[Interest] Any possible workaround for QTBUG-40889 ?

[Elvis Stansvik]

2016-06-30 18:59 GMT+02:00 Thiago Macieira <thiago.macieira at intel.com>:
> On quinta-feira, 30 de junho de 2016 17:16:54 PDT Elvis Stansvik wrote:
>> Would it be possible to install a QAbstractNativeEventFilter and
>> somehow "fix-up" the event combination that makes the event
>> compression fail? Has anyone else been in the same boat?
>
> Yes, in combination with a non-native filter that detects when the event has
> been delivered and processed. You need to keep a state:
>
>  if event has been seen
>  and event has not been delivered
>         swallow event
>

Hm, as an initial test, I installed a filter like

bool MotionEventFilter::nativeEventFilter(const QByteArray &eventType,
void *message, long *result)
{
    Q_UNUSED(result);

    if (eventType == "xcb_generic_event_t") {
        auto event = static_cast<xcb_generic_event_t *>(message);

        switch (event->response_type & ~0x80) {
        case XCB_MOTION_NOTIFY: {
            xcb_motion_notify_event_t *motion =
reinterpret_cast<xcb_motion_notify_event_t *>(event);
            std::cout << "XCB_MOTION_NOTIFY("
                      << "x: " << motion->event_x << ", y: " << motion->event_y
                      << ")" << std::endl;
            break;
        }
        case XCB_GE_GENERIC: {
            std::cout << "XCB_GE_GENERIC" << std::endl;
            break;
        }
        default:
            break;
        }
    }
    return false;
}

and all I get when moving the mouse over the window is

XCB_GE_GENERIC
XCB_GE_GENERIC
...

So the behavior doesn't really match what the fix commit message says,
unless I'm misunderstanding.

I thought I would get

XCB_MOTION_NOTIFY
XCB_GE_GENERIC
XCB_MOTION_NOTIFY
XCB_GE_GENERIC
...

On my end it seems mouse motions come in as only XCB_GE_GENERIC, not
as XCB_MOTION_NOTIFY and XCB_GE_GENERIC interleaved. Could that be why
compression is not working here? (XCB_GE_GENERIC are never
compressed?)

Sorry for all the questions, just trying to understand what's going on.

Elvis

> --
> Thiago Macieira - thiago.macieira (AT) intel.com
>   Software Architect - Intel Open Source Technology Center
>
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