I read tip number 489 on how to resize the form, and I have a few questions about it

[dimava]

here is the link:
http://www.vb-world.net/tips/tip489.html


now what I wanted to know was, how can I stop my form from going smaller then what I set it to in diesign time, and how can I make it enlarge it evenly, like so they cant make it into a rectange becuase my form is squarem, so I dont want my form to go from:

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to:




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[HaxSoft]

This takes care of the minimum width / height:

Public Sub Form_Resize()

  If Me.Width < minWid Then Me.Width = minWid
  If Me.Height < minHgt Then Me.Height = minHgt

End Sub

Where minHgt is the minimum height and minWid is the minimum width.

Now there is a factor, such as Form.Height / Form.Width that you can add to the Form_Resize event to make sure it always has a fixed Aspect Ratio, as graphics artists call it.

[Edited by HaxSoft on 08-25-2000 at 06:32 PM]

Private Sub Form_Resize()
    Me.Height = Me.Width
End Sub

[Joacim Andersson]

Changing the Width and Height properties in the Resize event is the simple way of doing it. It does cause some flickering and it doesn't keep your form in a square form when it's maximized.

To manage this you have to resort to API and sub-classing your form. If you haven't done any subclassing before then here's a bit of an advice: Do NOT use the End statement in your code and do NOT use the End button on the VB toolbar.
Unload the form with the Unload statement or use the close button of the form. Otherwise you will get a GPF.

Now that this have been mentioned lets go over to the code.
Add the following to a BAS code module:

Private Declare Function SetWindowLong _
 Lib "user32" Alias "SetWindowLongA" ( _
 ByVal hwnd As Long, _
 ByVal nIndex As Long, _
 ByVal dwNewLong As Long) As Long

Private Declare Function CallWindowProc _
 Lib "user32" Alias "CallWindowProcA" ( _
 ByVal lpPrevWndFunc As Long, _
 ByVal hwnd As Long, _
 ByVal Msg As Long, _
 ByVal wParam As Long, _
 ByVal lParam As Long) As Long

Private Declare Sub CopyMemory _
 Lib "kernel32" Alias "RtlMoveMemory" ( _
 Destination As Any, _
 Source As Any, _
 ByVal Length As Long)

Private Const GWL_WNDPROC = (-4)
Private Const WM_GETMINMAXINFO = &H24
Private Const WM_SIZING = &H214

Private Type RECT
    Left As Long
    Top As Long
    Right As Long
    Bottom As Long
End Type

Private Type POINTAPI
    x As Long
    y As Long
End Type

Private Type MINMAXINFO
    ptReserved As POINTAPI
    ptMaxSize As POINTAPI
    ptMaxPosition As POINTAPI
    ptMinTrackSize As POINTAPI
    ptMaxTrackSize As POINTAPI
End Type

Private lngHwnd As Long
Private lngPrevWndProc As Long

Public Sub HookForm(frm As Form)
    lngHwnd = frm.hwnd
    lngPrevWndProc = SetWindowLong(lngHwnd, GWL_WNDPROC, AddressOf WinProc)
End Sub

Public Sub UnhookForm()
    SetWindowLong lngHwnd, GWL_WNDPROC, lngPrevWndProc
End Sub

Public Function WinProc( _
 ByVal hw As Long, _
 ByVal uMsg As Long, _
 ByVal wParam As Long, _
 ByVal lParam As Long) As Long
    Select Case uMsg
        Case WM_GETMINMAXINFO
            Dim inf As MINMAXINFO
            CopyMemory inf, ByVal lParam, Len(inf)
            inf.ptMaxSize.x = Screen.Height \ Screen.TwipsPerPixelX
            inf.ptMaxTrackSize.x = Screen.Height \ Screen.TwipsPerPixelX
            inf.ptMinTrackSize.x = 30 'min width in pixels
            inf.ptMinTrackSize.y = 30 'min height in pixels
            CopyMemory ByVal lParam, inf, Len(inf)
        Case WM_SIZING
            Dim r As RECT, iWidth%, iHeight%
            CopyMemory r, ByVal lParam, Len(r)
            iWidth = r.Right - r.Left
            iHeight = r.Bottom - r.Top
            If iWidth < iHeight Then
                iHeight = iWidth
            Else
                iWidth = iHeight
            End If
            r.Bottom = r.Top + iHeight
            r.Right = r.Left + iWidth
            CopyMemory ByVal lParam, r, Len(r)
    End Select
    WinProc = CallWindowProc(lngPrevWndProc, hw, uMsg, wParam, lParam)
End Function

To use the code add the following code to the Load and Unload events of the form:

Private Sub Form_Load()
    HookForm Me
End Sub

Private Sub Form_Unload(Cancel As Integer)
    UnhookForm
End Sub

Do not forget to call the UnhookForm procedure in the Unload event.

Good luck!

[dimava]

thanks alot