Programming Windows with MFC

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Programming Windows with MFC
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Chapter 3

• The Mouse and the Keyboard

3
Getting Input from the Mouse

• Client-area mouse messages
• Nonclient-area mouse messages
• Event
• The press or release of a mouse button
• The double click of a mouse button
• The movement of the mouse

4
Client-Area Mouse Messages
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Number of Mouse Buttons

• Int nButtonCount GetSystemMetrics(SM_CMOUSEBUT
  TONS)
• 0
• No mouse installed

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Message-Map Macros and Message Handlers for
Client-Area Mouse Messages
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Mouse Message Handlers Prototype

• afx_msg void OnMsgName
• (UINT nFlags, CPoint point)

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The nFlags Parameter
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The TicTac Application
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CWndMessageBox

• int MessageBox
• (LPCTSTR lpszText,
• LPCTSTR lpszCaption NULL,
• UINT nType MB_OK)

• lpszText
• the text in the body of the message box
• lpszCaption
• the caption for the message box's title bar
• nType
• one or more bit flags defining the message box's
  style

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Message Box Types
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Nonclient-Area Mouse Messages
13
Message-Map Macros and Message Handlers for
Nonclient-Area Mouse Messages
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Message Handlers for Nonclient-area Messages

• afx_msg void OnMsgName
• (UINT nHitTest, CPoint point)
• point.x, point.y
• screen coordination
• nHitTest
• where the event occurred in the windows
  nonclient area

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Commonly Used Hit-Test Codes
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The WM_NCHITTEST Message

• Before a window receives a client-area or
  nonclient-area mouse message
• The cursors screen coordinates

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The WM_MOUSELEAVE and WM_MOUSEOVER Messages

• WM_MOUSELEAVE
• The cursor leaves a window
• WM_MOUSEOVER
• The cursor hovers over a window

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TrackMouseEvent

• To determine when the mouse cursor leaves or
  hovers
• Accept a pointer parameter
• TRACKMOUSEEVENT structure
• Winuser.h

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The Mouse Wheel

• Message
• WM_MOUSEWHEEL
• Message-Map Macro
• ON_WM_MOUSEWHEEL
• Handling Function
• OnMouseWheel

• BOOL OnMouseWheel (UINT nFlags,
• short zDelta, CPoint point)
• zDelta
• the distance the wheel was rotated

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Capturing the Mouse

• CWndSetCapture
• ReleaseCapture

// In CMainWindow's message map
ON_WM_LBUTTONDOWN () ON_WM_LBUTTONUP () void
CMainWindowOnLButtonDown (UINT nFlags, CPoint
point) SetCapture () void
CMainWindowOnLButtonUp (UINT nFlags, CPoint
point) ReleaseCapture ()
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Mouse Capturing in Action
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Getting Input from the Keyboard

• WM_KEYDOWN
• WM_KEYUP
• WM_CHAR

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The Input Focus

• Keyboard messages
• Directed to the window with the input focus
• No more than one window has the input focus
• WM_SETFOCUS/ WM_KILLFOCUS

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Keystorke Messages

• WM_KEYDOWN
• WM_KEYUP
• WM_SYSKEYDOWN
• WM_SYSKEYUP
• Alt and F10 key

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Keystorke Message Handlers

• afx_msg void OnMsgName
• (UINT nChar, UINT nRepCnt, UINT nflags)

• nChar
• the virtual key code of the key that was pressed
  or released.
• nRepCnt
• the repeat countthe number of keystrokes
  encoded in the message
• nFlags
• the key's scan code and zero or more of the bit
  flags

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Virtual Key Codes

• Windows identifies keys with the virtual key
  codes
• Winuser.h
• the letters and the numerals ANSI codes
• ? WM_CHAR messages better way

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Shift States and Toggles

• GetKeyState(VK_SHIFT)
• -returns a negative value if the Shift key
• GetKeyState(VK_CONTROL)
• -return a negative value if the Ctrl key is held
  down
• Ctrl-Left
• if ((nCharVK_LEFT) GetKeyState(VK_CONTROL)
  lt0))

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Character Messages

• ON_WM_CHAR ()
• void CMainWindowOnChar (UINT nChar, UINT
  nRepCnt, UINT nFlags)
• if ( ((nChargt_T(A))(nCharlt_T(Z)))
• ((nChargt_T(a))(nCharlt_T (z))))
• // Display the character
• else if (nChar VK_RETURN)
• // Process the Enter key

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The Caret

• The point where the next character will be
  inserted
• Per-thread resource

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CWnd Caret Handling Functions
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Simple Rules

• Create and destroy
• CreateCaret, CreateSolidCaret, CreateGrayCaret
• DestroyCaret
• Show and hide
• ShowCaret
• HideCaret
• Outside an OnPaint handler
• Should hide the caret to avoid corrupting
• Moving
• SetCaretPos
• GetCaretPos

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The Caret

• void CMainWindowOnSetFocus (CWnd pWnd)
• CreateSolidCaret (2, m_cyChar)
• SetCaretPos (m_ptCaretPos)
• ShowCaret ()
• void CMainWindowOnKillFocus (CWnd pWnd)
• HideCaret ()
• m_ptCaretPos GetCaretPos ()
• DestroyCaret ()

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The VisualKB Application
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VisualKB.cpp

• CMainWindowCMainWindow ()
• // Load the arrow cursor
• // and the I-beam cursor
• // and save their handles.
• m_hCursorArrow AfxGetApp()-gt
• LoadStandardCursor (IDC_ARROW)
• m_hCursorIBeam AfxGetApp ()-gt
• LoadStandardCursor (IDC_IBEAM)

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VisualKB.cpp

• void CMainWindowOnSetFocus (CWnd pWnd)
• // Show the caret when the VisualKB
• // window receives the input focus.
• CreateSolidCaret (max (2, GetSystemMetrics
  (SM_CXBORDER)), m_cyChar)
• SetCaretPos (m_ptCaretPos)
• ShowCaret ()
• void CMainWindowOnKillFocus (CWnd pWnd)
• // Hide the caret when the VisualKB
• // window loses the input focus.
• HideCaret ()
• m_ptCaretPos GetCaretPos ()
• DestroyCaret ()

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VisualKB.cpp

• void CMainWindowOnKeyDown (UINT nChar, UINT
  nRepCnt, UINT nFlags)
• switch (nChar)
• case VK_LEFT
• m_nTextPos-- PositionCaret ()
• break
• case VK_RIGHT
• m_nTextPos PositionCaret ()
• break
• case VK_HOME
• m_nTextPos 0 PositionCaret ()
• break
• case VK_END
• m_nTextPos m_strInputText.GetLength ()
• PositionCaret ()
• break

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VisualKB.cpp

• void CMainWindowOnChar (UINT nChar, UINT
  nRepCnt, UINT nFlags)
• ShowMessage (_T ("WM_CHAR"), nChar, nRepCnt,
  nFlags)
• CClientDC dc (this)
• switch (nChar)
• case VK_ESCAPE
• case VK_RETURN
• case VK_BACK
• default
• if ((nChar gt 0) (nChar lt 31)) return
• if (m_nTextPos m_strInputText.GetLength ())
• m_strInputText nChar
• m_nTextPos
• else
• m_strInputText.SetAt (m_nTextPos, nChar)
• // Update the contents of the text box.
• HideCaret ()

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