Windows: Enable dark mode; use dark title bar for dark themes

This is quite a hack, but Win32 apps don't seem to have documented
access to dark mode.

7 files changed, 171 insertions, 13 deletions

diff --git a/src/app.c b/src/app.c
index 7aa0153e..813fa396 100644
--- a/src/app.c
+++ b/src/app.c
@@ -1310,6 +1310,9 @@ void processEvents_App(enum iAppEventMode eventMode) {
 #if defined (iPlatformAppleDesktop)
                     handleCommand_MacOS(command_UserEvent(&ev));
 #endif
+#if defined (iPlatformMsys)
+                    handleCommand_Win32(command_UserEvent(&ev));
+#endif
                     if (isMetricsChange_UserEvent(&ev)) {
                         iConstForEach(PtrArray, iter, listWindows_App_(d)) {
                             iWindow *window = iter.ptr;
diff --git a/src/main.c b/src/main.c
index c8a9c335..61320e79 100644
--- a/src/main.c
+++ b/src/main.c
@@ -49,9 +49,8 @@ int main(int argc, char **argv) {
     registerURLHandler_MacOS();
 #endif
 #if defined (iPlatformMsys)
-    /* MSYS runtime takes care of WinMain. */
-    setDPIAware_Win32();
-    SDL_SetMainReady();
+    init_Win32(); /* DPI awareness, dark mode */
+    SDL_SetMainReady(); /* MSYS runtime takes care of WinMain. */
 #endif
     /* Initialize libraries. */
 #if defined (LAGRANGE_ENABLE_MPG123)
diff --git a/src/ui/root.c b/src/ui/root.c
index e0a12665..f15b59c4 100644
--- a/src/ui/root.c
+++ b/src/ui/root.c
@@ -380,7 +380,8 @@ static iBool handleRootCommands_(iWidget *root, const char *cmd) {
                                  argLabel_Command(cmd, "height"));
             SDL_SetWindowPosition(window->base.win, coord.x, coord.y);
             SDL_SetWindowSize(window->base.win, size.x, size.y);
-            window->place.snap = snap;
+            //window->place.snap = snap;
+            setSnap_MainWindow(get_MainWindow(), snap);
             return iTrue;
         }
     }
diff --git a/src/ui/window.c b/src/ui/window.c
index 164c2478..bd1254d7 100644
--- a/src/ui/window.c
+++ b/src/ui/window.c
@@ -571,6 +571,7 @@ void init_MainWindow(iMainWindow *d, iRect rect) {
 #if defined(iPlatformMsys)
     SDL_SetWindowMinimumSize(d->base.win, minSize.x * d->base.displayScale, minSize.y * d->base.displayScale);
     useExecutableIconResource_SDLWindow(d->base.win);
+    enableDarkMode_SDLWindow(d->base.win);
 #endif
 #if defined (iPlatformLinux)
     SDL_SetWindowMinimumSize(d->base.win, minSize.x * d->base.pixelRatio, minSize.y * d->base.pixelRatio);
diff --git a/src/ui/window.h b/src/ui/window.h
index f1827931..81fc2c06 100644
--- a/src/ui/window.h
+++ b/src/ui/window.h
@@ -193,7 +193,7 @@ void        draw_MainWindow                 (iMainWindow *);
 void        drawWhileResizing_MainWindow    (iMainWindow *, int w, int h); /* workaround for SDL bug */
 
 int         snap_MainWindow                 (const iMainWindow *);
-iBool       isFullscreen_Window             (const iMainWindow *);
+iBool       isFullscreen_MainWindow         (const iMainWindow *);
 
 #if defined (LAGRANGE_ENABLE_CUSTOM_FRAME)
 SDL_HitTestResult hitTest_MainWindow(const iMainWindow *d, iInt2 pos);
diff --git a/src/win32.c b/src/win32.c
index 63e7885a..05ed2c4b 100644
--- a/src/win32.c
+++ b/src/win32.c
@@ -22,6 +22,8 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 

 #include "win32.h"

 #include "ui/window.h"

+#include "ui/command.h"

+#include "prefs.h"

 #include "app.h"

 #include <SDL_syswm.h>

 

@@ -31,8 +33,131 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 #include <dwmapi.h>

 #include <d2d1.h>

 

-void setDPIAware_Win32(void) {

+/* Windows 10 Dark Mode Support

+

+Apparently Microsoft never documented the Win32 functions that control dark mode for

+apps and windows. Here we manually query certain entrypoints from uxtheme.dll and

+user32.dll and use them to enable dark mode for the application, and switch the title

+bar colors to dark or light depending on the Prefs UI color theme.

+

+Perhaps these Win32 APIs will be documented properly in some future version of Windows,

+but for now this is what we have to do to avoid having a white title bar in dark mode.

+

+Calling random functions from system DLLs is a great way to introduce crashes in the

+future! Be on the lookout for launch problems down the road.

+   

+Adapted from https://github.com/ysc3839/win32-darkmode. */

+

+enum WINDOWCOMPOSITIONATTRIB {

+        WCA_UNDEFINED = 0,

+        WCA_NCRENDERING_ENABLED = 1,

+        WCA_NCRENDERING_POLICY = 2,

+        WCA_TRANSITIONS_FORCEDISABLED = 3,

+        WCA_ALLOW_NCPAINT = 4,

+        WCA_CAPTION_BUTTON_BOUNDS = 5,

+        WCA_NONCLIENT_RTL_LAYOUT = 6,

+        WCA_FORCE_ICONIC_REPRESENTATION = 7,

+        WCA_EXTENDED_FRAME_BOUNDS = 8,

+        WCA_HAS_ICONIC_BITMAP = 9,

+        WCA_THEME_ATTRIBUTES = 10,

+        WCA_NCRENDERING_EXILED = 11,

+        WCA_NCADORNMENTINFO = 12,

+        WCA_EXCLUDED_FROM_LIVEPREVIEW = 13,

+        WCA_VIDEO_OVERLAY_ACTIVE = 14,

+        WCA_FORCE_ACTIVEWINDOW_APPEARANCE = 15,

+        WCA_DISALLOW_PEEK = 16,

+        WCA_CLOAK = 17,

+        WCA_CLOAKED = 18,

+        WCA_ACCENT_POLICY = 19,

+        WCA_FREEZE_REPRESENTATION = 20,

+        WCA_EVER_UNCLOAKED = 21,

+        WCA_VISUAL_OWNER = 22,

+        WCA_HOLOGRAPHIC = 23,

+        WCA_EXCLUDED_FROM_DDA = 24,

+        WCA_PASSIVEUPDATEMODE = 25,

+        WCA_USEDARKMODECOLORS = 26,

+        WCA_LAST = 27

+};

+

+struct WINDOWCOMPOSITIONATTRIBDATA {

+        enum WINDOWCOMPOSITIONATTRIB Attrib;

+        PVOID pvData;

+        SIZE_T cbData;

+};

+

+enum PreferredAppMode { Default, AllowDark, ForceDark, ForceLight };

+

+typedef void (WINAPI *RtlGetNtVersionNumbersFunc)(LPDWORD major, LPDWORD minor, LPDWORD build);

+typedef bool (WINAPI *AllowDarkModeForAppFunc)(BOOL allow);

+typedef enum PreferredAppMode (WINAPI *SetPreferredAppModeFunc)(enum PreferredAppMode appMode);

+typedef BOOL (WINAPI *SetWindowCompositionAttributeFunc)(HWND hWnd, struct WINDOWCOMPOSITIONATTRIBDATA *);

+typedef BOOL (WINAPI *AllowDarkModeForWindowFunc)(HWND hWnd, BOOL allow);

+

+static AllowDarkModeForWindowFunc        AllowDarkModeForWindow_;

+static SetWindowCompositionAttributeFunc SetWindowCompositionAttribute_;

+

+static DWORD ntBuildNumber_;

+static BOOL  isDark_;

+

+static iBool refreshTitleBarThemeColor_(HWND hwnd) {

+        BOOL dark = isDark_ColorTheme(prefs_App()->theme);

+    if (dark == isDark_) {

+        return FALSE;

+    }

+        if (ntBuildNumber_ < 18362) {

+        INT_PTR pDark = dark;

+                SetPropW(hwnd, L"UseImmersiveDarkModeColors", (HANDLE) pDark);

+    }

+        else if (SetWindowCompositionAttribute_) {

+                struct WINDOWCOMPOSITIONATTRIBDATA data = {

+            WCA_USEDARKMODECOLORS, &dark, sizeof(dark)

+        };

+                SetWindowCompositionAttribute_(hwnd, &data);

+        }

+    isDark_ = dark;

+    return TRUE;

+}

+

+static void enableDarkMode_Win32(void) {

+    RtlGetNtVersionNumbersFunc RtlGetNtVersionNumbers_ = 

+        (RtlGetNtVersionNumbersFunc)

+        GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlGetNtVersionNumbers");

+    if (!RtlGetNtVersionNumbers_) {

+        return;

+    }

+    DWORD major, minor;

+        RtlGetNtVersionNumbers_(&major, &minor, &ntBuildNumber_);

+        ntBuildNumber_ &= ~0xf0000000;

+    //printf("%u.%u %u\n", major, minor, ntBuildNumber_);

+    /* Windows 11 is apparently still NT version 10. */

+        if (!(major == 10 && minor == 0 && ntBuildNumber_ >= 17763)) {

+        return;

+    }

+    HMODULE hUxtheme = LoadLibraryExW(L"uxtheme.dll", NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);

+    if (hUxtheme) {

+                AllowDarkModeForWindow_ = (AllowDarkModeForWindowFunc) 

+            GetProcAddress(hUxtheme, MAKEINTRESOURCEA(133));

+        AllowDarkModeForAppFunc AllowDarkModeForApp_ = NULL;

+        SetPreferredAppModeFunc SetPreferredAppMode_ = NULL;

+        FARPROC ord135 = GetProcAddress(hUxtheme, MAKEINTRESOURCEA(135));

+        if (ord135) {

+            if (ntBuildNumber_ < 18362) {

+                AllowDarkModeForApp_ = (AllowDarkModeForAppFunc) ord135;

+                AllowDarkModeForApp_(TRUE);

+            }

+            else {

+                SetPreferredAppMode_ = (SetPreferredAppModeFunc) ord135;

+                SetPreferredAppMode_(AllowDark);

+            }

+        }

+        SetWindowCompositionAttribute_ = (SetWindowCompositionAttributeFunc)

+            GetProcAddress(GetModuleHandleW(L"user32.dll"), "SetWindowCompositionAttribute");

+    }

+}

+

+void init_Win32(void) {

     SetProcessDPIAware();

+    enableDarkMode_Win32();

 }

 

 float desktopDPI_Win32(void) {

@@ -51,15 +176,42 @@ float desktopDPI_Win32(void) {
     return ratio;

 }

 

+static HWND windowHandle_(SDL_Window *win) {

+    SDL_SysWMinfo wmInfo;

+    SDL_VERSION(&wmInfo.version);

+    if (SDL_GetWindowWMInfo(win, &wmInfo)) {

+        return wmInfo.info.win.window;

+    }

+    return NULL;

+}

+

 void useExecutableIconResource_SDLWindow(SDL_Window *win) {

     HINSTANCE handle = GetModuleHandle(NULL);

     HICON icon = LoadIcon(handle, "IDI_ICON1");

     if (icon) {

-        SDL_SysWMinfo wmInfo;

-        SDL_VERSION(&wmInfo.version);

-        if (SDL_GetWindowWMInfo(win, &wmInfo)) {

-            HWND hwnd = wmInfo.info.win.window;

-            SetClassLongPtr(hwnd, -14 /*GCL_HICON*/, (LONG_PTR) icon);

+        HWND hwnd = windowHandle_(win);

+        SetClassLongPtr(hwnd, -14 /*GCL_HICON*/, (LONG_PTR) icon);

+    }

+}

+

+void enableDarkMode_SDLWindow(SDL_Window *win) {

+    if (AllowDarkModeForWindow_) {

+        HWND hwnd = windowHandle_(win);

+        AllowDarkModeForWindow_(hwnd, TRUE);

+        refreshTitleBarThemeColor_(hwnd);

+    }    

+}

+

+void handleCommand_Win32(const char *cmd) {

+    if (equal_Command(cmd, "theme.changed")) {        

+        iMainWindow *mw = get_MainWindow();

+        SDL_Window *win = mw->base.win;

+        if (refreshTitleBarThemeColor_(windowHandle_(win)) &&

+            !isFullscreen_MainWindow(mw) &&

+            !argLabel_Command(cmd, "auto")) {

+            /* This will ensure that the non-client area is repainted. */

+            SDL_MinimizeWindow(win);

+            SDL_RestoreWindow(win);

         }

     }

 }

diff --git a/src/win32.h b/src/win32.h
index d53a2fe8..d3fe3faf 100644
--- a/src/win32.h
+++ b/src/win32.h
@@ -28,9 +28,11 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 

 iDeclareType(Window)

 

-void  setDPIAware_Win32(void);

+void  init_Win32(void);

 float desktopDPI_Win32(void);

-void  useExecutableIconResource_SDLWindow(SDL_Window *win);

+void  useExecutableIconResource_SDLWindow(SDL_Window *);

+void  enableDarkMode_SDLWindow(SDL_Window *);

+void  handleCommand_Win32(const char *cmd);

 

 #if defined (LAGRANGE_ENABLE_CUSTOM_FRAME)

 iInt2 cursor_Win32(void);