Chapter 7Controls

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Introduction (1/4)• Control– Special kind of window – Designed to convey information to the user or to

acquire input– Reduce the tedium of windows programming and

promote a consistent user interface

Introduction• Example: push button control– Don’t need to draw a rectangle on the screen– Don’t need to process the mouse message

– Everything is almost done. Just add it!!!– Notification will be given when clicked.

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Introduction• MFC Classic Controls

Control Type WNDCLASS MFC ClassButtons "BUTTON" CButtonList boxes "LISTBOX" CListBoxEdit controls "EDIT" CEditCombo boxes "COMBOBOX" CComboBoxScroll bars "SCROLLBAR" CScrollBarStatic controls "STATIC" CStatic

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How it works• Controls and its parent window

– Notification Message• When its states change• Example) A button is being clicked

– Member Functions of the control• Change or get the state of the control. • Example) Change a button to be inactive

Controls(Child Window) Parent Window

① Notification

② function call

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MFC Class Hierarchy

A control is also a window!

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Button Control (1/8)• Various kinds of the Button Control

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Button Control• Two ways of creating a control

① Create one by hand (coding)

② Create one using the dialog edit window

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Button control by hand• Procedure:– 1. Adding CButton object as a member variable

– 2. Call CButton‘s Create(..) member function to create• Ex) Call it inside CChildView::OnCreate() function

m_button.Create( _T(“Push Here!“), WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON, CRect(100, 100, 200, 130), this, 101);

In CChildView class : ChildView.h

CButton m_button; // adding CButton object

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Button Control• CButton::Create() member function

– Caption : title string– Style : Style as a button and as a window

Ex) WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON

– Rect : position and size– pParentWnd : pointer to parent window– UINT nID : ID of the control (ex, 101, 102…)

BOOL CButton::Create (Caption, Style, rect, pParentWindow,

ID) ;

Windows style CButton style

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Styles of CButtonStyle DescriptionBS_PUSHBUTTON Creates a standard push button controlBS_DEFPUSHBUTTON Creates a default push button; used in dialog boxes

to identify the push button that's clicked if Enter is pressed

BS_CHECKBOX Creates a check box controlBS_AUTOCHECKBOX Creates a check box control that checks and

unchecks itself when clicked

BS_3STATE Creates a three-state check box controlBS_AUTO3STATE Creates a three-state check box control that cycles

through three states—checked, unchecked, and indeterminate—when clicked

BS_RADIOBUTTON Creates a radio button controlBS_AUTORADIOBUTTON

Creates a radio button control that, when clicked, checks itself and unchecks other radio buttons in the group

BS_GROUPBOX Creates a group box control

Additional Styles of CButtonStyle DescriptionBS_LEFTTEXT Moves the text accompanying a radio button or

check box control from the button's right (the default) to its left

BS_RIGHTBUTTON Same as BS_LEFTTEXTBS_LEFT Left justifies the button text in the control rectangleBS_CENTER Centers the button text in the control rectangleBS_RIGHT Right justifies the button text in the control rectangleBS_TOP Positions the button text at the top of the control

rectangleBS_VCENTER Positions the button text in the center of the control

rectangle verticallyBS_BOTTOM Positions the button text at the bottom of the control

rectangleBS_MULTILINE Allows text too long to fit on one line to be broken

into two or more lines

When clicking a button• Windows sends Notification Message

• Message Handler for the notification

1. Add message handler MACRO in massage map

2. Implement the message handler function

Controls(Child Window) Parent Window

Notification

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Adding Message Handler• 1. Add message handler MACRO in massage map

• 2. Implement the message handler function

ON_BN_CLICKED( ID, function name)

Ex) ON_BN_CLICKED( 101, OnButtonClicked) // in massage map

void CChildView::OnButtonClicked( ) // message handler{ AfxMessageBox(_T(“Button is clicked."));}

When changing state of CButton• Call member functions of CButton

– Change(Set) the current state– Acquire(Get) the current state

Controls(Child Window) Parent Window

function call

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Member functions of CButton1. Change the state of the check box

2. Check the state of the check box

m_button.SetCheck(BST_CHECKED);m_button.SetCheck(BST_UNCHECKED);

if ( m_button.GetCheck() == BST_CHECKED ) AfxMessageBox(_T(“Button is checked”));

Radio button • Only one at a time is checked.• They are connected.

• You can make it manually// Radio Button Manual Creation Examplevoid CChildView::OnRadioButton1Clicked () {

m_wndRadioButton1.SetCheck (BST_CHECKED); m_wndRadioButton2.SetCheck

(BST_UNCHECKED); m_wndRadioButton3.SetCheck

(BST_UNCHECKED); }

Auto Radio Button• WS_GROUP connects Radio buttonsm_RadioButton1.Create (_T ("COM1"), WS_CHILD ¦ WS_VISIBLE ¦ WS_GROUP ¦ BS_AUTORADIOBUTTON, rect1, this, IDC_COM1); m_RadioButton2.Create (_T ("COM2"), WS_CHILD ¦ WS_VISIBLE ¦ BS_AUTORADIOBUTTON, rect2, this, IDC_COM2); m_RadioButton3.Create (_T ("COM3"), WS_CHILD ¦ WS_VISIBLE ¦ BS_AUTORADIOBUTTON, rect3, this, IDC_COM3);

m_RadioButton4.Create (_T (“Student1"), WS_CHILD ¦ WS_VISIBLE ¦ WS_GROUP ¦ BS_AUTORADIOBUTTON, rect4, this, IDC_COM1); m_RadioButton5.Create (_T (" Student2"), WS_CHILD ¦ WS_VISIBLE ¦ BS_AUTORADIOBUTTON, rect5, this, IDC_COM2);

Coding Practice• Creating the following program using

CButtons

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Button Control• Two ways of creating a control

① Create one by hand (coding)

② Create one using the dialog edit window

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Dialog Edit Window• Resource View -> Edit “Dialog”– Creating and designing controls using toolbox

• Control variables– Each control can be connected with a control

variable. – Call the member functions of the control variable

to change/get the state of the control

Coding Practice• Make a new project of Dialog Based

Application• Design the dialog using Dialog Edit Window

and tool box

Adding Event Message Handler • Use Properties window to add message

handlers

Adding Event Message Handler Alternative way• In dialog edit window, mouse right button

click on a control Add Event Handler

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Creating control variables• mouse right button click on a control

Add variables

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Creating control variables• Added things:

// In Header fileclass CTestDlg::public CDiglog{ ...

CButton m_button;}

// In Source filevoid CTestDlg::DoDataExchange(CDataExchange* pDX){

CFormView::DoDataExchange(pDX);//{{AFX_DATA_MAP(CExButtonView)DDX_Control(pDX, IDC_BUTTON1, m_button);//}}AFX_DATA_MAP

}

Coding Practice• Creating the following program using Dialog

based application template• When pushing the button, show the

information