Win32 C++：子窗口不可见答案

【问题标题】：Win32 C++: Child window is not visibleWin32 C++：子窗口不可见
【发布时间】：2017-03-11 11:07:25
【问题描述】：

我正在创建一个 win32 应用程序，其中子窗口应该是父窗口内的一个球。它编译没有错误，但只显示主窗口，这可能是什么问题？这是我的代码。

LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadStringW(hInstance, IDC_WINPR_LAB02, szWindowClass, MAX_LOADSTRING);
LoadStringW(hInstance, IDC_WINPR_LAB02, szWindowClass1, MAX_LOADSTRING);

WNDCLASSEXW wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WINPR_LAB02));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = CreateSolidBrush(RGB(255, 255, 0));
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_WINPR_LAB02);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
RegisterClassExW(&wcex);

HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW^WS_THICKFRAME,
    (GetSystemMetrics(SM_CXSCREEN) - 200) / 2, (GetSystemMetrics(SM_CYSCREEN) - 300) / 2, 200, 300, nullptr, nullptr, hInstance, nullptr);
SetWindowLong(hWnd, GWL_EXSTYLE, GetWindowLong(hWnd, GWL_EXSTYLE) |
    WS_EX_LAYERED);
SetLayeredWindowAttributes(hWnd, 0, (255 * 50) / 100, LWA_ALPHA);

WNDCLASSEXW wcex1;
memset(&wcex1, 0, sizeof(wcex1));
wcex1.style = CS_HREDRAW | CS_VREDRAW;
wcex1.lpfnWndProc = (WNDPROC)ChildProc;
wcex1.cbClsExtra = 0;
wcex1.cbWndExtra = 0;
wcex1.hInstance = hInstance;
wcex1.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WINPR_LAB02));
wcex1.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex1.hbrBackground = CreateSolidBrush(RGB(255, 0, 0));
wcex1.lpszMenuName = nullptr;
wcex1.lpszClassName = (LPCWSTR)szWindowClass1;
wcex1.hIconSm = LoadIcon(wcex1.hInstance, MAKEINTRESOURCE(IDI_SMALL));
RegisterClassExW(&wcex1);

HWND hWnd1 = CreateWindow(szWindowClass1, szTitle1, WS_CHILD | WS_OVERLAPPEDWINDOW | WS_VISIBLE,
    (GetSystemMetrics(SM_CXSCREEN) - 200) / 2, (GetSystemMetrics(SM_CYSCREEN) - 300) / 2, 200, 300, hWnd, nullptr, hInstance, nullptr);

SetWindowLong(hWnd1, GWL_STYLE, 0); //remove all window styles, check MSDN for details
HRGN region1 = CreateEllipticRgn(0, 0, 10, 10);
SetWindowRgn(hWnd1, region1, true);

ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
ShowWindow(hWnd1, nCmdShow);
UpdateWindow(hWnd1);

HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_WINPR_LAB02));
MSG msg;

while (GetMessage(&msg, nullptr, 0, 0))
{
    if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
}

return (int) msg.wParam;

}

感谢您的时间和帮助。

更新带有两个窗口的新代码，但两者似乎属于同一类，而实际上并非如此。

WNDCLASSEXW wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;// | CS_PARENTDC;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WINPR_LAB02));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = CreateSolidBrush(RGB(255, 255, 0));
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_WINPR_LAB02);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
RegisterClassExW(&wcex);

HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_CLIPCHILDREN | WS_OVERLAPPEDWINDOW^WS_THICKFRAME,
    (GetSystemMetrics(SM_CXSCREEN) - 200) / 2, (GetSystemMetrics(SM_CYSCREEN) - 300) / 2, 200, 300, nullptr, nullptr, hInstance, nullptr);
SetWindowLong(hWnd, GWL_EXSTYLE, GetWindowLong(hWnd, GWL_EXSTYLE) |
    WS_EX_LAYERED);
SetLayeredWindowAttributes(hWnd, 0, (255 * 60) / 100, LWA_ALPHA);

WNDCLASSEXW wcex1;
wcex1.cbSize = sizeof(WNDCLASSEX);
wcex1.style = CS_HREDRAW | CS_VREDRAW;
wcex1.lpfnWndProc = (WNDPROC)ChildProc;
wcex1.cbClsExtra = 0;
wcex1.cbWndExtra = 0;
wcex1.hInstance = hInstance;
wcex1.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WINPR_LAB02));
wcex1.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex1.hbrBackground = CreateSolidBrush(RGB(255, 0, 0));
wcex1.lpszMenuName = nullptr;
wcex1.lpszClassName = szWindowClass1;
wcex1.hIconSm = LoadIcon(wcex1.hInstance, MAKEINTRESOURCE(IDI_SMALL));
RegisterClassExW(&wcex1);

HWND hWnd1 = CreateWindow(szWindowClass1, szTitle1, WS_CHILDWINDOW | WS_VISIBLE | WS_OVERLAPPEDWINDOW,
    0, 0, 350, 300, hWnd, nullptr, hInstance, nullptr);
HRGN region1 = CreateEllipticRgn(0, 0, 75, 75);
SetWindowRgn(hWnd1, region1, true); //creates circle

ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);

【问题讨论】：

子窗口坐标相对于父窗口的客户区，而不是屏幕。因此您的子窗口位于父客户区之外。结果不可见
@RbMm，我将子窗口坐标更改为零，但仍然不可见
首先您创建一个具有 WS_OVERLAPPED 样式的子窗口（您应该从 CreateWindow 调用中删除它）。然后使用 SetWindowLong 从中删除所有样式（包括 WS_CHILD 和 WS_VISIBLE）。 SetWindowRgn 对子窗口无效。只需注释掉 SetWindowLong 和 SetWindowRgn，不要使用 ShowWindow。
@VuVirt 非常感谢，问题出在 SetWindowLong 上。现在我有两个窗口，但它们的背景颜色相同，即使它们有不同的类，可能是什么原因？
你为什么忽略检查错误？

标签： c++ winapi

【解决方案1】：

您应该避免对子窗口使用 WS_OVERLAPPED_WINDOW。为了将子窗口涂成红色，您的 ChildProc 应如下所示：

LRESULT CALLBACK ChildProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    int wmId, wmEvent;
    PAINTSTRUCT ps;
    HDC hdc;

    switch (message)
    {
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);
        // TODO: Add any drawing code here...
        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

我还附上了添加 ChildProc 时它在我的 PC 上的外观截图

【讨论】：