> ## 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.

# TCustomTeeGrid

> Abstract base class for TeeGrid with core architecture and functionality

## Overview

TCustomTeeGrid is the abstract base class for all TeeGrid implementations. It provides the core architecture, data management, and rendering framework that is shared between VCL and FireMonkey versions of TTeeGrid.

<Warning>
  TCustomTeeGrid is an abstract class and cannot be instantiated directly. Use `TTeeGrid` (VCL or FMX) instead.
</Warning>

## Architecture

TCustomTeeGrid serves as the foundation for the grid component hierarchy:

```text theme={null}
TCustomTeeControl (base control)
  └── TCustomTeeGrid (abstract grid)
      ├── TVCLTeeGrid (VCL implementation)
      │   └── TTeeGrid (VCL)
      └── TFMXTeeGrid (FMX implementation)
          └── TTeeGrid (FMX)
```

## Core Properties

### Data Management

<ResponseField name="Data" type="TVirtualData">
  The virtual data source providing content to the grid. This can be any descendant of TVirtualData including database sources, arrays, lists, or custom data providers.
</ResponseField>

<ResponseField name="DataSource" type="TComponent">
  Reference to a component that provides data, typically a TDataSource for database connectivity.
</ResponseField>

<ResponseField name="Root" type="TRowGroup" readOnly>
  The main row group that contains all grid data. This is the top-level group in master-detail hierarchies.
</ResponseField>

<ResponseField name="Current" type="TRowGroup">
  The currently focused row group. In a simple grid, this is the same as Root. In master-detail grids, this represents the active detail level.
</ResponseField>

### Visual Structure

<ResponseField name="Cells" type="TTextRender">
  Defines the rendering properties for grid cells including font, colors, alignment, and padding.
</ResponseField>

<ResponseField name="Columns" type="TColumns">
  The collection of columns defining the grid structure. Each column specifies how data is displayed and edited.
</ResponseField>

<ResponseField name="Rows" type="TRows">
  Row configuration including default height, alternating row colors, and row selection behavior.
</ResponseField>

<ResponseField name="Header" type="TColumnHeaderBand">
  The main column header band configuration.
</ResponseField>

<ResponseField name="Headers" type="TGridBands">
  Collection of additional header bands displayed above the grid.
</ResponseField>

<ResponseField name="Footer" type="TGridBands">
  Collection of footer bands displayed below the grid.
</ResponseField>

<ResponseField name="Indicator" type="TIndicator">
  Configuration for the row indicator column showing current row and edit state.
</ResponseField>

<ResponseField name="Margins" type="TMargins">
  Margins around the grid content area.
</ResponseField>

### Editing

<ResponseField name="Editing" type="TGridEditing">
  Comprehensive editing configuration including:

  * `Active` - Whether an editor is currently visible
  * `AlwaysVisible` - Keep editor always visible
  * `AutoEdit` - Start editing on keypress
  * `DoubleClick` - Require double-click to edit
  * `EnterKey` - Behavior when Enter is pressed (NextCell, NextRow, SameCell)
  * `EditorClass` - Custom editor class
</ResponseField>

<ResponseField name="ReadOnly" type="Boolean" default="False">
  Global read-only flag. When True, all cells are non-editable regardless of column settings.
</ResponseField>

### Selection

<ResponseField name="Selected" type="TGridSelection">
  Current selection in the grid including:

  * Selected cell coordinates
  * Selected rows
  * Selected range
</ResponseField>

## Public Methods

### Display and Rendering

<ParamField path="Paint" type="procedure">
  Renders the grid content. Override this method in derived classes to customize rendering.

  **Signature:**

  ```pascal theme={null}
  procedure Paint; override;
  ```
</ParamField>

<ParamField path="ClientWidth" type="function">
  Returns the available width for grid content, excluding scrollbars and margins.

  **Signature:**

  ```pascal theme={null}
  function ClientWidth: Single; override;
  ```

  **Returns:** Available width in pixels
</ParamField>

<ParamField path="ClientHeight" type="function">
  Returns the available height for grid content, excluding scrollbars and margins.

  **Signature:**

  ```pascal theme={null}
  function ClientHeight: Single; override;
  ```

  **Returns:** Available height in pixels
</ParamField>

### Data Operations

<ParamField path="RefreshData" type="procedure">
  Refreshes the grid display from the data source. Call this when the underlying data has changed.

  **Signature:**

  ```pascal theme={null}
  procedure RefreshData;
  ```
</ParamField>

<ParamField path="CanExpand" type="function">
  Determines if a row can be expanded to show detail data.

  **Signature:**

  ```pascal theme={null}
  function CanExpand(const Sender: TRender; const ARow: Integer): Boolean;
  ```

  **Parameters:**

  * `Sender` - The render object requesting expansion
  * `ARow` - Row index to check

  **Returns:** True if the row has expandable detail data
</ParamField>

### Clipboard Operations

<ParamField path="Copy" type="procedure">
  Copies the selected cells to the clipboard in tab-delimited format.

  **Signature:**

  ```pascal theme={null}
  procedure Copy(const ASelection: TGridSelection = nil); virtual; abstract;
  ```

  **Parameters:**

  * `ASelection` - Optional specific selection to copy (uses current selection if nil)
</ParamField>

<ParamField path="PasteSelected" type="procedure">
  Pastes clipboard content into the selected cells.

  **Signature:**

  ```pascal theme={null}
  procedure PasteSelected; virtual; abstract;
  ```
</ParamField>

### Utility Methods

<ParamField path="Assign" type="procedure">
  Copies all properties from another grid instance.

  **Signature:**

  ```pascal theme={null}
  procedure Assign(Source: TPersistent); override;
  ```
</ParamField>

<ParamField path="Loaded" type="procedure">
  Called after the component is loaded from a stream (DFM/FMX file). Override to perform post-load initialization.

  **Signature:**

  ```pascal theme={null}
  procedure Loaded; override;
  ```
</ParamField>

<ParamField path="MouseLeave" type="procedure">
  Handles mouse leave events. Call when the mouse cursor leaves the grid area.

  **Signature:**

  ```pascal theme={null}
  procedure MouseLeave;
  ```
</ParamField>

## Protected Methods

<Info>
  These methods are available for descendant classes and advanced customization.
</Info>

### Editor Management

<ParamField path="StartEditor" type="procedure">
  Initiates cell editing for the specified column and row.

  **Signature:**

  ```pascal theme={null}
  procedure StartEditor(const AColumn: TColumn; const ARow: Integer;
                       const AutoEdit: String = ''); overload; virtual; abstract;
  procedure StartEditor(const AutoEdit: String = ''); overload;
  ```

  **Parameters:**

  * `AColumn` - Column to edit
  * `ARow` - Row index to edit
  * `AutoEdit` - Optional initial text for auto-edit mode
</ParamField>

<ParamField path="StopEditor" type="procedure">
  Stops cell editing and commits changes.

  **Signature:**

  ```pascal theme={null}
  procedure StopEditor; virtual;
  ```
</ParamField>

<ParamField path="CancelEditor" type="procedure">
  Cancels cell editing without committing changes.

  **Signature:**

  ```pascal theme={null}
  procedure CancelEditor; virtual;
  ```
</ParamField>

### Scrolling

<ParamField path="HorizScrollChanged" type="procedure">
  Called when horizontal scroll position changes.

  **Signature:**

  ```pascal theme={null}
  procedure HorizScrollChanged(Sender: TObject); virtual; abstract;
  ```
</ParamField>

<ParamField path="VertScrollChanged" type="procedure">
  Called when vertical scroll position changes.

  **Signature:**

  ```pascal theme={null}
  procedure VertScrollChanged(Sender: TObject); virtual; abstract;
  ```
</ParamField>

<ParamField path="CheckScrollLimits" type="procedure">
  Validates and adjusts scroll positions to stay within valid bounds.

  **Signature:**

  ```pascal theme={null}
  procedure CheckScrollLimits(var X, Y: Single); virtual; abstract;
  ```
</ParamField>

### Data Events

<ParamField path="DataChanged" type="procedure">
  Called when the data source changes or is refreshed.

  **Signature:**

  ```pascal theme={null}
  procedure DataChanged; virtual;
  ```
</ParamField>

### Input Handling

<ParamField path="Key" type="procedure">
  Processes keyboard input.

  **Signature:**

  ```pascal theme={null}
  procedure Key(const AState: TKeyState);
  ```
</ParamField>

<ParamField path="Mouse" type="procedure">
  Processes mouse input.

  **Signature:**

  ```pascal theme={null}
  procedure Mouse(var AState: TMouseState);
  ```
</ParamField>

## Events

<ResponseField name="OnAfterDraw" type="TNotifyEvent">
  Fired after the grid is painted. Use for custom post-rendering operations.
</ResponseField>

<ResponseField name="OnSelect" type="TNotifyEvent">
  Fired when the selection changes.
</ResponseField>

## Example: Custom Grid Implementation

```pascal theme={null}
type
  TMyCustomGrid = class(TCustomTeeGrid)
  protected
    // Override abstract methods
    procedure CheckScrollLimits(var X, Y: Single); override;
    function HorizScrollBarHeight: Single; override;
    procedure HorizScrollChanged(Sender: TObject); override;
    function VertScrollBarWidth: Single; override;
    procedure VertScrollChanged(Sender: TObject); override;
    
    procedure StartEditor(const AColumn: TColumn; const ARow: Integer;
                         const AutoEdit: String = ''); override;
  public
    procedure Copy(const ASelection: TGridSelection = nil); override;
    procedure PasteSelected; override;
    function Painter: TPainter; override;
    function Height: Single; override;
    function Width: Single; override;
  end;
```

## See Also

<CardGroup cols={2}>
  <Card title="TTeeGrid" icon="table" href="/api/teegrid">
    Main grid component for VCL and FMX
  </Card>

  <Card title="TVirtualData" icon="database" href="/api/virtualdata">
    Abstract data interface
  </Card>
</CardGroup>