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#ifndef COMMON_H
#define COMMON_H
#include <memory>
#include <optional>
#include <windows.h>
#ifdef UNICODE
#define WA "W"
#else
#define WA "A"
#endif
int EBMessageBox(const TCHAR* tszText, const TCHAR* tszCaption, unsigned uType);
struct Win32Error : public std::exception
{
Win32Error(DWORD dwErr);
~Win32Error();
virtual const char* what() const noexcept override;
virtual const TCHAR* twhat() const noexcept;
private:
DWORD m_dwErr;
char* m_szMsg = NULL;
wchar_t* m_wszMsg = NULL;
};
struct Library
{
Library(const TCHAR* tszLibrary);
~Library();
template <typename T> T* GetProcAddress(const char* szProc);
private:
HMODULE m_hModule;
};
template <typename T>
T* Library::GetProcAddress(const char* const szProc)
{
return (T*)(void*)::GetProcAddress(m_hModule, szProc);
}
/* Create and return an object of type C. If construction fails,
* return nothing. The returned value must be checked before being
* used, as dereferencing is undefined if the value is empty. */
template <class C, typename ...T>
std::optional<C> maybe_make(T ...args)
{
try {
return C(args...);
} catch (...) {
return {};
}
}
/* Call Windows API function and throw error if NULL is returned. */
template <auto f, typename ...T>
inline auto throw_nil(T ...args)
{
auto r = f(args...);
if (!r) throw Win32Error(GetLastError());
return r;
}
/* Call Windows API function and show a warning if NULL is returned. */
template <auto f, typename ...T>
inline auto warn_nil(T ...args)
{
decltype(f(args...)) r;
try {
r = throw_nil<f>(args...);
} catch (Win32Error& e) {
EBMessageBox(e.twhat(), TEXT("System Error"), MB_ICONWARNING);
}
return r;
}
/* Return integer scaled for current DPI. */
inline int Dpi(const int i)
{
extern int g_iDPI;
return MulDiv(i, g_iDPI, 96);
}
inline int Cmp(const int a, const int b)
{
if (a == b) return 0;
if (a > b) return 1;
return -1;
}
#endif
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