[PATCH xwayland] xwayland: Throttle our cursor surface updates with a frame callback

[Jasper St. Pierre]

This makes sense to me.

Reviewed-by: Jasper St. Pierre <jstpierre at mecheye.net>

On Mon, May 25, 2015 at 12:15 PM, Rui Matos <tiagomatos at gmail.com> wrote:
> In some extreme cases with animated cursors at a high frame rate we
> could end up filling the wl_display outgoing buffer and end up with
> wl_display_flush() failing.
>
> In any case, using the frame callback to throttle ourselves is the
> right thing to do.
>
> Signed-off-by: Rui Matos <tiagomatos at gmail.com>
> ---
>  hw/xwayland/xwayland-cursor.c | 20 ++++++++++++++++++++
>  hw/xwayland/xwayland-input.c  |  2 ++
>  hw/xwayland/xwayland.h        |  1 +
>  3 files changed, 23 insertions(+)
>
> diff --git a/hw/xwayland/xwayland-cursor.c b/hw/xwayland/xwayland-cursor.c
> index 5a9d1fe..3ba5ad6 100644
> --- a/hw/xwayland/xwayland-cursor.c
> +++ b/hw/xwayland/xwayland-cursor.c
> @@ -82,6 +82,19 @@ xwl_unrealize_cursor(DeviceIntPtr device, ScreenPtr screen, CursorPtr cursor)
>      return xwl_shm_destroy_pixmap(pixmap);
>  }
>
> +static void
> +frame_callback(void *data,
> +               struct wl_callback *callback,
> +               uint32_t time)
> +{
> +    struct xwl_seat *xwl_seat = data;
> +    xwl_seat->cursor_frame_cb = NULL;
> +}
> +
> +static const struct wl_callback_listener frame_listener = {
> +    frame_callback
> +};
> +
>  void
>  xwl_seat_set_cursor(struct xwl_seat *xwl_seat)
>  {
> @@ -98,6 +111,9 @@ xwl_seat_set_cursor(struct xwl_seat *xwl_seat)
>          return;
>      }
>
> +    if (xwl_seat->cursor_frame_cb)
> +        return;
> +
>      cursor = xwl_seat->x_cursor;
>      pixmap = dixGetPrivate(&cursor->devPrivates, &xwl_cursor_private_key);
>      stride = cursor->bits->width * 4;
> @@ -117,6 +133,10 @@ xwl_seat_set_cursor(struct xwl_seat *xwl_seat)
>      wl_surface_damage(xwl_seat->cursor, 0, 0,
>                        xwl_seat->x_cursor->bits->width,
>                        xwl_seat->x_cursor->bits->height);
> +
> +    xwl_seat->cursor_frame_cb = wl_surface_frame(xwl_seat->cursor);
> +    wl_callback_add_listener(xwl_seat->cursor_frame_cb, &frame_listener, xwl_seat);
> +
>      wl_surface_commit(xwl_seat->cursor);
>  }
>
> diff --git a/hw/xwayland/xwayland-input.c b/hw/xwayland/xwayland-input.c
> index 5230d8c..a3142f4 100644
> --- a/hw/xwayland/xwayland-input.c
> +++ b/hw/xwayland/xwayland-input.c
> @@ -586,6 +586,8 @@ xwl_seat_destroy(struct xwl_seat *xwl_seat)
>      RemoveDevice(xwl_seat->keyboard, FALSE);
>      wl_seat_destroy(xwl_seat->seat);
>      wl_surface_destroy(xwl_seat->cursor);
> +    if (xwl_seat->cursor_frame_cb)
> +        wl_callback_destroy(xwl_seat->cursor_frame_cb);
>      wl_array_release(&xwl_seat->keys);
>      free(xwl_seat);
>  }
> diff --git a/hw/xwayland/xwayland.h b/hw/xwayland/xwayland.h
> index bfffa71..92d6d6e 100644
> --- a/hw/xwayland/xwayland.h
> +++ b/hw/xwayland/xwayland.h
> @@ -116,6 +116,7 @@ struct xwl_seat {
>      struct wl_keyboard *wl_keyboard;
>      struct wl_array keys;
>      struct wl_surface *cursor;
> +    struct wl_callback *cursor_frame_cb;
>      struct xwl_window *focus_window;
>      uint32_t id;
>      uint32_t pointer_enter_serial;
> --
> 2.4.0
>
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-- 
  Jasper