Access Cookbook, 2nd Edition [Electronic resources] نسخه متنی

Recipe 11.13 Collect and Display Information on the System and the Access Installation

11.13.1 Problem

Your application really needs to
know some information about the computer on which
it's running. In addition, you'd
like to add some professional polish and an About... box that shows
information about the computer, the resources, and the user. Access
doesn't provide any way to find this information.
How can you gather it?

11.13.2 Solution

You can use
the Windows API to retrieve information about the system on which
your program is running. By using these various functions as the
control sources for unbound controls, you can present a selection of
system information to your user.

Load

11-13.MDB and open
frmSystemInfo in regular form view (see Figure 11-15). This form includes five
"pages" of information about the
current computer and its resources. If you like the look of this
form, use it as-is in your own applications. (You'll
need to import the form, frmSystemInfo, its
subform, fsubInfo, and the module,
basSystemInfo, into your application, as directed
in Step 1.)

Figure 11-15. frmSystemInfo shows memory status information

To create a similar form in your own application, follow these steps:

1. Import the module basSystemInfo from
   

   11-13.MDB into your own application. This module
   contains all the constants, API declarations, and wrapper functions
   that you'll need.

2. Create a new form. Place an unbound text box (or checkbox, or option
   group; see fsubInfo for hints) on the form for
   each piece of information you wish to display. Set the control
   sources as shown in Table 11-13. The sample form,
   frmSystemInfo, uses an option group that lets you choose which page
   of the subform, fsubInfo, you'd
   like to see. This has nothing to do with the functionality of the
   sample beyond cosmetics; it just makes it easier to group the
   information.

11.13.3 Discussion

The functions used here employ
a variety of techniques to return the requested information. In
general, they query the low-level Windows API to retrieve hardware
and Windows environment information. We've wrapped
each low-level function in an Access function to handle data type
conversions from the dynamic link libraries (DLLs) used by Windows
into the format that Access can understand.

frmSystemInfo uses several functions to return
information about the current computer:

The
acbGetScreenX and acbGetScreenY functions use the GetSystemMetrics
API function to return the size of the screen in pixels. This API
function can return many other details about your system, including
the width of the window borders, the size of the icons, and whether a
mouse is installed. To call it, just pass it one of the constants
shown later, in Table 11-14; it will return the
requested value to you. For example:

Public Function acbGetScreenX( )
' Retrieve the screen width in pixels.
acbGetScreenX = GetSystemMetrics(SM_CXSCREEN)
End Function

Again, the

GetSystemMetrics function does the
work:

Public Function acbMouseInstalled( ) As Boolean
' Is a mouse installed?
acbMouseInstalled = CBool(GetSystemMetrics(SM_MOUSEPRESENT))
End Function

The

GetKeyboardType function provides the answers:

Public Function acbKeyboardType( )
' Retrieve information about the keyboard.
' Call GetKeyboardType with
'   0   Keyboard Type
'   1   Keyboard SubType (depends on the manufacturer)
'   2   Number of function keys
acbKeyboardType = GetKeyboardType(0)
End Function

The GlobalMemoryStatusEx function fills
in a user-defined data structure with information about the current
memory load, available and total real and virtual memory, and paging
space. We've wrapped all this information up in the
acbGetMemoryStatus function:

Public Function acbGetMemoryStatus(intItem As Integer) As Variant
' Retrieve system memory information
' In:
'    intItem: Which piece of information to retrieve
'        0: Memory load (0 to 100)
'        1: Total physical memory in bytes
'        2: Available physical memory in bytes
'        3: Total size in page file in bytes
'        4: Available page file in bytes
'        5: Total virtual memory in bytes
'        6: Available virtual memory in bytes
' Out:
'    Return Value: The requested information
Dim MS As MEMORYSTATUSEX
' Set the length member before you call GlobalMemoryStatus.
MS.dwLength = Len(MS)
GlobalMemoryStatusEx MS
Select Case intItem
Case 0
acbGetMemoryStatus = MS.dwMemoryLoad * 10000 / 1024
Case 1
acbGetMemoryStatus = MS.dwTotalPhys * 10000 / 1024
Case 2
acbGetMemoryStatus = MS.dwAvailPhys * 10000 / 1024
Case 3
acbGetMemoryStatus = MS.dwTotalPageFile * 10000 / 1024
Case 4
acbGetMemoryStatus = MS.dwAvailPageFile * 10000 / 1024
Case 5
acbGetMemoryStatus = MS.dwTotalVirtual * 10000 / 1024
Case 6
acbGetMemoryStatus = MS.dwAvailVirtual * 10000 / 1024
Case Else
acbGetMemoryStatus = 0
End Select
End Function

Although it seems odd, the code in acbGetMemoryStatus is performing an important conversion. Because the values filled in by the GlobalMemoryStatusEx method are so large, you must use Currency values to contain the results. In order to store large values, VBA scales the contents of Currency variables by a factor of 10,000. Therefore, when you want to use the values here, you must multiply them by 10,000. In addition, to convert from bytes to KB, the code divides the totals by the number of bytes in a kilobyte, 1024.

The GetVersionEx API function does the
work here. To simplify its use, we've provided the
acbGetOSInfo function, as follows. Note that the Platform ID value
simply indicates whether you're running a Windows
95-based operating system (such as Windows 98 or Windows ME) or a
Windows NT-based operating system, such as Windows 2000, Windows XP,
or Windows Server 2003. You can definitely retrieve more detailed
results than thissee the documentation at http://msdn.microsoft.com for more
information.

Public Function acbGetOSInfo(intItem As Integer) As Variant
' Retrieve operating system information
' In:
'    intItem: Which piece of information to retrieve
'        0: Major Version
'        1: Minor version
'        2: Build Number
'        3: Platform ID
'             0 = Win32s (not going to happen!)
'             1 = Win95
'             2 = WinNT
' Out:
'    Return Value: The requested information
Dim OSInfo As OSVERSIONINFO
' Set the length member before you call GetVersionEx.
OSInfo.dwOSVersionInfoSize = Len(OSInfo)
If GetVersionEx(OSInfo) Then
Select Case intItem
Case 0
acbGetOSInfo = OSInfo.dwMajorVersion
Case 1
acbGetOSInfo = OSInfo.dwMinorVersion
Case 2
' Get just the low word of the result.
acbGetOSInfo = OSInfo.dwBuildNumber And &HFFFF&
Case 3
acbGetOSInfo = OSInfo.dwPlatformId
End Select
Else
acbGetOSInfo = 0
End If
End Function

To retrieve the Windows
directory, call acbWindowsDirectory, shown in the
following code. For the Windows System directory, call
acbSystemDirectory; for the temporary storage
path, call acbTempPath; and to find out which
directory Access is running from, call
acbAccessDirectory. (Note that
acbAccessDirectory doesn't
actually use the Windows API to find the location of Access; the
SysCmd function in Access makes that information available.)

Public Function acbWindowsDirectory( )
' Retrieve the Windows directory.
Dim strBuffer As String
Dim intCount As Integer
strBuffer = Space(MAX_PATH)
intCount = GetWindowsDirectory(strBuffer, MAX_PATH)
acbWindowsDirectory = CleanPath(Left(strBuffer, intCount))
End Function

The GetSystemInfo API function provides
all the information. To make this easier for you,
we've provided the acbGetSystemStatus function,
shown in the following code. Call this function with a number
representing the piece of information you want.

Public Function acbGetSystemStatus(intItem As Integer) As Variant
' Retrieve system status information
' In:
'    intItem: Which piece of information to retrieve
'        0: Computer identifier, specific to OEM
'        1: Returns page size and specifies the granularity of page
'           protection and commitment
'        2: Lowest memory address accessible to applications and 
'           dynamic link libraries (DLLs)
'        3: Highest memory address accessible to applications and DLLs
'        4: Mask representing the set of processors configured into 
'           the system
'           Bit 0 is processor 0; bit 31 is processor 31
'        5: Returns the number of processors in the system
'        6: Type of the current processors in the system
'        7: Allocation granularity in which memory will be allocated 
'           on (usually 64K)
' Out:
'    Return Value: The requested information
Dim SI As SYSTEM_INFO
GetSystemInfo SI
Select Case intItem
Case 0
acbGetSystemStatus = SI.dwOemID
Case 1
acbGetSystemStatus = SI.dwPageSize
Case 2
acbGetSystemStatus = SI.lpMinimumApplicationAddress
Case 3
acbGetSystemStatus = SI.lpMaximumApplicationAddress
Case 4
acbGetSystemStatus = SI.dwActiveProcessorMask
Case 5
acbGetSystemStatus = SI.dwNumberOrfProcessors
Case 6
acbGetSystemStatus = SI.dwProcessorType
Case 7
acbGetSystemStatus = SI.dwAllocationGranularity
Case Else
acbGetSystemStatus = 0
End Select
End Function

 SM_CXSCREEN

 SM_CYSCREEN

 SM_CXVSCROLL

 SM_CYHSCROLL

 SM_CYCAPTION

 SM_CXBORDER

 SM_CYBORDER

 SM_CXFIXEDFRAME

 SM_CYFIXEDFRAME

 SM_CYVTHUMB

 SM_CXHTHUMB

 SM_CXICON

 SM_CYICON

 SM_CXCURSOR

 SM_CYCURSOR

 SM_CYMENU

 SM_CXFULLSCREEN

 SM_CYFULLSCREEN

 SM_CYKANJIWINDOW

 SM_MOUSEPRESENT

 SM_CYVSCROLL

 SM_CXHSCROLL

 SM_DEBUG

 SM_SWAPBUTTON

 SM_CXMIN

 SM_CYMIN

 SM_CXSIZE

 SM_CYSIZE

 SM_CXFRAME

 SM_CYFRAME

 SM_CXMINTRACK

 SM_CYMINTRACK

 SM_CXDOUBLECLK

 SM_CYDOUBLECLK

 SM_CXICONSPACING

 SM_CYICONSPACING

 SM_MENUDROPALIGNMENT

 SM_PENWINDOWS

 SM_DBCSENABLED

 SM_CMOUSEBUTTONS

 SM_SECURE

 SM_CXMINSPACING

 SM_CYMINSPACING

 SM_CXSMICON

 SM_CYSMICON

 SM_CXSMSIZE

 SM_CYSMSIZE

 SM_CXMENUSIZE

 SM_CYMENUSIZE

 SM_ARRANGE

 SM_CXMINIMIZED

 SM_CYMINIMIZED

 SM_CXMAXTRACK

 SM_CYMAXTRACK

 SM_CXMAXIMIZED

 SM_CYMAXIMIZED

 SM_NETWORK

 SM_CLEANBOOT

 SM_SHOWSOUNDS

 SM_CXMENUCHECK

 SM_CYMENUCHECK

 SM_SLOWMACHINE

 SM_CMETRICS

Some of the flags supported by
GetSystemMetrics behave differently under
different operating systems. Make sure you check the documentation
(online at http://msdn.microsoft.com) for
operating-system dependencies. You'll also find
other options that you can add to this form; we
didn't include every available option here.

In addition to the functions listed
here, you may find the SystemParametersInfo API function useful. It
allows you to set and retrieve many system parameters, but calling it
is a bit more difficult than calling
GetSystemMetrics. If you have access to a Windows
API reference, you may want to dig into this useful function.