Chapter 12 Mouse and Keyboard

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Chapter 12 Mouse and Keyboard (Main Page)

12.1 MousePointer constants.

12.2 Demonstrating the MousePointer property. 12.3 Demonstrating mouse events.

12.4 Mouse button constants.

12.5 Determining which mouse button was pressed. 12.6 Constants associated with variable Shift .

12.7 Determining which combination of Shift , Ctrl or Alt

was pressed.

12.8 Button and Shift bit fields. 12.9 Constants used with method Drag. 12.10 Demonstrating manual drag-and-drop. 12.11 Demonstrating automatic drag-and-drop. 12.12 Common key event constants.

12.13 Demonstrating key events.

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Constant Value Cursor Description

vbDefault 0 Default cursor. Describes the default cursor

for a form or control.

vbArrow 1 Arrow cursor. Typically used to indicate

that selections can be made.

vbCrosshair 2 Crosshair cursor. Typically used to indicate

precision.

vbIbeam 3 I-beam cursor. Typically used to indicate

that text can be input.

vbSizePointer 5 Sizing cursor. Typically used to indicate

that resizing is allowed in all directions.

vbSizeNESW 6 North-East-South-West cursor. Typically

used to indicate that resizing is allowed in this direction.

vbSizeNS 7 North-South cursor. Typically used to

indi-cate that resizing is allowed in this direc-tion.

vbSizeNWSE 8 North-West-South-East cursor. Typically

used to indicate that resizing is allowed in this direction.

vbSizeWE 9 West-East cursor. Typically used to indicate

that resizing is allowed in this direction.

vbUpArrow 10 Up arrow.

vbHourglass 11 Hourglass cursor. Typically used to indicate

that the program is busy performing some task.

vbNoDrop 12 No-drop cursor. Typically used to indicate

that a drop operation is not permitted. vbArrowHourglass 13 Arrow hourglass cursor. Typically used to

indicate that the program is busy perform-ing some task and that the user can still make selections with the mouse pointer. vbArrowQuestion 14 Arrow question mark cursor. Typically used

to indicate help is available for a feature.

vbSizeAll 15 Size all directions cursor.

vbCustom 99 Custom cursor. Typically used to display a

non-Visual Basic cursor).

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1 ' Fig. 12.2

2 ' Changing the mouse pointer

3 Option Explicit ' General declaration 4

5 Private Sub optCursor_Click(Index As Integer) 6 MousePointer = Index

7 End Sub

Fig. 12.2 Demonstrating the

MousePointer

property.

1 ' Fig. 12.3

2 ' Demonstrating mouse events

5 Private Sub Form_Load()

6 Call Randomize ' Randomize

7 End Sub

8

9 Private Sub cmdClear_Click() 10 Call Cls ' Clear Form

11 End Sub

12

13 Private Sub Form_Click()

14

Initial GUI at execution.

GUI after user selects arrowquestion.

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19 Case 2 20 ForeColor = vbMagenta 21 Case 3 22 ForeColor = vbRed 23 Case 4 24 ForeColor = vbBlue 25 End Select 26 27 End Sub 28

29 Private Sub Form_DblClick() 30

31 ' Randomly set Form BackColor 32 Select Case (1 + Int(Rnd() * 4)) 33 Case 1

34 BackColor = vbWhite 35 Case 2

36 BackColor = vbYellow

Fig. 12.3 Demonstrating mouse events (part 1 of 3). 37 Case 3 38 BackColor = vbGreen 39 Case 4 40 BackColor = vbCyan 41 End Select 42

43 ' Change chkMove BackColor to Form's BackColor 44 chkMove.BackColor = BackColor

45 End Sub

46

47 Private Sub Form_MouseDown(Button As Integer, _

48 Shift As Integer, X As Single, _ 49 Y As Single)

50

51 CurrentX = X ' Set x coordinate 52 CurrentY = Y ' Set y coordinate 53 Print "MouseDown"

54 End Sub

55

56 Private Sub Form_MouseUp(Button As Integer, _

57 Shift As Integer, X As Single, _ 58 Y As Single) 59 60 ' Reverse coordinates 61 CurrentX = Y 62 CurrentY = X 63 Print "MouseUp" 64 End Sub 65

66 Private Sub Form_MouseMove(Button As Integer, _

69

70 ' If checked enable printing operations 71 If chkMove.Value = 1 Then 72 CurrentX = X 73 CurrentY = Y 74 Print "MouseMove" 75 End If 76

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77 End Sub

Fig. 12.3 Demonstrating mouse events (part 2 of 3).

Fig. 12.3 Demonstrating mouse events (part 3 of 3).

GUI after user has clicked mouse in sev-eral different locations.

GUI after user has pressed Clear and then clicked EnableMouseMove and moved the mouse.

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.

1 ' Fig. 12.5 2 ' Mouse buttons

6 imgImage.Picture = LoadPicture("d:\images\ch12\mouse0.gif")

7 End Sub

8

12 Call SetPressedImage(Button)

13 End Sub

Fig. 12.5 Determining which mouse button was pressed (part 1 of 3). 14

15 Private Sub Form_MouseUp(Button As Integer, Shift As Integer, _ 16 X As Single, Y As Single)

17 18 Call SetReleasedImage

19 End Sub

20

21 Private Sub imgImage_MouseDown(Button As Integer, _ 22 Shift As Integer, _ 23 X As Single, Y As Single) 24 Call SetPressedImage(Button)

25 End Sub

26

27 Private Sub imgImage_MouseUp(Button As Integer, _ 28 Shift As Integer, _ 29 X As Single, Y As Single) 30 Call SetReleasedImage

31 End Sub

32

33 Private Sub SetPressedImage(b As Integer)

34 imgImage.Picture = LoadPicture("d:\images\ch12\mouse" & _ 35 b & ".gif")

36 End Sub

37

38 Private Sub SetReleasedImage()

40 End Sub

Constant Value Description

vbRightButton 1 The right mouse button.

vbLeftButton 2 The left mouse button.

vbMiddleButton 4 The center mouse button.

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Fig. 12.5 Determining which mouse button was pressed (part 2 of 3).

Fig. 12.5 Determining which mouse button was pressed (part 3 of 3).

vbShiftMask 1 Status of the Shift key.

vbCtrlMask 2 Status of the Ctrl key.

vbAltMask 4 Status of the Alt key.

Fig. 12.6 Constants associated with variable

Shift

.

GUI after user presses the left mouse button.

GUI after the user presses the right mouse button.

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1 ' Fig. 12.7 2 ' Mouse buttons

7 End Sub

8

10 Shift As Integer, x As Single, _ 11 Y As Single)

12

13 Dim a As Integer, c As Integer, s As Integer

14

15 a = Shift And vbAltMask ' Mask Alt bit 16 c = Shift And vbCtrlMask ' Mask Ctrl bit 17 s = Shift And vbShiftMask ' Mask Shift bit

18 19 If (a <> 0) Then ' Alt 20 lblKeys(a).BackColor = vbGreen 21 End If 22 23 If (s <> 0) Then ' Shift 24 lblKeys(s).BackColor = vbGreen 25 End If 26 27 If (c <> 0) Then ' Ctrl 28 lblKeys(c).BackColor = vbGreen 29 End If 30

31 imgImage.Picture = LoadPicture("d:\images\ch12\mouse" & _ 32 Button & ".gif")

33 End Sub

34

35 Private Sub Form_MouseUp(Button As Integer, Shift As Integer, _ 36 x As Single, Y As Single)

37

38 ' Change Label BackColors to Form's BackColor 39 lblKeys(1).BackColor = BackColor

40 lblKeys(2).BackColor = BackColor 41 lblKeys(4).BackColor = BackColor

42

43 ' Load mouse image of unpressed buttons

45 End Sub

Fig. 12.7 Determining which combination of Shift, Ctrl or Alt was pressed (part 1 of 2).

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Fig. 12.7 Determining which combination of Shift, Ctrl or Alt was pressed (part 2 of 2).

GUI after user presses the right mouse button while Ctrl is held down.

GUI after user presses the left mouse but-ton while Shift is held down.

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Fig. 12.8

Button

and

Shift

bit fields.

1 ' Fig. 12.10

2 ' Demonstrating manual drag-and-drop

3 Option Explicit ' General declaration 4 Dim mCurrentCell As Integer ' General declaration 5

6 Private Sub Form_Load() 7 Dim x As Integer 8

9 mCurrentCell = 2 ' Lower left corner

10

11 For x = 1 To 64

12

13 If x Mod 2 Then

14 picSquare(x).Picture = LoadPicture("d:\images\ch12\" & _ 15 "w_marble.jpg") 16 Else

17 picSquare(x).Picture = LoadPicture("d:\images\ch12\" & _ 18 "b_marble.jpg") 19 End If

20

21 Next x

vbCancelDrag 0 Cancels drag-and-drop operation. Event

proce-dure DragDrop is not called.

vbBeginDrag 1 Begins drag-and-drop operation. Event

proce-dure DragDrop is called.

vbEndDrag 2 Terminates drag-and-drop operation. Event

procedure DragDrop is called. Fig. 12.9 Constants used with method

Drag

.

... _M _R _L

Least significant bits Most significant bits

Button bit field

... _A _C _S

Least significant bits Shift bit field

Key M R L A C S

Bit representing middle mouse button Bit representing right mouse button Bit representing left mouse button Bit representing Alt key

Bit representing Ctrl key Bit representing Shift key Most significant bits

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24 "b_knight.jpg")

25 End Sub

26

27 Private Sub picSquare_MouseDown(Index As Integer, _ 28 Button As Integer, _ 29 Shift As Integer, _ 30 x As Single, Y As Single)

31

32 ' If on the PictureBox displaying the image 33 ' then enable dragging.

34 If Index = mCurrentCell Then

35 picSquare(mCurrentCell).Drag vbBeginDrag

36 End If

37

38 End Sub

Fig. 12.10 Demonstrating manual drag-and-drop (part 1 of 4). 39

40 Private Sub picSquare_DragOver(Index As Integer, _ 41 Source As Control, _

42 x As Single, Y As Single, _ 43 State As Integer)

44

45 ' Display icon while dragging over a PictureBox

46 picSquare(Index).DragIcon = LoadPicture("d:\images" & _ 47 "\ch12\knight.cur")

48 End Sub

49

50 Private Sub picSquare_DragDrop(Index As Integer, _ 51 Source As Control, _ 52 x As Single, Y As Single) 53

54 ' Draw image at new position 55 If Index Mod 2 Then

56 picSquare(Index).Picture = LoadPicture("d:\images\ch" & _ 57 "12\w_knight.jpg")

58 Else

59 picSquare(Index).Picture = LoadPicture("d:\images\ch" & _ 60 "12\b_knight.jpg")

61 End If

62

63 ' Remove last image only if the drop is at 64 ' a different location.

65 If mCurrentCell <> Index Then 66 If Source.Index Mod 2 Then

67 Source.Picture = LoadPicture("d:\images\ch12" & _ 68 "\w_marble.jpg") 69 Else

70 Source.Picture = LoadPicture("d:\images\ch12" & _ 71 "\b_marble.jpg") 72 End If

73

74 End If

75

76 ' Update current image position 77 mCurrentCell = Index

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Fig. 12.10 Demonstrating manual drag-and-drop (part 3 of 4).

Fig. 12.10 Demonstrating manual drag-and-drop (part 4 of 4).

GUI when the user is performing a drag operation. Note the change in the mouse pointer. Since a drop has not occurred, the original image is still visible.

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1 ' Fig. 12.11

2 ' Demonstrating Automatic drag-and-drop 3 Option Explicit ' General declaration 4

5 Private Sub Form_Load() 6 Dim a As Integer 7

8 ' Set all DragMode properties to Automatic 9 For a = cmdButton.LBound To cmdButton.UBound 10 cmdButton(a).DragMode = 1 ' Automatic

11 Next a

12

13 End Sub

14

15 Private Sub Form_DragDrop(Source As Control, X As Single, _ 16 Y As Single)

17

18 Dim w As Integer, h As Integer

19

20 ' Center control on mouse pointer 21 w = X - Source.Width / 2

22 h = Y - Source.Height / 2

23

24 ' Move button to location where drop occurs 25 Call Source.Move(w, h)

26 End Sub

Fig. 12.11 Demonstrating automatic drag-and-drop (part 1 of 2).

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Fig. 12.11 Demonstrating automatic drag-and-drop (part 2 of 2).

Constant ASCII value(s) Description

vbKeyA - vbKeyZ 65-90 A key through Z key.

vbKeyNumpad0 - vbKeyNumpad9

96-105 Keypad numeric keys 0 through 9.

vbKey0 - vbKey9 48-57 Numeric keys 0 through 9.

vbKeyF1 - vbKeyF16 112-127 Function keys F1 through F16.

vbKeyDecimal 110 Decimal point key (Period key).

vbKeyBack 8 Backspace key.

vbKeyTab 9 Tab key.

vbKeyReturn 13 Return key (or Enter key).

vbKeyShift 16 Shift key.

vbKeyControl 17 Ctrl key.

vbKeyCapital 20 Caps Lock key.

vbKeyEscape 27 Escape key.

vbKeySpace 32 Space bar.

vbKeyInsert 45 Insert key.

GUI after user has dragged and dropped three buttons. A drag-and-drop operation is occurring on a button.

GUI after user has dragged and dropped all buttons.

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1 ' Fig. 12.13

2 ' Demonstrating KeyDown, KeyUp, and KeyPress

3 Option Explicit ' General declaration 4 Dim mTitleString As String ' General declaration 5

7 ' Store Caption value for use in KeyPress 8 mTitleString = Caption & Space$(5)

9 End Sub

10

11 Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)

12

13 ' Determine which, if any, of the Shift, Ctrl, 14 ' or Alt keys is pressed

15 Select Case Shift

16 Case vbShiftMask ' Shift 17 ForeColor = vbYellow

18 Case vbAltMask ' Alt 19 ForeColor = vbRed

20 Case vbCtrlMask ' Ctrl 21 ForeColor = vbGreen

22 Case vbShiftMask + vbAltMask ' Shift + Alt 23 ForeColor = vbBlue

Fig. 12.13 Demonstrating key events (part 1 of 3).

24 Case vbShiftMask + vbCtrlMask ' Shift + Ctrl 25 ForeColor = vbMagenta

26 Case vbAltMask + vbCtrlMask ' Alt + Ctrl 27 ForeColor = vbCyan

28 Case vbAltMask + vbCtrlMask + vbShiftMask ' All three 29 Call Cls

30 End Select

31

32 ' Test for letter key

33 If KeyCode >= vbKeyA And KeyCode <= vbKeyZ Then 34 Print Chr$(KeyCode); ' Print the character 35 ElseIf KeyCode = vbKeyReturn Then ' Return key 36 Print ' Print on next line

37 End If

38

39 End Sub

40

41 Private Sub Form_KeyPress(KeyAscii As Integer) 42 ' Update title bar to display the key pressed 43 Caption = mTitleString & "(" & Chr$(KeyAscii) & ")"

44 End Sub

45

46 Private Sub Form_KeyUp(KeyCode As Integer, Shift As Integer) 47 ' When key is released, change ForeColor to black

vbKeyDelete 46 Delete key.

Constant ASCII value(s) Description

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GUI after user has typed text.

GUI after user has held Shift, Ctrl and Alt

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1 ' Fig. 12.14

2 ' Demonstrating the KeyPreview property.

5 Private Sub Form_Load() 6 Call Randomize

7

8 ' Allow Form to get key events first 9 KeyPreview = True

10 End Sub

11

12 Private Sub Form_KeyPress(KeyAscii As Integer)

13

14 ' Only allow numeric keys

15 If KeyAscii >= vbKey0 And KeyAscii <= vbKey9 Then 16 txtInput.Text = txtInput.Text & Chr$(KeyAscii)

17 End If

18

19 End Sub

20

21 Private Sub txtInput_KeyPress(KeyAscii As Integer) 22 KeyAscii = 0 ' Disable event handling

23 End Sub

24

25 Private Sub txtInput_KeyUp(KeyCode As Integer, Shift As Integer)

26

27 Select Case Int(Rnd() * 3) 28 Case 0 29 txtInput.BackColor = vbYellow 30 Case 1 31 txtInput.BackColor = vbCyan 32 Case 2 33 txtInput.BackColor = vbRed 34 End Select 35 36 End Sub

Fig. 12.14 Demonstrating property

KeyPreview

.

GUI after user enters a series of numbers.