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How to use System-Wide Hotkeys in your Qt application

First of all, this method can only be used in Windows because it makes use of the RegisterHotKey function which is a Win32 API function. So if you want to trigger a function in your Qt application even when your application is out of focus or minimized or even hidden then follow the steps below one by one:

1. Include the required header files in your code.

#include “windows.h”

2. Add required libraries to your qmake project (.PRO file)

LIBS += -lUser32





3. Call RegisterHotKey function when your program starts. (Note that in this example I am trying to use ALT+CTRL+M as the global hotkey to be used by my program.)

if(!RegisterHotKey(HWND(winId()), 0, MOD_ALT | MOD_CONTROL, 0x4D))
{
QMessageBox::warning(this, “Warning”, “Can’t register hotkey ALT+CTRL+M”);
}

4. Override the nativeEvent function in your MainWindow app.
To do this first add the following code to your MainWindow class:

bool nativeEvent(const QByteArray &eventType, void *message, long *result);

And write the function body like this:

bool MainWindow::nativeEvent(const QByteArray &eventType, void *message, long *result)
{
Q_UNUSED(eventType);
Q_UNUSED(result);
MSG *msg = static_cast<MSG*>(message);
if(msg->message == WM_HOTKEY)
{
QMessageBox::information(this, “OK”, “Hotkey pressed!”);
true;
}
return false;
}

For any questions that you might have please put a comment below.





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