ContextMenu.md

ContextMenu Class

Overview

AutoCAD allows developers to append custom menu items to the context (right-click) menu of specific entity types or the default context menu. This is done via the ContextMenuExtension class.

Namespace

Autodesk.AutoCAD.Windows

Key Classes

Class	Description
ContextMenuExtension	A custom menu definition.
MenuItem	An individual clickable item.
Application.AddObjectContextMenuExtension	Registers menu for an entity type.
Application.AddDefaultContextMenuExtension	Registers menu for "nothing selected" state.

Code Examples

Example 1: Adding Menu to Specific Entity Type

using Autodesk.AutoCAD.Windows;
using Autodesk.AutoCAD.Runtime;

public class MyPlugin : IExtensionApplication
{
    private ContextMenuExtension _circleMenu;

    public void Initialize()
    {
        _circleMenu = new ContextMenuExtension();
        _circleMenu.Title = "Circle Tools"; // Submenu title (optional)
        
        MenuItem item = new MenuItem("Calculate Area Info");
        item.Click += OnCalculateArea;
        _circleMenu.MenuItems.Add(item);
        
        // Register for ALL Circle objects
        Application.AddObjectContextMenuExtension(
            RXObject.GetClass(typeof(Circle)), 
            _circleMenu
        );
    }

    public void Terminate()
    {
        // Always cleanup
        Application.RemoveObjectContextMenuExtension(
             RXObject.GetClass(typeof(Circle)), 
             _circleMenu
        );
    }

    private void OnCalculateArea(object sender, EventArgs e)
    {
        // Context logic
        // The selected objects are in the SelectionSet
        // ...
    }
}

Example 2: Adding to Global Context Menu

// This menu appears when you right-click empty space
Application.AddDefaultContextMenuExtension(_myMenu);

Example 3: Handling Click Event

private void OnMenuClick(object sender, EventArgs e)
{
    Document doc = Application.DocumentManager.MdiActiveDocument;
    Editor ed = doc.Editor;
    
    // Execute logic
    // Note: Context menu runs in UI thread.
    // If you need to run a command, use SendStringToExecute
    doc.SendStringToExecute("MY_COMMAND ", true, false, false);
}

Example 4: Dynamic Enabling/Disabling

_menu.Popup += (s, e) =>
{
    MenuItem item = _menu.MenuItems[0];
    
    // Check condition
    bool valid = CheckSomeCondition();
    
    item.Enabled = valid;
    item.Visible = true; // or hide it
};

Example 5: Submenus

MenuItem parentItem = new MenuItem("Advanced Tools");

MenuItem child1 = new MenuItem("Tool A");
MenuItem child2 = new MenuItem("Tool B");

parentItem.MenuItems.Add(child1);
parentItem.MenuItems.Add(child2);

_menu.MenuItems.Add(parentItem);

Example 6: Separators

MenuItem separator = new MenuItem(""); 
// Assigning a standard separator style might be required depending on API version
// Or simply adding a separator directly:
_menu.MenuItems.Add(new MenuItem(null)); // Often interpreted as separator

Example 7: Accessing Selected Object

// When right-clicking an object, the Valid SelectionSet usually contains it
private void OnEntityClick(object sender, EventArgs e)
{
    Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
    PromptSelectionResult sel = ed.SelectImplied(); // Logic varies
    
    if (sel.Status == PromptStatus.OK)
    {
        // Process selected object
    }
}

Example 8: Removing Menu at Runtime

// You can remove menus dynamically if settings change
Application.RemoveObjectContextMenuExtension(...);

Best Practices

1. Clean Up: Always remove your extensions in the Terminate() method of your IExtensionApplication. Failing to do so can leave dead menu items until AutoCAD restarts.
2. Performance: Do not perform heavy logic in the Popup event check; it delays the menu appearing.
3. Context: Remember that the user might have multiple objects selected. Your command should handle ActiveSelectionSet.

Related Objects

• Application
• Entity

References

• Autodesk ContextMenuExtension Reference