Wsrtjtyk

I'm trying to create a program that tracks the focused window of an application. I've come across a few partial answers, but I don't think it's working.

This is an Objective C++ part of a Qt application, so it might have to do with the RunLoop, but I'm not certain.

void focusObserverCallback( AXObserverRef observer, AXUIElementRef element,

                             CFStringRef notificationName, void * contextData )

{

    // Never executes.

    qInfo("Focus changed.");

}



QString updateActiveWindow (void)

{

    NSRunningApplication* app = [[NSWorkspace sharedWorkspace]

                                  frontmostApplication];

    pid_t pid = [app processIdentifier];

    AXUIElementRef appElem = AXUIElementCreateApplication(pid);

    if (!appElem) {

      qInfo() << "!appElem";

      return nullptr;

    }



    // Get the accessibility element corresponding to the frontmost window

    // of the frontmost application.

    CFStringRef appName=nullptr;

    AXUIElementRef window = nullptr;

    if (AXUIElementCopyAttributeValue (appElem, kAXTitleAttribute, ((CFTypeRef*)&appName)) !=kAXErrorSuccess){

        if(appElem)

         CFRelease(appElem);

    }

    focusedAppName=toQString(appName);

    if (AXUIElementCopyAttributeValue (appElem, kAXFocusedWindowAttribute, (CFTypeRef*)&window) != kAXErrorSuccess) {

      if(appElem)

        CFRelease(appElem);

    }



    AXObserverRef observer = nullptr;

    if(AXObserverCreate(pid, focusObserverCallback, &observer) !=kAXErrorSuccess){

        qInfo("Failed to register observer");

    }



    AXObserverAddNotification(observer, window, kAXApplicationActivatedNotification, nullptr);



    CFRunLoopAddSource([[NSRunLoop currentRunLoop] getCFRunLoop],

            AXObserverGetRunLoopSource(observer),

            kCFRunLoopDefaultMode );



    // Finally, get the title of the frontmost window.

    CFStringRef title = nullptr;

    if(AXUIElementCopyAttributeValue(window, kAXTitleAttribute, (CFTypeRef*)&title)!=kAXErrorSuccess){

        qInfo("Problem Copying title");

    }

    focusedAppTitle= toQString(title);

    return toQString(title);

}

What this code does, is it runs once to grab the name and the title of the frontmost application's frontmost window. That part works like a charm.

Problem is, it doesn't register the callback, and it doesn't fire when the window loses focus. I'm completely new to Objective C, so there might be other issues (e.g. Garbage Collection). If you can suggest some changes to those, I'd be doubly obliged.

An application sends kAXApplicationActivatedNotification when the application is activated and becomes the front most application. Observe the application's kAXFocusedWindowChangedNotification to observe focused window changes of the application.