Q183544: HOWTO: Call CLSID And ProgID Related COM APIs in Visual Basic
Article: Q183544
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:4.0,5.0
Operating System(s):
Keyword(s): kbGrpDSVB
Last Modified: 11-JAN-2001
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The information in this article applies to:
- Microsoft Visual Basic Learning Edition for Windows, version 5.0
- Microsoft Visual Basic Professional Edition for Windows, version 5.0
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0
- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0
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SUMMARY
=======
This article demonstrates how to use a set of related Component Object Model
(COM) APIs that retrieve and manipulate CLSIDs and ProgIDs. The following APIs
are discussed:
- CLSIDFromProgID: To retrieve the CLSID of a COM object with a given ProgID.
- StringFromCLSID: To convert a CLSID structure to a string.
- CLSIDFromString: To convert a CLSID in string format to a structure.
- ProgIDFromCLSID: To retrieve a ProgID with a given CLSID.
MORE INFORMATION
================
WARNING: One or more of the following functions are discussed in this article;
VarPtr, VarPtrArray, VarPtrStringArray, StrPtr, ObjPtr. These functions are not
supported by Microsoft Technical Support. They are not documented in the Visual
Basic documentation and are provided in this Knowledge Base article "as is."
Microsoft does not guarantee that they will be available in future releases of
Visual Basic.
1. Create a new ActiveX DLL project (Project1) in Visual Basic (Class1 is
created by default).
2. Compile the default project. Now, you have a test component: Project1.dll,
which contains a COM class (Project1.Class1)
3. Create a new Standard EXE project (Project1) in Visual Basic. Form1 is
created by default.
4. Add three TextBoxes, one Command button, and one ListBox to Form1.
5. Add the following code to Form1's code module:
' ========== CODE FOR FORM1 ==============
Option Explicit
'CLSID/GUID structure
'====================
Private Type GUID
Data1 As Long
Data2 As Integer
Data3 As Integer
Data4(7) As Byte
End Type
'API Declarations:
'=================
Private Declare Function CLSIDFromProgID _
Lib "ole32.dll" (ByVal lpszProgID As Long, _
pCLSID As GUID) As Long
Private Declare Function ProgIDFromCLSID _
Lib "ole32.dll" (pCLSID As GUID, lpszProgID As Long) As Long
Private Declare Function StringFromCLSID _
Lib "ole32.dll" (pCLSID As GUID, lpszProgID As Long) As Long
Private Declare Function CLSIDFromString _
Lib "ole32.dll" (ByVal lpszProgID As Long, _
pCLSID As GUID) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias _
"RtlMoveMemory" (pDst As Any, pSrc As Any, ByVal ByteLen As Long)
Private Sub Command1_Click()
Dim strProgID As String * 255
Dim pProgID As Long
Dim udtCLSID As GUID
Dim strCLSID As String * 255
Dim pCLSID As Long
Dim lngRet As Long
Dim strTemp As String
Dim i As Integer
'Take a ProgID.
strTemp = Text1.Text
'Get CLSID.
lngRet = CLSIDFromProgID(StrPtr(strTemp), udtCLSID)
'Display CLSID elements.
With List1
.AddItem Hex(udtCLSID.Data1)
.AddItem Hex(udtCLSID.Data2)
.AddItem Hex(udtCLSID.Data3)
For i = 0 To 7
.AddItem Hex(udtCLSID.Data4(i))
Next
End With
'Convert CLSID to a string and get the pointer back.
lngRet = StringFromCLSID(udtCLSID, pCLSID)
'Get the CLSID string and display it.
StringFromPointer pCLSID, strCLSID
Text2.Text = strCLSID
'Reinitialize the CLSID.
With udtCLSID
.Data1 = 0
.Data2 = 0
.Data3 = 0
For i = 0 To 7
.Data4(i) = 0
Next
End With
'Convert the string back to CLSID.
strTemp = Text2.Text
lngRet = CLSIDFromString(StrPtr(strTemp), udtCLSID)
'Get a pointer to ProgID string. This is a Unicode string.
lngRet = ProgIDFromCLSID(udtCLSID, pProgID)
'Get the ProgID and display it.
StringFromPointer pProgID, strProgID
Text3.Text = strProgID
End Sub
'This function takes a pointer to a Unicode string, a string buffer
'and place the bytes in the Visual Basic string buffer.
Private Sub StringFromPointer(pOLESTR As Long, strOut As String)
Dim ByteArray(255) As Byte
Dim intTemp As Integer
Dim intCount As Integer
Dim i As Integer
intTemp = 1
'Walk the string and retrieve the first byte of each WORD.
While intTemp <> 0
CopyMemory intTemp, ByVal pOLESTR + i, 2
ByteArray(intCount) = intTemp
intCount = intCount + 1
i = i + 2
Wend
'Copy the byte array to our string.
CopyMemory ByVal strOut, ByteArray(0), intCount
End Sub
Private Sub Form_Load()
Text1.Text = "Project1.Class1"
End Sub
6. Run the project, and press Command1. The following appears:
Text1: Displays the ProgID of the component that you want to get the CLSID
from.
Text2: Displays the CLSID retrieved in string format.
Test3: Displays the ProgID retrieved based on the CLSID.
List1: Displays the members of the CLSID structure in hex format.
Additional query words:
======================================================================
Keywords : kbGrpDSVB
Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500 kbVB500 kbVB400Search kbVB400
Version : WINDOWS:4.0,5.0
Issue type : kbhowto
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