HOWTO: Determine the Size of the Desktop Area

• Standard, Professional, and Enterprise Editions of Microsoft Visual Basic, 32-bit only, for Windows, version 4.0

SUMMARY

It is often useful to determine the size and position of the display area taking the system tray into account. There are at least two methods to obtain this information: One requires the use of an OCX, while another makes a call to the Win32 API. This article demonstrates the step-by-step approaches to both of these methods.

MORE INFORMATION

Method 1

NOTE: The SYSINFO.OCX control is in the \VB4\TOOLS\SYSINFO folder of the Visual Basic CD-ROM. It does not ship with the diskette version, and it is not automatically installed by Visual Basic Setup. Copy SYSINFO.OCX to the \WINDOWS\SYSTEM folder, and register it with REGOCX32.EXE.

Use the SYSINFO.OCX control in your project. It has a number of useful properties, four of which disclose the size and position of the desktop area in twips. Follow the steps below:

1. Start Visual Basic. Form1 is created by default.

2. Add a Command button to Form1.

3. From the Tools menu, choose Custom Controls and check the "Microsoft System Info" component. If the component is not listed, click the browse button and locate SYSINFO.OCX.

4. Add a SysInfo control to Form1.

5. Add the following code to the Command1_Click event:

      Private Sub Command1_Click()
   
        With SysInfo1
          Print "WorkAreaLeft: " & .WorkAreaLeft / Screen.TwipsPerPixelX
          Print "WorkAreaTop: " & .WorkAreaTop / Screen.TwipsPerPixelY
          Print "WorkAreaWidth: " & .WorkAreaWidth / Screen.TwipsPerPixelX
          Print "WorkAreaHeight: " & .WorkAreaHeight / Screen.TwipsPerPixelY
        End With
   
      End Sub
   
   

6. Choose Start from the Run menu, or press the F5 key to run the project.

7. Click the Command button to observe the size of the work area.

Method 2

The SystemParametersInfo function has many uses, including the ability to determine the size and position of the desktop. Follow the steps below:

1. Start Visual Basic. Form1 is created by default.

2. From the Insert menu, choose Module to add a single code module to the project. Module1 is created by default.

3. Add the following code to Module1:

   Type RECT

        Left As Long
        Top As Long
        Right As Long
        Bottom As Long
   

   End Type

   Public Const SPI_GETWORKAREA = 48

      Declare Function SystemParametersInfo Lib "user32" _
        Alias "SystemParametersInfoA" (ByVal uAction As Long, _
        ByVal uParam As Long, lpvParam As Any, ByVal fuWinIni As Long) _
        As Long
   
   

4. Add a Command button to Form1.

5. Add the following code to the Command1_Click event:

      Private Sub Command1_Click()
   
        Dim lRet As Long
        Dim apiRECT As RECT
   
        lRet = SystemParametersInfo(SPI_GETWORKAREA, vbNull, apiRECT, 0)
   
        If lRet Then
          Print "WorkAreaLeft: " & apiRECT.Left
          Print "WorkAreaTop: " & apiRECT.Top
          Print "WorkAreaWidth: " & apiRECT.Right - apiRECT.Left
          Print "WorkAreaHeight: " & apiRECT.Bottom - apiRECT.Top
        Else
          Print "Call to SystemParametersInfo failed."
        End If
   
      End Sub
   
   

6. Choose Start from the Run menu, or press the F5 key to run the project.

7. Click the Command button to observe the size of the work area.

REFERENCES

SYSINFO.HLP in the \TOOLS\SYSINFO directory on the Visual Basic 4.0 CD-ROM.

Win32 SDK on the MSDN Visual Basic starter kit. This can be installed by running SETUP.EXE from the MSDN directory on the Visual Basic 4.0 CD-ROM.

For more information, please see the following articles on the Microsoft Knowledge Base: