CS 325

1
CS 325

• Unix Programming Environment
• and
• Windows Programming
• with Microsoft Foundation Classes (MFC)

2
Windows Lecture 10

• Today
• Dialog Windows
• Communicating with the dialog
• DoDataExchange
• OnInitDialog
• Assignment 3 due Today, in class
• Assignment 4 Twenty (20) improvements on
  Project 3
• If you need project 3 code I will provide
• Just ask

3
Common Errors Cause and Effect

• Using wrong menu or dialog name
• Program will crash on startup
• Make sure you match the name specified in .rc
  file
• Calling create twice -- Assertion error
• CBrush b new CBrush()
• b-gtcreateSolidBrush(RED)
• b-gtcreateSolidBrush(BLUE)
• Using the Resource Wizard
• Wizard adds code that may duplicate or invalidate
  existing code. He may also change your resource
  description
• Program no longer compiles
• Creating wrong project type
• LNK ERROR- main or winmain32 undefined
• Forgetting to add MFC in shared dll
• begin_threadx/end_threadx undefined

4
Launching The Game

• class CGOApp public CWinApp
• public
• BOOL InitInstance()
• // CWND m_pMainWnd
• m_pMainWnd new CWinGo
• m_pMainWnd-gtShowWindow(m_nCmdShow)
• m_pMainWnd-gtUpdateWindow()
• //cast CWND to known type and call OnNew()
• ((CWinGo) m_pMainWnd)-gtOnNew()
• //parens required as -gt has higher precedence
• //without parent result of OnNew (here void) is
  cast
• return TRUE
• GoApp

5
DoubleBuffering (Why isnt it automatic!)

• afx_msg void CKalahFrameWndOnPaint()
• //step 1 set up a buffer
• CPaintDC paintDC(this)
• CDC dbufdc
• dbufdc.CreateCompatibleDC(paintDC)
• CRect screen
• GetClientRect(screen)
• CBitmap bmp
• bmp.CreateCompatibleBitmap(paintDC,
  screen.Width(),screen.Height() )
• dbufdc.SelectObject(bmp)
• //step2 draw on dbbufdc
• dbbuddc.TextOut()
• dbbufdc.FillRect(CRect(x,y,xw, yh), pBrush)
• //step3 copy buffer to screen
• paintDC.BitBlt(0, 0, screen.Width(),
  screen.Height(),
• dbufdc, 0, 0, SRCCOPY )
• This example isn't perfect ideally OnPaint
  would consist of only step 3

6
Class Exercises

• The code for the dialog example is on the web
• Zip1 (Zip file)
• Complete the OnDec routine
• Add WS_SYSMENU to Style, what happens?
• Clean up organization of the dialog window
• Make fields just large enough to do the job
• Re-arrange the fields (all buttons on one line,
  etc)

7
Simple (standalone) dialog app

• Goal create a dialog box that has one input
  field, one display field, and three buttons
• Input field allows the user to enter a number
• One button increments this value, one decrements
• Third button exits the routine
• New value displayed in the one output field
• Files
• dialogDlg.cpp, dialogDlg.h (C class
  code/header)
• dialogs_ids.h (mnemonics ids for linkage)
• dialog.rc (resource file, defines form of dialog
  box)

8
The file dialog_ids.h

• define IDC_NUM 6010
• //will be user input field (input)
• define IDC_ANS 6020
• //will be result field (output)
• define IDC_INC 6030
• //button to increment
• define IDC_DEC 6040
• //button to decrement
• define IDC_QUIT 6050
• //button to exit

• Define message identifiers and their numeric
  equivalent
• Allows us to refer to messages within the program
  using meaningful names
• Note IDC_ prefix
• Convention

9
The file dialog.rc (part 1)

• include ltafxwin.hgt
• include "dialog_ids.h"
• MyDialog DIALOG 200,200,200,250
• STYLE DS_MODALFRAME WS_CAPTION WS_POPUP
  WS_VISIBLE
• //continued on next slide

• Include files needed
• Define the MyDialog dialog box
• Definition gives location/size
• Style of dialog box
• Fields in dialog box (next slide)
• Style
• ModalFrame keeps application from continuing
  until dialog box is finished
• Caption provides a caption on the top of the
  dialog box
• Popup indicates a stand-alone window (not part of
  a bigger app)

10
The file dialog.rc (part 2)

• Set the dialog caption
• Define a static control field (displays text,
  does not generate events), left justified
  (LTEXT), (20,20) is top left corner, box is 50x10
• Defines an edit box, associated with IDC_NUM,
  location size, ES_NUMBER indicates will only
  accept numeric input
• Define button, associated with IDC_INC, location
  size
• Define an edit box (for output), associate with
  IDC_ANS, location size, readonly, user tabs do
  not stop on this field
• Define button, associated with IDC_QUIT, location
  size

• CAPTION "Dialog Example"
• LTEXT "Enter a number", IDC_STATIC,
  20,20,50,10
• EDITTEXT IDC_NUM, 20, 60, 50, 20, ES_NUMBER
• DEFPUSHBUTTON "Increment", IDC_INC, 20, 100,
  50, 30
• DEFPUSHBUTTON "Decrement", IDC_DEC, 80, 100,
  50, 30
• EDITTEXT IDC_ANS, 20, 140, 50, 20, ES_READONLY
• NOT WS_TABSTOP
• DEFPUSHBUTTON "Exit", IDC_QUIT, 20, 180, 30,
  20

11
RECAP rc Dialog Elements

• LTEXT "text to display",
• IDC_STATIC, x, y, w, h
• EDITTEXT
• IDC_IDNAME1, x, y, w, h, ES_PROPERTIES
• DEFPUSHBUTTON "caption for button"
• IDC_IDNAME2, x, y, w, h
• GROUPBOX "caption for groupbox",
• IDC_IDNAME3, x, y, w, h
• AUTORADIOBUTTON "caption for radio item",
• IDC_IDNAME3, x, y, w, h

12
The file dialogDlg.h

• include ltafxwin.hgt
• include "dialog_ids.h
• class CDialogDlg public CDialog
• public
• CDialogDlg()
• afx_msg void OnInc( )
• afx_msg void OnDec( )
• afx_msg void OnQuit( )
• private
• DECLARE_MESSAGE_MAP( )

• Notice here we do not inherit from CFrameWnd, but
  rather CDialog
• Our dialog class has a constructor and three
  basic events it reacts to
• Reacts when the user clicks the OnInc button
• Reacts when the user clicks the OnDec button
• Reacts when the user clicks the Quit button
• Standard message map to set up linkages between
  class events

13
The file dialogDlg.cpp (part 1)

• include ltstrstreagt
• using namespace std
• include dialogDlg.h"
• CDialogDlgCDialogDlg()
• CDialog("MyDialog")
• afx_msg void CDialogDlgOnQuit()
• SendMessage(WM_CLOSE)
• afx_msg void CDialogDlgOnDec()

• Include ltstrstreamgt
• Need to convert integers to string for output
• Constructor
• Invokes parent constructor with name of resources
  (found in dialog.rc file) to use to build the
  dialog box
• Handle Quit button
• OnDec button not yet implemented

14
The file dialogDlg.cpp (part 2)

• Get access to the input box(represented by
  IDC_NUM in our resource file)
• Move the text in the dialog box into an array
  (arText)
• Convert it to an integer
• Increment the integer
• Write the integer to an output string stream,
  making sure to insert the NULL terminator
• Get access to the output box (represented by
  IDC_ANS in our resource file)
• Move output string to this box
• Clear the input box
• Set the focus to the input box

• afx_msg void CDialogDlgOnInc()
• CEdit pNum (CEdit ) GetDlgItem(IDC_NUM)c
  har arText32pNum-gtGetWindowText(arText,
  32)int num atoi(arText)numostrstream
  ss ltlt num ltlt '\0'CEdit pAns (CEdit )
  GetDlgItem(IDC_ANS)pAns-gtSetWindowText(s.str())
  pNum-gtSetWindowText("")pNum-gtSetFocus( )

15
CObject GetDlgItem(int resource_id)

• //declare CEdit (for rc EDITTEXT)
• CEdit pNum
• //casting result
• pNum (CEdit ) GetDlgItem(IDC_NUM)
• //Remember inheritance/polymorphism rules
• //All MFC Classes inherit from CObject
• pCEdit COBJECT //Not allowed
• pCObject CEDIT //Allowed base can point to
  subclass
• pCEdit (CEdit ) pCObject //Allowed
• //though we risk runtime error

16
The file dialogDlg.cpp (part 3)

• BEGIN_MESSAGE_MAP
• ( CDialogDlg, CDialog )
• ON_COMMAND( IDC_INC, OnInc )
• ON_COMMAND( IDC_DEC, OnDec )
• ON_COMMAND( IDC_QUIT, OnQuit )
• END_MESSAGE_MAP( )
• class CDialogApp public CWinApp
• public
• BOOL InitInstance()
• CDialogDlg myDialogWin
• myDialogWin.DoModal()
• //we wait for modal dialog
• return FALSE//NO WINDOW!
• //when dialog ends we are //ready to quit
• dialogApp

• Message map captures three events (clicking of
  three buttons)
• Overall application framework is different
• Creates a dialogApp object, makes it the
  applications main window
• DoModal() implies nothing else can be done until
  this window is closed
• Return FALSE indicating the program is now over
  (dialog window was closed)

17
Class Exercises

• The code for the dialog example is on the web
• Zip1 (Zip file)
• Complete the OnDec routine
• Add WS_SYSMENU to Style, what happens?
• Clean up organization of the dialog window
• Make fields just large enough to do the job
• Re-arrange the fields (all buttons on one line,
  etc)

18
Class Exercises

• Execute this program
• Zip2
• Add the stanza ES_PASSWORD at the end of the
  EDITTEXT field for IDC_NUM in the demo.rc file.
  How does this change things?
• EDITTEXT IDC_NUM, 10, 40, 50, 20,
• ES_NUMBER ES_PASSWORD

19
Dialog boxes in a bigger app

• Our last example used dialog boxes in a
  standalone environment
• Can include dialog boxes in larger applications
• Use to get information
• Use to display results
• Provides a simple interface for many actions
• Write a basic application
• Must enter a specific code to start the
  application
• Application just puts colored squares on window

20
File organization for sample app

• LoginWin.h header file for main window
• LoginWin.cpp code for main window routines
• Menu items (Login and Quit)
• Handle left mouse clicks
• dialogDlg.h header file for dialog box
• dialogDlg.cpp code for dialog box
• Validate the secret code that was entered
• identifiers.h global identifiers (mnemonics)
• demo.rc resource file (menu dialog box)

21
MessageMaps

• In the past
• Only one for the main window (instance of class
  derived from CFrameWnd).
• Only one for the main dialog(instance of class
  derived from Cdialog).
• This time, we will have 2 message maps in a
  single application
• One for the CFrameWnd
• One for the CDialog

22
2 Message Maps

• //Message Map for instance of class derived from
  CFrameWnd
• BEGIN_MESSAGE_MAP (CLoginWin, CFrameWnd)ON_COMMA
  ND(IDM_LOGIN, OnLogin)ON_COMMAND(IDM_QUIT,
  OnQuit)ON_WM_LBUTTONDOWN()
• END_MESSAGE_MAP()

• //Message Map for instance of class derived from
  CDialog
• BEGIN_MESSAGE_MAP ( CDialogDlg, CDialog )
• ON_COMMAND( IDC_OK, OnOK )
• ON_COMMAND( IDC_EXIT, OnExit )
• END_MESSAGE_MAP( )

23
Login.h DialogDlg.h files

• include ltafxwin.hgt
• include "identifiers.h"
• class CLoginWin
• public CFrameWnd
• public
• CLoginWin()
• afx_msg void OnLogin()
• afx_msg void OnQuit()
• .
• private
• int m_iFlag
• DECLARE_MESSAGE_MAP( )

• include ltafxwin.hgt
• include "identifiers.h"
• class CDialogDlg
• public CDialog
• public
• CDialogDlg()
• afx_msg void OnOK()
• afx_msg void OnExit()
• private
• DECLARE_MESSAGE_MAP()

24
Resource File (demo.rc)

• MyDialog DIALOG 20,20,100,100
• CAPTION "Login Process"
• LTEXT "Enter the secret number",
• IDC_STATIC, 10,10,50,10
• EDITTEXT IDC_NUM,
• 10, 40, 50, 20, ES_NUMBER
• DEFPUSHBUTTON "OK",
• IDC_OK, 10, 70, 50, 10
• DEFPUSHBUTTON "Exit Program",
• IDC_EXIT, 10, 85, 50, 10

• include ltafxres.hgt
• include "identifiers.h"
• MyMenus MENU
• POPUP "File"
• MENUITEM "Login", IDM_LOGIN
• MENUITEM "Quit", IDM_QUIT

25
LoginWin.cpp file (part 1)

• include LoginWin.h"
• include "dialogDlg.h"
• CLoginWinCLoginWin() m_iFlag(0)
• Create(NULL, "Login Example",WS_OVERLAPPEDWINDOW
  ,CRect(100,100,500,500),
• NULL,"MyMenus")
• afx_msg void CLoginWinOnQuit()
  SendMessage(WM_CLOSE)
• afx_msg void CLoginWinOnLogin()
• CDialogDlg loginBox
• if (loginBox.DoModal() IDOK) m_iFlag 1
• else SendMessage(WM_CLOSE)

• Standard include files constructor
• Exit routine when user selects Quit option from
  the menu
• Create a dialog window when user selects Login
  from menu. Check return code of dialog box to
  determine action.

26
LoginWin.cpp file (part 2)

• afx_msg void CLoginWinOnLButtonDown (UINT
  flags, CPoint point)
• if (m_iFlag) CClientDC dc(this) int
  size, r, g, b size rand()50 r
  rand()256 g rand()256 b
  rand()256 CBrush pBrush new CBrush()
  pBrush-gtCreateSolidBrush(RGB(r,g,b))
  dc.FillRect(CRect(point.x, point.y,
  point.xsize, point.ysize), pBrush)
• delete pBrush

• Routine draws randomly placed, randomly colored
  rectangles on the window (assuming the user
  entered a valid number)

27
LoginWin.cpp file (part 3)

• BEGIN_MESSAGE_MAP (CLoginWin, CFrameWnd)ON_COMMA
  ND(IDM_LOGIN, OnLogin)ON_COMMAND(IDM_QUIT,
  OnQuit)ON_WM_LBUTTONDOWN()
• END_MESSAGE_MAP()
• class CLoginApp public CWinApp
• public
• BOOL InitInstance() m_pMainWnd new
  CLoginWinm_pMainWnd-gtShowWindow
  (m_nCmdShow)m_pMainWnd-gtUpdateWindow()retu
  rn TRUE
• loginApp

• Message map for main window
• Must handle two menu options and left mouse
  button
• Standard application driver routine

28
DialogDlg.cpp (part 1)

• include "dialog.h"
• CDialogDlgCDialogDlg() CDialog("MyDialog")
  
• afx_msg void CDialogDlgOnExit()
  EndDialog(IDNO)
• BEGIN_MESSAGE_MAP
• ( CDialogDlg, CDialog )
• ON_COMMAND( IDC_OK, OnOK )
• ON_COMMAND( IDC_EXIT, OnExit )
• END_MESSAGE_MAP( )

• Standard Constructor
• If user selects exit, then return IDNO
• Message map handles two events (two buttons)

29
DialogDlg.cpp (part 2)

• Check number the user entered
• Get access to the number via GetDlgItem
• Move the number into an array and convert integer
• Check against the secret number
• Display results for user
• When this function (OnOK) ends, return from
  DoModal either IDOK or IDNO

• afx_msg void CDialogDlgOnOK() CEdit pNum
• (CEdit ) GetDlgItem(IDC_NUM)char
  arText32pNum-gtGetWindowText(arText, 32)int
  num atoi(arText)if (num 31415)
  MessageBox(Authorization Approved", "LoginResu
  lts") EndDialog(IDOK)else
  MessageBox("Authorization Failed", "Login
  Results") EndDialog(IDNO)

30
Class Exercises

• Execute this program
• Zip2
• Add the stanza ES_PASSWORD at the end of the
  EDITTEXT field for IDC_NUM in the demo.rc file.
  How does this change things?
• EDITTEXT IDC_NUM, 10, 40, 50, 20,
• ES_NUMBER ES_PASSWORD

31
DoDataExchange

• Purpose
• Allows us to automatically obtain information
  from Dialog controls without having to write the
  code ourselves
• Also allows us to validate data obtained from
  controls
• When is it called?
• The DoDataExchange function is automatically
  called by a function UpdateData(),
• UpdateData() is called by
• DoModal() to transfer information from your
  data members to dialog controls as you enter into
  dialog (overriden method)
• OnOK() to transfer information as you go out of
  dialog (method we created that will cause our
  return of DoModal)
• UpdateData() can also be called by you.
• DoDataExchange should not be called directly.
• However, if you want it to be called, you must
  override this method

32
DoDataExchange

• Override the DoDataExchange function
• Called base class function
• Map controls(Text Boxes) to member variables
  within the dialog class
• Takes a CDataExchange object that will contain
  information about the direction and validation of
  the data
• Lets look at our login example

33
DoDataExchange
Dialog Object
Actual Dialog
UpdateData() automatically by DoModal()
m_strName
UpdateData() explicitly by OnOK()
Dialog constructor
getName()
IDM_ID
m_strID
Main Window Object
34
LoginDlg.h

• class CLoginDlg public CDialog
• public
• CLoginDlg(CString)
• afx_msg void OnOK()
• CString getName(void)
• void DoDataExchange
• (CDataExchange pDX)
• private
• int m_iPassword
• CString m_strName
• DECLARE_MESSAGE_MAP()

• Constructor
• Initialize user ID
• OnOK
• Call UpdateData
• getName
• Returns the last user ID entered if password was
  correct
• DoDataExchange
• New method we must add

35
LoginDlg.cpp

• afx_msg void CLoginDlgOnOK()
• UpdateData() //makes a call to DoDataExchange
• //in this case our pass word is 50 for everyone
• if (m_iPassword 50)
• EndDialog(IDOK)
• else
• EndDialog(IDNO)
• //Accessor method
• CString CLoginDlggetName(void)
• return m_strName

36
LoginDlg.cpp

• void CLoginDlgDoDataExchange(CDataExchange
  pDX)
• //call to the base class DoDataExchange
• CDialogDoDataExchange(pDX)
• //methods to exchange data to and from
  CLoginDlg controls
• //and CLoginDlg data members
• DDX_Text(pDX, IDC_NUM, m_iPassword)
• DDX_Text(pDX, IDC_ID, m_strName)
• Questions you should ask
• (1) How does this take place?
• (2) What information does the variable pDX hold?
• (3) How do I know does the ID know which control
  it is paired with?
• (4) What on earth is a control?

37
Types you can transfer

• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, BYTE value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, short value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, int value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, UINT value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, long value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, DWORD value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, CString value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, float value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, double value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, COleCurrency value )
• void AFXAPI DDX_Text( CDataExchange pDX, int
  nIDC, COleDateTime value )

38
LoginWin.h

• class CLoginWin public CFrameWnd
• public
• CLoginWin()
• afx_msg void OnLButtonDown(UINT, CPoint p)
• afx_msg void OnLogin()
• afx_msg void OnQuit()
• afx_msg void OnOk()
• private
• BOOL m_bGo
• CString m_iID
• DECLARE_MESSAGE_MAP()

39
LoginWin.cpp

• afx_msg void CLoginWinOnLogin()
• //instantiate the Dialog
• CLoginDlg loginBox(m_iID)
• //display dialog box
• int ans loginBox.DoModal()
• // if DoModal returns IDOK, then the user
  entered a valid password
• if (ans IDOK)
• m_iIDloginBox.getName()
• m_bGo TRUE
• else
• m_bGo FALSE

40
LoginWin.cpp

• afx_msg void CLoginWinOnLButtonDown(UINT,
  CPoint p)
• if (m_bGo)
• MessageBox ("You get to see this cool message
  box!!!")
• else
• MessageBox("Shame on you for trying to see the
  really cool message box without permission")

41
DoDataExchange
Dialog Object
Actual Dialog
UpdateData() automatically by DoModal()
m_strName
UpdateData() explicitly by OnOK()
Dialog constructor
getName()
IDM_ID
m_strID
Main Window Object
42
Homework Exercises

• Create a text file (using a text editor) that
  contains ids and their respective numerical
  passwords
• A real app should encrypt this file
• Change this program to look up the id and
  password in a text file to check for valid login
• Try to add another text box to your resource file
  and try getting information from your window
  class to your dialog class then to your dialog
  text box.
• Using MS Dev Studio help files, look up
• DoDataExchange
• UpdateData