[Qemu-devel] [Bug 1578192] [NEW] GTK+ interface doesn't translate keycodes properly with Wayland backend

[wyzu]

Public bug reported:

I already posted this on the mailing list
(https://lists.nongnu.org/archive/html/qemu-devel/2016-05/msg00119.html)
but I decided to do a formal bug report so it can be tracked and doesn't
get lost.

... I'm no expert, but it looks like GTK+ key events come in at the
ui/gtk.c:gd_key_event callback function, which calls
ui/gtk.c:gd_map_keycode to translate the GTK+ keycode into the Qemu
keycode before sending it on using qemu_input_event_send_key_number. The
problem is that gd_map_keycode is incomplete when GTK+ is running on a
backend other than X11.

static int gd_map_keycode(GtkDisplayState *s, GdkDisplay *dpy, int gdk_keycode)
{
    int qemu_keycode;

#ifdef GDK_WINDOWING_WIN32
    if (GDK_IS_WIN32_DISPLAY(dpy)) {
        qemu_keycode = MapVirtualKey(gdk_keycode, MAPVK_VK_TO_VSC);
        switch (qemu_keycode) {
        case 103:   /* alt gr */
            qemu_keycode = 56 | SCANCODE_GREY;
            break;
        }
        return qemu_keycode;
    }
#endif

    if (gdk_keycode < 9) {
        qemu_keycode = 0;
    } else if (gdk_keycode < 97) {
        qemu_keycode = gdk_keycode - 8;
#ifdef GDK_WINDOWING_X11
    } else if (GDK_IS_X11_DISPLAY(dpy) && gdk_keycode < 158) {
        if (s->has_evdev) {
            qemu_keycode = translate_evdev_keycode(gdk_keycode - 97);
        } else {
            qemu_keycode = translate_xfree86_keycode(gdk_keycode - 97);
        }
#endif
    } else if (gdk_keycode == 208) { /* Hiragana_Katakana */
        qemu_keycode = 0x70;
    } else if (gdk_keycode == 211) { /* backslash */
        qemu_keycode = 0x73;
    } else {
        qemu_keycode = 0;
    }

    return qemu_keycode;
}

In my case, I'm using GTK+'s Wayland backend, so keycodes 97 through 157
(this includes KEY_HOME(102), KEY_PAGEUP(104), KEY_PAGEDOWN(109),
KEY_END(107), etc.) are never translated into a qemu_keycode, and the
final 'else' block is hit, causing gd_map_keycode to return 0, which is
an invalid keycode and thus cannot be handled by xen-kbdfront. At least
that's my best guess as to what is happening.

The solution that comes to mind is provide an alternative to
translate_{evdev,xfree86}_keycode that is compatable with
Wayland/libinput, but I don't know exactly which API would provide this
functionality, much less do I have a patch. Intuition tells me that
translate_evdev_keycode would probably work under Wayland because Weston
uses libinput which uses evdev as its backend, but I don't know this for
a fact, and I don't know if it would be the Right Way (i.e. Wayland or
libinput might provide an API for this purpose, but I don't know).

I may try to do some testing with translate_evdev_keycode on Wayland and
also look into any possible APIs for keycode translation, but I just
wanted to put it out there and get some feedback awhile.

Qemu 2.2.1 from Xen 4.6.1 (relevant code appears unchanged in Qemu master)
GTK+ 3.18.7
Wayland 1.9.0
Weston 1.9.0
libinput 1.2.3

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1578192

Title:
  GTK+ interface doesn't translate keycodes properly with Wayland
  backend

Status in QEMU:
  New

Bug description:
  I already posted this on the mailing list
  (https://lists.nongnu.org/archive/html/qemu-
  devel/2016-05/msg00119.html) but I decided to do a formal bug report
  so it can be tracked and doesn't get lost.

  ... I'm no expert, but it looks like GTK+ key events come in at the
  ui/gtk.c:gd_key_event callback function, which calls
  ui/gtk.c:gd_map_keycode to translate the GTK+ keycode into the Qemu
  keycode before sending it on using qemu_input_event_send_key_number.
  The problem is that gd_map_keycode is incomplete when GTK+ is running
  on a backend other than X11.

  static int gd_map_keycode(GtkDisplayState *s, GdkDisplay *dpy, int 
gdk_keycode)
  {
      int qemu_keycode;

  #ifdef GDK_WINDOWING_WIN32
      if (GDK_IS_WIN32_DISPLAY(dpy)) {
          qemu_keycode = MapVirtualKey(gdk_keycode, MAPVK_VK_TO_VSC);
          switch (qemu_keycode) {
          case 103:   /* alt gr */
              qemu_keycode = 56 | SCANCODE_GREY;
              break;
          }
          return qemu_keycode;
      }
  #endif

      if (gdk_keycode < 9) {
          qemu_keycode = 0;
      } else if (gdk_keycode < 97) {
          qemu_keycode = gdk_keycode - 8;
  #ifdef GDK_WINDOWING_X11
      } else if (GDK_IS_X11_DISPLAY(dpy) && gdk_keycode < 158) {
          if (s->has_evdev) {
              qemu_keycode = translate_evdev_keycode(gdk_keycode - 97);
          } else {
              qemu_keycode = translate_xfree86_keycode(gdk_keycode - 97);
          }
  #endif
      } else if (gdk_keycode == 208) { /* Hiragana_Katakana */
          qemu_keycode = 0x70;
      } else if (gdk_keycode == 211) { /* backslash */
          qemu_keycode = 0x73;
      } else {
          qemu_keycode = 0;
      }

      return qemu_keycode;
  }

  In my case, I'm using GTK+'s Wayland backend, so keycodes 97 through
  157 (this includes KEY_HOME(102), KEY_PAGEUP(104), KEY_PAGEDOWN(109),
  KEY_END(107), etc.) are never translated into a qemu_keycode, and the
  final 'else' block is hit, causing gd_map_keycode to return 0, which
  is an invalid keycode and thus cannot be handled by xen-kbdfront. At
  least that's my best guess as to what is happening.

  The solution that comes to mind is provide an alternative to
  translate_{evdev,xfree86}_keycode that is compatable with
  Wayland/libinput, but I don't know exactly which API would provide
  this functionality, much less do I have a patch. Intuition tells me
  that translate_evdev_keycode would probably work under Wayland because
  Weston uses libinput which uses evdev as its backend, but I don't know
  this for a fact, and I don't know if it would be the Right Way (i.e.
  Wayland or libinput might provide an API for this purpose, but I don't
  know).

  I may try to do some testing with translate_evdev_keycode on Wayland
  and also look into any possible APIs for keycode translation, but I
  just wanted to put it out there and get some feedback awhile.

  Qemu 2.2.1 from Xen 4.6.1 (relevant code appears unchanged in Qemu master)
  GTK+ 3.18.7
  Wayland 1.9.0
  Weston 1.9.0
  libinput 1.2.3

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