Macro panel_event

macro_rules! panel_event {
    (
        $handler_name:ident {
            $(
                $method:ident ( $first_param:ident : $first_type:ty $(, $param:ident : $param_type:ty)* $(,)? ) -> $return_type:ty
            ),* $(,)?
        }
    ) => { ... };
}

Macro to create a custom event handler for panels

This creates an NSWindowDelegate that responds to window events with type-safe callbacks.

This macro generates a type-safe delegate class with strongly typed callbacks. Users specify parameter types directly in the macro, and callbacks receive properly typed arguments instead of raw pointers.

References

• objc2 NSWindowDelegate trait documentation
• Apple NSWindowDelegate documentation

Selector Generation Rules

The macro generates Objective-C selectors based on how you declare the methods:

• Single parameter: method_name(param: Type) → methodName:

  • Example: window_did_become_key(notification: &NSNotification) → windowDidBecomeKey:

• Multiple parameters: method_name(first: Type1, second: Type2) → methodName:second:

  • Example: window_will_resize(window: &NSWindow, to_size: &NSSize) → windowWillResize:toSize:
  • The first parameter is always anonymous (:) in the selector
  • Subsequent parameters use their names as selector parts

Parameter Naming: The macro automatically converts snake_case to camelCase:

• to_size → toSize
• to_object → toObject
• for_client → forClient

You can use Rust’s conventional snake_case naming and the macro will generate the correct camelCase selectors to match Apple’s NSWindowDelegate signatures.

Important: Always check the references above to ensure your method names and parameter names match the exact NSWindowDelegate protocol signatures.

Usage:

use tauri_nspanel::tauri_panel;

tauri_panel! {
    panel_event!(MyPanelEventHandler {
        window_did_become_key(notification: &NSNotification) -> (),
        window_should_close(window: &NSWindow) -> Bool,
        window_will_resize(window: &NSWindow, to_size: &NSSize) -> NSSize,
        window_will_return_field_editor(sender: &NSWindow, client: Option<&AnyObject>) -> Option<Retained<NSObject>>
    })
}

let handler = MyPanelEventHandler::new();

handler.window_did_become_key(|notification| {
    // notification is already typed as &NSNotification
    println!("Window became key: {:?}", notification);
});

handler.window_should_close(|window| {
    // window is already typed as &NSWindow
    println!("Should close window: {:?}?", window);
    Bool::new(true) // Allow closing
});

Type Specification

You must specify the exact types for parameters, including references:

• Object types usually take references: &NSWindow, &NSNotification
• Value types also take references: &NSSize, &NSRect, &NSPoint
• Optional parameters: Option<&AnyObject>
• The macro does NOT automatically add references

Return Values

Methods must specify their return type explicitly:

• -> () for void methods (no return value)
• -> Bool for BOOL returns (objc2 Bool type)
• -> Option<Retained<NSObject>> for nullable object returns
• -> NSSize for NSSize value returns
• -> NSRect for NSRect value returns
• -> NSPoint for NSPoint value returns
• Other types as needed by the delegate method

The macro handles conversion between Rust types and Objective-C types automatically.