add isLightTheme function

src/hxwindowmode/WindowColorMode.hx

@@ -36,7 +36,9 @@ class WindowColorMode {
 	 * Useful for checking if you need to force redraw the window header.
 	 */
 	public static var isWindows10(get, never):Bool;
-	public static function get_isWindows10():Bool {
+
+	@:noCompletion
+	private static inline function get_isWindows10():Bool {
 		#if lime
 		//could use some C++ code but this works too
 		return (lime.system.System.platformLabel.toLowerCase().indexOf("windows 10") != -1);
@@ -153,9 +155,19 @@ class WindowColorMode {
 	 */
 	public static inline function redrawWindowHeader() {
 		#if lime
+		#if !desktop
+		trace('`redrawWindowHeader` is not available on this platform!');
+		#end
 		for (i in 0...2) lime.app.Application.current.window.borderless = !lime.app.Application.current.window.borderless;
 		#end
 	}
+
+	public static inline function isLightTheme() {
+		#if(!cpp || !windows)
+		trace('`isLightTheme` is not available on this platform!');
+		#end
+		return WindowBackend.isLightTheme();
+	}
 }
 
 enum abstract WindowCornerType(Int) {

src/hxwindowmode/backend/WindowBackend.hx

@@ -18,4 +18,7 @@ extern class WindowBackend {
 
 	@:native("nativeWindowColorMode::updateWindow")
 	private static function updateWindow():Void;
+
+	@:native("nativeWindowColorMode::isLightTheme")
+	private static function isLightTheme():Bool;
 }

src/hxwindowmode/backend/build.xml

@@ -18,5 +18,6 @@
 	<target id="haxe">
 		<files id="hxWindowColorMode" />
         <lib name="dwmapi.lib" if="windows" />
+		<lib name="Advapi32.lib" if="windows" />
 	</target>
 </xml>

src/hxwindowmode/backend/src/windowbackend.cpp

@@ -3,11 +3,14 @@
 #ifdef HX_WINDOWS
 #include <Windows.h>
 #include <dwmapi.h>
+#include <vector>
+#include <string>
+#include <stdexcept>
 #endif
 
 bool nativeWindowColorMode::setWindowColorMode(bool isDarkMode)
 {
-	#ifdef HX_WINDOWS
+#ifdef HX_WINDOWS
 	HWND window = GetActiveWindow();
 	int isDark = (isDarkMode ? 1 : 0);
 	bool hasChanged = (DwmSetWindowAttribute(window, 19, &isDark, sizeof(isDark)) == S_OK);
@@ -19,50 +22,85 @@ bool nativeWindowColorMode::setWindowColorMode(bool isDarkMode)
 	UpdateWindow(window);
 
 	return hasChanged;
-	#else
+#else
 	return false;
-	#endif
+#endif
 }
 
 void nativeWindowColorMode::setWindowBorderColor(::Array<int> color, bool setHeader, bool setBorder)
 {
-	#ifdef HX_WINDOWS
+#ifdef HX_WINDOWS
 	HWND window = GetActiveWindow();
 	auto finalColor = RGB(color[0], color[1], color[2]);
 
-	if(setHeader)
+	if (setHeader)
 		DwmSetWindowAttribute(window, 35, &finalColor, sizeof(COLORREF));
-	if(setBorder)
+	if (setBorder)
 		DwmSetWindowAttribute(window, 34, &finalColor, sizeof(COLORREF));
 
 	UpdateWindow(window);
-	#endif
+#endif
 }
 
 void nativeWindowColorMode::setWindowTitleColor(::Array<int> color)
 {
-	#ifdef HX_WINDOWS
+#ifdef HX_WINDOWS
 	HWND window = GetActiveWindow();
 	auto finalColor = RGB(color[0], color[1], color[2]);
 
 	DwmSetWindowAttribute(window, 36, &finalColor, sizeof(COLORREF));
 	UpdateWindow(window);
-	#endif
+#endif
 }
 
 void nativeWindowColorMode::setWindowCornerType(int cornerType)
 {
-	#ifdef HX_WINDOWS
+#ifdef HX_WINDOWS
 	HWND window = GetActiveWindow();
 
 	DwmSetWindowAttribute(window, 33, &cornerType, sizeof(cornerType));
 	UpdateWindow(window);
-	#endif
+#endif
 }
 
 void nativeWindowColorMode::updateWindow()
 {
-	#ifdef HX_WINDOWS
+#ifdef HX_WINDOWS
 	UpdateWindow(GetActiveWindow());
-	#endif
+#endif
+}
+
+/**
+ * @see https://stackoverflow.com/questions/51334674/how-to-detect-windows-10-light-dark-mode-in-win32-application
+ */
+bool nativeWindowColorMode::isLightTheme()
+{
+#ifdef HX_WINDOWS
+	// The value is expected to be a REG_DWORD, which is a signed 32-bit little-endian
+	auto buffer = std::vector<char>(4);
+	auto cbData = static_cast<DWORD>(buffer.size() * sizeof(char));
+	auto res = RegGetValueW(
+		HKEY_CURRENT_USER,
+		L"Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize",
+		L"AppsUseLightTheme",
+		RRF_RT_REG_DWORD, // expected value type
+		nullptr,
+		buffer.data(),
+		&cbData);
+
+	if (res != ERROR_SUCCESS)
+	{
+		throw std::runtime_error("Error: error_code=" + std::to_string(res));
+	}
+
+	// convert bytes written to our buffer to an int, assuming little-endian
+	auto i = int(buffer[3] << 24 |
+				 buffer[2] << 16 |
+				 buffer[1] << 8 |
+				 buffer[0]);
+
+	return i == 1;
+#else
+	return false;
+#endif
 }

src/hxwindowmode/backend/src/windowbackend.hpp

@@ -9,4 +9,5 @@ namespace nativeWindowColorMode
 	void setWindowTitleColor(::Array<int> color);
 	void setWindowCornerType(int cornerType);
 	void updateWindow();
+	bool isLightTheme();
 }