cursor: avoid sending unnecessary pointer motion events

If the current Cursor.maybeResetState() function is called while in
passthrough mode, it will send a pointer motion event. This is
unnecessary as we have already sent the same pointer motion event at
least once.

Also refactor the code slightly and improve naming.

river/Cursor.zig

@@ -774,29 +774,9 @@ fn processMotion(self: *Self, device: *wlr.InputDevice, time: u32, delta_x: f64,
 /// Handle potential change in location of views on the output, as well as
 /// the target view of a cursor operation potentially being moved to a non-visible tag,
 /// becoming fullscreen, etc.
-pub fn maybeResetState(self: *Self) void {
+pub fn updateState(self: *Self) void {
-    switch (self.mode) {
+    if (self.shouldExitMode()) {
-        .passthrough => {},
-        .down => |target| {
-            // If the target view is no longer visible, abort the operation.
-            if (target.current.tags & target.output.current.tags == 0) {
         self.mode = .passthrough;
-            }
-        },
-        .resize, .move => {
-            // If the target view is no longer visible, or now fullscreen or no
-            // longer floating, abort the operation.
-            const target = if (self.mode == .resize) self.mode.resize.view else self.mode.move;
-            if (target.current.tags & target.output.current.tags == 0 or
-                (!target.current.float and target.output.current.layout != null) or
-                target.current.fullscreen)
-            {
-                self.mode = .passthrough;
-            }
-        },
-    }
-
-    if (self.mode == .passthrough) {
         var now: os.timespec = undefined;
         os.clock_gettime(os.CLOCK_MONOTONIC, &now) catch @panic("CLOCK_MONOTONIC not supported");
         const msec = @intCast(u32, now.tv_sec * std.time.ms_per_s +
@@ -805,6 +785,23 @@ pub fn maybeResetState(self: *Self) void {
     }
 }
 
+fn shouldExitMode(self: Self) bool {
+    switch (self.mode) {
+        .passthrough => return false,
+        .down => |target| {
+            // The target view is no longer visible
+            return target.current.tags & target.output.current.tags == 0;
+        },
+        .resize, .move => {
+            const target = if (self.mode == .resize) self.mode.resize.view else self.mode.move;
+            // The target view is no longer visible, is part of the layout, or is fullscreen.
+            return target.current.tags & target.output.current.tags == 0 or
+                (!target.current.float and target.output.current.layout != null) or
+                target.current.fullscreen;
+        },
+    }
+}
+
 /// Pass an event on to the surface under the cursor, if any.
 fn passthrough(self: *Self, time: u32) void {
     assert(self.mode == .passthrough);

river/InputManager.zig

@@ -178,9 +178,9 @@ pub fn inputAllowed(self: Self, wlr_surface: *wlr.Surface) bool {
         true;
 }
 
-pub fn maybeResetCursorState(self: Self) void {
+pub fn updateCursorState(self: Self) void {
     var it = self.seats.first;
-    while (it) |node| : (it = node.next) node.data.cursor.maybeResetState();
+    while (it) |node| : (it = node.next) node.data.cursor.updateState();
 }
 
 fn handleInhibitActivate(

river/Root.zig

@@ -405,7 +405,7 @@ fn commitTransaction(self: *Self) void {
 
         output.damage.addWhole();
     }
-    server.input_manager.maybeResetCursorState();
+    server.input_manager.updateCursorState();
 }
 
 /// Send the new output configuration to all wlr-output-manager clients

river/XdgToplevel.zig

@@ -273,7 +273,7 @@ fn handleCommit(listener: *wl.Listener(*wlr.Surface), surface: *wlr.Surface) voi
                 view.current = view.pending;
                 if (self_tags_changed) view.output.sendViewTags();
                 view.output.damage.addWhole();
-                server.input_manager.maybeResetCursorState();
+                server.input_manager.updateCursorState();
             }
         } else {
             // If the client has not yet acked our configure, we need to send a