IconHandler
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An icon handling class for icon extraction from files and registry
Introduction
IconHandler is a class for getting icons from files and the default associated icons by the extension of the file.
Background
It was originally writtin for a P2P project that never got out, called Kibutz. I decided to add the shell and resource functions becouse of a comment I got here. The const value has also been fixed (check IconSize).
Using the code
The class includes four simple-to-use functions:
IconFromFile(Filename,IconSize,Index)
This will get a single icon from a file with the specific index. If no icon was found or if the index was outside of the bounds,nullwill be returned.IconsFromFile(Filename,IconSize)
This will return anIcontyped array of icons.IconFromExtension(Extension,IconSize)
This will return an icon associated with an extension -- if it exists -- by using Shell API; if notnullwill be returned.IconFromResource(string ResourceName)
This will return an icon from the assembly resource if it exists.
/*
/*
* IconHandler - by Gil Schmidt
*
* - Originaly was writtin for a p2p project called Kibutz.
* - The IconFromExtension might give you some problems if it won't find an
* icon for it( try/catch should be used).
*
* [Updated]
*
* - Added Shell function for getting file extension after getting some commet
* about it, check link below.
* (http://www.codeguru.com/Csharp/Csharp/cs_misc/icons/article.php/c4261/)
* - IconFromResource was added for having all the common needed functions for
* handling icons.
* - Readed DestroyIcon and adding GetManagedIcon, after verifying it's needed
* (thanks DrGui and Kenneth Broendum).
* - Removed the IconFromExtension that pulled the icon from the registry
* (IconFromExtensionShell is default now).
* - Fixed IconCount mistake (if the number of icon in the file was 0 and the
* index that was selected was also 0 the ExtractIconEx still got to run and
* crashed (thanks SickLab).
* - Fixed iIcon (it was changed from IntPtr to int. on x64 systems IntPtr is
* 8 bytes which caused the mistake to popup) parameter in SHFILEINFO struct
* (Thanks Stefan Mayr).
*
* contact me at: Gil_Smdt@Hotmail.com
*
*/
using System;
using System.Drawing;
using System.Runtime.InteropServices;
using Microsoft.Win32;
using System.Reflection;
using System.IO;
namespace IconHandler
{
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;
};
public enum IconSize : uint
{
Large = 0x0, //32x32
Small = 0x1 //16x16
}
//the function that will extract the icons from a file
public class IconHandler
{
const uint SHGFI_ICON = 0x100;
const uint SHGFI_USEFILEATTRIBUTES = 0x10;
[DllImport("Shell32", CharSet=CharSet.Auto)]
internal extern static int ExtractIconEx (
[MarshalAs(UnmanagedType.LPTStr)]
string lpszFile, //size of the icon
int nIconIndex,
//index of the icon (in case we have more
//than 1 icon in the file
IntPtr[] phIconLarge, //32x32 icon
IntPtr[] phIconSmall, //16x16 icon
int nIcons); //how many to get
[DllImport("shell32.dll")]
static extern IntPtr SHGetFileInfo(
string pszPath, //path
uint dwFileAttributes, //attributes
ref SHFILEINFO psfi, //struct pointer
uint cbSizeFileInfo, //size
uint uFlags); //flags
//we need this function to release the unmanaged resource,
//the unmanaged resource will be copies to a managed one and
//it will be returned.
[DllImport("user32.dll", CharSet = CharSet.Auto)]
extern static bool DestroyIcon(IntPtr handle);
//will return an array of icons
public static Icon[] IconsFromFile(string Filename,IconSize Size)
{
int IconCount = ExtractIconEx(Filename,-1,null,null,0);
//checks how many icons.
IntPtr[] IconPtr = new IntPtr[IconCount];
Icon TempIcon;
//extracts the icons by the size that was selected.
if (Size == IconSize.Small)
ExtractIconEx(Filename,0,null,IconPtr,IconCount);
else
ExtractIconEx(Filename,0,IconPtr,null,IconCount);
Icon[] IconList = new Icon[IconCount];
//gets the icons in a list.
for (int i = 0; i < IconCount; i++)
{
TempIcon = (Icon) Icon.FromHandle(IconPtr[i]);
IconList[i] = GetManagedIcon(ref TempIcon);
}
return IconList;
}
//extract one selected by index icon from a file.
public static Icon IconFromFile(
string Filename,IconSize Size,int Index)
{
int IconCount = ExtractIconEx(Filename,-1,null,null,0);
//checks how many icons.
if (IconCount <= 0 || Index >= IconCount) return null;
// no icons were found.
Icon TempIcon;
IntPtr[] IconPtr = new IntPtr[1];
//extracts the icon that we want in the selected size.
if (Size == IconSize.Small)
ExtractIconEx(Filename,Index,null,IconPtr,1);
else
ExtractIconEx(Filename,Index,IconPtr,null,1);
TempIcon = Icon.FromHandle(IconPtr[0]);
return GetManagedIcon(ref TempIcon);
}
public static Icon IconFromExtension(string Extension,IconSize Size)
{
try
{
Icon TempIcon;
//add '.' if nessesry
if (Extension[0] != '.') Extension = '.' + Extension;
//temp struct for getting file shell info
SHFILEINFO TempFileInfo = new SHFILEINFO();
SHGetFileInfo(
Extension,
0,
ref TempFileInfo,
(uint)Marshal.SizeOf(TempFileInfo),
SHGFI_ICON | SHGFI_USEFILEATTRIBUTES | (uint) Size);
TempIcon = (Icon) Icon.FromHandle(TempFileInfo.hIcon);
return GetManagedIcon(ref TempIcon);
}
catch (Exception e)
{
System.Diagnostics.Debug.WriteLine(
"error while trying to get icon for " + Extension +
" :" + e.Message);
return null;
}
}
/*
* this is the built in funcion provided by .Net framework for getting
* a file icon, i thought it's worth mentioning.
*
public static Icon IconFromExtension(string Filename)
{
return Icon.ExtractAssociatedIcon(Filename);
}
*/
public static Icon IconFromResource(string ResourceName)
{
Assembly TempAssembly = Assembly.GetCallingAssembly();
return new Icon(TempAssembly.GetManifestResourceStream(
ResourceName));
}
public static void SaveIconFromImage(
Image SourceImage,string IconFilename,IconSize DestenationIconSize)
{
Size NewIconSize = DestenationIconSize ==
IconSize.Large ? new Size(32,32) : new Size(16,16);
Bitmap RawImage = new Bitmap(SourceImage,NewIconSize);
Icon TempIcon = Icon.FromHandle(RawImage.GetHicon());
FileStream NewIconStream = new FileStream(
IconFilename,FileMode.Create);
TempIcon.Save(NewIconStream);
NewIconStream.Close();
}
public static void SaveIcon(Icon SourceIcon,string IconFilename)
{
FileStream NewIconStream = new FileStream(
IconFilename,FileMode.Create);
SourceIcon.Save(NewIconStream);
NewIconStream.Close();
}
public static Icon GetManagedIcon(ref Icon UnmanagedIcon)
{
Icon ManagedIcon = (Icon) UnmanagedIcon.Clone();
DestroyIcon(UnmanagedIcon.Handle);
return ManagedIcon;
}
}
}
/* EOF */
Points of interest
What got me to write this was that I didn't find anything like this around. It's not complicated code, but when you want to use icons you don't plan on wasting your time dealing with it a lot. So, it's comfortable to have this little piece of code around.
History
- 12 January, 2005 - Original version posted
- 1 February, 2006 - First update
- 23 May, 2007 - Second update