Tech Articles


Calling SHGetKnownFolderPath from PowerBuilder


Up through Windows XP, if you wanted to get the physical location of certain defined folders (e.g. the users Documents folder), you would use the SHGetFolderPath function in the Windows API.  Roland Smith has examples of using that on his Topwiz Software site.  That function continues to work in later versions of Windows, although it's basically a wrapper for the SHGetKnownFolderPath function.

SHGetFolderPath uses CSIDL values, whereas SHGetKnownFolderPath uses KnownFolderID GUIDs.  One difference is that there are a lot more KnownFolderIDs than there are CSIDLs.  That means some of the defined folder locations you may want to get the physical location for can't be accessed through the older SHGetFolderPath method.  And that's exactly the situation I ran into.


I needed to find the user's Downloads folder, and there isn't a CSIDL value for that.  So, I needed to see how to call the SHGetKnownFolderPath function from PowerBuilder.  As with many OLE and Windows API calls, it can save you a lot of time if you can find some Visual Basic code that does what you need to do, and you can convert the syntax.  And fortunately, I found some that did this.



So, with a little tweaking, I ended up with this:

//Local External Functions:

 Function Long CLSIDFromString (ref string lpszGuid, ref blob pGuid ) Library "ole32"   
 Function Long SHGetKnownFolderPath( ref blob nFolder,int dwFlags,uLong hToken , ref long pszPath) LIBRARY "Shell32.dll"   
 Subroutine CopyMemory ( ref String pDest, long pSrc, long ByteLen) Library "kernel32" Alias For "RtlMoveMemory"   
 Subroutine CoTaskMemFree ( long hMem) Library "ole32"   
 Function Long lstrlenW ( long ptr) Library "kernel32"   

//PowerScript

 blob     guid  
 long     ll_rc, ll_folderpointer, ll_folderlen  
 string ls_folder, ls_folder_id  
 ls_folder_id = '{374DE290-123F-4565-9164-39C4925E467B}'  
 IF CLSIDFromString (ls_folder_id, guid ) = 0 THEN  
      IF SHGetKnownFolderPath ( guid, 0, 0, ll_folderpointer ) = 0 THEN  
           IF ll_folderpointer <>0 THEN  
                ll_folderlen = lstrlenW ( ll_folderpointer )  
                If ll_folderlen <> 0 THEN  
                     ls_folder = Space ( ll_folderlen )                      
                     CopyMemory ( ls_folder, ll_folderpointer, ll_folderlen * 2 )  
                END IF  
           END IF  
           CoTaskMemFree ( ll_folderpointer )  
      END IF  
 END IF  
 MessageBox ( "Downloads Folder", ls_folder )  


Hope you find that useful as well.

 

 

 

 

 

 

Comments (0)
There are no comments posted here yet

Find Articles by Tag

Window SQL Server PowerServer Mobile CrypterObject SnapDevelop HTTPClient Outlook SQL Trial BLOB Source Control Database Object DataWindow JSON .NET Std Framework OrcaScript GhostScript Elevate Conference PowerScript (PS) Icon Android Database Table Data Testing PowerBuilder Compiler Design Deployment PFC JSONParser SqlModelMapper DataType Sort Menu RESTClient Error RibbonBar Builder PostgreSQL ODBC driver Installation Database Connection Application PDF Automated Testing CI/CD Web API DragDrop PowerServer Web REST Transaction Charts Open Source OAuth RichTextEdit Control TFS CoderObject Interface Web Service Proxy Migration Database Profile Service Source Code SDK DevOps Configuration Stored Procedure Performance DataWindow JSONGenerator IDE Debug File UI OLE ActiveX NativePDF Event Event Handling Platform Array 64-bit Class SOAP WebBrowser Graph Windows OS Text MessageBox DLL iOS Database Painter XML Import JSON TreeView Windows 10 Icons Export ODBC Repository Authorization Branch & Merge Database Table Schema Encoding InfoMaker Data JSON Excel Mobile Oracle COM PostgreSQL Variable 32-bit API Export JSON TLS/SSL Event Handler PBDOM External Functions Encryption Debugger Syntax PDFlib Git License Filter Database Import Bug OAuth 2.0 Script Azure WinAPI Debugging SVN SqlExecutor Validation SnapObjects .NET Assembly TortoiseGit Model PowerBuilder Expression Database Table Resize C# UI Themes Jenkins RibbonBar UI Modernization Authentication PowerBuilder (Appeon) Linux OS .NET DataStore Messagging