Home > Articles > Programming > General Programming/Other Languages

Delphi 6 Shell Links

  • Print
  • + Share This
Like this article? We recommend

Like this article? We recommend

Using IShellLink

Shell links seem kind of magical: You right-click on the desktop, create a new shortcut, and something happens that causes an icon to appear on the desktop. That something is actually a pretty mundane occurrence once you know what's going on. A shell link is actually just a file with an .LNK extension that lives in some particular directory. When Windows starts, it looks in certain directories for LNK files, which represent links residing in different shell folders. These shell folders (or special folders) include items such as Network Neighborhood, Send To, Startup, the Desktop, and so on. The shell stores the link/folder correspondence in the System Registry—they're found mostly under the following key if you're interested in looking:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
[ccc]\Shell Folders

Creating a shell link in a special folder is just a matter of placing a link file in a particular directory. Rather than spelunking through the Registry, you can use SHGetSpecialFolderPath() to obtain the directory path for the various special folders. This method is defined as follows:

function SHGetSpecialFolderPath(hwndOwner: HWND; lpszPath: PChar;
 nFolder: Integer; fCreate: BOOL): BOOL; stdcall;
  • hwndOwner contains the handle of a window that will serve as the owner to any dialogs the function might invoke.

  • lpszPath is a pointer to a buffer to receive the path. This buffer must be at least MAX_PATH characters in length.

  • nFolder identifies the special folder for which you want to obtain the path.

  • fCreate indicates whether a folder should be created if it doesn't exist.

Creating a Shell Link

The IShellLink interface is an encapsulation of a shell link object, but it has no concept of how to read or write itself to a file on disk. However, implementers of the IShellLink interface are also required to support the IPersistFile interface in order to provide file access. IPersistFile is an interface that provides methods for reading and writing to and from disk, and it's defined as follows:

type
 IPersistFile = interface(IPersist)
  ['{0000010B-0000-0000-C000-000000000046}']
  function IsDirty: HResult; stdcall;
  function Load(pszFileName: POleStr; dwMode: Longint): HResult;
   stdcall;
  function Save(pszFileName: POleStr; fRemember: BOOL): HResult;
   stdcall;
  function SaveCompleted(pszFileName: POleStr): HResult;
   stdcall;
  function GetCurFile(out pszFileName: POleStr): HResult;
   stdcall;
 end;

Because the class that implements IShellLink is also required to implement IPersistFile, you can QueryInterface the IShellLink instance for an IPersistFile instance using the as operator, as shown here:

var
 SL: IShellLink;
 PF: IPersistFile;
begin
 OleCheck(CoCreateInstance(CLSID_ShellLink, nil, CLSCTX_INPROC_SERVER,
  IShellLink, SL));
 PF := SL as IPersistFile;
 // use PF and SL
end;

Using COM interface objects works the same as using normal Object Pascal objects. The following code, for example, creates a desktop shell link to the Notepad application:

procedure MakeNotepad;
const
 // NOTE: Assumed location for Notepad:
 AppName = 'c:\windows\notepad.exe';
var
 SL: IShellLink;
 PF: IPersistFile;
 LnkName: WideString;
begin
 OleCheck(CoCreateInstance(CLSID_ShellLink, nil, CLSCTX_INPROC_SERVER,
  IShellLink, SL));
 { IShellLink implementers are required to implement IPersistFile }
 PF := SL as IPersistFile;
 OleCheck(SL.SetPath(PChar(AppName)));  // set link path to proper file
 { create a path location and filename for link file }
 LnkName := GetFolderLocation('Desktop') + '\' +
  ChangeFileExt(ExtractFileName(AppName), '.lnk');
 PF.Save(PWideChar(LnkName), True);   // save link file
end;

In this procedure, the SetPath() method of IShellLink is used to point the link to an executable file or document (Notepad in this case). Then a path and filename for the link is created using the path returned by GetFolderLocation('Desktop') and by using the ChangeFileExt() function to change the extension of Notepad from .EXE to .LNK. This new filename is stored in LnkName. After that, the Save() method saves the link to a disk file. When the procedure terminates and the SL and PF interface instances fall out of scope, their respective references will be released.

Getting and Setting Link Information

As you can see from the definition of the IShellLink interface, it contains a number of GetXXX() and SetXXX() methods that allow you to get and set different aspects of the shell link. Consider the following record declaration, which contains fields for each of the possible values that can be set or retrieved:

type
 TShellLinkInfo = record
  PathName: string;
  Arguments: string;
  Description: string;
  WorkingDirectory: string;
  IconLocation: string;
  IconIndex: Integer;
  ShowCmd: Integer;
  HotKey: Word;
 end;

Given this record, you can create functions that retrieve the settings of a given shell link to the record or that set a link's values to those indicated by the record's contents. Such functions are shown in Listing 1. WinShell.pas is a unit that contains the complete source for these functions.

Listing 1—WinShell.pas—Unit Containing Functions That Operate on Shell Links

unit WinShell;

interface

uses SysUtils, Windows, Registry, ActiveX, ShlObj;

type
 EShellOleError = class(Exception);

 TShellLinkInfo = record
  PathName: string;
  Arguments: string;
  Description: string;
  WorkingDirectory: string;
  IconLocation: string;
  IconIndex: integer;
  ShowCmd: integer;
  HotKey: word;
 end;

 TSpecialFolderInfo = record
  Name: string;
  ID: Integer;
 end;

const
 SpecialFolders: array[0..29] of TSpecialFolderInfo = (
  (Name: 'Alt Startup'; ID: CSIDL_ALTSTARTUP),
  (Name: 'Application Data'; ID: CSIDL_APPDATA),
  (Name: 'Recycle Bin'; ID: CSIDL_BITBUCKET),
  (Name: 'Common Alt Startup'; ID: CSIDL_COMMON_ALTSTARTUP),
  (Name: 'Common Desktop'; ID: CSIDL_COMMON_DESKTOPDIRECTORY),
  (Name: 'Common Favorites'; ID: CSIDL_COMMON_FAVORITES),
  (Name: 'Common Programs'; ID: CSIDL_COMMON_PROGRAMS),
  (Name: 'Common Start Menu'; ID: CSIDL_COMMON_STARTMENU),
  (Name: 'Common Startup'; ID: CSIDL_COMMON_STARTUP),
  (Name: 'Controls'; ID: CSIDL_CONTROLS),
  (Name: 'Cookies'; ID: CSIDL_COOKIES),
  (Name: 'Desktop'; ID: CSIDL_DESKTOP),
  (Name: 'Desktop Directory'; ID: CSIDL_DESKTOPDIRECTORY),
  (Name: 'Drives'; ID: CSIDL_DRIVES),
  (Name: 'Favorites'; ID: CSIDL_FAVORITES),
  (Name: 'Fonts'; ID: CSIDL_FONTS),
  (Name: 'History'; ID: CSIDL_HISTORY),
  (Name: 'Internet'; ID: CSIDL_INTERNET),
  (Name: 'Internet Cache'; ID: CSIDL_INTERNET_CACHE),
  (Name: 'Network Neighborhood'; ID: CSIDL_NETHOOD),
  (Name: 'Network Top'; ID: CSIDL_NETWORK),
  (Name: 'Personal'; ID: CSIDL_PERSONAL),
  (Name: 'Printers'; ID: CSIDL_PRINTERS),
  (Name: 'Printer Links'; ID: CSIDL_PRINTHOOD),
  (Name: 'Programs'; ID: CSIDL_PROGRAMS),
  (Name: 'Recent Documents'; ID: CSIDL_RECENT),
  (Name: 'Send To'; ID: CSIDL_SENDTO),
  (Name: 'Start Menu'; ID: CSIDL_STARTMENU),
  (Name: 'Startup'; ID: CSIDL_STARTUP),
  (Name: 'Templates'; ID: CSIDL_TEMPLATES));

function CreateShellLink(const AppName, Desc: string; Dest: Integer): string;
function GetSpecialFolderPath(Folder: Integer; CanCreate: Boolean): string;
procedure GetShellLinkInfo(const LinkFile: WideString;
 var SLI: TShellLinkInfo);
procedure SetShellLinkInfo(const LinkFile: WideString;
 const SLI: TShellLinkInfo);

implementation

uses ComObj;

function GetSpecialFolderPath(Folder: Integer; CanCreate: Boolean): string;
var
 FilePath: array[0..MAX_PATH] of char;
begin
 { Get path of selected location }
 SHGetSpecialFolderPathW(0, FilePath, Folder, CanCreate);
 Result := FilePath;
end;

function CreateShellLink(const AppName, Desc: string; Dest: Integer): string;
{ Creates a shell link for application or document specified in }
{ AppName with description Desc. Link will be located in folder }
{ specified by Dest, which is one of the string constants shown }
{ at the top of this unit. Returns the full path name of the  }
{ link file. }
var
 SL: IShellLink;
 PF: IPersistFile;
 LnkName: WideString;
begin
 OleCheck(CoCreateInstance(CLSID_ShellLink, nil, CLSCTX_INPROC_SERVER,
  IShellLink, SL));
 { The IShellLink implementer must also support the IPersistFile }
 { interface. Get an interface pointer to it. }
 PF := SL as IPersistFile;
 OleCheck(SL.SetPath(PChar(AppName))); // set link path to proper file
 if Desc <> '' then
  OleCheck(SL.SetDescription(PChar(Desc))); // set description
 { create a path location and filename for link file }
 LnkName := GetSpecialFolderPath(Dest, True) + '\' +
       ChangeFileExt(AppName, 'lnk');
 PF.Save(PWideChar(LnkName), True);     // save link file
 Result := LnkName;
end;

procedure GetShellLinkInfo(const LinkFile: WideString;
 var SLI: TShellLinkInfo);
{ Retrieves information on an existing shell link }
var
 SL: IShellLink;
 PF: IPersistFile;
 FindData: TWin32FindData;
 AStr: array[0..MAX_PATH] of char;
begin
 OleCheck(CoCreateInstance(CLSID_ShellLink, nil, CLSCTX_INPROC_SERVER,
  IShellLink, SL));
 { The IShellLink implementer must also support the IPersistFile }
 { interface. Get an interface pointer to it. }
 PF := SL as IPersistFile;
 { Load file into IPersistFile object }
 OleCheck(PF.Load(PWideChar(LinkFile), STGM_READ));
 { Resolve the link by calling the Resolve interface function. }
 OleCheck(SL.Resolve(0, SLR_ANY_MATCH or SLR_NO_UI));
 { Get all the info! }
 with SLI do
 begin
  OleCheck(SL.GetPath(AStr, MAX_PATH, FindData, SLGP_SHORTPATH));
  PathName := AStr;
  OleCheck(SL.GetArguments(AStr, MAX_PATH));
  Arguments := AStr;
  OleCheck(SL.GetDescription(AStr, MAX_PATH));
  Description := AStr;
  OleCheck(SL.GetWorkingDirectory(AStr, MAX_PATH));
  WorkingDirectory := AStr;
  OleCheck(SL.GetIconLocation(AStr, MAX_PATH, IconIndex));
  IconLocation := AStr;
  OleCheck(SL.GetShowCmd(ShowCmd));
  OleCheck(SL.GetHotKey(HotKey));
 end;
end;

procedure SetShellLinkInfo(const LinkFile: WideString;
 const SLI: TShellLinkInfo);
{ Sets information for an existing shell link }
var
 SL: IShellLink;
 PF: IPersistFile;
begin
 OleCheck(CoCreateInstance(CLSID_ShellLink, nil, CLSCTX_INPROC_SERVER,
  IShellLink, SL));
 { The IShellLink implementer must also support the IPersistFile }
 { interface. Get an interface pointer to it. }
 PF := SL as IPersistFile;
 { Load file into IPersistFile object }
 OleCheck(PF.Load(PWideChar(LinkFile), STGM_SHARE_DENY_WRITE));
 { Resolve the link by calling the Resolve interface function. }
 OleCheck(SL.Resolve(0, SLR_ANY_MATCH or SLR_UPDATE or SLR_NO_UI));
 { Set all the info! }
 with SLI, SL do
 begin
  OleCheck(SetPath(PChar(PathName)));
  OleCheck(SetArguments(PChar(Arguments)));
  OleCheck(SetDescription(PChar(Description)));
  OleCheck(SetWorkingDirectory(PChar(WorkingDirectory)));
  OleCheck(SetIconLocation(PChar(IconLocation), IconIndex));
  OleCheck(SetShowCmd(ShowCmd));
  OleCheck(SetHotKey(HotKey));
 end;
 PF.Save(PWideChar(LinkFile), True);  // save file
end;

end.

One method of IShellLink that has yet to be explained is the Resolve() method. Resolve() should be called after the IPersistFile interface of IShellLink is used to load a link file. This searches the specified link file and fills the IShellLink object with values specified in the file.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020