请问关于无模式对话框问题（问题比较奇怪，标题中不好描述）

[tjuzhangrui]

我在项目中需要进行串口通信，在下载数据的过程中，希望能显示一个对话框，提示“数据下载中，请稍候”。于是就建立一个无模式的对话框，在对话框中写上这几个字，然后在开始串口通信的函数中：
void CView::OnStart()
{
CWaitDlg* dlg=new CWaitDlg;
dlg->Create();
dlg->ShowWindow(SW_SHOWNORMAL);
//下面的就是打开串口等操作
DCB dcb;

g_hComDev = CreateFile( "COM1", GENERIC_READ | GENERIC_WRITE, 0, NULL,
OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL );
if( g_hComDev == NULL ) return;

memset( &g_OverlappedRead, 0, sizeof( OVERLAPPED ) );
memset( &g_OverlappedWrite, 0, sizeof( OVERLAPPED ) );

COMMTIMEOUTS CommTimeOuts;
CommTimeOuts.ReadIntervalTimeout = 0xFFFFFFFF;
CommTimeOuts.ReadTotalTimeoutMultiplier = 0;
CommTimeOuts.ReadTotalTimeoutConstant = 0;
CommTimeOuts.WriteTotalTimeoutMultiplier = 0;
CommTimeOuts.WriteTotalTimeoutConstant = 0;
SetCommTimeouts( g_hComDev, &CommTimeOuts );

g_OverlappedRead.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
g_OverlappedWrite.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );

dcb.DCBlength = sizeof( DCB );
GetCommState( g_hComDev, &dcb );
dcb.BaudRate = 9600;
dcb.ByteSize = 8;
dcb.StopBits = ONESTOPBIT;
dcb.Parity = NOPARITY;
if( !SetCommState( g_hComDev, &dcb ) ||
!SetupComm( g_hComDev, 10000, 10000 ) ||
g_OverlappedRead.hEvent == NULL ||
g_OverlappedWrite.hEvent == NULL ){
DWORD dwError = GetLastError();
if( g_OverlappedRead.hEvent != NULL ) CloseHandle (g_OverlappedRead.hEvent );
if( g_OverlappedWrite.hEvent != NULL ) CloseHandle( g_OverlappedWrite.hEvent );
CloseHandle( g_hComDev );
AfxMessageBox("串口设置失败！");
}
BOOL bWriteStat;
DWORD dwBytesWritten=g_lDatalen*2+6;


bWriteStat=WriteFile(g_hComDev,
g_pSerialData,
g_lDatalen*2+6,
&dwBytesWritten,
&g_OverlappedWrite);
if(!bWriteStat){
if(GetLastError()==ERROR_IO_PENDING){
WaitForSingleObject( g_OverlappedWrite.hEvent, INFINITE );
g_pDlgWait->DestroyWindow();
//设置绘图线程的开始事件为由信号状态
g_eventStart.SetEvent();
}
}
}


现在的问题是无模式的对话框无法正确显示
但如果简单的
void CView::OnStart()
{
CWaitDlg* dlg=new CWaitDlg;
dlg->Create();
dlg->ShowWindow(SW_SHOWNORMAL);
}
就可以正确的显示

难道后面这些串口的操作也会影响无模式对话框吗？

谢谢！

[寻开心]

消息发送和响应的问题
调用了ShowWindow但是并没有被执行
而是进入了下面的其他的处理

[jerry]

进程在执行你的COM操作，被阻塞了没空去响应界面的绘制

[84830388]

应该创建子线程来显示。否则在同一个线程中只能顺序执行。

[kelinwang19]

建议做个消息处理函数来处理串口的操作，可以在showwindow之后发送一个消息，然后进入该处理函数进行处理

[寻开心]

在 pDlg->ShowWindow();
后面再加入：
pDlg->UpdateWindow();
调用，要求系统立刻更新界面就可以了