Re: [PATCH 4/4] ui/gtk: enable backend to send multi-touch events

[Marc-André Lureau]

Hi Sergio

On Sat, Feb 18, 2023 at 8:23 PM Sergio Lopez <slp@redhat.com> wrote:
>
> GTK3 provides the infrastructure to receive and process multi-touch
> events through the "touch-event" signal and the GdkEventTouch type.
> Make use of it to transpose events from the host to the guest.
>
> This allows users of machines with hardware capable of receiving
> multi-touch events to run guests that can also receive those events
> and interpret them as gestures, when appropriate.
>
> An example of this in action can be seen here:
>
>  https://fosstodon.org/@slp/109545849296546767
>
> Signed-off-by: Sergio Lopez <slp@redhat.com>

> ---
>  ui/gtk.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 84 insertions(+)
>
> diff --git a/ui/gtk.c b/ui/gtk.c
> index fd82e9b1ca..bf1e7f086d 100644
> --- a/ui/gtk.c
> +++ b/ui/gtk.c
> @@ -130,6 +130,13 @@ typedef struct VCChardev VCChardev;
>  DECLARE_INSTANCE_CHECKER(VCChardev, VC_CHARDEV,
>                           TYPE_CHARDEV_VC)
>
> +struct touch_slot {
> +    int x;
> +    int y;
> +    int tracking_id;
> +};
> +static struct touch_slot touch_slots[INPUT_EVENT_SLOTS_MAX];
> +
>  bool gtk_use_gl_area;
>
>  static void gd_grab_pointer(VirtualConsole *vc, const char *reason);
> @@ -1058,6 +1065,74 @@ static gboolean gd_scroll_event(GtkWidget *widget, 
> GdkEventScroll *scroll,
>  }
>
>
> +static gboolean gd_touch_event(GtkWidget *widget, GdkEventTouch *touch,
> +                               void *opaque)
> +{
> +    VirtualConsole *vc = opaque;
> +    struct touch_slot *slot;
> +    uint64_t num_slot = (uint64_t) touch->sequence;

Perhaps use GPOINTER_TO_UINT?

> +    int update;
> +    int type = -1;
> +    int i;
> +
> +    if (num_slot >= INPUT_EVENT_SLOTS_MAX) {
> +        return FALSE;
> +    }

Hmm, a pointer < INPUT_EVENT_SLOTS_MAX ?

This seems to work because the wayland GDK backend uses presumably
evdev slot id + 1.. We may want to have some slot id mapping, or at
least report some warning for discarded events.

> +
> +    slot = &touch_slots[num_slot];
> +    slot->x = touch->x;
> +    slot->y = touch->y;
> +
> +    switch (touch->type) {
> +    case GDK_TOUCH_BEGIN:
> +        type = INPUT_MULTITOUCH_TYPE_BEGIN;
> +        slot->tracking_id = num_slot;
> +        break;
> +    case GDK_TOUCH_UPDATE:
> +        type = INPUT_MULTITOUCH_TYPE_UPDATE;
> +        break;
> +    case GDK_TOUCH_END:
> +    case GDK_TOUCH_CANCEL:
> +        type = INPUT_MULTITOUCH_TYPE_END;
> +        break;
> +    default:
> +        fprintf(stderr, "%s: unexpected touch event\n", __func__);
> +    }
> +
> +    for (i = 0; i < INPUT_EVENT_SLOTS_MAX; ++i) {
> +        if (i == num_slot) {
> +            update = type;
> +        } else {
> +            update = INPUT_MULTITOUCH_TYPE_UPDATE;
> +        }
> +
> +        slot = &touch_slots[i];
> +
> +        if (slot->tracking_id == -1) {
> +            continue;
> +        }
> +
> +        if (update == INPUT_MULTITOUCH_TYPE_END) {
> +            slot->tracking_id = -1;
> +            qemu_input_queue_mtt(vc->gfx.dcl.con, update, i, 
> slot->tracking_id);
> +        } else {
> +            qemu_input_queue_mtt(vc->gfx.dcl.con, update, i, 
> slot->tracking_id);
> +            qemu_input_queue_btn(vc->gfx.dcl.con, INPUT_BUTTON_TOUCH, true);
> +            qemu_input_queue_mtt_abs(vc->gfx.dcl.con,
> +                                     INPUT_AXIS_X, (int) slot->x,
> +                                     0, surface_width(vc->gfx.ds),
> +                                     i, slot->tracking_id);
> +            qemu_input_queue_mtt_abs(vc->gfx.dcl.con,
> +                                     INPUT_AXIS_Y, (int) slot->y,
> +                                     0, surface_height(vc->gfx.ds),
> +                                     i, slot->tracking_id);
> +        }
> +        qemu_input_event_sync();

Shouldn't you sync at the end of the loop? (otherwise you get several
SYN_REPORT, no?)

> +    }
> +
> +    return TRUE;
> +}
> +
>  static const guint16 *gd_get_keymap(size_t *maplen)
>  {
>      GdkDisplay *dpy = gdk_display_get_default();
> @@ -1977,6 +2052,8 @@ static void gd_connect_vc_gfx_signals(VirtualConsole 
> *vc)
>                           G_CALLBACK(gd_key_event), vc);
>          g_signal_connect(vc->gfx.drawing_area, "key-release-event",
>                           G_CALLBACK(gd_key_event), vc);
> +        g_signal_connect(vc->gfx.drawing_area, "touch-event",
> +                         G_CALLBACK(gd_touch_event), vc);
>
>          g_signal_connect(vc->gfx.drawing_area, "enter-notify-event",
>                           G_CALLBACK(gd_enter_event), vc);
> @@ -2086,6 +2163,7 @@ static GSList *gd_vc_gfx_init(GtkDisplayState *s, 
> VirtualConsole *vc,
>                                GSList *group, GtkWidget *view_menu)
>  {
>      bool zoom_to_fit = false;
> +    int i;
>
>      vc->label = qemu_console_get_label(con);
>      vc->s = s;
> @@ -2133,6 +2211,7 @@ static GSList *gd_vc_gfx_init(GtkDisplayState *s, 
> VirtualConsole *vc,
>                            GDK_BUTTON_PRESS_MASK |
>                            GDK_BUTTON_RELEASE_MASK |
>                            GDK_BUTTON_MOTION_MASK |
> +                          GDK_TOUCH_MASK |
>                            GDK_ENTER_NOTIFY_MASK |
>                            GDK_LEAVE_NOTIFY_MASK |
>                            GDK_SCROLL_MASK |
> @@ -2168,6 +2247,11 @@ static GSList *gd_vc_gfx_init(GtkDisplayState *s, 
> VirtualConsole *vc,
>          s->free_scale = true;
>      }
>
> +    for (i = 0; i < INPUT_EVENT_SLOTS_MAX; i++) {
> +        struct touch_slot *slot = &touch_slots[i];
> +        slot->tracking_id = -1;
> +    }
> +
>      return group;
>  }
>
> --
> 2.38.1
>
>


-- 
Marc-André Lureau