamField>

<ParamField path="Selectable" type="Boolean" default="true">
  Controls whether the column can be selected by the user.
</ParamField>

<ParamField path="ParentFormat" type="Boolean" default="true">
  When `true`, inherits formatting from the parent column or grid.
</ParamField>

<ParamField path="DataFormat" type="TDataFormat">
  Formatting strings for numbers and date-time data types. Controls how data values are displayed in cells.

  Includes properties:

  * `Float`: Format string for floating-point numbers (default: `"0.###"`)
  * `Date`: Format string for date values
  * `DateTime`: Format string for date-time values
  * `Time`: Format string for time values
</ParamField>

<ParamField path="Format" type="TFormat">
  Custom brush, stroke, and font properties for the column. Defines the visual appearance of column cells.
</ParamField>

<ParamField path="Margins" type="TMargins">
  Edge spacing inside grid cells. Controls padding within cells.
</ParamField>

<ParamField path="TextAlign" type="TTextAlign">
  Horizontal and vertical text alignment within cells.
</ParamField>

<ParamField path="TextAlignment" type="TColumnTextAlign" default="Automatic">
  Column text alignment mode:

  * `Automatic`: Automatically aligns based on data type (e.g., right-align numbers)
  * `Custom`: Uses the `TextAlign` property
</ParamField>

<ParamField path="Locked" type="TColumnLocked" default="None">
  Locks the column to a specific position:

  * `None`: Column scrolls normally
  * `Left`: Column is locked to the left side
  * `Right`: Column is locked to the right side
</ParamField>

<ParamField path="Render" type="TRender">
  Optional custom render instance used to paint column cell contents. Enables custom drawing logic.
</ParamField>

<ParamField path="TagObject" type="TObject">
  Custom user-defined object associated with the column. Useful for storing additional metadata.
</ParamField>

## Key Methods

<ParamField path="CanDisplay" type="Boolean">
  Returns `true` if the column can be displayed (is visible and has valid width).
</ParamField>

<ParamField path="HasItems" type="Boolean">
  Returns `true` if the column has sub-columns in its `Items` collection.
</ParamField>

<ParamField path="Level" type="Integer">
  Returns the hierarchical level of the column. Top-level columns return 0, their children return 1, etc.
</ParamField>

<ParamField path="Right" type="Single">
  Returns the right edge position of the column (Left + Width).
</ParamField>

<ParamField path="HorizAlign" type="THorizontalAlign">
  Returns the effective horizontal alignment for the column based on `TextAlignment` setting and data type.
</ParamField>

<ParamField path="ParentColumns" type="TColumns">
  Returns the parent `TColumns` collection that owns this column.
</ParamField>

## Events

<ParamField path="OnPaint" type="TColumnPaintEvent">
  Event triggered when painting the column. Allows custom painting logic.

  ```pascal theme={null}
  procedure TForm1.Column1Paint(const Sender: TColumn; 
    var AData: TRenderData; var DefaultPaint: Boolean);
  begin
    // Custom painting code
    if not DefaultPaint then
    begin
      // Override default painting
    end;
  end;
  ```
</ParamField>

## Usage Example

```pascal theme={null}
var
  Column: TColumn;
begin
  // Create and configure a column
  Column := Grid.Columns.Add('Customer Name');
  Column.Width.Value := 200;
  Column.ReadOnly := False;
  Column.TextAlignment := TColumnTextAlign.Automatic;
  
  // Configure data formatting
  Column.DataFormat.Float := '0.00';
  Column.DataFormat.Date := 'mm/dd/yyyy';
  
  // Add sub-columns
  Column.Items.Add('First Name');
  Column.Items.Add('Last Name');
  Column.Expanded := True;
end;
```

## Hierarchical Columns

Columns can contain sub-columns through the `Items` property:

```pascal theme={null}
var
  ParentCol, ChildCol: TColumn;
begin
  // Create parent column
  ParentCol := Grid.Columns.Add('Address');
  
  // Add child columns
  ChildCol := ParentCol.Items.Add('Street');
  ChildCol := ParentCol.Items.Add('City');
  ChildCol := ParentCol.Items.Add('State');
  
  // Control visibility of sub-columns
  ParentCol.Expanded := True; // Show sub-columns
end;
```

## Related Classes

* [TColumns](/api/tcolumns) - Collection of TColumn instances
* [TRows](/api/trows) - Grid rows class
* [TRowGroup](/api/trowgroup) - Row group with headers and footers