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#pragma once
namespace windows_user {
EXTERN_C IMAGE_DOS_HEADER __ImageBase;
inline HINSTANCE GetCurrentInstance(){ return ((HINSTANCE)&__ImageBase); }
template<typename Type>
LRESULT CALLBACK WindowCallback(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) noexcept;
template<typename Type>
class window_class
{
public:
static LPCWSTR Name() {
return Type::class_name();
}
static ATOM Register() {
WNDCLASSEX wcex = {};
wcex.cbSize = sizeof(WNDCLASSEX);
// defaults that can be overriden
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.hInstance = GetCurrentInstance();
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.style = 0;
wcex.hIcon = NULL;
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.lpszMenuName = NULL;
Type::change_class(wcex);
// not overridable
wcex.lpszClassName = Name();
wcex.lpfnWndProc = WindowCallback<Type>;
return RegisterClassEx(&wcex);
}
private:
~window_class();
window_class();
window_class(window_class&);
window_class& operator=(window_class&);
};
namespace detail {
template<typename Type>
std::unique_ptr<Type> find(HWND hwnd) {
return std::unique_ptr<Type>(reinterpret_cast<Type*>(GetWindowLongPtr(hwnd, GWLP_USERDATA)));
}
void erase(HWND hwnd) {
SetWindowLongPtr(hwnd, GWLP_USERDATA, 0);
}
template<typename Type>
std::unique_ptr<Type> insert(HWND hwnd, std::unique_ptr<Type> type) {
if (!type) {
return nullptr;
}
SetLastError(0);
ON_UNWIND(unwind_userdata, [&](){erase(hwnd);});
auto result = SetWindowLongPtr(hwnd, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(type.get()));
LONG winerror = !result ? GetLastError() : ERROR_SUCCESS;
if (!!winerror || !!result) {
return nullptr;
}
unwind_userdata.dismiss();
return type;
}
}
template<typename Type>
LRESULT CALLBACK WindowCallback(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) noexcept {
auto type = detail::find<Type>(hWnd);
// don't delete type
ON_UNWIND(unwind_type, [&](){type.release();});
if (message == WM_NCCREATE) {
if (type) {
// the slot where we would store our type instance is full. abort.
return FALSE;
}
auto cs = reinterpret_cast<LPCREATESTRUCT>(lParam);
auto param = reinterpret_cast<Type::param_type*>(cs->lpCreateParams);
type = detail::insert(hWnd, std::unique_ptr<Type>(new (std::nothrow) Type(hWnd, cs, param)));
if (!type) {
return FALSE;
}
}
LRESULT lResult = 0;
bool handled = false;
if (type) {
std::tie(handled, lResult) = type->message(hWnd, message, wParam, lParam);
}
if (!handled) {
lResult = DefWindowProc(hWnd, message, wParam, lParam);
}
if (message == WM_NCDESTROY) {
detail::erase(hWnd);
// let type destruct
unwind_type.dismiss();
}
return lResult;
}
}
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