LRESULT CALLBACK WindowProc::wndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
MSG msg { hwnd, uMsg, wParam, lParam };
// We dispatch certain messages back to the child widget, so that their
// potential callbacks will die along with the child when the time comes
HWND handler = getHandler(msg);
// Try to get the this pointer
Widget* w = hwnd_cast<Widget*>(handler);
if(w) {
if(uMsg == WM_NCDESTROY) {
w->kill();
return returnUnknown(msg);
}
LRESULT res = 0;
if(w->handleMessage(msg, res)) {
return res;
}
}
if(handler != hwnd) {
w = hwnd_cast<Widget*>(hwnd);
}
// If this fails there's something wrong
dwtassert(w, "Expected to get a pointer to a widget - something's wrong");
if(!w) {
return returnUnknown(msg);
}
return w->getDispatcher().chain(msg);
}
void Widget::setHandle(HWND hwnd) {
if(itsHandle) {
throw DWTException("You may not attach to a widget that's already attached");
}
itsHandle = hwnd;
dwtassert((::GetWindowLongPtr(hwnd, GWLP_USERDATA) == 0), "Userdata already set");
::SetLastError(0);
LONG_PTR ret = ::SetWindowLongPtr(hwnd, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(this));
if(ret == 0 && ::GetLastError() != 0) {
throw Win32Exception("Error while setting pointer");
}
}
