Register Global Hotkey under Qt and Mac OS X

Question

Having read through various posts and threads that lead me nowhere I need your help.

I do have a Qt Application for Mac OS X that at some point of use will be in the background and not active. When this is the case I want to add a global hotkey so that the user can easily turn certain features on or off by clicking pre-defined hotkeys. The following isn't working while the app is in the background and not focused.

QShortcut *shortcut = new QShortcut(QKeySequence(Qt::Key_F12), parent);
shortcut->setContext(Qt::ApplicationShortcut);

So far I found Qxt which happens to be outdated for Qt 5.5. Then there is DDHotkey which requires a certain compiler which we can not use for various reasons. Lastly, I found the solution of adding a global AppleScript which registers an event, again, not what I am looking for.

tell application "System Events" to tell process "myApp"
    click menu item "myButton" of menu 1 of menu bar item "Menu" of menu bar 1
end tell

Is there a way to use objective-c or cocoa to accomplish exactly what I am looking for? Please lead me in the right direction if I may have missed something.

Thanks in advance!

---

To those who seek a more Qt way, check the following repository: https://github.com/ddqd/qxtglobalshortcut5

It makes use of the outdated qxt library but gets it working again. The person tested it until Qt 5.4, we use it successfully under Qt 5.5.

Answer 1

This might be what you're looking for https://github.com/jaz303/JFHotkeyManager

You could also look at this example from Apple, using the RegisterEventHotKey API call which I think will point you in the right direction. https://developer.apple.com/library/prerelease/mac/samplecode/FunkyOverlayWindow/Listings/FunkyOverlayWindow_OverlayWindow_m.html#//apple_ref/doc/uid/DTS10000391-FunkyOverlayWindow_OverlayWindow_m-DontLinkElementID_8

Or you could try this code

#import <Carbon/Carbon.h>

EventHandlerUPP hotKeyFunction;

pascal OSStatus hotKeyHandler(EventHandlerCallRef nextHandler,EventRef theEvent, void *userData)
{    
    Notify *obj =  userData;
    [obj foo];    
    return noErr;
}

@implementation Notify

- (id)init
{
    self = [super init];
    if (self) {
        //handler
        hotKeyFunction = NewEventHandlerUPP(hotKeyHandler);
        EventTypeSpec eventType;
        eventType.eventClass = kEventClassKeyboard;
        eventType.eventKind = kEventHotKeyReleased;
        InstallApplicationEventHandler(hotKeyFunction,1,&eventType,self,NULL);
        //hotkey
        UInt32 keyCode = 80; //F19    
        EventHotKeyRef theRef = NULL;
        EventHotKeyID keyID;
        keyID.signature = 'FOO '; //arbitrary string
        keyID.id = 1;
        RegisterEventHotKey(keyCode,0,keyID,GetApplicationEventTarget(),0,&theRef);

    }        
    return self;
}

- (void)foo
{

}

@end

And the header

#include "notify.mm"
@interface Notify
 - (id)init;
 - (void)foo;
@end

Simply this is just a object with a method and a constructor, in objective-c this is called init, or initialize, and variants. Calling it should be straight forward with "new".

E.x

#include "notify.h"
int main(){
  Notify* object = new Notify();
}

However, some basic understanding of Objective-C is needed. It's mostly syntax differences in my opinion. But I'm no Objective-C expert myself. Anyway, there is a lot of ways to solve it, this might not be the best idea. You can also call Objective-C code from inside of a C++ class of yours. Take a look at the links bellow for a great example of how that's done.

https://el-tramo.be/blog/mixing-cocoa-and-qt/

https://github.com/remko/mixing-cocoa-and-qt/

http://philjordan.eu/article/mixing-objective-c-c++-and-objective-c++