Analogously in the case of GUI toolkits, one would usually act on a button release, but only if it was preceded by a button press. The app however could encounter a press without a release (mouse dragged off the button) or a release without a press (mouse dragged onto the button). In the former case the button is informed that the press has been cancelled (by the pointer leaving) before it was released. And in the latter case the button simply ignores a 'release' that had no press before it. So there's another precedent for button cancellation of sorts...
-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to mir in Ubuntu. https://bugs.launchpad.net/bugs/1547864 Title: libinput doesn't handle EV_KEY event with a value of 255 (BUTTON_CANCLED), to support Android home buttons Status in Mir: Triaged Status in libinput package in Ubuntu: New Status in mir package in Ubuntu: Triaged Bug description: I port Ubuntu Touch to LG L90 Dual. When I press a button below the screen (it's the touch button and is part of the touch screen), then slide the finger up, a letter will repeatedly appear in any text field selected (for instance, if the button is a menu button, letter 'e' will appear repeatedly). Using evtest with the touch screen device, I can see what happened: Event: time 75.605520, type 1 (EV_KEY), code 139 (KEY_MENU), value 1 Event: time 75.605525, -------------- EV_SYN ------------ Event: time 75.707065, type 1 (EV_KEY), code 139 (KEY_MENU), value 255 (See the full log here: http://paste.ubuntu.com/15112114/) When I place the finger down, touch screen will send an event with type 1 (EV_KEY), code 139 (KEY_MENU), and value 1, indicating that the button is placed. And when I move the finger away from the button, touch screen will send an event with type 1 (EV_KEY), code 139 (KEY_MENU), and value 255. Digging in kernel code reveals that this is defined as "BUTTON_CANCLED". Looking in libevent code, it seems that it always assume that anything that is not 0 will be considered as pressed, which makes it looks like the button is hold. To manage notifications about this bug go to: https://bugs.launchpad.net/mir/+bug/1547864/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
