main.cpp

# Carbon Events API C++ Project for Mac OS 9

## Project Files

1. **Main.cpp** - Main application source file.
2. **HelloWorld.r** - Resource file for defining UI elements.

## Main.cpp

```cpp
#include <Carbon/Carbon.h>

// Function Prototypes
OSStatus MyWindowEventHandler(EventHandlerCallRef callRef, EventRef event, void *userData);
void CreateMyWindow();
void CreateButton(WindowPtr window);

int main(int argc, char* argv[]) {
    IBNibRef nibRef;
    OSStatus err;

    // Initialize the Toolbox
    err = MoreMasterPointers(64);
    if (err == noErr) {
        err = InitCursor();
    }

    // Create the main window
    CreateMyWindow();

    // Run the event loop
    RunApplicationEventLoop();

    return 0;
}

void CreateMyWindow() {
    Rect windowRect = {100, 100, 300, 400}; // Position and dimensions of the window
    WindowRef window;

    CreateNewWindow(kDocumentWindowClass, kWindowStandardDocumentAttributes, &windowRect, &window);
    SetWindowTitleWithCFString(window, CFSTR("Hello World Window"));
    ShowWindow(window);

    // Create a button
    CreateButton(window);

    // Set up event handler for the window
    EventTypeSpec eventTypes[] = {
        { kEventClassCommand, kEventCommandProcess }
    };

    InstallWindowEventHandler(window, NewEventHandlerUPP(MyWindowEventHandler), GetEventTypeCount(eventTypes), eventTypes, (void *)window, NULL);
}

void CreateButton(WindowPtr window) {
    ControlRef button;
    Rect buttonBounds = { 110, 110, 140, 180 }; // Position and dimensions of the button

    CreatePushButtonControl(window, &buttonBounds, CFSTR("Click Me"), &button);
    SetControlCommandID(button, 'bttn');
}

OSStatus MyWindowEventHandler(EventHandlerCallRef callRef, EventRef event, void *userData) {
    OSStatus err = eventNotHandledErr;
    HICommand command;

    if (GetEventClass(event) == kEventClassCommand && GetEventKind(event) == kEventCommandProcess) {
        GetEventParameter(event, kEventParamDirectObject, typeHICommand, NULL, sizeof(command), NULL, &command);

        if (command.commandID == 'bttn') {
            // Code to display "Hello"
            CFUserNotificationDisplayNotice(0, kCFUserNotificationNoteAlertLevel, NULL, NULL, NULL, CFSTR("Hello"), CFSTR("Button clicked!"), NULL);
            err = noErr;
        }
    }

    return err;
}