1 files changed, 105 insertions, 0 deletions
diff --git a/c/win.h b/c/win.h
new file mode 100644
index 0000000..038f8ea
--- /dev/null
+++ b/c/win.h
@@ -0,0 +1,105 @@
+#ifndef WIN_H
+#define WIN_H
+
+#include <optional>
+#include <windows.h>
+
+int EBMessageBox(const wchar_t* wszText, const wchar_t* wszCaption, unsigned uType);
+int GetRelativeCursorPos(HWND hWnd, POINT* pt);
+
+/* Win32Error: Exception for Windows API errors. */
+struct Win32Error : public std::exception
+{
+	Win32Error();
+	Win32Error(DWORD code);
+	~Win32Error();
+	const char* what() const noexcept override;
+	const wchar_t* What() const noexcept;
+	DWORD code;
+private:
+	char* m_szMsg = NULL;
+	wchar_t* m_wszMsg = NULL;
+};
+
+/* Library: Wrapper for loading and freeing dynamically linked libraries. */
+struct Library
+{
+	static std::optional<Library> Maybe(const wchar_t* lib);
+	Library(const wchar_t* lib);
+	~Library();
+	template <class T> T* GetProcAddress(const char* szProc);
+private:
+	Library(HMODULE hModule);
+	HMODULE m_hModule;
+};
+
+template <typename T>
+T* Library::GetProcAddress(const char* const szProc)
+{
+	return (T*)(void*)::GetProcAddress(m_hModule, szProc);
+}
+
+/* Variable template for caching values from GetSystemMetrics. */
+template <int I>
+auto Metric = GetSystemMetrics(I);
+
+/* Check result of Windows API call, throwing error on NULL. */
+template <typename T>
+inline T require(const T x)
+{
+	if (!x) throw Win32Error();
+	return x;
+}
+
+/* Check result of Windows API call, showing a warning on NULL. */
+template <typename T>
+inline T prefer(const T x)
+{
+	if (!x) {
+		EBMessageBox(Win32Error().What(), L"System Error", MB_ICONWARNING);
+		return (T)NULL;
+	}
+	return x;
+}
+
+/* Return integer scaled for current DPI. */
+inline int Dpi(const int i)
+{
+	extern int g_dpi;
+	return MulDiv(i, g_dpi, 96);
+}
+
+/* Get window rectangle relative to parent. */
+inline BOOL GetRelativeRect(const HWND hWnd, RECT* const rr)
+{
+	if (!GetClientRect(hWnd, rr)) return 0;
+	return MapWindowPoints(hWnd, GetParent(hWnd), (POINT*)rr, 2);
+}
+
+inline BOOL SetWindowRect(const HWND hWnd,
+    const long left, const long top, const long right, const long bottom)
+{
+	return MoveWindow(hWnd,
+	    left, top,
+	    right-left, bottom-top,
+	    TRUE);
+}
+
+inline BOOL SetWindowRect(const HWND hWnd, const RECT r)
+{
+	return SetWindowRect(hWnd, r.left, r.top, r.right, r.bottom);
+}
+
+inline BOOL EBIsThemeActive()
+{
+	extern BOOL (*IsThemeActive)();
+	return IsThemeActive? IsThemeActive(): 0;
+}
+
+inline BOOL EBSetWindowTheme(HWND hWnd, LPCWSTR pszSubAppName, LPCWSTR pszSubIdList)
+{
+	extern BOOL (*SetWindowTheme)(HWND, LPCWSTR, LPCWSTR);
+	return SetWindowTheme? SetWindowTheme(hWnd, pszSubAppName, pszSubIdList): 0;
+}
+
+#endif