mfc - 从调用弹出对话框到用户可以看到对话框，如何显示等待光标？

Question

所以，我想显示一个 CDialog给用户:

void CMeetingScheduleAssistantDlg::OnOptionsOutlookCalendarOptions()
{
    COutlookCalendarSettingsDlg dlgSettings(this);

    dlgSettings.DoModal();
}

现在，弹出对话框(在 OnInitDialog 中)在幕后运行一个控制台应用程序。此控制台应用程序正在与 通信微软图形 .

因此，对话框可能需要几秒钟才能显示。

我用这个方法执行控制台应用程序:

bool CMeetingScheduleAssistantApp::ExecuteProgram(CString strCommand, DWORD& rExitCode)
{
    PROCESS_INFORMATION processInformation = { nullptr };
    STARTUPINFO         startupInfo = { 0 };
    int                 nStrBuffer;
    BOOL                bProcessResult, bExitCodeProcess;
    bool                bOK = false;
    CWaitCursor         wait;

    SetProgramExecuting(true);

    rExitCode = -1;

    startupInfo.cb = sizeof(startupInfo);
    nStrBuffer = strCommand.GetLength() + 50;

    bProcessResult = CreateProcess(nullptr, strCommand.GetBuffer(nStrBuffer),
        nullptr, nullptr, FALSE,
        NORMAL_PRIORITY_CLASS | CREATE_NO_WINDOW,
        nullptr, nullptr, &startupInfo, &processInformation);
    strCommand.ReleaseBuffer();

    if (!bProcessResult)
    {
        // CreateProcess() failed
        // Get the error from the system
        LPVOID lpMsgBuf;
        DWORD dw = GetLastError();
        FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
            nullptr, dw, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPTSTR)&lpMsgBuf, 0, nullptr);

        // Display the error
        CString strError = (LPTSTR)lpMsgBuf;
        TRACE(_T("Authenticate failed at CreateProcess()\nCommand=%s\nMessage=%s\n\n"), strCommand, strError);

        // Free resources created by the system
        LocalFree(lpMsgBuf);

        SetProgramExecuting(false);

        // We failed.
        return false;
    }
    else
    {
        // Successfully created the process.  Wait for it to finish.
        DWORD WaitResult;
        do
        {
            WaitResult = MsgWaitForMultipleObjects(1,
                // only 1 wait object
                &processInformation.hProcess, // worker thread
                FALSE,   // stop if any
                INFINITE,  // no timeout
                QS_ALLINPUT);
            if (WaitResult == WAIT_OBJECT_0 + 1)
            {
                // Handle windows message
                MSG Msg;
                while (PeekMessage(&Msg, nullptr, 0, (UINT)-1, PM_REMOVE))
                {
                    TRACE3("%d %d %d\n", Msg.message, Msg.wParam, Msg.lParam);
                    TranslateMessage(&Msg);
                    DispatchMessage(&Msg);
                }
            }
        } while (WaitResult != WAIT_OBJECT_0);
        ASSERT(WaitResult == WAIT_OBJECT_0);

        // Get the exit code.
        bExitCodeProcess = GetExitCodeProcess(processInformation.hProcess, &rExitCode);

        // Close the handles.
        CloseHandle(processInformation.hProcess);
        CloseHandle(processInformation.hThread);

        if (!bExitCodeProcess)
        {
            // Could not get exit code.
            TRACE(_T("Executed command but couldn't get exit code.\nCommand=%s\n"), strCommand);
            SetProgramExecuting(false);
            return false;
        }

        SetProgramExecuting(false);
        return true;
    }
}

内 OnInitDialog ，就在 ExecuteProgram 之前被调用，我尝试使用:

CWaitCursor wait;

但这没什么区别。那么如何从我调用弹出对话框的那一刻起显示等待光标，直到用户可以看到该对话框？

Answer 1

一种解决方案是使用 Modeless Dialog .您可以创建一个类似于 wait cursor 的对话框。对话。

你表明Modeless Dialog就在之前 dlgSettings.DoModal();代码中的语句。请使用 TOP_MOST同时显示 Modeless Dialog .

最后，隐藏/关闭 Modeless Dialog来自 OnInitDialog()一旦处理结束。

另一种方法可能是:

添加 public as 成员 CWaitCursor* m_pWaitCursor在 COutlookCalendarSettingsDlg类(class)。现在修改代码为

void CMeetingScheduleAssistantDlg::OnOptionsOutlookCalendarOptions()
{
    COutlookCalendarSettingsDlg dlgSettings(this);
    dlgSettings->m_pWaitCursor = new CWaitCursor();
    dlgSettings.DoModal();
}

然后修改 OnInitDialog的 COutlookCalendarSettingsDlg至 delete CWaitCursor 的实例在从它回来之前。

delete m_pWaitCursor;

更新

我想我会对这个答案添加一个适用于其他情况的更新。你要做的是使用 CPersistantWaitCursor反而。文章提供了一个小例子:

#include "PersistentWaitCursor.h"

void CMyWnd::DoSomeLengthyOperation()
{
    // Create and show the wait cursor
    CPersistentWaitCursor waitCursor;

    // Do some lengthy operation
    ...

    // waitCursor goes out of scope and cursor is restored
}

BOOL CMyWnd::OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message)
{
    if (CPersistentWaitCursor::WaitCursorShown())
    {
        // We are showing the wait cursor
        RestoreWaitCursor();
        return TRUE;
    }

    // Let the base class deal with this one
    return CWnd::OnSetCursor(pWnd, nHitTest, message);
}

查看文章以了解有关其工作原理的完整详细信息。但我可以确认，对于我的其他一些冗长的操作，这增强了 CPersistantWaitCursor成功了。