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#ifndef WIN_H
#define WIN_H
#include <optional>
#include <windows.h>
/* Run given procedure at creation of next window. */
void WithNextWindow(void (*proc)(HWND));
/* Display message box centered in main window. */
int EBMessageBox(const wchar_t* wszText, const wchar_t* wszCaption, UINT uType);
/* Retrieve mouse position relative to given window's client area. */
int GetRelativeCursorPos(HWND hWnd, POINT* pt) noexcept;
/* Cached values from GetSystemMetrics. */
template <int I> auto Metric = GetSystemMetrics(I);
/* Exception for Windows API errors. */
struct Win32Error : public std::exception
{
Win32Error() noexcept;
Win32Error(DWORD code) noexcept;
~Win32Error() noexcept;
const char* what() const noexcept override;
const wchar_t* What() const noexcept;
DWORD code;
private:
char* m_szMsg = nullptr;
wchar_t* m_wszMsg = nullptr;
};
/* Wrapper for loading and freeing dynamically linked libraries. */
struct Library
{
/* Non-throwing named constructor. */
static std::optional<Library> Maybe(const wchar_t* lib) noexcept;
Library(const wchar_t* lib);
~Library() noexcept;
template <class T> T* GetProcAddress(const char* szProc) noexcept;
private:
/* Non-throwing constructor used by Maybe. */
Library(HMODULE hModule) noexcept;
HMODULE m_hModule;
};
template <typename T>
T* Library::GetProcAddress(const char* const szProc) noexcept
{
return (T*)(void*)::GetProcAddress(m_hModule, szProc);
}
/* 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)0;
}
return x;
}
/* Return integer scaled for current DPI. */
inline int Dpi(const int i)
{
extern int g_dpi;
return MulDiv(i, g_dpi, 96);
}
/* Retrieve given window's rectangle relative to parent's client area. */
inline BOOL GetRelativeRect(const HWND hWnd, RECT* const rr)
{
if (!GetClientRect(hWnd, rr)) return 0;
return MapWindowPoints(hWnd, GetParent(hWnd), reinterpret_cast<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);
}
/* The following functions call uxtheme.dll functions, if uxtheme.dll
* exists, and otherwise do nothing. */
inline BOOL EBIsThemeActive()
{
extern BOOL (*IsThemeActive)();
return IsThemeActive? IsThemeActive(): 0;
}
inline BOOL EBSetWindowTheme(const HWND hWnd, const wchar_t* const pszSubAppName,
const wchar_t* const pszSubIdList)
{
extern BOOL (*SetWindowTheme)(HWND, const wchar_t*, const wchar_t*);
return SetWindowTheme? SetWindowTheme(hWnd, pszSubAppName, pszSubIdList): 0;
}
#endif
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