Hello,
This is my first time on any mailing list so please advise me if I'm doing
something wrong.
For some reason (I'm porting a low level C++ window management library on mac)
I cannot use NSApplicationMain nor NSApplication -run method. So I create a
function to dispatch NSEvent working like this :
loop begin (non infinite)
[NSApp nextEventMatchingMask:blabla..]
[NSApp sendEvent:..]
loop end
And I call it periodically. Until now it worked pretty well (the window is
displayed, key/mouse event are dispatched, ...) – I was only using main thread.
But now I'm stuck with a problem : is there any way to create/destroy
window/view, make them live (e.g. rendering process) and get event
notification; all that only in a worker thread (like we can do on Linux or
Windows) ?
From what I've read in the doc the NSWindow can be created/destroyed in any
thread but this is not true for NSView. So I though of using NSObject
-performSelectorOnMainThread:..-like methods. But, again, the documentation is
against me :
> This method queues the message on the run loop of the main thread using the
> default run loop modes—that is, the modes associated with the
> NSRunLoopCommonModes constant. As part of its normal run loop processing, the
> main thread dequeues the message (assuming it is running in one of the
> default run loop modes) and invokes the desired method.
And I tested : if I call some dummy function like this in a worker thread
nothing happen (as expected) :
-(void)dummy:(NSString *)msg
{
NSLog(@"Hello %@", msg);
}
-(id)initWithStuff:...
{
if ((self = [super init])) {
[self performSelectorOnMainThread:@selector(dummy:)
withObject:@"World"
waitUntilDone:YES];
:
:
}
It get stuck forever in performSelectorOnMainThread:.. because the selector is
never executed. Of course, I could set waitUntilDone to NO but later I will
require to wait for my view to be initialized.
So have any of you an idea of how to make it work ? Or is it really impossible
? One idea that crossed my mind was to call some method in the main thread
periodically but that would require to change the public API of the library...
which is not an option for me. The only thing I can do is play in some GetEvent
and Display functions called by the user in the worker thread. You can see
below what should the lib-user be able to do.
#include <SFML/Window.hpp>
sf::Window App;
void threadProc() {
App.Create(sf::VideoMode(800, 600, 32), "SFML Threads");
// Create the main window // Start main loop
while (App.IsOpened()) {
// Process events
sf::Event Event;
while (App.GetEvent(Event)) {
// Close window : exit
if (Event.Type == sf::Event::Closed)
App.Close();
// Escape key : exit
if (Event.Type == sf::Event::KeyPressed && Event.Key.Code ==
sf::Key::Escape)
App.Close();
}
// Display window on screen
App.Display();
}
}
int main(int, char**)
{
sf::Thread Thread(threadProc);
Thread.Launch();
Thread.Wait();
return 0;
}
This C++ code display a window with white titlebar and a spinning wheel.
The only thing that is working is rendering stuff from a worker thread works!
(Also as expected by the documentation.)
And if it can be done to work so I'll have some other trouble with event
dispatching... arg!
If you need any other information please tell me.
Thank you very much for your time =)
Marco
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