In .Net (C# or VB: don't care), given a file path string, FileInfo struct, or FileSystemInfo struct for a real existing file, how can I determine the icon(s) used by the shell (explorer) for that file?
I'm not currently planning to use this for anything, but I became curious about how to do it when looking at this question and I thought it would be useful to have archived here on SO.
Imports System.Drawing
Module Module1
Sub Main()
Dim filePath As String = "C:\myfile.exe"
Dim TheIcon As Icon = IconFromFilePath(filePath)
If TheIcon IsNot Nothing Then
''#Save it to disk, or do whatever you want with it.
Using stream As New System.IO.FileStream("c:\myfile.ico", IO.FileMode.CreateNew)
TheIcon.Save(stream)
End Using
End If
End Sub
Public Function IconFromFilePath(filePath As String) As Icon
Dim result As Icon = Nothing
Try
result = Icon.ExtractAssociatedIcon(filePath)
Catch ''# swallow and return nothing. You could supply a default Icon here as well
End Try
Return result
End Function
End Module
Please ignore everyone telling you to use the registry! The registry is NOT AN API. The API you want is SHGetFileInfo with SHGFI_ICON. You can get a P/Invoke signature here:
You should use SHGetFileInfo.
Icon.ExtractAssociatedIcon works just as well as SHGetFileInfo in most cases, but SHGetFileInfo can work with UNC paths (e.g. a network path like "\\ComputerName\SharedFolder\") while Icon.ExtractAssociatedIcon cannot. If you need or might need to use UNC paths, it would be best to use SHGetFileInfo instead of Icon.ExtractAssociatedIcon.
This is good CodeProject article on how to use SHGetFileInfo.
Nothing more than a C# version of Stefan's answer.
using System.Drawing;
class Class1
{
public static void Main()
{
var filePath = @"C:\myfile.exe";
var theIcon = IconFromFilePath(filePath);
if (theIcon != null)
{
// Save it to disk, or do whatever you want with it.
using (var stream = new System.IO.FileStream(@"c:\myfile.ico", System.IO.FileMode.CreateNew))
{
theIcon.Save(stream);
}
}
}
public static Icon IconFromFilePath(string filePath)
{
var result = (Icon)null;
try
{
result = Icon.ExtractAssociatedIcon(filePath);
}
catch (System.Exception)
{
// swallow and return nothing. You could supply a default Icon here as well
}
return result;
}
}
This works for me in my projects, hope this helps someone.
It's C# with P/Invokes it will work so far on x86/x64 systems since WinXP.
(Shell.cs)
using System;
using System.Drawing;
using System.IO;
using System.Runtime.InteropServices;
namespace IconExtraction
{
internal sealed class Shell : NativeMethods
{
#region OfExtension
///<summary>
/// Get the icon of an extension
///</summary>
///<param name="filename">filename</param>
///<param name="overlay">bool symlink overlay</param>
///<returns>Icon</returns>
public static Icon OfExtension(string filename, bool overlay = false)
{
string filepath;
string[] extension = filename.Split('.');
string dirpath = Path.Combine(System.AppDomain.CurrentDomain.BaseDirectory, "cache");
Directory.CreateDirectory(dirpath);
if (String.IsNullOrEmpty(filename) || extension.Length == 1)
{
filepath = Path.Combine(dirpath, "dummy_file");
}
else
{
filepath = Path.Combine(dirpath, String.Join(".", "dummy", extension[extension.Length - 1]));
}
if (File.Exists(filepath) == false)
{
File.Create(filepath);
}
Icon icon = OfPath(filepath, true, true, overlay);
return icon;
}
#endregion
#region OfFolder
///<summary>
/// Get the icon of an extension
///</summary>
///<returns>Icon</returns>
///<param name="overlay">bool symlink overlay</param>
public static Icon OfFolder(bool overlay = false)
{
string dirpath = Path.Combine(System.AppDomain.CurrentDomain.BaseDirectory, "cache", "dummy");
Directory.CreateDirectory(dirpath);
Icon icon = OfPath(dirpath, true, true, overlay);
return icon;
}
#endregion
#region OfPath
///<summary>
/// Get the normal,small assigned icon of the given path
///</summary>
///<param name="filepath">physical path</param>
///<param name="small">bool small icon</param>
///<param name="checkdisk">bool fileicon</param>
///<param name="overlay">bool symlink overlay</param>
///<returns>Icon</returns>
public static Icon OfPath(string filepath, bool small = true, bool checkdisk = true, bool overlay = false)
{
Icon clone;
SHGFI_Flag flags;
SHFILEINFO shinfo = new SHFILEINFO();
if (small)
{
flags = SHGFI_Flag.SHGFI_ICON | SHGFI_Flag.SHGFI_SMALLICON;
}
else
{
flags = SHGFI_Flag.SHGFI_ICON | SHGFI_Flag.SHGFI_LARGEICON;
}
if (checkdisk == false)
{
flags |= SHGFI_Flag.SHGFI_USEFILEATTRIBUTES;
}
if (overlay)
{
flags |= SHGFI_Flag.SHGFI_LINKOVERLAY;
}
if (SHGetFileInfo(filepath, 0, ref shinfo, Marshal.SizeOf(shinfo), flags) == 0)
{
throw (new FileNotFoundException());
}
Icon tmp = Icon.FromHandle(shinfo.hIcon);
clone = (Icon)tmp.Clone();
tmp.Dispose();
if (DestroyIcon(shinfo.hIcon) != 0)
{
return clone;
}
return clone;
}
#endregion
}
}
(NativeMethods.cs)
using System;
using System.Drawing;
using System.Runtime.InteropServices;
namespace IconExtraction
{
internal class NativeMethods
{
public struct SHFILEINFO
{
public IntPtr hIcon;
public int iIcon;
public uint dwAttributes;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public string szDisplayName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
public string szTypeName;
};
[DllImport("user32.dll")]
public static extern int DestroyIcon(IntPtr hIcon);
[DllImport("shell32.dll", CharSet = CharSet.Auto, BestFitMapping = false, ThrowOnUnmappableChar = true)]
public static extern IntPtr ExtractIcon(IntPtr hInst, string lpszExeFileName, int nIconIndex);
[DllImport("Shell32.dll", BestFitMapping = false, ThrowOnUnmappableChar = true)]
public static extern int SHGetFileInfo(string pszPath, int dwFileAttributes, ref SHFILEINFO psfi, int cbFileInfo, SHGFI_Flag uFlags);
[DllImport("Shell32.dll")]
public static extern int SHGetFileInfo(IntPtr pszPath, uint dwFileAttributes, ref SHFILEINFO psfi, int cbFileInfo, SHGFI_Flag uFlags);
}
public enum SHGFI_Flag : uint
{
SHGFI_ATTR_SPECIFIED = 0x000020000,
SHGFI_OPENICON = 0x000000002,
SHGFI_USEFILEATTRIBUTES = 0x000000010,
SHGFI_ADDOVERLAYS = 0x000000020,
SHGFI_DISPLAYNAME = 0x000000200,
SHGFI_EXETYPE = 0x000002000,
SHGFI_ICON = 0x000000100,
SHGFI_ICONLOCATION = 0x000001000,
SHGFI_LARGEICON = 0x000000000,
SHGFI_SMALLICON = 0x000000001,
SHGFI_SHELLICONSIZE = 0x000000004,
SHGFI_LINKOVERLAY = 0x000008000,
SHGFI_SYSICONINDEX = 0x000004000,
SHGFI_TYPENAME = 0x000000400
}
}
The problem with the registry approach is that you are not explicitly getting the icon index id. Sometimes (if not all times), you get an icon ResourceID which is an alias the application developer used to name the icon's slot.
The registry method therefore implies that all developers use ResourceIDs which are the same as the implicit icon index id (which is zero based, absolute, deterministic).
Scan the registry location and you will see lots of negative numbers, sometimes even text references - i.e. not the icon index id. An implicit method seems better as it lets the OS do the work.
Only testing this new method now but it makes sense and hopefully solves this problem.
If you're only interested in an icon for a specific extension and if you don't mind creating a temporary file you can follow the example displayed here
C# code:
public Icon LoadIconFromExtension(string extension)
{
string path = string.Format("dummy{0}", extension);
using (File.Create(path)) { }
Icon icon = Icon.ExtractAssociatedIcon(path);
File.Delete(path);
return icon;
}
This link seems to have some info. It involves a lot of registry traversing, but it seems doable. The examples are in C++
- determine extension
- in registry, go to
"HKCR\.{extension}", read the default value (let's call itfiletype) - in
"HKCR\{filetype}\DefaultIcon", read the default value: this is the path to the icon file (or icon container file, like an .exe with an embedded icon resource) - if needed, use your preferred method of extracting the icon resource out of the mentioned file
edit/moved up from the comments:
If the icon is in a container file (this is quite common), there will be a counter after the path, like this: "foo.exe,3". This means it is icon number 4 (the index is zero-based) of the available icons. A value of ",0" is implicit (and optional). If the counter is 0 or missing, the fist available icon will be used by the shell.
来源：https://stackoverflow.com/questions/462270/get-file-icon-used-by-shell