rwm: generalize interactive seat operations

This also allows moving some windows and resizing some other windows at
the same time in the same operation, which is certainly a niche use case
but not really any more complex for us to support.

The main motivation for this patch is reducing the amount of duplication
in the protocol text and in code.

 protocol/river-window-management-v1.xml | 170 ++++++++++++--------------------
 river/Seat.zig                          |  14 +--
 2 files changed, 70 insertions(+), 114 deletions(-)

diff --git a/protocol/river-window-management-v1.xml b/protocol/river-window-management-v1.xml
index c98c28c..2c266dc 100644
--- a/protocol/river-window-management-v1.xml
+++ b/protocol/river-window-management-v1.xml
@@ -522,9 +522,9 @@
         interactive move be started, perhaps when a client-side rendered
         titlebar is dragged.
 
-        The window manager may use the river_seat_v1.move_add_window and
-        river_seat_v1.move_start_serial requests to start a move or ignore this
-        event entirely.
+        The window manager may use the river_seat_v1.op_start_serial and
+        river_seat_v1.op_add_move_window requests to interactively move the
+        window or ignore this event entirely.
 
         This event is double-buffered state and will be followed by a
         river_window_manager_v1.update event.
@@ -548,9 +548,9 @@
         interactive resize be started, perhaps when the corner of client-side
         rendered decorations is dragged.
 
-        The window manager may use the river_seat_v1.resize_add_window and
-        river_seat_v1.resize_start_serial requests to start a resize or ignore
-        this event entirely.
+        The window manager may use the river_seat_v1.op_start_serial and
+        river_seat_v1.op_add_resize_window requests to interactively resize the
+        window or ignore this event entirely.
 
         This event is double-buffered state and will be followed by a
         river_window_manager_v1.update event.
@@ -1120,25 +1120,28 @@
       <arg name="window" type="object" interface="river_window_v1"/>
     </event>
 
-    <request name="move_start_serial">
-      <description summary="start an interactive move">
-        Start an interactive move with a river_window_v1.move_requested event
-        serial. Windows can be added to the move with the move_add_window
-        request.
+    <request name="op_start_serial">
+      <description summary="start an interactive operation with a serial">
+        Start an interactive seat operation with a serial from either the
+        river_window_v1.move_requested or river_window_v1.resize_requested
+        event.
 
-        All windows must be added after this request and before the next
-        river_window_manager_v1.commit request. Other move_add_window requests
-        will have no effect.
+        A set of windows added to the operation with the op_add_move_window and
+        op_add_resize_window requests will be moved/resized based on input
+        corresponding to the provided serial (e.g. pointer or touch input).
 
-        No windows are implicitly included in the move, even the window that
-        requested the move must be explicitly added with the move_add_window
-        request.
+        All windows must be added to the operation in the same
+        river_window_manager_v1.commit sequence as the op_start_serial request.
 
-        The move continues until the pointer button, touch point or similar
-        corresponding to the given serial is released or the move_end request is
+        No windows are implicitly included in the operation, even the window
+        that requested the move/resize must be explicitly added to the
+        operation.
+
+        The operation continues until the pointer button, touch point or similar
+        corresponding to the given serial is released or the op_end request is
         made and applied with a river_window_management_v1.commit request.
 
-        This request is ignored if a move or resize is already in progress.
+        This request is ignored if an operation is already in progress.
 
         This request is double-buffered state and will not be applied until the
         next river_window_manager_v1.commit request.
@@ -1146,110 +1149,67 @@
       <arg name="serial" type="uint"/>
     </request>
 
-    <request name="move_start_pointer">
-      <description summary="start an interactive pointer move">
-        Start an interactive pointer move. Windows can be added to the move with
-        the move_add_window request.
+    <request name="op_start_pointer">
+      <description summary="start an interactive pointer operation">
+        Start an interactive pointer operation. A set of windows added to the
+        operation with the op_add_move_window and op_add_resize_window requests
+        will be moved/resized based on the movement of the pointer.
 
-        All windows must be added after this request and before the next
-        river_window_manager_v1.commit request. Other move_add_window requests
-        will have no effect.
+        All windows must be added to the operation in the same
+        river_window_manager_v1.commit sequence as the op_start_serial request.
 
-        The pointer move continues until the move_end request is made and
+        The pointer operation continues until the op_end request is made and
         applied with a river_window_management_v1.commit request.
 
-        This request is ignored if a move or resize is already in progress.
+        This request is ignored if an operation is already in progress.
 
         This request is double-buffered state and will not be applied until the
         next river_window_manager_v1.commit request.
       </description>
     </request>
 
-    <request name="move_add_window">
-      <description summary="add a window to an interactive move">
-        This request causes the position of a window to be updated by an in
-        progress interactive move. Multiple windows may be added to a single
-        interactive move and all added windows will have their position updated.
-
-        All windows must be added after the move_start_serial or
-        move_start_pointer request and before the next
-        river_window_manager_v1.commit request. Other move_add_window requests
-        will have no effect.
+    <request name="op_add_move_window">
+      <description summary="add movement of a window to an operation">
+        This request causes the position of a window to be updated by an
+        operation started in the same river_window_manager_v1.commit sequence as
+        this request.
 
-        This request is double-buffered state and will not be applied until the
-        next river_window_manager_v1.commit request.
-      </description>
-      <arg name="window" type="object" interface="river_window_v1"/>
-    </request>
+        Multiple windows may be added to and moved or resized by a single
+        operation.
 
-    <request name="move_end">
-      <description summary="end an interactive move">
-        End an interactive move.
+        If a window is added more than once to a single operation, only the most
+        recent op_add_move_window or op_add_resize_window request will have an
+        effect.
 
-        This request is ignored if there is no move in progress.
+        This request is ignored if not made in the same
+        river_window_manager_v1.commit sequence as the op_start_serial or
+        op_start_pointer request that starts an operation.
 
         This request is double-buffered state and will not be applied until the
         next river_window_manager_v1.commit request.
       </description>
+      <arg name="window" type="object" interface="river_window_v1"/>
     </request>
 
-    <request name="resize_start_serial">
-      <description summary="start an interactive resize">
-        Start an interactive resize with a river_window_v1.resize_requested
-        event serial. Windows can be added to the resize with the
-        resize_add_window request.
-
-        All windows must be added after this request and before the next
-        river_window_manager_v1.commit request. Other resize_add_window requests
-        will have no effect.
-
-        No windows are implicitly included in the resize, even the window that
-        requested the resize must be explicitly added with the resize_add_window
-        request.
-
-        The resize continues until the pointer button, touch point or similar
-        corresponding to the given serial is released or the resize_end request
-        is made and applied with a river_window_management_v1.commit request.
-
-        This request is ignored if a move or resize is already in progress.
-
-        This request is double-buffered state and will not be applied until the
-        next river_window_manager_v1.commit request.
-      </description>
-      <arg name="serial" type="uint"/>
-    </request>
-
-    <request name="resize_start_pointer">
-      <description summary="start an interactive pointer resize">
-        Start an interactive pointer resize. Windows can be added to the resize
-        with the resize_add_window request.
-
-        All windows must be added after this request and before the next
-        river_window_manager_v1.commit request. Other resize_add_window requests
-        will have no effect.
-
-        The pointer resize continues until the resize_end request is made and
-        applied with a river_window_management_v1.commit request.
+    <request name="op_add_resize_window">
+      <description summary="add resize of a window to an operation">
+        This request causes the position/dimensions of a window to be updated by
+        an operation started in the same river_window_manager_v1.commit sequence
+        as this request.
 
-        This request is ignored if a pointer resize or resize is already in
-        progress.
+        Multiple windows may be added to and moved or resized by a single
+        operation.
 
-        This request is double-buffered state and will not be applied until the
-        next river_window_manager_v1.commit request.
-      </description>
-    </request>
+        If a window is added more than once to a single operation, only the most
+        recent op_add_move_window or op_add_resize_window request will have an
+        effect.
 
-    <request name="resize_add_window">
-      <description summary="add a window to an interactive resize">
-        This request causes the position/dimensions of a window to be updated by
-        an in progress interactive resize. Multiple windows may be added to a
-        single interactive resize and all added windows will have their position
-        updated.
+        This request is ignored if not made in the same
+        river_window_manager_v1.commit sequence as the op_start_serial or
+        op_start_pointer request that starts an operation.
 
-        All windows must be added after the resize_start_serial or
-        resize_start_pointer request and before the next
-        river_window_manager_v1.commit request. Other resize_add_window requests
-        will have no effect.
+        The edges argument determines which edges of the window are resized from
+        during the operation.
 
         It is a protocol error to set the edges argument to none. It is also an
         error to set both the top and bottom edges or both the left and right
@@ -1263,11 +1223,11 @@
       <arg name="edges" type="uint" enum="river_window_v1.edges"/>
     </request>
 
-    <request name="resize_end">
-      <description summary="end an interactive resize">
-        End an interactive resize.
+    <request name="op_end">
+      <description summary="end an interactive operation">
+        End an interactive operation.
 
-        This request is ignored if there is no interactive resize in progress.
+        This request is ignored if there is no operation in progress.
 
         This request is double-buffered state and will not be applied until the
         next river_window_manager_v1.commit request.
diff --git a/river/Seat.zig b/river/Seat.zig
index beee5af..fe39cd2 100644
--- a/river/Seat.zig
+++ b/river/Seat.zig
@@ -394,15 +394,11 @@ fn handleRequest(
         .focus_shell_surface => {},
         .clear_focus => seat.uncommitted.focus = .none,
 
-        .move_start_serial => {},
-        .move_start_pointer => {},
-        .move_add_window => {},
-        .move_end => {},
-
-        .resize_start_serial => {},
-        .resize_start_pointer => {},
-        .resize_add_window => {},
-        .resize_end => {},
+        .op_start_serial => {},
+        .op_start_pointer => {},
+        .op_add_move_window => {},
+        .op_add_resize_window => {},
+        .op_end => {},
 
         .pointer_confine_to_region => {},
         .pointer_warp => {},