Presentation Adapters

Presentation adapters control how terminal content is rendered and displayed. They implement the IHex1bTerminalPresentationAdapter interface and handle all visual output.

Built-in Adapters

ConsolePresentationAdapter

The default adapter for displaying content in a real terminal:

var terminal = new Hex1bTerminalBuilder()
    .WithConsolePresentation()
    .WithAppWorkload(BuildUI)
    .Build();

This adapter:

• Writes directly to System.Console
• Uses ANSI escape sequences for colors and formatting
• Manages the alternate screen buffer
• Handles cursor positioning and visibility

HeadlessPresentationAdapter

For testing and automation without a display:

var terminal = new Hex1bTerminalBuilder()
    .WithHeadlessPresentation(80, 24)  // Width x Height
    .WithAppWorkload(BuildUI)
    .Build();

This adapter:

• Maintains an in-memory buffer of the screen
• Allows programmatic inspection of rendered content
• Perfect for unit and integration testing
• No actual console output

The IHex1bTerminalPresentationAdapter Interface

public interface IHex1bTerminalPresentationAdapter
{
    /// <summary>
    /// Initialize the adapter with the parent terminal.
    /// </summary>
    void Initialize(Hex1bTerminal terminal);
    
    /// <summary>
    /// Render the cell buffer to the display.
    /// </summary>
    void Render(ReadOnlySpan<CellAttributes> buffer, int width, int height);
    
    /// <summary>
    /// Set the cursor position.
    /// </summary>
    void SetCursorPosition(int x, int y);
    
    /// <summary>
    /// Show or hide the cursor.
    /// </summary>
    void SetCursorVisible(bool visible);
    
    /// <summary>
    /// Set the cursor shape.
    /// </summary>
    void SetCursorShape(CursorShape shape);
    
    /// <summary>
    /// Get the current terminal size.
    /// </summary>
    (int Width, int Height) GetSize();
    
    /// <summary>
    /// Clean up resources.
    /// </summary>
    void Dispose();
}

Creating a Custom Adapter

You can create custom presentation adapters for specialized rendering needs:

public class WebSocketPresentationAdapter : IHex1bTerminalPresentationAdapter
{
    private readonly WebSocket _socket;
    private Hex1bTerminal? _terminal;
    
    public WebSocketPresentationAdapter(WebSocket socket)
    {
        _socket = socket;
    }
    
    public void Initialize(Hex1bTerminal terminal)
    {
        _terminal = terminal;
    }
    
    public void Render(ReadOnlySpan<CellAttributes> buffer, int width, int height)
    {
        // Convert buffer to JSON and send over WebSocket
        var data = SerializeBuffer(buffer, width, height);
        _socket.SendAsync(data, WebSocketMessageType.Text, true, CancellationToken.None);
    }
    
    public void SetCursorPosition(int x, int y)
    {
        // Send cursor position update
    }
    
    // ... implement other methods
}

Presentation Filters

You can also apply filters to transform the presentation output:

public interface IHex1bTerminalPresentationFilter
{
    void Filter(Span<CellAttributes> buffer, int width, int height);
}

Filters are useful for:

• Recording terminal sessions (e.g., Asciinema)
• Applying visual effects
• Capturing screenshots
• Accessibility transformations

Use Cases

Adapter	Use Case
ConsolePresentationAdapter	Real terminal applications
HeadlessPresentationAdapter	Unit tests, CI/CD
Custom WebSocket adapter	Web-based terminals
Custom recording adapter	Session recording

Next Steps

• Learn about Workload Adapters for different workload types
• See Using the Emulator for a step-by-step tutorial