c++ - C++ win32 中的 WM_COMMAND 捕捉按钮按下

Question

我正在尝试使用 WM_Command 在 c++ win32 中获取按钮按下事件

HWND hBtn;
HWND  hBtnParent = HWND("UploadVideo");
HWND SelectVideoBTN, UploadBTN;
HWND hWnd;

HINSTANCE hUpload;
WNDCLASSEX wcexUpload;
int nCmdShowUpload = 1;
using namespace std;

LRESULT CALLBACK WindowProcedure(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK WindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    loader::alert("rrr");
    switch (message)
    {
    case WM_COMMAND:
        if (LOWORD(wParam) == WORD(SelectVideoBTN)) {
            loader::alert("hello");
        }
        break;
    default:
        return DefWindowProc(hwnd, message, wParam, lParam);
    }
    return 0;
}

SelectVideoBTN = CreateWindow(
            L"BUTTON",  // Predefined class; Unicode assumed 
            L"Select Video's",      // Button text 
            WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,  // Styles 
            10,         // x position 
            460,         // y position 
            100,        // Button width
            25,        // Button height
            hWnd,     // Parent window
            NULL,       // No menu.
            (HINSTANCE)GetWindowLong(hWnd, GWL_HINSTANCE),
            NULL);      // Pointer not needed.

        UploadBTN = CreateWindow(
            L"BUTTON",  // Predefined class; Unicode assumed 
            L"Upload",      // Button text 
            WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,  // Styles 
            390,         // x position 
            460,         // y position 
            100,        // Button width
            25,        // Button height
            hWnd,     // Parent window
            NULL,       // No menu.
            (HINSTANCE)GetWindowLong(hWnd, GWL_HINSTANCE),
            NULL);      // Pointer not needed.

我一直在看这个例子 - http://forums.devshed.com/programming-42/create-button-clicked-148407.html - 但我不能完全让它工作，它甚至不会调用 CALLBACK WindowProcedure - 有没有人可以帮助我？

按钮出现在我创建的 window 上，我创建了 window -

WNDCLASSEX vidUploader;

    vidUploader.cbSize = sizeof(WNDCLASSEX);

    vidUploader.style = CS_HREDRAW | CS_VREDRAW;
    vidUploader.lpfnWndProc = WndProc;
    vidUploader.cbClsExtra = 0;
    vidUploader.cbWndExtra = 0;
    vidUploader.hInstance = hUpload;
    vidUploader.hIcon = LoadIcon(hUpload, MAKEINTRESOURCE(IDI_P2GOVIDEOUPLOADER20));
    vidUploader.hCursor = LoadCursor(NULL, IDC_ARROW);
    vidUploader.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    vidUploader.lpszMenuName = MAKEINTRESOURCE(IDC_P2GOVIDEOUPLOADER20);
    vidUploader.lpszClassName = (LPCWSTR)(L"UploadVideo");
    vidUploader.hIconSm = LoadIcon(wcexUpload.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    RegisterClassEx(&vidUploader);

    hInst = hUpload; // Store instance handle in our global variable

然后创建窗口

    hWnd = CreateWindow((LPCWSTR)(L"UploadVideo"), (LPCWSTR)(L"Upload Video's"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 500, 100, NULL, NULL, hUpload, NULL);
if (!hWnd)
        {
            MessageBox(NULL, _T("Call to CreateWindow failed!"), _T("Win32 Guided Tour"), NULL);

            return 1;
        }


    // The parameters to ShowWindow explained:
    // hWnd: the value returned from CreateWindow
    // nCmdShow: the fourth parameter from WinMain
    ShowWindow(hWnd,
        nCmdShowUpload);

    UpdateWindow(hWnd);

Answer 1

子窗口(即具有 WS_CHILD 窗口样式的窗口)由唯一的数值标识，通常称为控件 ID 或窗口 ID。例如，它在收到 WM_COMMAND 消息时传递给父级。但是，您从未为按钮控件分配控件 ID，父窗口无法识别它们。如果是子窗口，调用 CreateWindow 时的 hMenu 参数重载以携带唯一标识符:

hMenu
For a child window, hMenu specifies the child-window identifier, an integer value used by a dialog box control to notify its parent about events. The application determines the child-window identifier; it must be unique for all child windows with the same parent window.

换句话说，您的应用程序选择一个数值分配给控件。由于较低的 ID 已被对话管理器使用(例如 IDOK)，通常的做法是从 100 开始分配控件 ID(请参阅 Why do dialog editors start assigning control IDs with 100?)。

在你的WM_COMMAND然后，您可以将 LOWORD(wParam) 与分配给按钮控件的标识符进行比较。

您需要对代码应用以下更改。

// Declare control IDs. This is usually done in a file called Resource.h
#define IDC_SELECT_VIDEO (100)

更改您的窗口创建代码:

SelectVideoBTN = CreateWindow(
            L"BUTTON",  // Predefined class; Unicode assumed 
            L"Select Video's",      // Button text 
            WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,  // Styles 
            10,         // x position 
            460,        // y position 
            100,        // Button width
            25,         // Button height
            hWnd,       // Parent window
            (HMENU)IDC_SELECT_VIDEO, // Assign appropriate control ID
            (HINSTANCE)GetWindowLong(hWnd, GWL_HINSTANCE),
            NULL);      // Pointer not needed.

检查 WM_COMMAND 处理程序中的控件 ID:

    switch (message)
    {
    case WM_COMMAND:
        if (LOWORD(wParam) == IDC_SELECT_VIDEO) {
            loader::alert("hello");
        }
        break;
    default:
        return DefWindowProc(hwnd, message, wParam, lParam);
    }

---

如果您的窗口过程根本没有被调用，这可能意味着您没有在调用线程上发送消息。 GUI 线程总是需要一个消息循环。标准的消息循环就足够了:

MSG msg = {0};
while (GetMessage(&msg, NULL, 0, 0))
{
    TranslateMessage(&msg);
    DispatchMessage(&msg);
}