BM_GETCHECK无法正常工作

Question

我有这样的代码:

In WM_CREATE

    hCheckBox = CreateWindowEx(0,"Button","Random text", WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS| BS_AUTOCHECKBOX | BS_TEXT | WS_GROUP | WS_TABSTOP,150,323,300,20,hwnd,0,hInstance,0) ;


In WM_COMMAND

    if ( SendMessage( hCheckBox , BM_GETCHECK, (WPARAM) NULL, (LPARAM) NULL ) == BST_CHECKED )
        MessageBox( 0, "Working", "Msg", 0 );

如果选中复选框并不重要,它永远不会返回BST_CHECKED.试着让它在最后2小时工作:(

Answer 1

是否hCheckBox是本地自动变量并不完全明显.如果是这样,我可以向您保证,从CreateWindow发生火灾到收到WM_COMMAND消息的时间,它没有保持其值.请改用:

LRESULT chk = SendDlgItemMessage(hDlg, IDC_CHECKBOX_CTRL_ID, BM_GETCHECK, 0, 0);

hDlg您的对话框或主窗口在哪里处理,并且IDC_CHECKBOX_CTRL_ID是控件ID.为此,您需要将控制ID指定为create-call的HMENU参数的非零值:

hCheckBox = CreateWindowEx(0,"Button","Random text", WS_CHILD | WS_VISIBLE | 
    WS_CLIPSIBLINGS| BS_AUTOCHECKBOX | BS_TEXT | WS_GROUP |
    WS_TABSTOP,150,323,300,20,hwnd, IDC_CHECKBOX_CTRL_ID, hInstance,0);

如果不明显的话.将IDC_CHECKBOX_CTRL_ID定义为非零整数.

编辑

假设控件设置正确,您应该能够在WndProc中为此复选框处理WM_COMMAND,如下所示

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    int wmId, wmEvent;
    switch (message)
    {
    case WM_CREATE:
        CreateWindowExA(0,"Button","Random text", WS_CHILD | WS_VISIBLE | 
            WS_CLIPSIBLINGS| BS_AUTOCHECKBOX | BS_TEXT | WS_GROUP |
            WS_TABSTOP,100,100,300,48, hWnd, (HMENU)IDC_CHECKBOX_CTRL_ID, hInst, 0);
        break;

    case WM_COMMAND:
        wmId = LOWORD(wParam);
        wmEvent = HIWORD(wParam);

        // Parse the menu selections:
        if (wmId == IDC_CHECKBOX_CTRL_ID)
        {
            if (wmEvent == BN_CLICKED)
            {
                LRESULT chkState = SendMessage((HWND)lParam, BM_GETCHECK, 0, 0);
                if (chkState == BST_CHECKED)
                    MessageBoxA(hWnd, "Checkbox is checked!", "CheckBox", MB_OK);
            }
            break;
        };
        // fall-thru intentional

    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    };

    return 0;
}

我只是把它撞到了一个带有空白窗口的股票通用WIN32应用程序.结果如下图所示: