wayland: Basic support for zwp_tablet_*v2 protocol

src/video/wayland/SDL_waylandevents.c

@@ -40,6 +40,7 @@
 #include "xdg-shell-client-protocol.h"
 #include "keyboard-shortcuts-inhibit-unstable-v1-client-protocol.h"
 #include "text-input-unstable-v3-client-protocol.h"
+#include "tablet-unstable-v2-client-protocol.h"
 
 #ifdef HAVE_LIBDECOR_H
 #include <libdecor.h>
@@ -1646,6 +1647,361 @@ Wayland_add_text_input_manager(SDL_VideoData *d, uint32_t id, uint32_t version)
     }
 }
 
+static void
+tablet_tool_handle_type(void* data, struct zwp_tablet_tool_v2* tool, uint32_t type)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_hardware_serial(void* data, struct zwp_tablet_tool_v2* tool, uint32_t serial_hi, uint32_t serial_lo)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_hardware_id_wacom(void* data, struct zwp_tablet_tool_v2* tool, uint32_t id_hi, uint32_t id_lo)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_capability(void* data, struct zwp_tablet_tool_v2* tool, uint32_t capability)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_done(void* data, struct zwp_tablet_tool_v2* tool)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_removed(void* data, struct zwp_tablet_tool_v2* tool)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_proximity_in(void* data, struct zwp_tablet_tool_v2* tool, uint32_t serial, struct zwp_tablet_v2* tablet, struct wl_surface* surface)
+{
+    struct SDL_WaylandTabletInput* input = data;
+    SDL_WindowData* window;
+
+    if (!surface) {
+        return;
+    }
+
+    if (!SDL_WAYLAND_own_surface(surface)) {
+        return;
+    }
+
+    window = (SDL_WindowData*)wl_surface_get_user_data(surface);
+
+    if (window) {
+        input->tool_focus = window;
+        input->tool_prox_serial = serial;
+
+        input->is_down = SDL_FALSE;
+
+        input->btn_stylus = SDL_FALSE;
+        input->btn_stylus2 = SDL_FALSE;
+        input->btn_stylus3 = SDL_FALSE;
+
+        SDL_SetMouseFocus(window->sdlwindow);
+        SDL_SetCursor(NULL);
+    }
+}
+
+static void
+tablet_tool_handle_proximity_out(void* data, struct zwp_tablet_tool_v2* tool)
+{
+    struct SDL_WaylandTabletInput* input = data;
+
+    if (input->tool_focus) {
+        SDL_SetMouseFocus(NULL);
+        input->tool_focus = NULL;
+    }
+}
+
+uint32_t
+tablet_tool_btn_to_sdl_button(struct SDL_WaylandTabletInput* input)
+{
+    unsigned int tool_btn = input->btn_stylus3 << 2 | input->btn_stylus2 << 1 | input->btn_stylus << 0;
+    switch (tool_btn) {
+        case 0b000:
+            return SDL_BUTTON_LEFT;
+        case 0b001:
+            return SDL_BUTTON_RIGHT;
+        case 0b010:
+            return SDL_BUTTON_MIDDLE;
+        case 0b100:
+            return SDL_BUTTON_X1;
+        default:
+            return SDL_BUTTON_LEFT;
+    }
+}
+
+static void
+tablet_tool_handle_down(void* data, struct zwp_tablet_tool_v2* tool, uint32_t serial)
+{
+    struct SDL_WaylandTabletInput* input = data;
+    SDL_WindowData* window = input->tool_focus;
+    input->is_down = SDL_TRUE;
+    if (!window) {
+        /* tablet_tool_handle_proximity_out gets called when moving over the libdecoration csd.
+         * that sets input->tool_focus (window) to NULL, but handle_{down,up} events are still
+         * received. To prevent SIGSEGV this returns when this is the case.
+         */
+        return;
+    }
+
+    SDL_SendMouseButton(window->sdlwindow, 0, SDL_PRESSED, tablet_tool_btn_to_sdl_button(input));
+}
+
+static void
+tablet_tool_handle_up(void* data, struct zwp_tablet_tool_v2* tool)
+{
+    struct SDL_WaylandTabletInput* input = data;
+    SDL_WindowData* window = input->tool_focus;
+
+    input->is_down = SDL_FALSE;
+
+    if (!window) {
+        /* tablet_tool_handle_proximity_out gets called when moving over the libdecoration csd.
+         * that sets input->tool_focus (window) to NULL, but handle_{down,up} events are still
+         * received. To prevent SIGSEGV this returns when this is the case.
+         */
+        return;
+    }
+
+    SDL_SendMouseButton(window->sdlwindow, 0, SDL_RELEASED, tablet_tool_btn_to_sdl_button(input));
+}
+
+static void
+tablet_tool_handle_motion(void* data, struct zwp_tablet_tool_v2* tool, wl_fixed_t sx_w, wl_fixed_t sy_w)
+{
+    struct SDL_WaylandTabletInput* input = data;
+    SDL_WindowData* window = input->tool_focus;
+
+    input->sx_w = sx_w;
+    input->sy_w = sy_w;
+    if (input->tool_focus) {
+        const int sx = wl_fixed_to_int(sx_w);
+        const int sy = wl_fixed_to_int(sy_w);
+        SDL_SendMouseMotion(window->sdlwindow, 0, 0, sx, sy);
+    }
+}
+
+static void
+tablet_tool_handle_pressure(void* data, struct zwp_tablet_tool_v2* tool, uint32_t pressure)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_distance(void* data, struct zwp_tablet_tool_v2* tool, uint32_t distance)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_tilt(void* data, struct zwp_tablet_tool_v2* tool, wl_fixed_t xtilt, wl_fixed_t ytilt)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_button(void* data, struct zwp_tablet_tool_v2* tool, uint32_t serial, uint32_t button, uint32_t state)
+{
+    struct SDL_WaylandTabletInput* input = data;
+
+    if (input->is_down) {
+        tablet_tool_handle_up(data, tool);
+        input->is_down = SDL_TRUE;
+    }
+
+    switch (button) {
+        /* see %{_includedir}/linux/input-event-codes.h */
+        case 0x14b: /* BTN_STYLUS */
+            input->btn_stylus = state == ZWP_TABLET_PAD_V2_BUTTON_STATE_PRESSED ? SDL_TRUE : SDL_FALSE;
+            break;
+        case 0x14c: /* BTN_STYLUS2 */
+            input->btn_stylus2 = state == ZWP_TABLET_PAD_V2_BUTTON_STATE_PRESSED ? SDL_TRUE : SDL_FALSE;
+            break;
+        case 0x149: /* BTN_STYLUS3 */
+            input->btn_stylus3 = state == ZWP_TABLET_PAD_V2_BUTTON_STATE_PRESSED ? SDL_TRUE : SDL_FALSE;
+            break;
+    }
+
+    if (input->is_down) {
+        tablet_tool_handle_down(data, tool, serial);
+    }
+}
+
+static void
+tablet_tool_handle_rotation(void* data, struct zwp_tablet_tool_v2* tool, wl_fixed_t degrees)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_slider(void* data, struct zwp_tablet_tool_v2* tool, int32_t position)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_wheel(void* data, struct zwp_tablet_tool_v2* tool, int32_t degrees, int32_t clicks)
+{
+    /* unimplemented */
+}
+
+static void
+tablet_tool_handle_frame(void* data, struct zwp_tablet_tool_v2* tool, uint32_t time)
+{
+    /* unimplemented */
+}
+
+
+static const struct zwp_tablet_tool_v2_listener tablet_tool_listener = {
+    tablet_tool_handle_type,
+    tablet_tool_handle_hardware_serial,
+    tablet_tool_handle_hardware_id_wacom,
+    tablet_tool_handle_capability,
+    tablet_tool_handle_done,
+    tablet_tool_handle_removed,
+    tablet_tool_handle_proximity_in,
+    tablet_tool_handle_proximity_out,
+    tablet_tool_handle_down,
+    tablet_tool_handle_up,
+    tablet_tool_handle_motion,
+    tablet_tool_handle_pressure,
+    tablet_tool_handle_distance,
+    tablet_tool_handle_tilt,
+    tablet_tool_handle_rotation,
+    tablet_tool_handle_slider,
+    tablet_tool_handle_wheel,
+    tablet_tool_handle_button,
+    tablet_tool_handle_frame
+};
+
+struct SDL_WaylandTabletObjectListNode*
+tablet_object_list_new_node(void* object)
+{
+    struct SDL_WaylandTabletObjectListNode* node;
+
+    node = SDL_calloc(1, sizeof *node);
+    if (node == NULL) {
+        return NULL;
+    }
+
+    node->next = NULL;
+    node->object = object;
+
+    return node;
+}
+
+void tablet_object_list_append(struct SDL_WaylandTabletObjectListNode* head, void* object)
+{
+    if (head->object == NULL) {
+        head->object = object;
+        return;
+    }
+
+    while (head->next) {
+        head = head->next;
+    }
+
+    head->next = tablet_object_list_new_node(object);
+}
+
+void tablet_object_list_destroy(struct SDL_WaylandTabletObjectListNode* head, void (*deleter)(void* object))
+{
+    while (head) {
+        struct SDL_WaylandTabletObjectListNode* next = head->next;
+        if (head->object) {
+            (*deleter)(head->object);
+        }
+        SDL_free(head);
+        head = next;
+    }
+}
+
+
+static void
+tablet_seat_handle_tablet_added(void* data, struct zwp_tablet_seat_v2* seat, struct zwp_tablet_v2* tablet)
+{
+    struct SDL_WaylandTabletInput* input = data;
+
+    tablet_object_list_append(input->tablets, tablet);
+}
+
+static void
+tablet_seat_handle_tool_added(void* data, struct zwp_tablet_seat_v2* seat, struct zwp_tablet_tool_v2* tool)
+{
+    struct SDL_WaylandTabletInput* input = data;
+
+    zwp_tablet_tool_v2_add_listener(tool, &tablet_tool_listener, data);
+    zwp_tablet_tool_v2_set_user_data(tool, data);
+
+    tablet_object_list_append(input->tools, tool);
+}
+
+static void
+tablet_seat_handle_pad_added(void* data, struct zwp_tablet_seat_v2* seat, struct zwp_tablet_pad_v2* pad)
+{
+    struct SDL_WaylandTabletInput* input = data;
+
+    tablet_object_list_append(input->pads, pad);
+}
+
+static const struct zwp_tablet_seat_v2_listener tablet_seat_listener = {
+    tablet_seat_handle_tablet_added,
+    tablet_seat_handle_tool_added,
+    tablet_seat_handle_pad_added
+};
+
+void
+Wayland_input_add_tablet(struct SDL_WaylandInput *input, struct SDL_WaylandTabletManager* tablet_manager)
+{
+    struct SDL_WaylandTabletInput* tablet_input;
+
+    if (!tablet_manager || !input || !input->seat) {
+        return;
+    }
+
+    tablet_input = SDL_calloc(1, sizeof *tablet_input);
+    if (tablet_input == NULL) {
+        return;
+    }
+
+    input->tablet = tablet_input;
+
+    tablet_input->seat = (struct SDL_WaylandTabletSeat*)zwp_tablet_manager_v2_get_tablet_seat((struct zwp_tablet_manager_v2*)tablet_manager, input->seat);
+
+    tablet_input->tablets = tablet_object_list_new_node(NULL);
+    tablet_input->tools = tablet_object_list_new_node(NULL);
+    tablet_input->pads = tablet_object_list_new_node(NULL);
+
+    zwp_tablet_seat_v2_add_listener((struct zwp_tablet_seat_v2*)tablet_input->seat, &tablet_seat_listener, tablet_input);
+}
+
+#define TABLET_OBJECT_LIST_DELETER(fun) (void (*)(void*))fun
+void
+Wayland_input_destroy_tablet(struct SDL_WaylandInput* input)
+{
+    tablet_object_list_destroy(input->tablet->pads, TABLET_OBJECT_LIST_DELETER(zwp_tablet_pad_v2_destroy));
+    tablet_object_list_destroy(input->tablet->tools, TABLET_OBJECT_LIST_DELETER(zwp_tablet_tool_v2_destroy));
+    tablet_object_list_destroy(input->tablet->tablets, TABLET_OBJECT_LIST_DELETER(zwp_tablet_v2_destroy));
+
+    zwp_tablet_seat_v2_destroy((struct zwp_tablet_seat_v2*)input->tablet->seat);
+
+    SDL_free(input->tablet);
+    input->tablet = NULL;
+}
+
 void
 Wayland_display_add_input(SDL_VideoData *d, uint32_t id, uint32_t version)
 {
@@ -1671,6 +2027,10 @@ Wayland_display_add_input(SDL_VideoData *d, uint32_t id, uint32_t version)
     wl_seat_add_listener(input->seat, &seat_listener, input);
     wl_seat_set_user_data(input->seat, input);
 
+    if (d->tablet_manager) {
+        Wayland_input_add_tablet(input, d->tablet_manager);
+    }
+
     WAYLAND_wl_display_flush(d->display);
 }
 
@@ -1711,6 +2071,10 @@ void Wayland_display_destroy_input(SDL_VideoData *d)
         wl_touch_destroy(input->touch);
     }
 
+    if (input->tablet) {
+        Wayland_input_destroy_tablet(input);
+    }
+
     if (input->seat)
         wl_seat_destroy(input->seat);
 

src/video/wayland/SDL_waylandevents_c.h

@@ -29,6 +29,34 @@
 #include "SDL_waylanddatamanager.h"
 #include "SDL_waylandkeyboard.h"
 
+struct SDL_WaylandTabletSeat;
+
+struct SDL_WaylandTabletObjectListNode {
+    void* object;
+    struct SDL_WaylandTabletObjectListNode* next;
+};
+
+struct SDL_WaylandTabletInput {
+    struct SDL_WaylandTabletSeat* seat;
+
+    struct SDL_WaylandTabletObjectListNode* tablets;
+    struct SDL_WaylandTabletObjectListNode* tools;
+    struct SDL_WaylandTabletObjectListNode* pads;
+
+    SDL_WindowData *tool_focus;
+    uint32_t tool_prox_serial;
+
+    /* Last motion location */
+    wl_fixed_t sx_w;
+    wl_fixed_t sy_w;
+
+    SDL_bool is_down;
+
+    SDL_bool btn_stylus;
+    SDL_bool btn_stylus2;
+    SDL_bool btn_stylus3;
+};
+
 typedef struct {
     // repeat_rate in range of [1, 1000]
     int32_t repeat_rate;
@@ -80,6 +108,8 @@ struct SDL_WaylandInput {
     } pointer_curr_axis_info;
 
     SDL_WaylandKeyboardRepeat keyboard_repeat;
+
+    struct SDL_WaylandTabletInput* tablet;
 };
 
 extern void Wayland_PumpEvents(_THIS);
@@ -107,6 +137,9 @@ extern void Wayland_display_destroy_relative_pointer_manager(SDL_VideoData *d);
 extern int Wayland_input_grab_keyboard(SDL_Window *window, struct SDL_WaylandInput *input);
 extern int Wayland_input_ungrab_keyboard(SDL_Window *window);
 
+extern void Wayland_input_add_tablet(struct SDL_WaylandInput *input, struct SDL_WaylandTabletManager* tablet_manager);
+extern void Wayland_input_destroy_tablet(struct SDL_WaylandInput *input);
+
 #endif /* SDL_waylandevents_h_ */
 
 /* vi: set ts=4 sw=4 expandtab: */

src/video/wayland/SDL_waylandvideo.c

@@ -52,6 +52,7 @@
 #include "idle-inhibit-unstable-v1-client-protocol.h"
 #include "xdg-activation-v1-client-protocol.h"
 #include "text-input-unstable-v3-client-protocol.h"
+#include "tablet-unstable-v2-client-protocol.h"
 
 #ifdef HAVE_LIBDECOR_H
 #include <libdecor.h>
@@ -610,6 +611,11 @@ display_handle_global(void *data, struct wl_registry *registry, uint32_t id,
         Wayland_add_data_device_manager(d, id, version);
     } else if (SDL_strcmp(interface, "zxdg_decoration_manager_v1") == 0) {
         d->decoration_manager = wl_registry_bind(d->registry, id, &zxdg_decoration_manager_v1_interface, 1);
+    } else if (SDL_strcmp(interface, "zwp_tablet_manager_v2") == 0) {
+        d->tablet_manager = wl_registry_bind(d->registry, id, &zwp_tablet_manager_v2_interface, 1);
+        if (d->input) {
+            Wayland_input_add_tablet(d->input, d->tablet_manager);
+        }
 
 #ifdef SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH
     } else if (SDL_strcmp(interface, "qt_touch_extension") == 0) {
@@ -769,6 +775,9 @@ Wayland_VideoQuit(_THIS)
     Wayland_touch_destroy(data);
 #endif /* SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH */
 
+    if (data->tablet_manager)
+        zwp_tablet_manager_v2_destroy((struct zwp_tablet_manager_v2*)data->tablet_manager);
+
     if (data->data_device_manager)
         wl_data_device_manager_destroy(data->data_device_manager);
 

src/video/wayland/SDL_waylandvideo.h

@@ -34,6 +34,7 @@
 
 struct xkb_context;
 struct SDL_WaylandInput;
+struct SDL_WaylandTabletManager;
 
 #ifdef SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH
 struct SDL_WaylandTouch;
@@ -77,6 +78,7 @@ typedef struct {
 
     struct xkb_context *xkb_context;
     struct SDL_WaylandInput *input;
+    struct SDL_WaylandTabletManager *tablet_manager;
 
 #ifdef SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH
     struct SDL_WaylandTouch *touch;

wayland-protocols/tablet-unstable-v2.xml

@@ -0,0 +1,1178 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="tablet_unstable_v2">
+
+  <copyright>
+    Copyright 2014 © Stephen "Lyude" Chandler Paul
+    Copyright 2015-2016 © Red Hat, Inc.
+
+    Permission is hereby granted, free of charge, to any person
+    obtaining a copy of this software and associated documentation files
+    (the "Software"), to deal in the Software without restriction,
+    including without limitation the rights to use, copy, modify, merge,
+    publish, distribute, sublicense, and/or sell copies of the Software,
+    and to permit persons to whom the Software is furnished to do so,
+    subject to the following conditions:
+
+    The above copyright notice and this permission notice (including the
+    next paragraph) shall be included in all copies or substantial
+    portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+    NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+    BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+    ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  </copyright>
+
+  <description summary="Wayland protocol for graphics tablets">
+    This description provides a high-level overview of the interplay between
+    the interfaces defined this protocol. For details, see the protocol
+    specification.
+
+    More than one tablet may exist, and device-specifics matter. Tablets are
+    not represented by a single virtual device like wl_pointer. A client
+    binds to the tablet manager object which is just a proxy object. From
+    that, the client requests wp_tablet_manager.get_tablet_seat(wl_seat)
+    and that returns the actual interface that has all the tablets. With
+    this indirection, we can avoid merging wp_tablet into the actual Wayland
+    protocol, a long-term benefit.
+
+    The wp_tablet_seat sends a "tablet added" event for each tablet
+    connected. That event is followed by descriptive events about the
+    hardware; currently that includes events for name, vid/pid and
+    a wp_tablet.path event that describes a local path. This path can be
+    used to uniquely identify a tablet or get more information through
+    libwacom. Emulated or nested tablets can skip any of those, e.g. a
+    virtual tablet may not have a vid/pid. The sequence of descriptive
+    events is terminated by a wp_tablet.done event to signal that a client
+    may now finalize any initialization for that tablet.
+
+    Events from tablets require a tool in proximity. Tools are also managed
+    by the tablet seat; a "tool added" event is sent whenever a tool is new
+    to the compositor. That event is followed by a number of descriptive
+    events about the hardware; currently that includes capabilities,
+    hardware id and serial number, and tool type. Similar to the tablet
+    interface, a wp_tablet_tool.done event is sent to terminate that initial
+    sequence.
+
+    Any event from a tool happens on the wp_tablet_tool interface. When the
+    tool gets into proximity of the tablet, a proximity_in event is sent on
+    the wp_tablet_tool interface, listing the tablet and the surface. That
+    event is followed by a motion event with the coordinates. After that,
+    it's the usual motion, axis, button, etc. events. The protocol's
+    serialisation means events are grouped by wp_tablet_tool.frame events.
+
+    Two special events (that don't exist in X) are down and up. They signal
+    "tip touching the surface". For tablets without real proximity
+    detection, the sequence is: proximity_in, motion, down, frame.
+
+    When the tool leaves proximity, a proximity_out event is sent. If any
+    button is still down, a button release event is sent before this
+    proximity event. These button events are sent in the same frame as the
+    proximity event to signal to the client that the buttons were held when
+    the tool left proximity.
+
+    If the tool moves out of the surface but stays in proximity (i.e.
+    between windows), compositor-specific grab policies apply. This usually
+    means that the proximity-out is delayed until all buttons are released.
+
+    Moving a tool physically from one tablet to the other has no real effect
+    on the protocol, since we already have the tool object from the "tool
+    added" event. All the information is already there and the proximity
+    events on both tablets are all a client needs to reconstruct what
+    happened.
+
+    Some extra axes are normalized, i.e. the client knows the range as
+    specified in the protocol (e.g. [0, 65535]), the granularity however is
+    unknown. The current normalized axes are pressure, distance, and slider.
+
+    Other extra axes are in physical units as specified in the protocol.
+    The current extra axes with physical units are tilt, rotation and
+    wheel rotation.
+
+    Since tablets work independently of the pointer controlled by the mouse,
+    the focus handling is independent too and controlled by proximity.
+    The wp_tablet_tool.set_cursor request sets a tool-specific cursor.
+    This cursor surface may be the same as the mouse cursor, and it may be
+    the same across tools but it is possible to be more fine-grained. For
+    example, a client may set different cursors for the pen and eraser.
+
+    Tools are generally independent of tablets and it is
+    compositor-specific policy when a tool can be removed. Common approaches
+    will likely include some form of removing a tool when all tablets the
+    tool was used on are removed.
+
+    Warning! The protocol described in this file is experimental and
+    backward incompatible changes may be made. Backward compatible changes
+    may be added together with the corresponding interface version bump.
+    Backward incompatible changes are done by bumping the version number in
+    the protocol and interface names and resetting the interface version.
+    Once the protocol is to be declared stable, the 'z' prefix and the
+    version number in the protocol and interface names are removed and the
+    interface version number is reset.
+  </description>
+
+  <interface name="zwp_tablet_manager_v2" version="1">
+    <description summary="controller object for graphic tablet devices">
+      An object that provides access to the graphics tablets available on this
+      system. All tablets are associated with a seat, to get access to the
+      actual tablets, use wp_tablet_manager.get_tablet_seat.
+    </description>
+
+    <request name="get_tablet_seat">
+      <description summary="get the tablet seat">
+	Get the wp_tablet_seat object for the given seat. This object
+	provides access to all graphics tablets in this seat.
+      </description>
+      <arg name="tablet_seat" type="new_id" interface="zwp_tablet_seat_v2"/>
+      <arg name="seat" type="object" interface="wl_seat" summary="The wl_seat object to retrieve the tablets for" />
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="release the memory for the tablet manager object">
+	Destroy the wp_tablet_manager object. Objects created from this
+	object are unaffected and should be destroyed separately.
+      </description>
+    </request>
+  </interface>
+
+  <interface name="zwp_tablet_seat_v2" version="1">
+    <description summary="controller object for graphic tablet devices of a seat">
+      An object that provides access to the graphics tablets available on this
+      seat. After binding to this interface, the compositor sends a set of
+      wp_tablet_seat.tablet_added and wp_tablet_seat.tool_added events.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="release the memory for the tablet seat object">
+	Destroy the wp_tablet_seat object. Objects created from this
+	object are unaffected and should be destroyed separately.
+      </description>
+    </request>
+
+    <event name="tablet_added">
+      <description summary="new device notification">
+	This event is sent whenever a new tablet becomes available on this
+	seat. This event only provides the object id of the tablet, any
+	static information about the tablet (device name, vid/pid, etc.) is
+	sent through the wp_tablet interface.
+      </description>
+      <arg name="id" type="new_id" interface="zwp_tablet_v2" summary="the newly added graphics tablet"/>
+    </event>
+
+    <event name="tool_added">
+      <description summary="a new tool has been used with a tablet">
+	This event is sent whenever a tool that has not previously been used
+	with a tablet comes into use. This event only provides the object id
+	of the tool; any static information about the tool (capabilities,
+	type, etc.) is sent through the wp_tablet_tool interface.
+      </description>
+      <arg name="id" type="new_id" interface="zwp_tablet_tool_v2" summary="the newly added tablet tool"/>
+    </event>
+
+    <event name="pad_added">
+      <description summary="new pad notification">
+	This event is sent whenever a new pad is known to the system. Typically,
+	pads are physically attached to tablets and a pad_added event is
+	sent immediately after the wp_tablet_seat.tablet_added.
+	However, some standalone pad devices logically attach to tablets at
+	runtime, and the client must wait for wp_tablet_pad.enter to know
+	the tablet a pad is attached to.
+
+	This event only provides the object id of the pad. All further
+	features (buttons, strips, rings) are sent through the wp_tablet_pad
+	interface.
+      </description>
+      <arg name="id" type="new_id" interface="zwp_tablet_pad_v2" summary="the newly added pad"/>
+    </event>
+  </interface>
+
+  <interface name="zwp_tablet_tool_v2" version="1">
+    <description summary="a physical tablet tool">
+      An object that represents a physical tool that has been, or is
+      currently in use with a tablet in this seat. Each wp_tablet_tool
+      object stays valid until the client destroys it; the compositor
+      reuses the wp_tablet_tool object to indicate that the object's
+      respective physical tool has come into proximity of a tablet again.
+
+      A wp_tablet_tool object's relation to a physical tool depends on the
+      tablet's ability to report serial numbers. If the tablet supports
+      this capability, then the object represents a specific physical tool
+      and can be identified even when used on multiple tablets.
+
+      A tablet tool has a number of static characteristics, e.g. tool type,
+      hardware_serial and capabilities. These capabilities are sent in an
+      event sequence after the wp_tablet_seat.tool_added event before any
+      actual events from this tool. This initial event sequence is
+      terminated by a wp_tablet_tool.done event.
+
+      Tablet tool events are grouped by wp_tablet_tool.frame events.
+      Any events received before a wp_tablet_tool.frame event should be
+      considered part of the same hardware state change.
+    </description>
+
+    <request name="set_cursor">
+      <description summary="set the tablet tool's surface">
+	Sets the surface of the cursor used for this tool on the given
+	tablet. This request only takes effect if the tool is in proximity
+	of one of the requesting client's surfaces or the surface parameter
+	is the current pointer surface. If there was a previous surface set
+	with this request it is replaced. If surface is NULL, the cursor
+	image is hidden.
+
+	The parameters hotspot_x and hotspot_y define the position of the
+	pointer surface relative to the pointer location. Its top-left corner
+	is always at (x, y) - (hotspot_x, hotspot_y), where (x, y) are the
+	coordinates of the pointer location, in surface-local coordinates.
+
+	On surface.attach requests to the pointer surface, hotspot_x and
+	hotspot_y are decremented by the x and y parameters passed to the
+	request. Attach must be confirmed by wl_surface.commit as usual.
+
+	The hotspot can also be updated by passing the currently set pointer
+	surface to this request with new values for hotspot_x and hotspot_y.
+
+	The current and pending input regions of the wl_surface are cleared,
+	and wl_surface.set_input_region is ignored until the wl_surface is no
+	longer used as the cursor. When the use as a cursor ends, the current
+	and pending input regions become undefined, and the wl_surface is
+	unmapped.
+
+	This request gives the surface the role of a wp_tablet_tool cursor. A
+	surface may only ever be used as the cursor surface for one
+	wp_tablet_tool. If the surface already has another role or has
+	previously been used as cursor surface for a different tool, a
+	protocol error is raised.
+      </description>
+      <arg name="serial" type="uint" summary="serial of the enter event"/>
+      <arg name="surface" type="object" interface="wl_surface" allow-null="true"/>
+      <arg name="hotspot_x" type="int" summary="surface-local x coordinate"/>
+      <arg name="hotspot_y" type="int" summary="surface-local y coordinate"/>
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the tool object">
+	This destroys the client's resource for this tool object.
+      </description>
+    </request>
+
+    <enum name="type">
+      <description summary="a physical tool type">
+	Describes the physical type of a tool. The physical type of a tool
+	generally defines its base usage.
+
+	The mouse tool represents a mouse-shaped tool that is not a relative
+	device but bound to the tablet's surface, providing absolute
+	coordinates.
+
+	The lens tool is a mouse-shaped tool with an attached lens to
+	provide precision focus.
+      </description>
+      <entry name="pen" value="0x140" summary="Pen"/>
+      <entry name="eraser" value="0x141" summary="Eraser"/>
+      <entry name="brush" value="0x142" summary="Brush"/>
+      <entry name="pencil" value="0x143" summary="Pencil"/>
+      <entry name="airbrush" value="0x144" summary="Airbrush"/>
+      <entry name="finger" value="0x145" summary="Finger"/>
+      <entry name="mouse" value="0x146" summary="Mouse"/>
+      <entry name="lens" value="0x147" summary="Lens"/>
+    </enum>
+
+    <event name="type">
+      <description summary="tool type">
+	The tool type is the high-level type of the tool and usually decides
+	the interaction expected from this tool.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_tool.done event.
+      </description>
+      <arg name="tool_type" type="uint" enum="type" summary="the physical tool type"/>
+    </event>
+
+    <event name="hardware_serial">
+      <description summary="unique hardware serial number of the tool">
+	If the physical tool can be identified by a unique 64-bit serial
+	number, this event notifies the client of this serial number.
+
+	If multiple tablets are available in the same seat and the tool is
+	uniquely identifiable by the serial number, that tool may move
+	between tablets.
+
+	Otherwise, if the tool has no serial number and this event is
+	missing, the tool is tied to the tablet it first comes into
+	proximity with. Even if the physical tool is used on multiple
+	tablets, separate wp_tablet_tool objects will be created, one per
+	tablet.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_tool.done event.
+      </description>
+      <arg name="hardware_serial_hi" type="uint" summary="the unique serial number of the tool, most significant bits"/>
+      <arg name="hardware_serial_lo" type="uint" summary="the unique serial number of the tool, least significant bits"/>
+    </event>
+
+    <event name="hardware_id_wacom">
+      <description summary="hardware id notification in Wacom's format">
+	This event notifies the client of a hardware id available on this tool.
+
+	The hardware id is a device-specific 64-bit id that provides extra
+	information about the tool in use, beyond the wl_tool.type
+	enumeration. The format of the id is specific to tablets made by
+	Wacom Inc. For example, the hardware id of a Wacom Grip
+	Pen (a stylus) is 0x802.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_tool.done event.
+      </description>
+      <arg name="hardware_id_hi" type="uint" summary="the hardware id, most significant bits"/>
+      <arg name="hardware_id_lo" type="uint" summary="the hardware id, least significant bits"/>
+    </event>
+
+    <enum name="capability">
+      <description summary="capability flags for a tool">
+	Describes extra capabilities on a tablet.
+
+	Any tool must provide x and y values, extra axes are
+	device-specific.
+      </description>
+      <entry name="tilt" value="1" summary="Tilt axes"/>
+      <entry name="pressure" value="2" summary="Pressure axis"/>
+      <entry name="distance" value="3" summary="Distance axis"/>
+      <entry name="rotation" value="4" summary="Z-rotation axis"/>
+      <entry name="slider" value="5" summary="Slider axis"/>
+      <entry name="wheel" value="6" summary="Wheel axis"/>
+    </enum>
+
+    <event name="capability">
+      <description summary="tool capability notification">
+	This event notifies the client of any capabilities of this tool,
+	beyond the main set of x/y axes and tip up/down detection.
+
+	One event is sent for each extra capability available on this tool.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_tool.done event.
+      </description>
+      <arg name="capability" type="uint" enum="capability" summary="the capability"/>
+    </event>
+
+    <event name="done">
+      <description summary="tool description events sequence complete">
+	This event signals the end of the initial burst of descriptive
+	events. A client may consider the static description of the tool to
+	be complete and finalize initialization of the tool.
+      </description>
+    </event>
+
+    <event name="removed">
+      <description summary="tool removed">
+	This event is sent when the tool is removed from the system and will
+	send no further events. Should the physical tool come back into
+	proximity later, a new wp_tablet_tool object will be created.
+
+	It is compositor-dependent when a tool is removed. A compositor may
+	remove a tool on proximity out, tablet removal or any other reason.
+	A compositor may also keep a tool alive until shutdown.
+
+	If the tool is currently in proximity, a proximity_out event will be
+	sent before the removed event. See wp_tablet_tool.proximity_out for
+	the handling of any buttons logically down.
+
+	When this event is received, the client must wp_tablet_tool.destroy
+	the object.
+      </description>
+    </event>
+
+    <event name="proximity_in">
+      <description summary="proximity in event">
+	Notification that this tool is focused on a certain surface.
+
+	This event can be received when the tool has moved from one surface to
+	another, or when the tool has come back into proximity above the
+	surface.
+
+	If any button is logically down when the tool comes into proximity,
+	the respective button event is sent after the proximity_in event but
+	within the same frame as the proximity_in event.
+      </description>
+      <arg name="serial" type="uint"/>
+      <arg name="tablet" type="object" interface="zwp_tablet_v2" summary="The tablet the tool is in proximity of"/>
+      <arg name="surface" type="object" interface="wl_surface" summary="The current surface the tablet tool is over"/>
+    </event>
+
+    <event name="proximity_out">
+      <description summary="proximity out event">
+	Notification that this tool has either left proximity, or is no
+	longer focused on a certain surface.
+
+	When the tablet tool leaves proximity of the tablet, button release
+	events are sent for each button that was held down at the time of
+	leaving proximity. These events are sent before the proximity_out
+	event but within the same wp_tablet.frame.
+
+	If the tool stays within proximity of the tablet, but the focus
+	changes from one surface to another, a button release event may not
+	be sent until the button is actually released or the tool leaves the
+	proximity of the tablet.
+      </description>
+    </event>
+
+    <event name="down">
+      <description summary="tablet tool is making contact">
+	Sent whenever the tablet tool comes in contact with the surface of the
+	tablet.
+
+	If the tool is already in contact with the tablet when entering the
+	input region, the client owning said region will receive a
+	wp_tablet.proximity_in event, followed by a wp_tablet.down
+	event and a wp_tablet.frame event.
+
+	Note that this event describes logical contact, not physical
+	contact. On some devices, a compositor may not consider a tool in
+	logical contact until a minimum physical pressure threshold is
+	exceeded.
+      </description>
+      <arg name="serial" type="uint"/>
+    </event>
+
+    <event name="up">
+      <description summary="tablet tool is no longer making contact">
+	Sent whenever the tablet tool stops making contact with the surface of
+	the tablet, or when the tablet tool moves out of the input region
+	and the compositor grab (if any) is dismissed.
+
+	If the tablet tool moves out of the input region while in contact
+	with the surface of the tablet and the compositor does not have an
+	ongoing grab on the surface, the client owning said region will
+	receive a wp_tablet.up event, followed by a wp_tablet.proximity_out
+	event and a wp_tablet.frame event. If the compositor has an ongoing
+	grab on this device, this event sequence is sent whenever the grab
+	is dismissed in the future.
+
+	Note that this event describes logical contact, not physical
+	contact. On some devices, a compositor may not consider a tool out
+	of logical contact until physical pressure falls below a specific
+	threshold.
+      </description>
+    </event>
+
+    <event name="motion">
+      <description summary="motion event">
+	Sent whenever a tablet tool moves.
+      </description>
+      <arg name="x" type="fixed" summary="surface-local x coordinate"/>
+      <arg name="y" type="fixed" summary="surface-local y coordinate"/>
+    </event>
+
+    <event name="pressure">
+      <description summary="pressure change event">
+	Sent whenever the pressure axis on a tool changes. The value of this
+	event is normalized to a value between 0 and 65535.
+
+	Note that pressure may be nonzero even when a tool is not in logical
+	contact. See the down and up events for more details.
+      </description>
+      <arg name="pressure" type="uint" summary="The current pressure value"/>
+    </event>
+
+    <event name="distance">
+      <description summary="distance change event">
+	Sent whenever the distance axis on a tool changes. The value of this
+	event is normalized to a value between 0 and 65535.
+
+	Note that distance may be nonzero even when a tool is not in logical
+	contact. See the down and up events for more details.
+      </description>
+      <arg name="distance" type="uint" summary="The current distance value"/>
+    </event>
+
+    <event name="tilt">
+      <description summary="tilt change event">
+	Sent whenever one or both of the tilt axes on a tool change. Each tilt
+	value is in degrees, relative to the z-axis of the tablet.
+	The angle is positive when the top of a tool tilts along the
+	positive x or y axis.
+      </description>
+      <arg name="tilt_x" type="fixed" summary="The current value of the X tilt axis"/>
+      <arg name="tilt_y" type="fixed" summary="The current value of the Y tilt axis"/>
+    </event>
+
+    <event name="rotation">
+      <description summary="z-rotation change event">
+	Sent whenever the z-rotation axis on the tool changes. The
+	rotation value is in degrees clockwise from the tool's
+	logical neutral position.
+      </description>
+      <arg name="degrees" type="fixed" summary="The current rotation of the Z axis"/>
+    </event>
+
+    <event name="slider">
+      <description summary="Slider position change event">
+	Sent whenever the slider position on the tool changes. The
+	value is normalized between -65535 and 65535, with 0 as the logical
+	neutral position of the slider.
+
+	The slider is available on e.g. the Wacom Airbrush tool.
+      </description>
+      <arg name="position" type="int" summary="The current position of slider"/>
+    </event>
+
+    <event name="wheel">
+      <description summary="Wheel delta event">
+	Sent whenever the wheel on the tool emits an event. This event
+	contains two values for the same axis change. The degrees value is
+	in the same orientation as the wl_pointer.vertical_scroll axis. The
+	clicks value is in discrete logical clicks of the mouse wheel. This
+	value may be zero if the movement of the wheel was less
+	than one logical click.
+
+	Clients should choose either value and avoid mixing degrees and
+	clicks. The compositor may accumulate values smaller than a logical
+	click and emulate click events when a certain threshold is met.
+	Thus, wl_tablet_tool.wheel events with non-zero clicks values may
+	have different degrees values.
+      </description>
+      <arg name="degrees" type="fixed" summary="The wheel delta in degrees"/>
+      <arg name="clicks" type="int" summary="The wheel delta in discrete clicks"/>
+    </event>
+
+    <enum name="button_state">
+      <description summary="physical button state">
+	Describes the physical state of a button that produced the button event.
+      </description>
+      <entry name="released" value="0" summary="button is not pressed"/>
+      <entry name="pressed" value="1" summary="button is pressed"/>
+    </enum>
+
+    <event name="button">
+      <description summary="button event">
+	Sent whenever a button on the tool is pressed or released.
+
+	If a button is held down when the tool moves in or out of proximity,
+	button events are generated by the compositor. See
+	wp_tablet_tool.proximity_in and wp_tablet_tool.proximity_out for
+	details.
+      </description>
+      <arg name="serial" type="uint"/>
+      <arg name="button" type="uint" summary="The button whose state has changed"/>
+      <arg name="state" type="uint" enum="button_state" summary="Whether the button was pressed or released"/>
+    </event>
+
+    <event name="frame">
+      <description summary="frame event">
+	Marks the end of a series of axis and/or button updates from the
+	tablet. The Wayland protocol requires axis updates to be sent
+	sequentially, however all events within a frame should be considered
+	one hardware event.
+      </description>
+      <arg name="time" type="uint" summary="The time of the event with millisecond granularity"/>
+    </event>
+
+    <enum name="error">
+      <entry name="role" value="0" summary="given wl_surface has another role"/>
+    </enum>
+  </interface>
+
+  <interface name="zwp_tablet_v2" version="1">
+    <description summary="graphics tablet device">
+      The wp_tablet interface represents one graphics tablet device. The
+      tablet interface itself does not generate events; all events are
+      generated by wp_tablet_tool objects when in proximity above a tablet.
+
+      A tablet has a number of static characteristics, e.g. device name and
+      pid/vid. These capabilities are sent in an event sequence after the
+      wp_tablet_seat.tablet_added event. This initial event sequence is
+      terminated by a wp_tablet.done event.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the tablet object">
+	This destroys the client's resource for this tablet object.
+      </description>
+    </request>
+
+    <event name="name">
+      <description summary="tablet device name">
+	This event is sent in the initial burst of events before the
+	wp_tablet.done event.
+      </description>
+      <arg name="name" type="string" summary="the device name"/>
+    </event>
+
+    <event name="id">
+      <description summary="tablet device USB vendor/product id">
+	This event is sent in the initial burst of events before the
+	wp_tablet.done event.
+      </description>
+      <arg name="vid" type="uint" summary="USB vendor id"/>
+      <arg name="pid" type="uint" summary="USB product id"/>
+    </event>
+
+    <event name="path">
+      <description summary="path to the device">
+	A system-specific device path that indicates which device is behind
+	this wp_tablet. This information may be used to gather additional
+	information about the device, e.g. through libwacom.
+
+	A device may have more than one device path. If so, multiple
+	wp_tablet.path events are sent. A device may be emulated and not
+	have a device path, and in that case this event will not be sent.
+
+	The format of the path is unspecified, it may be a device node, a
+	sysfs path, or some other identifier. It is up to the client to
+	identify the string provided.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet.done event.
+      </description>
+      <arg name="path" type="string" summary="path to local device"/>
+    </event>
+
+    <event name="done">
+      <description summary="tablet description events sequence complete">
+	This event is sent immediately to signal the end of the initial
+	burst of descriptive events. A client may consider the static
+	description of the tablet to be complete and finalize initialization
+	of the tablet.
+      </description>
+    </event>
+
+    <event name="removed">
+      <description summary="tablet removed event">
+	Sent when the tablet has been removed from the system. When a tablet
+	is removed, some tools may be removed.
+
+	When this event is received, the client must wp_tablet.destroy
+	the object.
+      </description>
+    </event>
+  </interface>
+
+  <interface name="zwp_tablet_pad_ring_v2" version="1">
+    <description summary="pad ring">
+      A circular interaction area, such as the touch ring on the Wacom Intuos
+      Pro series tablets.
+
+      Events on a ring are logically grouped by the wl_tablet_pad_ring.frame
+      event.
+    </description>
+
+    <request name="set_feedback">
+      <description summary="set compositor feedback">
+	Request that the compositor use the provided feedback string
+	associated with this ring. This request should be issued immediately
+	after a wp_tablet_pad_group.mode_switch event from the corresponding
+	group is received, or whenever the ring is mapped to a different
+	action. See wp_tablet_pad_group.mode_switch for more details.
+
+	Clients are encouraged to provide context-aware descriptions for
+	the actions associated with the ring; compositors may use this
+	information to offer visual feedback about the button layout
+	(eg. on-screen displays).
+
+	The provided string 'description' is a UTF-8 encoded string to be
+	associated with this ring, and is considered user-visible; general
+	internationalization rules apply.
+
+	The serial argument will be that of the last
+	wp_tablet_pad_group.mode_switch event received for the group of this
+	ring. Requests providing other serials than the most recent one will be
+	ignored.
+      </description>
+      <arg name="description" type="string" summary="ring description"/>
+      <arg name="serial" type="uint" summary="serial of the mode switch event"/>
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the ring object">
+	This destroys the client's resource for this ring object.
+      </description>
+    </request>
+
+    <enum name="source">
+      <description summary="ring axis source">
+	Describes the source types for ring events. This indicates to the
+	client how a ring event was physically generated; a client may
+	adjust the user interface accordingly. For example, events
+	from a "finger" source may trigger kinetic scrolling.
+      </description>
+      <entry name="finger" value="1" summary="finger"/>
+    </enum>
+
+    <event name="source">
+      <description summary="ring event source">
+	Source information for ring events.
+
+	This event does not occur on its own. It is sent before a
+	wp_tablet_pad_ring.frame event and carries the source information
+	for all events within that frame.
+
+	The source specifies how this event was generated. If the source is
+	wp_tablet_pad_ring.source.finger, a wp_tablet_pad_ring.stop event
+	will be sent when the user lifts the finger off the device.
+
+	This event is optional. If the source is unknown for an interaction,
+	no event is sent.
+      </description>
+      <arg name="source" type="uint" enum="source" summary="the event source"/>
+    </event>
+
+    <event name="angle">
+      <description summary="angle changed">
+	Sent whenever the angle on a ring changes.
+
+	The angle is provided in degrees clockwise from the logical
+	north of the ring in the pad's current rotation.
+      </description>
+      <arg name="degrees" type="fixed" summary="the current angle in degrees"/>
+    </event>
+
+    <event name="stop">
+      <description summary="interaction stopped">
+	Stop notification for ring events.
+
+	For some wp_tablet_pad_ring.source types, a wp_tablet_pad_ring.stop
+	event is sent to notify a client that the interaction with the ring
+	has terminated. This enables the client to implement kinetic scrolling.
+	See the wp_tablet_pad_ring.source documentation for information on
+	when this event may be generated.
+
+	Any wp_tablet_pad_ring.angle events with the same source after this
+	event should be considered as the start of a new interaction.
+      </description>
+    </event>
+
+    <event name="frame">
+      <description summary="end of a ring event sequence">
+	Indicates the end of a set of ring events that logically belong
+	together. A client is expected to accumulate the data in all events
+	within the frame before proceeding.
+
+	All wp_tablet_pad_ring events before a wp_tablet_pad_ring.frame event belong
+	logically together. For example, on termination of a finger interaction
+	on a ring the compositor will send a wp_tablet_pad_ring.source event,
+	a wp_tablet_pad_ring.stop event and a wp_tablet_pad_ring.frame event.
+
+	A wp_tablet_pad_ring.frame event is sent for every logical event
+	group, even if the group only contains a single wp_tablet_pad_ring
+	event. Specifically, a client may get a sequence: angle, frame,
+	angle, frame, etc.
+      </description>
+      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
+    </event>
+  </interface>
+
+  <interface name="zwp_tablet_pad_strip_v2" version="1">
+    <description summary="pad strip">
+      A linear interaction area, such as the strips found in Wacom Cintiq
+      models.
+
+      Events on a strip are logically grouped by the wl_tablet_pad_strip.frame
+      event.
+    </description>
+
+    <request name="set_feedback">
+      <description summary="set compositor feedback">
+	Requests the compositor to use the provided feedback string
+	associated with this strip. This request should be issued immediately
+	after a wp_tablet_pad_group.mode_switch event from the corresponding
+	group is received, or whenever the strip is mapped to a different
+	action. See wp_tablet_pad_group.mode_switch for more details.
+
+	Clients are encouraged to provide context-aware descriptions for
+	the actions associated with the strip, and compositors may use this
+	information to offer visual feedback about the button layout
+	(eg. on-screen displays).
+
+	The provided string 'description' is a UTF-8 encoded string to be
+	associated with this ring, and is considered user-visible; general
+	internationalization rules apply.
+
+	The serial argument will be that of the last
+	wp_tablet_pad_group.mode_switch event received for the group of this
+	strip. Requests providing other serials than the most recent one will be
+	ignored.
+      </description>
+      <arg name="description" type="string" summary="strip description"/>
+      <arg name="serial" type="uint" summary="serial of the mode switch event"/>
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the strip object">
+	This destroys the client's resource for this strip object.
+      </description>
+    </request>
+
+    <enum name="source">
+      <description summary="strip axis source">
+	Describes the source types for strip events. This indicates to the
+	client how a strip event was physically generated; a client may
+	adjust the user interface accordingly. For example, events
+	from a "finger" source may trigger kinetic scrolling.
+      </description>
+      <entry name="finger" value="1" summary="finger"/>
+    </enum>
+
+    <event name="source">
+      <description summary="strip event source">
+	Source information for strip events.
+
+	This event does not occur on its own. It is sent before a
+	wp_tablet_pad_strip.frame event and carries the source information
+	for all events within that frame.
+
+	The source specifies how this event was generated. If the source is
+	wp_tablet_pad_strip.source.finger, a wp_tablet_pad_strip.stop event
+	will be sent when the user lifts their finger off the device.
+
+	This event is optional. If the source is unknown for an interaction,
+	no event is sent.
+      </description>
+      <arg name="source" type="uint" enum="source" summary="the event source"/>
+    </event>
+
+    <event name="position">
+      <description summary="position changed">
+	Sent whenever the position on a strip changes.
+
+	The position is normalized to a range of [0, 65535], the 0-value
+	represents the top-most and/or left-most position of the strip in
+	the pad's current rotation.
+      </description>
+      <arg name="position" type="uint" summary="the current position"/>
+    </event>
+
+    <event name="stop">
+      <description summary="interaction stopped">
+	Stop notification for strip events.
+
+	For some wp_tablet_pad_strip.source types, a wp_tablet_pad_strip.stop
+	event is sent to notify a client that the interaction with the strip
+	has terminated. This enables the client to implement kinetic
+	scrolling. See the wp_tablet_pad_strip.source documentation for
+	information on when this event may be generated.
+
+	Any wp_tablet_pad_strip.position events with the same source after this
+	event should be considered as the start of a new interaction.
+      </description>
+    </event>
+
+    <event name="frame">
+      <description summary="end of a strip event sequence">
+	Indicates the end of a set of events that represent one logical
+	hardware strip event. A client is expected to accumulate the data
+	in all events within the frame before proceeding.
+
+	All wp_tablet_pad_strip events before a wp_tablet_pad_strip.frame event belong
+	logically together. For example, on termination of a finger interaction
+	on a strip the compositor will send a wp_tablet_pad_strip.source event,
+	a wp_tablet_pad_strip.stop event and a wp_tablet_pad_strip.frame
+	event.
+
+	A wp_tablet_pad_strip.frame event is sent for every logical event
+	group, even if the group only contains a single wp_tablet_pad_strip
+	event. Specifically, a client may get a sequence: position, frame,
+	position, frame, etc.
+      </description>
+      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
+    </event>
+  </interface>
+
+  <interface name="zwp_tablet_pad_group_v2" version="1">
+    <description summary="a set of buttons, rings and strips">
+      A pad group describes a distinct (sub)set of buttons, rings and strips
+      present in the tablet. The criteria of this grouping is usually positional,
+      eg. if a tablet has buttons on the left and right side, 2 groups will be
+      presented. The physical arrangement of groups is undisclosed and may
+      change on the fly.
+
+      Pad groups will announce their features during pad initialization. Between
+      the corresponding wp_tablet_pad.group event and wp_tablet_pad_group.done, the
+      pad group will announce the buttons, rings and strips contained in it,
+      plus the number of supported modes.
+
+      Modes are a mechanism to allow multiple groups of actions for every element
+      in the pad group. The number of groups and available modes in each is
+      persistent across device plugs. The current mode is user-switchable, it
+      will be announced through the wp_tablet_pad_group.mode_switch event both
+      whenever it is switched, and after wp_tablet_pad.enter.
+
+      The current mode logically applies to all elements in the pad group,
+      although it is at clients' discretion whether to actually perform different
+      actions, and/or issue the respective .set_feedback requests to notify the
+      compositor. See the wp_tablet_pad_group.mode_switch event for more details.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the pad object">
+	Destroy the wp_tablet_pad_group object. Objects created from this object
+	are unaffected and should be destroyed separately.
+      </description>
+    </request>
+
+    <event name="buttons">
+      <description summary="buttons announced">
+	Sent on wp_tablet_pad_group initialization to announce the available
+	buttons in the group. Button indices start at 0, a button may only be
+	in one group at a time.
+
+	This event is first sent in the initial burst of events before the
+	wp_tablet_pad_group.done event.
+
+	Some buttons are reserved by the compositor. These buttons may not be
+	assigned to any wp_tablet_pad_group. Compositors may broadcast this
+	event in the case of changes to the mapping of these reserved buttons.
+	If the compositor happens to reserve all buttons in a group, this event
+	will be sent with an empty array.
+      </description>
+      <arg name="buttons" type="array" summary="buttons in this group"/>
+    </event>
+
+    <event name="ring">
+      <description summary="ring announced">
+	Sent on wp_tablet_pad_group initialization to announce available rings.
+	One event is sent for each ring available on this pad group.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_pad_group.done event.
+      </description>
+      <arg name="ring" type="new_id" interface="zwp_tablet_pad_ring_v2"/>
+    </event>
+
+    <event name="strip">
+      <description summary="strip announced">
+	Sent on wp_tablet_pad initialization to announce available strips.
+	One event is sent for each strip available on this pad group.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_pad_group.done event.
+      </description>
+      <arg name="strip" type="new_id" interface="zwp_tablet_pad_strip_v2"/>
+    </event>
+
+    <event name="modes">
+      <description summary="mode-switch ability announced">
+	Sent on wp_tablet_pad_group initialization to announce that the pad
+	group may switch between modes. A client may use a mode to store a
+	specific configuration for buttons, rings and strips and use the
+	wl_tablet_pad_group.mode_switch event to toggle between these
+	configurations. Mode indices start at 0.
+
+	Switching modes is compositor-dependent. See the
+	wp_tablet_pad_group.mode_switch event for more details.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_pad_group.done event. This event is only sent when more than
+	more than one mode is available.
+      </description>
+      <arg name="modes" type="uint" summary="the number of modes"/>
+    </event>
+
+    <event name="done">
+      <description summary="tablet group description events sequence complete">
+	This event is sent immediately to signal the end of the initial
+	burst of descriptive events. A client may consider the static
+	description of the tablet to be complete and finalize initialization
+	of the tablet group.
+      </description>
+    </event>
+
+    <event name="mode_switch">
+      <description summary="mode switch event">
+	Notification that the mode was switched.
+
+	A mode applies to all buttons, rings and strips in a group
+	simultaneously, but a client is not required to assign different actions
+	for each mode. For example, a client may have mode-specific button
+	mappings but map the ring to vertical scrolling in all modes. Mode
+	indices start at 0.
+
+	Switching modes is compositor-dependent. The compositor may provide
+	visual cues to the client about the mode, e.g. by toggling LEDs on
+	the tablet device. Mode-switching may be software-controlled or
+	controlled by one or more physical buttons. For example, on a Wacom
+	Intuos Pro, the button inside the ring may be assigned to switch
+	between modes.
+
+	The compositor will also send this event after wp_tablet_pad.enter on
+	each group in order to notify of the current mode. Groups that only
+	feature one mode will use mode=0 when emitting this event.
+
+	If a button action in the new mode differs from the action in the
+	previous mode, the client should immediately issue a
+	wp_tablet_pad.set_feedback request for each changed button.
+
+	If a ring or strip action in the new mode differs from the action
+	in the previous mode, the client should immediately issue a
+	wp_tablet_ring.set_feedback or wp_tablet_strip.set_feedback request
+	for each changed ring or strip.
+      </description>
+      <arg name="time" type="uint" summary="the time of the event with millisecond granularity"/>
+      <arg name="serial" type="uint"/>
+      <arg name="mode" type="uint" summary="the new mode of the pad"/>
+    </event>
+  </interface>
+
+  <interface name="zwp_tablet_pad_v2" version="1">
+    <description summary="a set of buttons, rings and strips">
+      A pad device is a set of buttons, rings and strips
+      usually physically present on the tablet device itself. Some
+      exceptions exist where the pad device is physically detached, e.g. the
+      Wacom ExpressKey Remote.
+
+      Pad devices have no axes that control the cursor and are generally
+      auxiliary devices to the tool devices used on the tablet surface.
+
+      A pad device has a number of static characteristics, e.g. the number
+      of rings. These capabilities are sent in an event sequence after the
+      wp_tablet_seat.pad_added event before any actual events from this pad.
+      This initial event sequence is terminated by a wp_tablet_pad.done
+      event.
+
+      All pad features (buttons, rings and strips) are logically divided into
+      groups and all pads have at least one group. The available groups are
+      notified through the wp_tablet_pad.group event; the compositor will
+      emit one event per group before emitting wp_tablet_pad.done.
+
+      Groups may have multiple modes. Modes allow clients to map multiple
+      actions to a single pad feature. Only one mode can be active per group,
+      although different groups may have different active modes.
+    </description>
+
+    <request name="set_feedback">
+      <description summary="set compositor feedback">
+	Requests the compositor to use the provided feedback string
+	associated with this button. This request should be issued immediately
+	after a wp_tablet_pad_group.mode_switch event from the corresponding
+	group is received, or whenever a button is mapped to a different
+	action. See wp_tablet_pad_group.mode_switch for more details.
+
+	Clients are encouraged to provide context-aware descriptions for
+	the actions associated with each button, and compositors may use
+	this information to offer visual feedback on the button layout
+	(e.g. on-screen displays).
+
+	Button indices start at 0. Setting the feedback string on a button
+	that is reserved by the compositor (i.e. not belonging to any
+	wp_tablet_pad_group) does not generate an error but the compositor
+	is free to ignore the request.
+
+	The provided string 'description' is a UTF-8 encoded string to be
+	associated with this ring, and is considered user-visible; general
+	internationalization rules apply.
+
+	The serial argument will be that of the last
+	wp_tablet_pad_group.mode_switch event received for the group of this
+	button. Requests providing other serials than the most recent one will
+	be ignored.
+      </description>
+      <arg name="button" type="uint" summary="button index"/>
+      <arg name="description" type="string" summary="button description"/>
+      <arg name="serial" type="uint" summary="serial of the mode switch event"/>
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the pad object">
+	Destroy the wp_tablet_pad object. Objects created from this object
+	are unaffected and should be destroyed separately.
+      </description>
+    </request>
+
+    <event name="group">
+      <description summary="group announced">
+	Sent on wp_tablet_pad initialization to announce available groups.
+	One event is sent for each pad group available.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_pad.done event. At least one group will be announced.
+      </description>
+      <arg name="pad_group" type="new_id" interface="zwp_tablet_pad_group_v2"/>
+    </event>
+
+    <event name="path">
+      <description summary="path to the device">
+	A system-specific device path that indicates which device is behind
+	this wp_tablet_pad. This information may be used to gather additional
+	information about the device, e.g. through libwacom.
+
+	The format of the path is unspecified, it may be a device node, a
+	sysfs path, or some other identifier. It is up to the client to
+	identify the string provided.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_pad.done event.
+      </description>
+      <arg name="path" type="string" summary="path to local device"/>
+    </event>
+
+    <event name="buttons">
+      <description summary="buttons announced">
+	Sent on wp_tablet_pad initialization to announce the available
+	buttons.
+
+	This event is sent in the initial burst of events before the
+	wp_tablet_pad.done event. This event is only sent when at least one
+	button is available.
+      </description>
+      <arg name="buttons" type="uint" summary="the number of buttons"/>
+    </event>
+
+    <event name="done">
+      <description summary="pad description event sequence complete">
+	This event signals the end of the initial burst of descriptive
+	events. A client may consider the static description of the pad to
+	be complete and finalize initialization of the pad.
+      </description>
+    </event>
+
+    <enum name="button_state">
+      <description summary="physical button state">
+	Describes the physical state of a button that caused the button
+	event.
+      </description>
+      <entry name="released" value="0" summary="the button is not pressed"/>
+      <entry name="pressed" value="1" summary="the button is pressed"/>
+    </enum>
+
+    <event name="button">
+      <description summary="physical button state">
+	Sent whenever the physical state of a button changes.
+      </description>
+      <arg name="time" type="uint" summary="the time of the event with millisecond granularity"/>
+      <arg name="button" type="uint" summary="the index of the button that changed state"/>
+      <arg name="state" type="uint" enum="button_state"/>
+    </event>
+
+    <event name="enter">
+      <description summary="enter event">
+	Notification that this pad is focused on the specified surface.
+      </description>
+      <arg name="serial" type="uint" summary="serial number of the enter event"/>
+      <arg name="tablet" type="object" interface="zwp_tablet_v2" summary="the tablet the pad is attached to"/>
+      <arg name="surface" type="object" interface="wl_surface" summary="surface the pad is focused on"/>
+    </event>
+
+    <event name="leave">
+      <description summary="enter event">
+	Notification that this pad is no longer focused on the specified
+	surface.
+      </description>
+      <arg name="serial" type="uint" summary="serial number of the leave event"/>
+      <arg name="surface" type="object" interface="wl_surface" summary="surface the pad is no longer focused on"/>
+    </event>
+
+    <event name="removed">
+      <description summary="pad removed event">
+	Sent when the pad has been removed from the system. When a tablet
+	is removed its pad(s) will be removed too.
+
+	When this event is received, the client must destroy all rings, strips
+	and groups that were offered by this pad, and issue wp_tablet_pad.destroy
+	the pad itself.
+      </description>
+    </event>
+  </interface>
+</protocol>