How To Create a Resolution-Independent Form

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Article ID: 182070 - View products that this article applies to.
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SUMMARY

If a Form takes up most of the screen at 640 x 480 (VGA) resolution, it only takes 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 for an Single Document Interface (SDI) application. It does not address special considerations for Multiple Document Interface (MDI) applications.

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, do 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 adjusts the Height. Other controls may not have a FontSize property and need some other property set to make FontSize appear correctly.

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
               ' Be sure to resize and reposition before changing the FontSize
               .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 adjusts for the new resolution.

REFERENCES

For additional information, please see the following articles in the Microsoft Knowledge Base:
187562 How To Resize the Controls in SSTab When Form is Resized
253940 PRB: Incorrect Screen Object Width/Height After Desktop Resized
206907 BUG: Reposition or Resize a Control After Changing Font Causes Incorrect Positioning and Sizing

Properties

Article ID: 182070 - Last Review: March 10, 2005 - Revision: 2.3
APPLIES TO
  • Microsoft Visual Basic 5.0 Learning Edition
  • Microsoft Visual Basic 6.0 Learning Edition
  • Microsoft Visual Basic 5.0 Professional Edition
  • Microsoft Visual Basic 6.0 Professional Edition
  • Microsoft Visual Basic 5.0 Enterprise Edition
  • Microsoft Visual Basic 6.0 Enterprise Edition
  • Microsoft Visual Basic 4.0 Standard Edition
  • Microsoft Visual Basic 4.0 Professional Edition
  • Microsoft Visual Basic 4.0 Professional Edition
  • Microsoft Visual Basic 4.0 16-bit Enterprise Edition
  • Microsoft Visual Basic 4.0 32-Bit Enterprise Edition
Keywords: 
kbdisplay kbforms kbhowto KB182070

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