HOWTO: Create a Resolution-Independent Form

• 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

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