wayland: Support axis relative direction

This allows clients to be aware of "natural scrolling" settings in the
compostior and adjust accordingly to optionally keep the same wheel and
trackpad behaviour accross platforms.

Testing using the "testmouse" example, behaviour in the demo is now the
same regardless of the compositor setting for scrolling.

src/video/wayland/SDL_waylandevents.c

@@ -64,7 +64,9 @@
 #include "../../events/SDL_keysym_to_scancode_c.h"
 
 /* Clamp the wl_seat version on older versions of libwayland. */
-#if SDL_WAYLAND_CHECK_VERSION(1, 21, 0)
+#if SDL_WAYLAND_CHECK_VERSION(1, 22, 0)
+#define SDL_WL_SEAT_VERSION 9
+#elif SDL_WAYLAND_CHECK_VERSION(1, 21, 0)
 #define SDL_WL_SEAT_VERSION 8
 #else
 #define SDL_WL_SEAT_VERSION 5
@@ -844,11 +846,31 @@ static void pointer_handle_axis(void *data, struct wl_pointer *pointer,
     }
 }
 
-static void pointer_handle_frame(void *data, struct wl_pointer *pointer)
+static void
+pointer_handle_axis_relative_direction(void *data, struct wl_pointer *pointer,
+                    uint32_t axis, uint32_t axis_relative_direction)
+{
+    struct SDL_WaylandInput *input = data;
+    if (axis != WL_POINTER_AXIS_VERTICAL_SCROLL) {
+        return;
+    }
+    switch (axis_relative_direction) {
+        case WL_POINTER_AXIS_RELATIVE_DIRECTION_IDENTICAL:
+            input->pointer_curr_axis_info.direction = SDL_MOUSEWHEEL_NORMAL;
+            break;
+        case WL_POINTER_AXIS_RELATIVE_DIRECTION_INVERTED:
+            input->pointer_curr_axis_info.direction = SDL_MOUSEWHEEL_FLIPPED;
+            break;
+    }
+}
+
+static void
+pointer_handle_frame(void *data, struct wl_pointer *pointer)
 {
     struct SDL_WaylandInput *input = data;
     SDL_WindowData *window = input->pointer_focus;
     float x, y;
+    SDL_MouseWheelDirection direction = input->pointer_curr_axis_info.direction;
 
     switch (input->pointer_curr_axis_info.x_axis_type) {
     case AXIS_EVENT_CONTINUOUS:
@@ -885,7 +907,7 @@ static void pointer_handle_frame(void *data, struct wl_pointer *pointer)
 
     if (x != 0.0f || y != 0.0f) {
         SDL_SendMouseWheel(input->pointer_curr_axis_info.timestamp_ns,
-                           window->sdlwindow, 0, x, y, SDL_MOUSEWHEEL_NORMAL);
+                           window->sdlwindow, 0, x, y, direction);
     }
 }
 
@@ -927,7 +949,8 @@ static const struct wl_pointer_listener pointer_listener = {
     pointer_handle_axis_source,   /* Version 5 */
     pointer_handle_axis_stop,     /* Version 5 */
     pointer_handle_axis_discrete, /* Version 5 */
-    pointer_handle_axis_value120  /* Version 8 */
+    pointer_handle_axis_value120,  /* Version 8 */
+    pointer_handle_axis_relative_direction /* Version 9 */
 };
 
 static void touch_handler_down(void *data, struct wl_touch *touch, uint32_t serial,

src/video/wayland/SDL_waylandevents_c.h

@@ -21,9 +21,12 @@
 
 #include "SDL_internal.h"
 
+
 #ifndef SDL_waylandevents_h_
 #define SDL_waylandevents_h_
 
+#include "../../events/SDL_mouse_c.h"
+
 #include "SDL_waylandvideo.h"
 #include "SDL_waylandwindow.h"
 #include "SDL_waylanddatamanager.h"
@@ -151,6 +154,7 @@ struct SDL_WaylandInput
 
         /* Event timestamp in nanoseconds */
         Uint64 timestamp_ns;
+        SDL_MouseWheelDirection direction;
     } pointer_curr_axis_info;
 
     SDL_WaylandKeyboardRepeat keyboard_repeat;

wayland-protocols/wayland.xml

@@ -177,6 +177,9 @@
     <description summary="callback object">
       Clients can handle the 'done' event to get notified when
       the related request is done.
+
+      Note, because wl_callback objects are created from multiple independent
+      factory interfaces, the wl_callback interface is frozen at version 1.
     </description>
 
     <event name="done" type="destructor">
@@ -187,7 +190,7 @@
     </event>
   </interface>
 
-  <interface name="wl_compositor" version="5">
+  <interface name="wl_compositor" version="6">
     <description summary="the compositor singleton">
       A compositor.  This object is a singleton global.  The
       compositor is in charge of combining the contents of multiple
@@ -453,6 +456,9 @@
       If the buffer uses a format that has an alpha channel, the alpha channel
       is assumed to be premultiplied in the color channels unless otherwise
       specified.
+
+      Note, because wl_buffer objects are created from multiple independent
+      factory interfaces, the wl_buffer interface is frozen at version 1.
     </description>
 
     <request name="destroy" type="destructor">
@@ -624,8 +630,9 @@
     <event name="source_actions" since="3">
       <description summary="notify the source-side available actions">
 	This event indicates the actions offered by the data source. It
-	will be sent right after wl_data_device.enter, or anytime the source
-	side changes its offered actions through wl_data_source.set_actions.
+	will be sent immediately after creating the wl_data_offer object,
+	or anytime the source side changes its offered actions through
+	wl_data_source.set_actions.
       </description>
       <arg name="source_actions" type="uint" summary="actions offered by the data source"
 	   enum="wl_data_device_manager.dnd_action"/>
@@ -867,11 +874,8 @@
 	a drag-and-drop icon. If the icon surface already has another role,
 	it raises a protocol error.
 
-	The current and pending input regions of the icon wl_surface are
-	cleared, and wl_surface.set_input_region is ignored until the
-	wl_surface is no longer used as the icon surface. When the use
-	as an icon ends, the current and pending input regions become
-	undefined, and the wl_surface is unmapped.
+	The input region is ignored for wl_surfaces with the role of a
+	drag-and-drop icon.
       </description>
       <arg name="source" type="object" interface="wl_data_source" allow-null="true" summary="data source for the eventual transfer"/>
       <arg name="origin" type="object" interface="wl_surface" summary="surface where the drag originates"/>
@@ -1352,7 +1356,7 @@
     </event>
   </interface>
 
-  <interface name="wl_surface" version="5">
+  <interface name="wl_surface" version="6">
     <description summary="an onscreen surface">
       A surface is a rectangular area that may be displayed on zero
       or more outputs, and shown any number of times at the compositor's
@@ -1384,8 +1388,9 @@
       that this request gives a role to a wl_surface. Often, this
       request also creates a new protocol object that represents the
       role and adds additional functionality to wl_surface. When a
-      client wants to destroy a wl_surface, they must destroy this 'role
-      object' before the wl_surface.
+      client wants to destroy a wl_surface, they must destroy this role
+      object before the wl_surface, otherwise a defunct_role_object error is
+      sent.
 
       Destroying the role object does not remove the role from the
       wl_surface, but it may stop the wl_surface from "playing the role".
@@ -1405,6 +1410,8 @@
       <entry name="invalid_transform" value="1" summary="buffer transform value is invalid"/>
       <entry name="invalid_size" value="2" summary="buffer size is invalid"/>
       <entry name="invalid_offset" value="3" summary="buffer offset is invalid"/>
+      <entry name="defunct_role_object" value="4"
+             summary="surface was destroyed before its role object"/>
     </enum>
 
     <request name="destroy" type="destructor">
@@ -1433,8 +1440,9 @@
 
 	When the bound wl_surface version is 5 or higher, passing any
 	non-zero x or y is a protocol violation, and will result in an
-	'invalid_offset' error being raised. To achieve equivalent semantics,
-	use wl_surface.offset.
+        'invalid_offset' error being raised. The x and y arguments are ignored
+        and do not change the pending state. To achieve equivalent semantics,
+        use wl_surface.offset.
 
 	Surface contents are double-buffered state, see wl_surface.commit.
 
@@ -1786,9 +1794,37 @@
       <arg name="x" type="int" summary="surface-local x coordinate"/>
       <arg name="y" type="int" summary="surface-local y coordinate"/>
     </request>
+
+    <!-- Version 6 additions -->
+
+    <event name="preferred_buffer_scale" since="6">
+      <description summary="preferred buffer scale for the surface">
+	This event indicates the preferred buffer scale for this surface. It is
+	sent whenever the compositor's preference changes.
+
+	It is intended that scaling aware clients use this event to scale their
+	content and use wl_surface.set_buffer_scale to indicate the scale they
+	have rendered with. This allows clients to supply a higher detail
+	buffer.
+      </description>
+      <arg name="factor" type="int" summary="preferred scaling factor"/>
+    </event>
+
+    <event name="preferred_buffer_transform" since="6">
+      <description summary="preferred buffer transform for the surface">
+	This event indicates the preferred buffer transform for this surface.
+	It is sent whenever the compositor's preference changes.
+
+	It is intended that transform aware clients use this event to apply the
+	transform to their content and use wl_surface.set_buffer_transform to
+	indicate the transform they have rendered with.
+      </description>
+      <arg name="transform" type="uint" enum="wl_output.transform"
+	   summary="preferred transform"/>
+    </event>
    </interface>
 
-  <interface name="wl_seat" version="8">
+  <interface name="wl_seat" version="9">
     <description summary="group of input devices">
       A seat is a group of keyboards, pointer and touch devices. This
       object is published as a global during start up, or when such a
@@ -1921,7 +1957,7 @@
 
   </interface>
 
-  <interface name="wl_pointer" version="8">
+  <interface name="wl_pointer" version="9">
     <description summary="pointer input device">
       The wl_pointer interface represents one or more input devices,
       such as mice, which control the pointer location and pointer_focus
@@ -1965,11 +2001,9 @@
 	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.
+	The input region is ignored for wl_surfaces with the role of
+	a cursor. When the use as a cursor ends, the wl_surface is
+	unmapped.
 
 	The serial parameter must match the latest wl_pointer.enter
 	serial number sent to the client. Otherwise the request will be
@@ -2278,9 +2312,65 @@
       <arg name="axis" type="uint" enum="axis" summary="axis type"/>
       <arg name="value120" type="int" summary="scroll distance as fraction of 120"/>
     </event>
+
+    <!-- Version 9 additions -->
+
+    <enum name="axis_relative_direction">
+      <description summary="axis relative direction">
+	This specifies the direction of the physical motion that caused a
+	wl_pointer.axis event, relative to the wl_pointer.axis direction.
+      </description>
+      <entry name="identical" value="0"
+	  summary="physical motion matches axis direction"/>
+      <entry name="inverted" value="1"
+	  summary="physical motion is the inverse of the axis direction"/>
+    </enum>
+
+    <event name="axis_relative_direction" since="9">
+      <description summary="axis relative physical direction event">
+	Relative directional information of the entity causing the axis
+	motion.
+
+	For a wl_pointer.axis event, the wl_pointer.axis_relative_direction
+	event specifies the movement direction of the entity causing the
+	wl_pointer.axis event. For example:
+	- if a user's fingers on a touchpad move down and this
+	  causes a wl_pointer.axis vertical_scroll down event, the physical
+	  direction is 'identical'
+	- if a user's fingers on a touchpad move down and this causes a
+	  wl_pointer.axis vertical_scroll up scroll up event ('natural
+	  scrolling'), the physical direction is 'inverted'.
+
+	A client may use this information to adjust scroll motion of
+	components. Specifically, enabling natural scrolling causes the
+	content to change direction compared to traditional scrolling.
+	Some widgets like volume control sliders should usually match the
+	physical direction regardless of whether natural scrolling is
+	active. This event enables clients to match the scroll direction of
+	a widget to the physical direction.
+
+	This event does not occur on its own, it is coupled with a
+	wl_pointer.axis event that represents this axis value.
+	The protocol guarantees that each axis_relative_direction event is
+	always followed by exactly one axis event with the same
+	axis number within the same wl_pointer.frame. Note that the protocol
+	allows for other events to occur between the axis_relative_direction
+	and its coupled axis event.
+
+	The axis number is identical to the axis number in the associated
+	axis event.
+
+	The order of wl_pointer.axis_relative_direction,
+	wl_pointer.axis_discrete and wl_pointer.axis_source is not
+	guaranteed.
+      </description>
+      <arg name="axis" type="uint" enum="axis" summary="axis type"/>
+      <arg name="direction" type="uint" enum="axis_relative_direction"
+	  summary="physical direction relative to axis motion"/>
+    </event>
   </interface>
 
-  <interface name="wl_keyboard" version="8">
+  <interface name="wl_keyboard" version="9">
     <description summary="keyboard input device">
       The wl_keyboard interface represents one or more keyboards
       associated with a seat.
@@ -2407,7 +2497,7 @@
     </event>
   </interface>
 
-  <interface name="wl_touch" version="8">
+  <interface name="wl_touch" version="9">
     <description summary="touchscreen input device">
       The wl_touch interface represents a touchscreen
       associated with a seat.
@@ -2861,6 +2951,8 @@
     <enum name="error">
       <entry name="bad_surface" value="0"
 	     summary="the to-be sub-surface is invalid"/>
+      <entry name="bad_parent" value="1"
+	     summary="the to-be sub-surface parent is invalid"/>
     </enum>
 
     <request name="get_subsurface">
@@ -2870,14 +2962,18 @@
 	plain wl_surface into a sub-surface.
 
 	The to-be sub-surface must not already have another role, and it
-	must not have an existing wl_subsurface object. Otherwise a protocol
-	error is raised.
+	must not have an existing wl_subsurface object. Otherwise the
+	bad_surface protocol error is raised.
 
 	Adding sub-surfaces to a parent is a double-buffered operation on the
 	parent (see wl_surface.commit). The effect of adding a sub-surface
 	becomes visible on the next time the state of the parent surface is
 	applied.
 
+	The parent surface must not be one of the child surface's descendants,
+	and the parent must be different from the child surface, otherwise the
+	bad_parent protocol error is raised.
+
 	This request modifies the behaviour of wl_surface.commit request on
 	the sub-surface, see the documentation on wl_subsurface interface.
       </description>
@@ -2932,12 +3028,10 @@
       synchronized mode, and then assume that all its child and grand-child
       sub-surfaces are synchronized, too, without explicitly setting them.
 
-      If the wl_surface associated with the wl_subsurface is destroyed, the
-      wl_subsurface object becomes inert. Note, that destroying either object
-      takes effect immediately. If you need to synchronize the removal
-      of a sub-surface to the parent surface update, unmap the sub-surface
-      first by attaching a NULL wl_buffer, update parent, and then destroy
-      the sub-surface.
+      Destroying a sub-surface takes effect immediately. If you need to
+      synchronize the removal of a sub-surface to the parent surface update,
+      unmap the sub-surface first by attaching a NULL wl_buffer, update parent,
+      and then destroy the sub-surface.
 
       If the parent wl_surface object is destroyed, the sub-surface is
       unmapped.
@@ -2948,8 +3042,7 @@
 	The sub-surface interface is removed from the wl_surface object
 	that was turned into a sub-surface with a
 	wl_subcompositor.get_subsurface request. The wl_surface's association
-	to the parent is deleted, and the wl_surface loses its role as
-	a sub-surface. The wl_surface is unmapped immediately.
+	to the parent is deleted. The wl_surface is unmapped immediately.
       </description>
     </request>