qcam: Remove custom event dispatcher

The qcam application installs a custom event dispatcher based on the Qt
event loop. As the camera manager now creates an internal thread, it
doesn't use that event dispatcher of the application thread at all.

Furthermore, the custom event dispatcher is buggy, as it doesn't
dispatch messages posted to the main thread's event loop. This isn't an
issue as no messages are posted there in the first place, but would
cause incorrect behaviour if we were to use that feature (for instance
to deliver signals from the camera manager thread to the application
thread).

Fixing the event dispatcher requires a change in the libcamera public
API, as there's currently no way to dispatch messages using the public
API (Thread::dispatchMessages() is not exposed). This isn't worth it at
the moment, so just remove the custom event dispatcher. If qcam later
needs the libcamera request and buffer completion signals to be
delivered in the application thread, it will need to handle that
internally, using Qt's cross-thread signal delivery.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/qcam/main.cpp

@@ -15,7 +15,6 @@
 
 #include "main_window.h"
 #include "../cam/options.h"
-#include "qt_event_dispatcher.h"
 
 void signalHandler(int signal)
 {
@@ -62,9 +61,7 @@ int main(int argc, char **argv)
 	sa.sa_handler = &signalHandler;
 	sigaction(SIGINT, &sa, nullptr);
 
-	std::unique_ptr<EventDispatcher> dispatcher(new QtEventDispatcher());
 	CameraManager *cm = new CameraManager();
-	cm->setEventDispatcher(std::move(dispatcher));
 
 	ret = cm->start();
 	if (ret) {