DOCUMENT:Q182070  05-MAR-1998  [vbwin]
TITLE   :HOWTO: Create a Resolution-Independent Form
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:4.0,5.0
OPER/SYS:WINDOWS
KEYWORDS:VB4ALL VB4WIN vb5all vb5howto VBKBObj VBKBVB

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The information in this article applies to:

 - Microsoft Visual Basic Learning, Professional, and Enterprise Editions
   for Windows, version 5.0
 - Microsoft Visual Basic Standard, Professional, and Enterprise Editions,
   16-bit and 32-bit, for Windows, version 4.0
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SUMMARY
=======

If a Form takes up most of the screen at 640 x 480 (VGA) resolution, it
will only take up a small portion of the screen at 1600 x 1200. Normally,
this is exactly what you want to happen, but some circumstances arise where
you want a Form to retain the same proportional size and position
regardless of screen resolution. This article discusses a simple way to
accomplish this.

MORE INFORMATION
================

When designing Forms to be resized at run-time, keep the following in mind:

 - When designing Forms, it is best to design them for the lowest screen
   resolution you expect users to run. Even using the technique outlined
   here, it is best to stay with this rule because Forms resize better
   going to higher resolutions than they do going to lower ones.

 - Use TrueType Fonts because they are scalable. Also, try to use Fonts
   that will be available on the user's system. Otherwise, a substituted
   Font may not scale properly.

 - Because resizing may not always be exact, especially with Fonts, make
   the controls a little larger than the minimum necessary. Also, try to
   leave a little space between controls.

 - Some controls, like CheckBoxes and Option buttons, will not resize, and
   some controls may require special handling. For example, the Height
   property of ComboBoxes is read-only at run-time, but changing the font
   size will adjust the Height.

Step-by-Step Example
--------------------

1. Change the video resolution to 800 x 600.

2. Start a new project in Visual Basic. Form1 is created by default.

3. Add a Label, a CommandButton, and any other types of controls you would
   like to test.

4. Copy the following code into the Form's module:

      Option Explicit

      Dim MyForm As FRMSIZE
      Dim DesignX As Integer
      Dim DesignY As Integer

      Private Sub Form_Load()
      Dim ScaleFactorX As Single, ScaleFactorY As Single  ' Scaling factors
      ' Size of Form in Pixels at design resolution
      DesignX = 800
      DesignY = 600
      RePosForm = True   ' Flag for positioning Form
      DoResize = False   ' Flag for Resize Event
      ' Set up the screen values
      Xtwips = Screen.TwipsPerPixelX
      Ytwips = Screen.TwipsPerPixelY
      Ypixels = Screen.Height / Ytwips ' Y Pixel Resolution
      Xpixels = Screen.Width / Xtwips  ' X Pixel Resolution

      ' Determine scaling factors
      ScaleFactorX = (Xpixels / DesignX)
      ScaleFactorY = (Ypixels / DesignY)
      ScaleMode = 1  ' twips
      'Exit Sub  ' uncomment to see how Form1 looks without resizing
      Resize_For_Resolution ScaleFactorX, ScaleFactorY, Me
      Label1.Caption = "Current resolution is " & Str$(Xpixels) + _
       "  by " + Str$(Ypixels)
      MyForm.Height = Me.Height ' Remember the current size
      MyForm.Width = Me.Width
      End Sub

      Private Sub Form_Resize()
      Dim ScaleFactorX As Single, ScaleFactorY As Single

      If Not DoResize Then  ' To avoid infinite loop
         DoResize = True
         Exit Sub
      End If

      RePosForm = False
      ScaleFactorX = Me.Width / MyForm.Width   ' How much change?
      ScaleFactorY = Me.Height / MyForm.Height
      Resize_For_Resolution ScaleFactorX, ScaleFactorY, Me
      MyForm.Height = Me.Height ' Remember the current size
      MyForm.Width = Me.Width
      End Sub

      Private Sub Command1_Click()
      Dim ScaleFactorX As Single, ScaleFactorY As Single

      DesignX = Xpixels
      DesignY = Ypixels
      RePosForm = True
      DoResize = False
      ' Set up the screen values
      Xtwips = Screen.TwipsPerPixelX
      Ytwips = Screen.TwipsPerPixelY
      Ypixels = Screen.Height / Ytwips ' Y Pixel Resolution
      Xpixels = Screen.Width / Xtwips  ' X Pixel Resolution

      ' Determine scaling factors
      ScaleFactorX = (Xpixels / DesignX)
      ScaleFactorY = (Ypixels / DesignY)
      Resize_For_Resolution ScaleFactorX, ScaleFactorY, Me
      Label1.Caption = "Current resolution is " & Str$(Xpixels) + _
       "  by " + Str$(Ypixels)
      MyForm.Height = Me.Height ' Remember the current size
      MyForm.Width = Me.Width
      End Sub

5. Add a Module from the Project menu and paste in the following code:

      Public Xtwips As Integer, Ytwips As Integer
      Public Xpixels As Integer, Ypixels As Integer

      Type FRMSIZE
         Height As Long
         Width As Long
      End Type

      Public RePosForm As Boolean
      Public DoResize As Boolean

      Sub Resize_For_Resolution(ByVal SFX As Single, _
       ByVal SFY As Single, MyForm As Form)
      Dim I As Integer
      Dim SFFont As Single

      SFFont = (SFX + SFY) / 2  ' average scale
      ' Size the Controls for the new resolution
      On Error Resume Next  ' for read-only or nonexistent properties
      With MyForm
        For I = 0 To .Count - 1
         If TypeOf .Controls(I) Is ComboBox Then   ' cannot change Height
           .Controls(I).Left = .Controls(I).Left * SFX
           .Controls(I).Top = .Controls(I).Top * SFY
           .Controls(I).Width = .Controls(I).Width * SFX
         Else
           .Controls(I).Move .Controls(I).Left * SFX, _
            .Controls(I).Top * SFY, _
            .Controls(I).Width * SFX, _
            .Controls(I).Height * SFY
         End If
           .Controls(I).FontSize = .Controls(I).FontSize * SFFont
        Next I
        If RePosForm Then
          ' Now size the Form
          .Move .Left * SFX, .Top * SFY, .Width * SFX, .Height * SFY
        End If
      End With
      End Sub

Try running this under different screen resolutions and the Form should
take up the same desktop area and retain its look and screen position. You
may notice that your design resizes better when changing to a higher
resolution than it does when changing to a lower one. You can also use the
Mouse to Resize the Form and it will re-scale automatically. Finally, if
you change video resolution while the Form is open, you can click on
Command1 and it will adjust for the new resolution.

Additional query words: scale
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Keywords          : VB4ALL VB4WIN vb5all vb5howto VBKBObj VBKBVB
Version           : WINDOWS:4.0,5.0
Platform          : WINDOWS
Issue type        : kbhowto

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