Support for preferred theme

include/SDL3/SDL_video.h

@@ -600,6 +600,19 @@ extern SDL_DECLSPEC const char * SDLCALL SDL_GetVideoDriver(int index);
  */
 extern SDL_DECLSPEC const char * SDLCALL SDL_GetCurrentVideoDriver(void);
 
+/**
+ * Set the preferred system theme.
+ * This is a hint to the system to use the preferred theme for the window
+ *
+ * \param theme the preferred system theme, light, dark, or unknown for auto.
+ * \threadsafety This function should only be called on the main thread.
+ *
+ * \since This function is available since SDL 3.6.0.
+ *
+ * \sa SDL_GetSystemTheme
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_SetPreferredSystemTheme(SDL_SystemTheme theme);
+
 /**
  * Get the current system theme.
  *

src/core/windows/SDL_windows.c

@@ -54,18 +54,6 @@ typedef enum {
     UXTHEME_APPMODE_MAX
 } UxthemePreferredAppMode;
 
-typedef enum {
-    WCA_UNDEFINED = 0,
-    WCA_USEDARKMODECOLORS = 26,
-    WCA_LAST = 27
-} WINDOWCOMPOSITIONATTRIB;
-
-typedef struct {
-    WINDOWCOMPOSITIONATTRIB Attrib;
-    PVOID pvData;
-    SIZE_T cbData;
-} WINDOWCOMPOSITIONATTRIBDATA;
-
 typedef struct {
     ULONG dwOSVersionInfoSize;
     ULONG dwMajorVersion;
@@ -80,7 +68,6 @@ typedef void (WINAPI *AllowDarkModeForWindow_t)(HWND, bool);
 typedef void (WINAPI *AllowDarkModeForApp_t)(bool);
 typedef void (WINAPI *RefreshImmersiveColorPolicyState_t)(void);
 typedef UxthemePreferredAppMode (WINAPI *SetPreferredAppMode_t)(UxthemePreferredAppMode);
-typedef BOOL (WINAPI *SetWindowCompositionAttribute_t)(HWND, const WINDOWCOMPOSITIONATTRIBDATA *);
 typedef void (NTAPI *RtlGetVersion_t)(NT_OSVERSIONINFOW *);
 
 // Fake window to help with DirectInput events.
@@ -438,12 +425,25 @@ bool WIN_WindowRectValid(const RECT *rect)
     return (rect->right > 0);
 }
 
-void WIN_UpdateDarkModeForHWND(HWND hwnd)
+UxthemePreferredAppMode WIN_PreferredUXTheme(const SDL_SystemTheme theme)
+{
+    switch (theme) {
+        case SDL_SYSTEM_THEME_DARK:
+                return UXTHEME_APPMODE_FORCE_DARK;
+        case SDL_SYSTEM_THEME_LIGHT:
+                return UXTHEME_APPMODE_FORCE_LIGHT;
+        case SDL_SYSTEM_THEME_UNKNOWN:
+        default:
+                return UXTHEME_APPMODE_ALLOW_DARK;
+    }
+}
+
+BOOL WIN_UpdatePreferredTheme(SDL_SystemTheme preferredTheme)
 {
 #if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
     HMODULE ntdll = LoadLibrary(TEXT("ntdll.dll"));
     if (!ntdll) {
-        return;
+        return false;
     }
     // There is no function to get Windows build number, so let's get it here via RtlGetVersion
     RtlGetVersion_t RtlGetVersionFunc = (RtlGetVersion_t)GetProcAddress(ntdll, "RtlGetVersion");
@@ -457,52 +457,29 @@ void WIN_UpdateDarkModeForHWND(HWND hwnd)
     os_info.dwBuildNumber &= ~0xF0000000;
     if (os_info.dwBuildNumber < 17763) {
         // Too old to support dark mode
-        return;
+        return false;
     }
     HMODULE uxtheme = LoadLibrary(TEXT("uxtheme.dll"));
     if (!uxtheme) {
-        return;
+        return false;
     }
     RefreshImmersiveColorPolicyState_t RefreshImmersiveColorPolicyStateFunc = (RefreshImmersiveColorPolicyState_t)GetProcAddress(uxtheme, MAKEINTRESOURCEA(104));
-    ShouldAppsUseDarkMode_t ShouldAppsUseDarkModeFunc = (ShouldAppsUseDarkMode_t)GetProcAddress(uxtheme, MAKEINTRESOURCEA(132));
-    AllowDarkModeForWindow_t AllowDarkModeForWindowFunc = (AllowDarkModeForWindow_t)GetProcAddress(uxtheme, MAKEINTRESOURCEA(133));
     if (os_info.dwBuildNumber < 18362) {
         AllowDarkModeForApp_t AllowDarkModeForAppFunc = (AllowDarkModeForApp_t)GetProcAddress(uxtheme, MAKEINTRESOURCEA(135));
         if (AllowDarkModeForAppFunc) {
-            AllowDarkModeForAppFunc(true);
+            AllowDarkModeForAppFunc(preferredTheme != SDL_SYSTEM_THEME_LIGHT);
         }
     } else {
         SetPreferredAppMode_t SetPreferredAppModeFunc = (SetPreferredAppMode_t)GetProcAddress(uxtheme, MAKEINTRESOURCEA(135));
         if (SetPreferredAppModeFunc) {
-            SetPreferredAppModeFunc(UXTHEME_APPMODE_ALLOW_DARK);
+            SetPreferredAppModeFunc(WIN_PreferredUXTheme(preferredTheme));
         }
     }
     if (RefreshImmersiveColorPolicyStateFunc) {
         RefreshImmersiveColorPolicyStateFunc();
     }
-    if (AllowDarkModeForWindowFunc) {
-        AllowDarkModeForWindowFunc(hwnd, true);
-    }
-    BOOL value;
-    // Check dark mode using ShouldAppsUseDarkMode, but use SDL_GetSystemTheme as a fallback
-    if (ShouldAppsUseDarkModeFunc) {
-        value = ShouldAppsUseDarkModeFunc() ? TRUE : FALSE;
-    } else {
-        value = (SDL_GetSystemTheme() == SDL_SYSTEM_THEME_DARK) ? TRUE : FALSE;
-    }
     FreeLibrary(uxtheme);
-    if (os_info.dwBuildNumber < 18362) {
-        SetProp(hwnd, TEXT("UseImmersiveDarkModeColors"), SDL_reinterpret_cast(HANDLE, SDL_static_cast(INT_PTR, value)));
-    } else {
-        HMODULE user32 = GetModuleHandle(TEXT("user32.dll"));
-        if (user32) {
-            SetWindowCompositionAttribute_t SetWindowCompositionAttributeFunc = (SetWindowCompositionAttribute_t)GetProcAddress(user32, "SetWindowCompositionAttribute");
-            if (SetWindowCompositionAttributeFunc) {
-                WINDOWCOMPOSITIONATTRIBDATA data = { WCA_USEDARKMODECOLORS, &value, sizeof(value) };
-                SetWindowCompositionAttributeFunc(hwnd, &data);
-            }
-        }
-    }
+    return true;
 #endif
 }
 

src/core/windows/SDL_windows.h

@@ -194,7 +194,7 @@ extern void WIN_RectToRECT(const SDL_Rect *sdlrect, RECT *winrect);
 // Returns false if a window client rect is not valid
 extern bool WIN_WindowRectValid(const RECT *rect);
 
-extern void WIN_UpdateDarkModeForHWND(HWND hwnd);
+extern BOOL WIN_UpdatePreferredTheme(SDL_SystemTheme preferredTheme);
 
 extern HICON WIN_CreateIconFromSurface(SDL_Surface *surface);
 

src/dynapi/SDL_dynapi.sym

@@ -1240,7 +1240,7 @@ SDL3_0.0.0 {
     SDL_GetDefaultTextureScaleMode;
     SDL_CreateGPURenderState;
     SDL_SetGPURenderStateFragmentUniforms;
-    SDL_SetGPURenderState;
+    SDL_SetRenderGPUState;
     SDL_DestroyGPURenderState;
     SDL_SetWindowProgressState;
     SDL_SetWindowProgressValue;
@@ -1268,6 +1268,7 @@ SDL3_0.0.0 {
     SDL_GetPenDeviceType;
     SDL_CreateAnimatedCursor;
     SDL_RotateSurface;
+    SDL_SetPreferredTheme;
     # extra symbols go here (don't modify this line)
   local: *;
 };

src/dynapi/SDL_dynapi_overrides.h

@@ -1294,3 +1294,4 @@
 #define SDL_GetPenDeviceType SDL_GetPenDeviceType_REAL
 #define SDL_CreateAnimatedCursor SDL_CreateAnimatedCursor_REAL
 #define SDL_RotateSurface SDL_RotateSurface_REAL
+#define SDL_SetPreferredSystemTheme SDL_SetPreferredSystemTheme_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -1302,3 +1302,4 @@ SDL_DYNAPI_PROC(int,SDL_GetSystemPageSize,(void),(),return)
 SDL_DYNAPI_PROC(SDL_PenDeviceType,SDL_GetPenDeviceType,(SDL_PenID a),(a),return)
 SDL_DYNAPI_PROC(SDL_Cursor*,SDL_CreateAnimatedCursor,(SDL_CursorFrameInfo *a,int b,int c,int d),(a,b,c,d),return)
 SDL_DYNAPI_PROC(SDL_Surface*,SDL_RotateSurface,(SDL_Surface *a,float b),(a,b),return)
+SDL_DYNAPI_PROC(void,SDL_SetPreferredSystemTheme,(SDL_SystemTheme theme),(theme),return)

src/tray/windows/SDL_tray.c

@@ -23,6 +23,7 @@
 
 #include "../SDL_tray_utils.h"
 #include "../../core/windows/SDL_windows.h"
+#include "../../video/windows/SDL_windowsvideo.h"
 
 #include <windowsx.h>
 #include <shellapi.h>
@@ -100,6 +101,20 @@ static SDL_TrayEntry *find_entry_with_id(SDL_Tray *tray, UINT_PTR id)
     return find_entry_in_menu(tray->menu, id);
 }
 
+static void TrayUpdateDarkMode(HWND hwnd, BOOL value)
+{
+    HMODULE user32 = GetModuleHandle(TEXT("user32.dll"));
+    if (!user32) {
+        return;
+    }
+
+    WINDOWCOMPOSITIONATTRIBDATA data = {
+        WCA_USEDARKMODECOLORS,
+        &value, sizeof(value)
+    };
+    SDL_GetVideoDevice()->internal->SetWindowCompositionAttribute(hwnd, &data);
+}
+
 LRESULT CALLBACK TrayWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
     SDL_Tray *tray = (SDL_Tray *) GetWindowLongPtr(hwnd, GWLP_USERDATA);
     SDL_TrayEntry *entry = NULL;
@@ -142,7 +157,9 @@ LRESULT CALLBACK TrayWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lPar
 
         case WM_SETTINGCHANGE:
             if (wParam == 0 && lParam != 0 && SDL_wcscmp((wchar_t *)lParam, L"ImmersiveColorSet") == 0) {
-                WIN_UpdateDarkModeForHWND(hwnd);
+                if (SDL_GetVideoDevice()->preferred_theme == SDL_SYSTEM_THEME_UNKNOWN) {
+                    TrayUpdateDarkMode(hwnd, SDL_GetSystemTheme() == SDL_SYSTEM_THEME_DARK);
+                }
             }
             break;
 
@@ -288,7 +305,7 @@ SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
     tray->hwnd = CreateWindowEx(0, TEXT("SDL_TRAY"), NULL, WS_OVERLAPPEDWINDOW,
                                 CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, NULL, NULL);
 
-    WIN_UpdateDarkModeForHWND(tray->hwnd);
+    TrayUpdateDarkMode(tray->hwnd, SDL_GetSystemTheme() == SDL_SYSTEM_THEME_DARK);
 
     SDL_zero(tray->nid);
     tray->nid.cbSize = sizeof(NOTIFYICONDATAW);

src/video/SDL_sysvideo.h

@@ -399,6 +399,12 @@ struct SDL_VideoDevice
     // Display the system-level window menu
     void (*ShowWindowSystemMenu)(SDL_Window *window, int x, int y);
 
+    /*
+     * Set the preferred theme (light, dark, etc) for the application
+     * This is a hint, and may be ignored by the platform.
+     */
+    void (*SetPreferredTheme)(SDL_VideoDevice *_this, SDL_SystemTheme theme);
+
     /* * * */
     // Data common to all drivers
     SDL_ThreadID thread;
@@ -421,6 +427,7 @@ struct SDL_VideoDevice
     bool setting_display_mode;
     Uint32 device_caps;
     SDL_SystemTheme system_theme;
+    SDL_SystemTheme preferred_theme;
     bool screen_keyboard_shown;
 
     /* * * */

src/video/SDL_video.c

@@ -770,6 +770,16 @@ bool SDL_OnVideoThread(void)
     return (_this && SDL_GetCurrentThreadID() == _this->thread);
 }
 
+void SDL_SetPreferredSystemTheme(SDL_SystemTheme theme)
+{
+    if (_this && theme != _this->preferred_theme) {
+        _this->preferred_theme = theme;
+        if (_this->SetPreferredTheme) {
+            _this->SetPreferredTheme(_this, theme);
+        }
+    }
+}
+
 void SDL_SetSystemTheme(SDL_SystemTheme theme)
 {
     if (_this && theme != _this->system_theme) {

src/video/windows/SDL_windowsevents.c

@@ -2416,8 +2416,10 @@ LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPara
 
     case WM_SETTINGCHANGE:
         if (wParam == 0 && lParam != 0 && SDL_wcscmp((wchar_t *)lParam, L"ImmersiveColorSet") == 0) {
-            SDL_SetSystemTheme(WIN_GetSystemTheme());
-            WIN_UpdateDarkModeForHWND(hwnd);
+            if (SDL_GetVideoDevice()->preferred_theme == SDL_SYSTEM_THEME_UNKNOWN) {
+                WIN_SetDarkModeColorsForHWND(SDL_GetVideoDevice(), data->window, WIN_GetSystemTheme() == SDL_SYSTEM_THEME_DARK ? TRUE : FALSE);
+                SDL_SetSystemTheme(WIN_GetSystemTheme());
+            }
         }
         if (wParam == SPI_SETMOUSE || wParam == SPI_SETMOUSESPEED) {
             WIN_UpdateMouseSystemScale();

src/video/windows/SDL_windowsvideo.c

@@ -237,6 +237,10 @@ static SDL_VideoDevice *WIN_CreateDevice(void)
     }
     device->internal = data;
     device->system_theme = WIN_GetSystemTheme();
+    device->preferred_theme = SDL_SYSTEM_THEME_UNKNOWN;
+    device->SetPreferredTheme = WIN_SetPreferredTheme;
+
+    WIN_SetPreferredTheme(device, device->system_theme);
 
 #if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
     data->userDLL = SDL_LoadObject("USER32.DLL");
@@ -260,6 +264,7 @@ static SDL_VideoDevice *WIN_CreateDevice(void)
         data->DisplayConfigGetDeviceInfo = (LONG (WINAPI *)(DISPLAYCONFIG_DEVICE_INFO_HEADER*))SDL_LoadFunction(data->userDLL, "DisplayConfigGetDeviceInfo");
         data->GetPointerType = (BOOL (WINAPI *)(UINT32, POINTER_INPUT_TYPE *))SDL_LoadFunction(data->userDLL, "GetPointerType");
         data->GetPointerPenInfo = (BOOL (WINAPI *)(UINT32, POINTER_PEN_INFO *))SDL_LoadFunction(data->userDLL, "GetPointerPenInfo");
+        data->SetWindowCompositionAttribute = (BOOL (WINAPI *)(HWND, const WINDOWCOMPOSITIONATTRIBDATA *))SDL_LoadFunction(data->userDLL, "SetWindowCompositionAttribute");
         /* *INDENT-ON* */ // clang-format on
     } else {
         SDL_ClearError();
@@ -877,4 +882,26 @@ bool WIN_IsPerMonitorV2DPIAware(SDL_VideoDevice *_this)
     return false;
 }
 
+void WIN_SetPreferredTheme(SDL_VideoDevice *_this, SDL_SystemTheme preferred)
+{
+    SDL_Window *window;
+    SDL_SystemTheme theme;
+
+    if (!WIN_UpdatePreferredTheme(preferred)) {
+        return;
+    }
+
+    if (preferred == SDL_SYSTEM_THEME_UNKNOWN) {
+        theme = WIN_GetSystemTheme();
+    } else {
+        theme = preferred;
+    }
+
+    for (window = _this->windows; window; window = window->next) {
+        WIN_SetDarkModeColorsForHWND(_this, window, preferred == SDL_SYSTEM_THEME_DARK);
+    }
+
+    SDL_SetSystemTheme(theme);
+}
+
 #endif // SDL_VIDEO_DRIVER_WINDOWS

src/video/windows/SDL_windowsvideo.h

@@ -510,6 +510,18 @@ typedef struct
     BOOL transition_on_maxed;
 } DWM_BLURBEHIND;
 
+typedef enum {
+    WCA_UNDEFINED = 0,
+    WCA_USEDARKMODECOLORS = 26,
+    WCA_LAST = 27
+} WINDOWCOMPOSITIONATTRIB;
+
+typedef struct {
+    WINDOWCOMPOSITIONATTRIB Attrib;
+    PVOID pvData;
+    SIZE_T cbData;
+} WINDOWCOMPOSITIONATTRIBDATA;
+
 // Private display data
 
 struct SDL_VideoData
@@ -572,6 +584,9 @@ struct SDL_VideoData
                                         UINT             *dpiX,
                                         UINT             *dpiY );
     HRESULT (WINAPI *SetProcessDpiAwareness)(PROCESS_DPI_AWARENESS dpiAwareness);
+
+    BOOL (WINAPI *SetWindowCompositionAttribute)(HWND, const WINDOWCOMPOSITIONATTRIBDATA *);
+
     /* *INDENT-ON* */ // clang-format on
 #endif                // !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
 
@@ -661,4 +676,6 @@ extern bool D3D_LoadDLL(void **pD3DDLL, IDirect3D9 **pDirect3D9Interface);
 extern SDL_SystemTheme WIN_GetSystemTheme(void);
 extern bool WIN_IsPerMonitorV2DPIAware(SDL_VideoDevice *_this);
 
+extern void WIN_SetPreferredTheme(SDL_VideoDevice *_this, SDL_SystemTheme theme);
+
 #endif // SDL_windowsvideo_h_

src/video/windows/SDL_windowswindow.c

@@ -722,8 +722,6 @@ bool WIN_CreateWindow(SDL_VideoDevice *_this, SDL_Window *window, SDL_Properties
             return WIN_SetError("Couldn't create window");
         }
 
-        WIN_UpdateDarkModeForHWND(hwnd);
-
         WIN_PumpEvents(_this);
 
         if (!SetupWindowData(_this, window, hwnd, parent)) {
@@ -734,6 +732,8 @@ bool WIN_CreateWindow(SDL_VideoDevice *_this, SDL_Window *window, SDL_Properties
             return false;
         }
 
+        WIN_SetDarkModeColorsForHWND(_this, window, _this->system_theme == SDL_SYSTEM_THEME_DARK ? TRUE : FALSE);
+
 #if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
         // Ensure that the IME isn't active on the new window until explicitly requested.
         WIN_StopTextInput(_this, window);
@@ -826,6 +826,18 @@ bool WIN_CreateWindow(SDL_VideoDevice *_this, SDL_Window *window, SDL_Properties
     return true;
 }
 
+void WIN_SetDarkModeColorsForHWND(SDL_VideoDevice *_this, SDL_Window *window, BOOL value)
+{
+#if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
+    HWND hwnd = window->internal->hwnd;
+    WINDOWCOMPOSITIONATTRIBDATA data = {
+        WCA_USEDARKMODECOLORS,
+        &value, sizeof(value)
+    };
+    _this->internal->SetWindowCompositionAttribute(hwnd, &data);
+#endif
+}
+
 void WIN_SetWindowTitle(SDL_VideoDevice *_this, SDL_Window *window)
 {
 #if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)

src/video/windows/SDL_windowswindow.h

@@ -107,6 +107,7 @@ struct SDL_WindowData
 };
 
 extern bool WIN_CreateWindow(SDL_VideoDevice *_this, SDL_Window *window, SDL_PropertiesID create_props);
+extern void WIN_SetDarkModeColorsForHWND(SDL_VideoDevice *_this, SDL_Window *window, BOOL value);
 extern void WIN_SetWindowTitle(SDL_VideoDevice *_this, SDL_Window *window);
 extern bool WIN_SetWindowIcon(SDL_VideoDevice *_this, SDL_Window *window, SDL_Surface *icon);
 extern bool WIN_SetWindowPosition(SDL_VideoDevice *_this, SDL_Window *window);