hvirtual/guicast/bcwindowevents.C

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#include "bcwindowbase.h"
#include "bcwindowevents.h"
#include "bctimer.h"

BC_WindowEvents::BC_WindowEvents(BC_WindowBase *window)
 : Thread(1, 0, 0)
{
        this->window = window;
        done = 0;
}

BC_WindowEvents::~BC_WindowEvents()
{
// First set done, then send dummy event through XSendEvent to unlock the loop in ::run()
        done = 1;
        XEvent event;
        XClientMessageEvent *ptr = (XClientMessageEvent*)&event;
        event.type = ClientMessage;
        ptr->message_type = XInternAtom(window->display, "DUMMY_XATOM", False);
        ptr->format = 32;
        XSendEvent(window->display, 
                window->win, 
                0, 
                0, 
                &event);
        window->flush();
        Thread::join();
}

void BC_WindowEvents::start()
{
        done = 0;
        Thread::start();
}


void BC_WindowEvents::run()
{
// Can't cancel in XNextEvent because X server never figures out it's not
// listening anymore and XCloseDisplay locks up.
        XEvent *event;
        while(!done)
        {
// XNextEvent should also be protected by XLockDisplay ...
// Currently implemented is a hackish solution, FIXME
// Impact of this solution on the performance has not been analyzed

// The proper solution is HARD because of :
// 1. idiotic xlib does not have XTryLockDisplay - we will need to _completely_ implement XLockDisplay by ourselves (including cascaded locking - it is not the same as mutex!)
// 2. the locking shemantic inside new lock_window and here will be really tricky, we should:
//      in lock_window check wheather BC_WindowEvents is in XNextEvent and it is send custom xevent to break out of the loop and make sure lock is not taken again if lock_window() is waiting on it
// 3. Send custom events from previous point through _separate_ xwindows display connection since XSendEvent would need to be protected by XLockDisplay which obviously can't be

                window->lock_window();
                while (XPending(window->display))
                {
                        event = new XEvent;
                        XNextEvent(window->display, event);
                        window->put_event(event);
                }
                
                window->unlock_window();
                Timer::delay(20);    // sleep 20ms
        }
}

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