如何获取 shell 命名空间中对象的 shell 图像索引？

Question

我想获取 shell 命名空间中对象的系统图像列表中的索引。

如果这个对象是一个文件，我可以使用SHGetFileInfo:

function GetFileImageIndex(const Filename: string): Integer;
var
   sfi: TSHFileInfo;
begin
   SHGetFileInfo(PChar(Filename), FILE_ATTRIBUTE_NORMAL, sfi, SizeOf(sfi), 
         SHGFI_USEFILEATTRIBUTES or SHGFI_SYSICONINDEX);
   Result := sfi.iIcon;
end;

除非我没有文件

我所拥有的东西在硬盘上不作为文件夹或文件存在，例如：

• Control Panel
• Homegroup
• Network

但是我仍然需要在系统图像列表中获取与这个东西对应的图标的索引。我从SHGetFileInfo 开始（因为它支持pidls）。但这分崩离析了。然后我尝试使用IExtractIcon，但结果崩溃了：

function GetObjectImageIndex(ParentFolder: IShellFolder; const ChildPidl: PItemIDList): Integer;
//var
//  sfi: TSHFileInfo;

//  extractIcon: IExtractIcon;
//  iconFile: WideString;
//  iconIndexInFile: Integer;
//  flags: Cardinal;
begin
    {
        This function is the shell namespace equivalent of GetFileImageIndex helper function.
    }
(*
    Won't work (MSDN: "The PIDL must be a fully qualified PIDL. Relative PIDLs are not allowed.")
    SHGetFileInfo(PWideChar(ChildPidl), FILE_ATTRIBUTE_NORMAL,
            sfi, SizeOf(sfi),
            SHGFI_PIDL or SHGFI_SYSICONINDEX);
*)

(*
    Won't work. Doesn't return an index into the system imagelist
    ParentFolder.GetUIObjectOf(0, 1, ChildPidl, IExtractIcon, nil, {out}extractIcon);
    SetLength(iconFile, MAX_PATH);
    extractIcon.GetIconLocation(0, PWideChar(iconFile), Length(iconFile), iconIndexInFile, {out}flags);
*)

    Result := -1; //TODO: Figure out how to do it.
end;

给定该文件夹中的IShellFolder 和pidl，我如何在该东西的系统图像列表中获取图标？

Answer 1

简单的答案是您将标识对象的绝对 PIDL 传递给SHGetFileInfo。您说您尝试过但没有成功，但这是解决问题的方法。

您应该返回SHGetFileInfo 并使其工作。看起来你已经有了一个相对的 PI​​DL 并停止了。用ILCombine 做一个绝对的PIDL，你应该回家了。

如果您没有包含 IShellFolder 的 PIDL，那么您需要阅读此主题：How to obtain the PIDL of an IShellFolder

Answer 2

function CreateGlobalChildIDList(AParentFolder: IShellFolder; const AChildIDList: PItemIDList): PItemIDList; forward;

function GetObjectImageIndex(AParentFolder: IShellFolder; const AChildIDList: PItemIDList): Integer;
var
  ShellIcon: IShellIcon;
  ChildIDList: PItemIDList;
  FileInfo: TSHFileInfo;
begin
  try
    Result := -1;
    try
      OleCheck(AParentFolder.QueryInterface(IShellIcon, ShellIcon));
      try
        OleCheck(ShellIcon.GetIconOf(AChildIDList, GIL_FORSHELL, Result));
      finally
        ShellIcon := nil;
      end;
    except
      Result := -1;
    end;

    if Result = -1 then
      begin
        ChildIDList := CreateGlobalChildIDList(AParentFolder, AChildIDList);
        try
          ZeroMemory(@FileInfo, SizeOf(FileInfo));
          SHGetFileInfo(PWideChar(ChildIDList), FILE_ATTRIBUTE_NORMAL, FileInfo, SizeOf(FileInfo), SHGFI_PIDL or SHGFI_SYSICONINDEX);
          Result := FileInfo.iIcon;
        finally
          CoTaskMemFree(ChildIDList);
        end;
      end;
  except
    Result := -1;
  end;
end;

  function CretaeGlobalChildIDList(AParentFolder: IShellFolder; const AChildIDList: PItemIDList): PItemIDList;
  var
    PersistFolder2: IPersistFolder2;
    PersistIDList: IPersistIDList;
    ParentIDList: PItemIDList;
  begin
    if Succeeded(AParentFolder.QueryInterface(IPersistFolder2, PersistFolder2)) then
      try
        OleCheck(PersistFolder2.GetCurFolder(ParentIDList));
        try
          Result := ILCombine(ParentIDList, AChildIDList);
        finally
          CoTaskMemFree(ParentIDList);
        end;
      finally
        PersistFolder2 := nil;
      end
    else
      if Succeeded(AParentFolder.QueryInterface(IPersistIDList, PersistIDList)) then
        try
          OleCheck(PersistIDList.GetIDList(ParentIDList));
          try
            Result := ILCombine(ParentIDList, AChildIDList);
          finally
            CoTaskMemFree(ParentIDList);
          end;
        finally
          PersistIDList := nil;
        end
      else
        raise Exception.Create('Cannot create PIDL');
  end;