streamline cursor clipping logic on windows

include/SDL3/SDL_hints.h

@@ -2560,23 +2560,6 @@ extern "C" {
  */
 #define SDL_HINT_MOUSE_RELATIVE_CURSOR_VISIBLE "SDL_MOUSE_RELATIVE_CURSOR_VISIBLE"
 
-/**
- * Controls how often SDL issues cursor confinement commands to the operating
- * system while relative mode is active, in case the desired confinement state
- * became out-of-sync due to interference from other running programs.
- *
- * The variable can be integers representing milliseconds between each
- * refresh. A value of zero means SDL will not automatically refresh the
- * confinement. The default value varies depending on the operating system,
- * this variable might not have any effects on inapplicable platforms such as
- * those without a cursor.
- *
- * This hint can be set anytime.
- *
- * \since This hint is available since SDL 3.1.3.
- */
-#define SDL_HINT_MOUSE_RELATIVE_CLIP_INTERVAL "SDL_MOUSE_RELATIVE_CLIP_INTERVAL"
-
 /**
  * A variable controlling whether mouse events should generate synthetic touch
  * events.

src/events/SDL_mouse.c

@@ -65,17 +65,6 @@ static void SDLCALL SDL_MouseDoubleClickTimeChanged(void *userdata, const char *
     }
 }
 
-static void SDLCALL SDL_MouseRelativeClipIntervalChanged(void *userdata, const char *name, const char *oldValue, const char *hint)
-{
-    SDL_Mouse *mouse = (SDL_Mouse *)userdata;
-
-    if (hint && *hint) {
-        mouse->relative_mode_clip_interval = SDL_atoi(hint);
-    } else {
-        mouse->relative_mode_clip_interval = 3000;
-    }
-}
-
 static void SDLCALL SDL_MouseDoubleClickRadiusChanged(void *userdata, const char *name, const char *oldValue, const char *hint)
 {
     SDL_Mouse *mouse = (SDL_Mouse *)userdata;
@@ -113,6 +102,13 @@ static void SDLCALL SDL_MouseRelativeSpeedScaleChanged(void *userdata, const cha
     }
 }
 
+static void SDLCALL SDL_MouseRelativeModeCenterChanged(void *userdata, const char *name, const char *oldValue, const char *hint)
+{
+    SDL_Mouse *mouse = (SDL_Mouse *)userdata;
+
+    mouse->relative_mode_center = SDL_GetStringBoolean(hint, true);
+}
+
 static void SDLCALL SDL_MouseRelativeSystemScaleChanged(void *userdata, const char *name, const char *oldValue, const char *hint)
 {
     SDL_Mouse *mouse = (SDL_Mouse *)userdata;
@@ -226,6 +222,9 @@ bool SDL_PreInitMouse(void)
     SDL_AddHintCallback(SDL_HINT_MOUSE_RELATIVE_SYSTEM_SCALE,
                         SDL_MouseRelativeSystemScaleChanged, mouse);
 
+    SDL_AddHintCallback(SDL_HINT_MOUSE_RELATIVE_MODE_CENTER,
+                        SDL_MouseRelativeModeCenterChanged, mouse);
+
     SDL_AddHintCallback(SDL_HINT_MOUSE_EMULATE_WARP_WITH_RELATIVE,
                         SDL_MouseWarpEmulationChanged, mouse);
 
@@ -249,9 +248,6 @@ bool SDL_PreInitMouse(void)
     SDL_AddHintCallback(SDL_HINT_MOUSE_RELATIVE_CURSOR_VISIBLE,
                         SDL_MouseRelativeCursorVisibleChanged, mouse);
 
-    SDL_AddHintCallback(SDL_HINT_MOUSE_RELATIVE_CLIP_INTERVAL,
-                        SDL_MouseRelativeClipIntervalChanged, mouse);
-
     mouse->was_touch_mouse_events = false; // no touch to mouse movement event pending
 
     mouse->cursor_shown = true;
@@ -1042,6 +1038,9 @@ void SDL_QuitMouse(void)
     SDL_RemoveHintCallback(SDL_HINT_MOUSE_RELATIVE_SYSTEM_SCALE,
                         SDL_MouseRelativeSystemScaleChanged, mouse);
 
+    SDL_RemoveHintCallback(SDL_HINT_MOUSE_RELATIVE_MODE_CENTER, 
+                        SDL_MouseRelativeModeCenterChanged, mouse);
+
     SDL_RemoveHintCallback(SDL_HINT_MOUSE_EMULATE_WARP_WITH_RELATIVE,
                         SDL_MouseWarpEmulationChanged, mouse);
 
@@ -1060,9 +1059,6 @@ void SDL_QuitMouse(void)
     SDL_RemoveHintCallback(SDL_HINT_MOUSE_RELATIVE_CURSOR_VISIBLE,
                         SDL_MouseRelativeCursorVisibleChanged, mouse);
 
-    SDL_RemoveHintCallback(SDL_HINT_MOUSE_RELATIVE_CLIP_INTERVAL,
-                        SDL_MouseRelativeClipIntervalChanged, mouse);
-
     for (int i = SDL_mouse_count; i--; ) {
         SDL_RemoveMouse(SDL_mice[i].instance_id, false);
     }

src/events/SDL_mouse_c.h

@@ -98,11 +98,11 @@ typedef struct
     bool relative_mode_warp;
     bool relative_mode_warp_motion;
     bool relative_mode_cursor_visible;
+    bool relative_mode_center;
     bool warp_emulation_hint;
     bool warp_emulation_active;
     bool warp_emulation_prohibited;
     Uint64 last_center_warp_time_ns;
-    int relative_mode_clip_interval;
     bool enable_normal_speed_scale;
     float normal_speed_scale;
     bool enable_relative_speed_scale;

src/video/windows/SDL_windowsevents.c

@@ -350,8 +350,6 @@ static void WIN_UpdateFocus(SDL_Window *window, bool expect_focus)
 
         WIN_UpdateWindowICCProfile(data->window, true);
     } else {
-        RECT rect;
-
         data->in_window_deactivation = true;
 
         SDL_SetKeyboardFocus(NULL);
@@ -361,10 +359,7 @@ static void WIN_UpdateFocus(SDL_Window *window, bool expect_focus)
         }
         WIN_ResetDeadKeys();
 
-        if (GetClipCursor(&rect) && SDL_memcmp(&rect, &data->cursor_clipped_rect, sizeof(rect)) == 0) {
-            ClipCursor(NULL);
-            SDL_zero(data->cursor_clipped_rect);
-        }
+        WIN_UnclipCursorForWindow(window);
 
         data->in_window_deactivation = false;
     }
@@ -1086,6 +1081,10 @@ LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPara
     case WM_NCACTIVATE:
     {
         // Don't immediately clip the cursor in case we're clicking minimize/maximize buttons
+        // This is the only place that this flag is set. This causes all subsequent calls to
+        // WIN_UpdateClipCursor for this window to be no-ops in this frame's message-pumping.
+        // This flag is unset at the end of message pumping each frame for every window, and
+        // should never be carried over between frames.
         data->skip_update_clipcursor = true;
 
         /* Update the focus here, since it's possible to get WM_ACTIVATE and WM_SETFOCUS without
@@ -1128,7 +1127,18 @@ LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPara
 
     case WM_MOUSEMOVE:
     {
-        /* SDL_Mouse *mouse = SDL_GetMouse(); */
+        SDL_Window *window = data->window;
+
+        if (window->flags & SDL_WINDOW_INPUT_FOCUS) {
+            bool wish_clip_cursor = (
+                window->flags & (SDL_WINDOW_MOUSE_RELATIVE_MODE | SDL_WINDOW_MOUSE_GRABBED) ||
+                (window->mouse_rect.w > 0 && window->mouse_rect.h > 0)
+            );
+            if (wish_clip_cursor) {
+                data->skip_update_clipcursor = false;
+                WIN_UpdateClipCursor(window);  
+            }
+        }
 
         if (!data->mouse_tracked) {
             TRACKMOUSEEVENT trackMouseEvent;
@@ -1146,7 +1156,7 @@ LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPara
             // Only generate mouse events for real mouse
             if (GetMouseMessageSource((ULONG)GetMessageExtraInfo()) != SDL_MOUSE_EVENT_SOURCE_TOUCH &&
                 lParam != data->last_pointer_update) {
-                SDL_SendMouseMotion(WIN_GetEventTimestamp(), data->window, SDL_GLOBAL_MOUSE_ID, false, (float)GET_X_LPARAM(lParam), (float)GET_Y_LPARAM(lParam));
+                SDL_SendMouseMotion(WIN_GetEventTimestamp(), window, SDL_GLOBAL_MOUSE_ID, false, (float)GET_X_LPARAM(lParam), (float)GET_Y_LPARAM(lParam));
             }
         }
     } break;
@@ -2102,28 +2112,6 @@ LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPara
 }
 
 #if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
-static void WIN_UpdateClipCursorForWindows(void)
-{
-    SDL_VideoDevice *_this = SDL_GetVideoDevice();
-    SDL_Window *window;
-    Uint64 now = SDL_GetTicks();
-    const int CLIPCURSOR_UPDATE_INTERVAL_MS = SDL_GetMouse()->relative_mode_clip_interval;
-
-    if (_this) {
-        for (window = _this->windows; window; window = window->next) {
-            SDL_WindowData *data = window->internal;
-            if (data) {
-                if (data->skip_update_clipcursor) {
-                    data->skip_update_clipcursor = false;
-                    WIN_UpdateClipCursor(window);
-                } else if (CLIPCURSOR_UPDATE_INTERVAL_MS > 0 && now >= (data->last_updated_clipcursor + CLIPCURSOR_UPDATE_INTERVAL_MS)) {
-                    WIN_UpdateClipCursor(window);
-                }
-            }
-        }
-    }
-}
-
 static void WIN_UpdateMouseCapture(void)
 {
     SDL_Window *focusWindow = SDL_GetKeyboardFocus();
@@ -2318,7 +2306,17 @@ void WIN_PumpEvents(SDL_VideoDevice *_this)
     }
 
     // Update the clipping rect in case someone else has stolen it
-    WIN_UpdateClipCursorForWindows();
+    if (_this) {
+        SDL_Window *window = _this->windows;
+        while (window) {
+            SDL_WindowData *data = window->internal;
+            if (data && data->skip_update_clipcursor) {
+                data->skip_update_clipcursor = false;
+                WIN_UpdateClipCursor(window);
+            }
+            window = window->next;
+        }
+    }
 
     // Update mouse capture
     WIN_UpdateMouseCapture();