How To Add Keyboard Functionality to MDI form Scrollbars (244312)

MORE INFORMATION

• GetWindow to obtain the Window Handle of the MDI form's client window so that it can be sent a message telling it to scroll.
• SendMessage to actually send the message.

Step-by-Step Example:

1. Start a new Standard EXE project. Form1 is created by default. Set the MDIChild property of Form1 to True.
2. Add the following code to the General Declarations section of Form1:

   Option Explicit
   
   ' The child window in the client area generates the scrollbars, sends a
   ' message to the MDI client to scroll to the bottom of the window, and
   ' traps the key pressed.
   
   Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
      processKey KeyCode
   End Sub
   
   Private Sub Form_Load()
      Move 2500, 2500
   End Sub
   					

3. On the Project menu, click Add MDI Form to add an MDI form to the project.
4. On the Project menu click Add Module to add a BAS module to the project.
5. Add the following code to the General Declarations section of Module1:

   Option Explicit
   
   Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
         (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, _
          lParam As Any) As Long
   
   Declare Function GetWindow Lib "user32" (ByVal hwnd As Long, _
          ByVal wCmd As Long) As Long
   
   Public Const SB_BOTTOM = 7
   Public Const SB_LEFT = 6
   Public Const SB_LINEDOWN = 1
   Public Const SB_LINELEFT = 0
   Public Const SB_LINERIGHT = 1
   Public Const SB_LINEUP = 0
   Public Const SB_PAGEDOWN = 3
   Public Const SB_PAGELEFT = 2
   Public Const SB_PAGERIGHT = 3
   Public Const SB_PAGEUP = 2
   Public Const SB_RIGHT = 7
   Public Const SB_THUMBPOSITION = 4
   Public Const SB_THUMBTRACK = 5
   Public Const SB_TOP = 6
   Public Const SB_ENDSCROLL = 8
   
   Public Const WM_HSCROLL = &H114
   Public Const WM_VSCROLL = &H115
   
   Public Const GW_CHILD = 5
   
   Public Sub processKey(KeyCode As Integer)
      Dim mdiclientwin As Long
   
      Select Case KeyCode
       Case vbKeyDown
         mdiclientwin = GetWindow(MDIForm1.hwnd, GW_CHILD)
         SendMessage mdiclientwin, WM_VSCROLL, SB_LINEDOWN, ByVal 0&
   
       Case vbKeyUp
         mdiclientwin = GetWindow(MDIForm1.hwnd, GW_CHILD)
         SendMessage mdiclientwin, WM_VSCROLL, SB_LINEUP, ByVal 0&
   
       Case vbKeyPageUp
         mdiclientwin = GetWindow(MDIForm1.hwnd, GW_CHILD)
         SendMessage mdiclientwin, WM_VSCROLL, SB_PAGEUP, ByVal 0&
   
       Case vbKeyPageDown
         mdiclientwin = GetWindow(MDIForm1.hwnd, GW_CHILD)
         SendMessage mdiclientwin, WM_VSCROLL, SB_PAGEDOWN, ByVal 0&
   
       Case vbKeyRight
         mdiclientwin = GetWindow(MDIForm1.hwnd, GW_CHILD)
         SendMessage mdiclientwin, WM_HSCROLL, SB_LINERIGHT, ByVal 0&
   
       Case vbKeyLeft
         mdiclientwin = GetWindow(MDIForm1.hwnd, GW_CHILD)
         SendMessage mdiclientwin, WM_HSCROLL, SB_LINELEFT, ByVal 0&
   
      End Select
   
   End Sub
   					

6. Run the project. The MDIForm scrolls down to the end. The UP, DOWN, PAGEUP, PAGEDOWN, LEFT and RIGHT keys are now functional.