func (wi *windowInternal) initializeFromExisting(window WindowHandle, settings ContextSettings) ThreadError {
wi.window = window
// We change the event procedure of the control (it is important to save the old one)
C.__SetWindowLongPtr(wi.window.Handle, C.GWLP_USERDATA, unsafe.Pointer(wi))
callback := C.__SetWindowLongPtr(wi.window.Handle, C.GWLP_WNDPROC, unsafe.Pointer(C.pGlobalOnEvent))
wi.callback = unsafe.Pointer(uintptr(callback))
return nil
}
//export globalOnEvent
func globalOnEvent(handle C.HWND, message C.UINT, wParam C.WPARAM, lParam C.LPARAM) C.LRESULT {
// Associate handle and Window instance when the creation message is received
if message == C.WM_CREATE {
// Get WindowImplWin32 instance (it was passed as the last argument of CreateWindow)
window := (*C.CREATESTRUCT)(unsafe.Pointer(uintptr(lParam))).lpCreateParams
// Set as the "user data" parameter of the window
C.__SetWindowLongPtr(handle, C.GWLP_USERDATA, unsafe.Pointer(window))
}
// Get the WindowImpl instance corresponding to the window handle
// Forward the event to the appropriate function
if wi := (*windowInternal)(C.__GetWindowLongPtr(handle, C.GWLP_USERDATA)); wi != nil {
events, errors := wi.processEvent(message, wParam, lParam)
wi.events = append(wi.events, events...)
wi.eventErrors = append(wi.eventErrors, errors...)
if callback := C.WNDPROC(wi.callback); callback != nil {
return C.CallWindowProc(callback, handle, message, wParam, lParam)
}
}
// We don't forward the WM_CLOSE message to prevent the OS from automatically destroying the window
if message == C.WM_CLOSE {
return 0
}
return C.DefWindowProcW(handle, message, wParam, lParam)
}
func (wi *windowInternal) close() ThreadError {
// Destroy the custom icon, if any
if wi.icon != nil {
C.DestroyIcon(wi.icon)
}
if wi.callback == nil {
// Destroy the window
if wi.window.IsValid() {
C.DestroyWindow(wi.window.Handle)
}
} else {
// The window is external : remove the hook on its message callback
C.__SetWindowLongPtr(wi.window.Handle, C.GWLP_WNDPROC, wi.callback)
}
return nil
}