Microsoft KB Archive/182070

= How To Create a Resolution-Independent Form =

Article ID: 182070

Article Last Modified on 3/10/2005

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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

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This article was previously published under Q182070



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
 Change the video resolution to 800 x 600. Start a new project in Visual Basic. Form1 is created by default. Add a Label, a CommandButton, and any other types of controls you would like to test.  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

  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. 

