Intro

When working with data grids, one size rarely fits all. Different types of data often require different visual representations and interaction patterns. That's where custom cell classes in TTMSFNCDataGrid come into play. By leveraging the power of custom cell classes, you can create rich, interactive grids that go beyond simple text display to include checkboxes, buttons, progress bars, images, and even hierarchical nodes.

Understanding Cell Classes in TTMSFNCDataGrid

At its core, TTMSFNCDataGrid uses a flexible cell class system that allows different types of content and behavior within the grid. All cell classes inherit from the base TTMSFNCDataGridCell class, which provides fundamental functionality for rendering content and handling user interactions.

The beauty of this system is that the grid can dynamically assign different cell types to different cells, rows, or columns based on your data and requirements. This means you can have a checkbox in one column, a progress bar in another, and buttons in a third—all within the same grid.

Available Built-in Cell Classes

TTMSFNCDataGrid comes with several pre-built cell classes, each designed for specific use cases:

1. TTMSFNCDataGridCell (Base Class)

The fundamental class that all other cell types inherit from. It handles basic functionality like:

• Rendering cell content
• Managing cell boundaries and positioning
• Handling user interactions
• Storing cell data

2. TTMSFNCDataGridNodeCell

Perfect for creating hierarchical data structures:

• Supports expandable/collapsible nodes
• Creates tree-like structures within the grid
• Manages parent-child relationships
• Includes customizable expand/collapse icons

3. TTMSFNCDataGridCheckBoxCell

Ideal for boolean data or row selection:

• Displays interactive checkboxes
• Supports checked/unchecked states
• Triggers OnChange events
• Perfect for multi-select scenarios

4. TTMSFNCDataGridButtonCell

Enables action buttons within cells:

• Creates clickable buttons
• Supports custom button text
• Triggers OnClick events
• Great for row-specific actions like "Edit" or "Delete"

5. TTMSFNCDataGridProgressBarCell

Visualizes progress or percentage data:

• Displays progress bars
• Supports value ranges (0-100 or custom max)
• Visual representation of completion status
• Ideal for task tracking or status indicators

6. TTMSFNCDataGridBitmapCell

Displays images within grid cells:

• Supports various image formats
• Customizable image alignment
• Perfect for product catalogs or user avatars
• Handles bitmap rendering efficiently

Implementing Custom Cell Classes

The real power comes from dynamically assigning cell classes based on your needs. This is achieved through the OnGetCellClass event, which fires for each cell and allows you to specify which cell class to use.

Basic Implementation

Here's a simple example that assigns different cell classes to different columns:

procedure TForm1.GridGetCellClass(Sender: TObject; ACol, ARow: Integer; 
  var CellClassType: TTMSFNCDataGridCellClass);
begin
  // Column 0: Standard cells
  if ACol = 0 then
    CellClassType := TTMSFNCDataGridCell
  
  // Column 1: Checkboxes
  else if ACol = 1 then
    CellClassType := TTMSFNCDataGridCheckBoxCell
  
  // Column 2: Buttons
  else if ACol = 2 then
    CellClassType := TTMSFNCDataGridButtonCell
  
  // Column 3: Progress bars
  else if ACol = 3 then
    CellClassType := TTMSFNCDataGridProgressBarCell
  
  // Default to standard cell
  else
    CellClassType := TTMSFNCDataGridCell;
end;

Practical Example: Building a Task Management Grid

Let's create a real-world example—a task management grid that showcases various cell classes:

procedure TForm1.SetupTaskGrid;
begin
  // Configure grid
  Grid.RowCount := 6;  // 1 header + 5 data rows
  Grid.ColumnCount := 5;
  
  // Set column headers
  Grid.Cells[0, 0] := 'Complete';
  Grid.Cells[1, 0] := 'Priority';
  Grid.Cells[2, 0] := 'Task Name';
  Grid.Cells[3, 0] := 'Progress';
  Grid.Cells[4, 0] := 'Action';
  
  // Configure column widths
  Grid.ColumnWidths[0] := 70;   // Checkbox column
  Grid.ColumnWidths[1] := 60;    // Priority
  Grid.ColumnWidths[2] := 200;   // Task name
  Grid.ColumnWidths[3] := 100;   // Progress bar
  Grid.ColumnWidths[4] := 80;    // Button
  Grid.ColumnWidths[5] := 50;    // Icon
  
  // Assign the OnGetCellClass event
  Grid.OnGetCellClass := GridGetCellClass;
  
  // Populate sample data
  PopulateTaskData;
end;

procedure TForm1.GridGetCellClass(Sender: TObject; ACol, ARow: Integer; 
  var CellClassType: TTMSFNCDataGridCellClass);
begin
  // Skip header row
  if ARow = 0 then
  begin
    CellClassType := TTMSFNCDataGridCell;
    Exit;
  end;
  
  case ACol of
    0: CellClassType := TTMSFNCDataGridCheckBoxCell;  // Complete checkbox
    3: CellClassType := TTMSFNCDataGridProgressBarCell; // Progress
    4: CellClassType := TTMSFNCDataGridButtonCell;     // Action button
  else
    CellClassType := TTMSFNCDataGridCell;
  end;
end;

procedure TForm1.PopulateTaskData;
begin
  // Task 1
  Grid.Booleans[0, 1] := False;  // Not complete
  Grid.Cells[1, 1] := 'High';
  Grid.Cells[2, 1] := 'Implement login system';
  Grid.ProgressValue[3, 1] := 75;  // 75% progress
  Grid.ControlTexts[4, 1] := 'Details';
   
  // Task 2
  Grid.Booleans[0, 2] := True;   // Complete
  Grid.Cells[1, 2] := 'Medium';
  Grid.Cells[2, 2] := 'Design database schema';
  Grid.ProgressValue[3, 2] := 100;  // 100% progress
  Grid.ControlTexts[4, 2] := 'Details';
  
  // Continue for other tasks...
end;

Working with Cell Class Properties

// Set checkbox state
Grid.Booleans[0, 1] := True;

// Handle checkbox changes
procedure TForm1.GridCellCheckBoxChange(Sender: TObject; AColumn, ARow: Integer);
begin
  if Grid.Booleans[AColumn, ARow] then
    TTMSFNCUtils.Log('Task marked as complete')
  else
    TTMSFNCUtils.Log('Task marked as incomplete');
end;

// Set button text
Grid.ControlTexts[4, 1] := 'Edit';

// Handle button clicks
procedure TForm1.GridCellButtonClick(Sender: TObject; AColumn, ARow: Integer);
begin
  TTMSFNCUtils.Log('Button clicked at row ' + IntToStr(ARow));
  // Perform action like opening an edit dialog
end;

Creating Your Own Cell Classes

Real-World Custom Cell Class Example: Star Rating Cell

For ultimate flexibility, you can create your own cell classes by inheriting from TTMSFNCDataGridCell.Let's create a practical custom cell class that you might actually use in a real application - a star rating cell. This is perfect for product reviews, customer feedback systems, or any scenario where users need to provide or view ratings.

The Star Rating Cell Class

Here's a complete implementation of a custom star rating cell that:

• Displays 1-5 stars
• Shows filled/empty stars based on the rating

Download Sample

Conclusion

Custom cell classes in TTMSFNCDataGrid open up a world of possibilities for creating rich, interactive data grids. By understanding the available cell types and how to implement them effectively, you can transform simple data displays into powerful, user-friendly interfaces.

Whether you're building a task management system with progress indicators and action buttons, a settings panel with checkboxes and dropdowns, or a product catalog with images and ratings, custom cell classes provide the flexibility you need.

Start experimenting with different cell classes in your projects, and you'll quickly discover how they can enhance both the functionality and visual appeal of your applications. The key is to match the right cell class to the right data type and user interaction pattern.

Happy coding, and may your grids be forever dynamic and engaging!