MFC 模态对话框的实现原理

1

TestDlg
dlg;

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if

(dlg.DoModal()
== IDOK)

4

{

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//处理完毕后的操作

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}

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.......

//后续处理

01

INT_PTR

CDialog::DoModal()

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{

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//对话框资源加载

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......

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//在创建模态窗口之前先让父窗口失效，不响应键盘、鼠标产生的消息

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HWND

hWndParent
= PreModal();

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AfxUnhookWindowCreate();

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BOOL

bEnableParent
= FALSE;

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if

(hWndParent
&& hWndParent != ::GetDesktopWindow() && ::IsWindowEnabled(hWndParent))

12

{

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::EnableWindow(hWndParent,
FALSE);

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bEnableParent
= TRUE;

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.......

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}

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//创建模态窗口，并进行消息循环，若窗口不关闭，则循环不退出

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AfxHookWindowCreate(

this

);

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VERIFY(RunModalLoop(dwFlags)
== m_nModalResult);

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//窗口关闭，销毁窗口

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DestroyWindow();

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PostModal();

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//释放资源，并让父窗口有效

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pMainWnd->EnableWindow(TRUE);

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//返回

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return

m_nModalResult;

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}

01

int

CWnd::RunModalLoop(

DWORD

dwFlags)

02

{

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//要检查窗口状态是否是模态窗口

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//若状态一直为模态，则一直进行消息循环

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for

(;;)

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{

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ASSERT(ContinueModal());

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//
phase1: check to see if we can do idle work

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while

(bIdle
&&

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!::PeekMessage(pMsg,
NULL, NULL, NULL, PM_NOREMOVE))

12

{

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ASSERT(ContinueModal());

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//
show the dialog when the message queue goes idle

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if

(bShowIdle)

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{

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ShowWindow(SW_SHOWNORMAL);

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UpdateWindow();

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bShowIdle
= FALSE;

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}

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//
call OnIdle while in bIdle state

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if

(!(dwFlags
& MLF_NOIDLEMSG) && hWndParent != NULL && lIdleCount == 0)

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{

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//
send WM_ENTERIDLE to the parent

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::SendMessage(hWndParent,
WM_ENTERIDLE, MSGF_DIALOGBOX, (

LPARAM

)m_hWnd);

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}

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if

((dwFlags
& MLF_NOKICKIDLE) ||

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!SendMessage(WM_KICKIDLE,
MSGF_DIALOGBOX, lIdleCount++))

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{

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//
stop idle processing next time

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bIdle
= FALSE;

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}

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}

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//在有消息的情况下取消息处理

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do

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{

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ASSERT(ContinueModal());

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//
pump message, but quit on WM_QUIT

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if

(!AfxPumpMessage())

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{

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AfxPostQuitMessage(0);

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return

-1;

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}

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//
show the window when certain special messages rec'd

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if

(bShowIdle
&&

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(pMsg->message
== 0x118 || pMsg->message == WM_SYSKEYDOWN))

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{

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ShowWindow(SW_SHOWNORMAL);

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UpdateWindow();

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bShowIdle
= FALSE;

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}

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if

(!ContinueModal())

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goto

ExitModal;

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//
reset "no idle" state after pumping "normal" message

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if

(AfxIsIdleMessage(pMsg))

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{

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bIdle
= TRUE;

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lIdleCount
= 0;

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}

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}

while

(::PeekMessage(pMsg,
NULL, NULL, NULL, PM_NOREMOVE));

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}

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ExitModal:

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m_nFlags
&= ~(WF_MODALLOOP|WF_CONTINUEMODAL);

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return

m_nModalResult;

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}

01

//thrdcore.cpp

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//
main running routine until thread exits

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int

CWinThread::Run()

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{

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//
for tracking the idle time state

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BOOL

bIdle
= TRUE; 

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LONG

lIdleCount
= 0; 

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//消息读取乃至分发
当为WM_QUIT时，退出循环

10

for

(;;)

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{

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//检查是否为空闲时刻

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while

(bIdle
&& 

14

!::PeekMessage(&m_msgCur,
NULL, NULL, NULL, PM_NOREMOVE))

15

{

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//
call OnIdle while in bIdle state

17

if

(!OnIdle(lIdleCount++))

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bIdle
= FALSE; 

//
assume "no idle" state

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}

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//有消息，读消息并分发

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do

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{

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//
pump message, but quit on WM_QUIT

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if

(!PumpMessage())

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return

ExitInstance();

27

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//
reset "no idle" state after pumping "normal" message

29

if

(IsIdleMessage(&m_msgCur))

30

{

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bIdle
= TRUE; 

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lIdleCount
= 0; 

33

}

34

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}

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while

(::PeekMessage(&m_msgCur,
NULL, NULL, NULL, PM_NOREMOVE));

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}

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}

1

pParentWnd->EnableWindow(FALSE);

2

3

CDialog
*pDlg;

4

pDlg
=

new

CDialog();

5

pDlg->Create();

6

pDlg->Show();

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pParentWnd->EnableWindow(TRUE);

1

if

(dlg.DoModal()
== IDOK)

01

void

CAppDoModelTestApp::OnTestModaltest()

02

{

03

CWnd*
pMainWnd = AfxGetMainWnd();

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pMainWnd->EnableWindow(FALSE);

05

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m_pTestDlg1
=

new

CModalDlg();

07

m_pTestDlg1->Create(IDD_DIALOG1);

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m_pTestDlg1->ShowWindow(SW_SHOW);

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m_pTestDlg2
=

new

CModalDlg();

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m_pTestDlg2->Create(IDD_DIALOG1);

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m_pTestDlg2->ShowWindow(SW_SHOW);

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}