我不明白为什么我在BeginPaint函数上出现了循环。我已经阅读了有关这种循环的文章,但几乎所有文章都建议:“不要忘记在WM_PAINT消息上使用BeginPaint函数,因为否则就需要后续的WM_PAINT消息”。这不是我的情况。你可以给我一些建议吗?
这是我的窗口类(“ CWindow”):
class CWindow {
public:
CWindow();
virtual ~CWindow();
bool RegisterClass(HINSTANCE hInstance);
bool CreateWnd(HINSTANCE hInstance);
bool Show(int nShow);
private:
HWND handleWindow;
ATOM atom;
bool isRegistered;
bool isCreated;
static LRESULT CALLBACK WindowProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
void OnPaint();
void OnDestroy();
};
WndProc函数。
LRESULT CALLBACK CWindow::WindowProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
CWindow* windowPtr = reinterpret_cast<CWindow*> ( GetWindowLongPtr( hWnd, GWLP_USERDATA ) );
PAINTSTRUCT ps;
HDC hdc;
switch( msg ) {
case WM_PAINT:
// There is a loop right here!
hdc = BeginPaint( windowPtr->handleWindow, &ps );
// The code below doesn't executed!
RECT rect;
(void)GetClientRect(windowPtr->handleWindow, &rect);
(void)DrawText(hdc, TEXT("Hello, Windows 98!"), -1, &rect,
DT_SINGLELINE | DT_CENTER | DT_VCENTER);
EndPaint( windowPtr->handleWindow, &ps );
break;
case WM_DESTROY:
windowPtr->OnDestroy();
break;
default:
return DefWindowProc( hWnd, msg, wParam, lParam );
}
return 0;
}
RegisterClass
bool CWindow::RegisterClass(HINSTANCE hInstance)
{
const TCHAR app_name[] = TEXT("HelloWin");
WNDCLASSEX windowClass;
ZeroMemory( &windowClass, sizeof(windowClass) );
windowClass.cbSize = sizeof(windowClass);
windowClass.style = CS_HREDRAW | CS_VREDRAW;
windowClass.lpfnWndProc = WindowProc;
windowClass.cbClsExtra = 0;
windowClass.cbWndExtra = 0;
windowClass.hInstance = hInstance;
windowClass.hIcon = 0;
windowClass.hIcon = 0;
windowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
windowClass.hbrBackground = 0;
windowClass.lpszMenuName = NULL;
windowClass.lpszClassName = app_name;
windowClass.hIconSm = NULL;
atom = RegisterClassEx( &windowClass );
DWORD errorCode = GetLastError();
if( errorCode ) {
isRegistered = 0;
std::wcout << L"ErrorCode: " << errorCode << std::endl;
} else {
isRegistered = 1;
}
return isRegistered;
}
CreateWindow
bool CWindow::CreateWnd(HINSTANCE hInstance)
{
handleWindow = CreateWindow((PCTSTR)atom, // window class name or atom
TEXT("The Hello Program"), // window caption
WS_OVERLAPPEDWINDOW, // window style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
CW_USEDEFAULT, // initial x size
CW_USEDEFAULT, // initial y size
NULL, // parent window handle
NULL, // window menu handle
hInstance, // program instance handle
NULL); // creation parameters
DWORD errorCode = GetLastError();
if( !handleWindow ) {
isCreated = 0;
} else {
isCreated = 1;
}
return isCreated;
}
显示
bool CWindow::Show(int nShow)
{
if( isCreated ) {
ShowWindow( handleWindow, nShow );
return UpdateWindow( handleWindow );
} else {
return 0;
}
}
WinMain
int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevINstance, LPSTR lpCmdLine, int nShow )
{
CWindow window;
window.RegisterClass( hInstance );
window.CreateWnd( hInstance );
window.Show( nShow );
int response = 0;
MSG msg;
while( GetMessage( &msg, 0, 0, 0 ) ) {
TranslateMessage( &msg );
DispatchMessage( &msg );
}
return 0;
}
答案 0 :(得分:1)
由于您从不致电.container
{
padding: 0 'min_margin_ammount' 0 0;
}
.your_div_with_items
{
margin: 0 33% 0 0;
}
,
numpy.hstack
返回一个 list_of_arrays = [ array_1, ..., array_n] #all these arrays have same shape[0]
big_array = np.hstack( list_of_arrays)
,您随后尝试取消引用:
SetWindowLongPtr
这将触发访问冲突异常,导致CWindow* windowPtr = reinterpret_cast<CWindow*>( GetWindowLongPtr( hWnd, GWLP_USERDATA ) );
调用甚至永远不会执行,从而使无效区域保持原样。结果,系统不断生成nullptr
消息。这与完全不调用BeginPaint( windowPtr->handleWindow, &ps )
相同。 1
要解决此问题,您将必须通过调用BeginPaint
将窗口句柄附加到窗口实例,或者仅使用传递到WM_PAINT
中的BeginPaint
参数。 / p>
1 请注意,在某些情况下,系统会静默处理您的WindowProc在64位版本的Windows上未处理的异常。