pinvoke.net: Edit: shell32.ExtractIcon

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Summary: The ExtractIconEx API

!!!!C# Signature:
 [DllImport("shell32.dll", CharSet=CharSet.Auto)]
 static extern uint ExtractIconEx(string szFileName, int nIconIndex,
   IntPtr[] phiconLarge, IntPtr[] phiconSmall, uint nIcons);

!!!!VB Signature:
 <DllImport("shell32.dll", CharSet:=CharSet.Auto)> _
 Shared Function ExtractIconEx(ByVal szFileName As String, _
                        ByVal nIconIndex As Integer, _
                        ByVal phiconLarge() As IntPtr, _
                        ByVal phiconSmall() As IntPtr, _
                        ByVal nIcons As UInteger) As UInteger
 End Function

!!!!VB 6 Signature:
 Declare Function ExtractIconEx _
         Lib "shell32.dll" _
         Alias "ExtractIconExA" _
            (ByVal lpszFile As String, _
             ByVal nIconIndex As Integer, _
             ByRef phiconLarge As Integer, _
             ByRef phiconSmall As Integer, _
             ByVal nIcons As Long) As Integer
!!!!User-Defined Types:
None.

!!!!Notes:
''szFile''
'''in''' A null-terminated string specifying the name of an executable file, DLL, or icon file from which icons will be extracted. 
''nIconIndex''
'''in''' Specifies the zero-based index of the first icon to extract. For example, if this value is zero, the function extracts the first icon in the specified file. 
If this value is –1 and phiconLarge and phiconSmall are both NULL, the function returns the total number of icons in the specified file. If the file is an executable file or DLL, the return value is the number of RT_GROUP_ICON resources. If the file is an .ico file, the return value is 1.

'''Windows 95/98/Me, Windows NT 4.0 and later''': If this value is a negative number and either phiconLarge or phiconSmall is not NULL, the function begins by extracting the icon whose resource identifier is equal to the absolute value of nIconIndex. For example, use -3 to extract the icon whose resource identifier is 3.

''phiconLarge''
'''out''' Pointer to an array of icon handles that receives handles to the large icons extracted from the file. If this parameter is NULL, no large icons are extracted from the file. 
''phiconSmall''
'''out''' Pointer to an array of icon handles that receives handles to the small icons extracted from the file. If this parameter is NULL, no small icons are extracted from the file. 
''nIcons''
'''in''' Specifies the number of icons to extract from the file.

!!!!Tips & Tricks:
'''For Windows CE:''' import coredll.dll not shell32.dll

'''For Windows CE 2.10 and later:''' the nIconIndex parameter must be zero or –N, where N is a specified resource identifier. The nIcons parameter must be 1.

'''For Windows CE 1.0 through 2.10:''' the function returns the total number of icons in the specified file if nIconIndex is –1 and phIconLarge and phiconSmall are both NULL. If the file is an executable file or DLL, the return value is the number of RT_GROUP_ICON resources. If the file is an .ICO file, the return value is 1.

To get other sizes of an icon, check sample at http://pinvoke.net/default.aspx/user32/LoadImage.html

!!!!Sample Code:
 namespace Martin.Hyldahl.Examples.ExtractIconEx
 {
    /* 
     * Example using ExtractIconEx
     * Created by Martin Hyldahl (alanadin@post8.tele.dk)
     * http://www.hyldahlnet.dk
     */

using System;
    using System.Drawing;
    using System.Runtime.InteropServices;

/// <summary>
	/// Example using ExtractIconEx
	/// </summary>
	public class ExtractIconExample
	{
        /* CONSTRUCTORS */
        static ExtractIconExample()
        {
        }

// HIDE INSTANCE CONSTRUCTOR
        private ExtractIconExample()
        {
        }

[DllImport("Shell32", CharSet=CharSet.Auto)]
        private static unsafe extern int ExtractIconEx (
            string lpszFile,
            int nIconIndex,
            IntPtr[] phIconLarge, 
            IntPtr[] phIconSmall,
            int nIcons);

[DllImport("user32.dll", EntryPoint="DestroyIcon", SetLastError=true)]
        private static unsafe extern int DestroyIcon(IntPtr hIcon);

public static Icon ExtractIconFromExe(string file, bool large)
        {
            unsafe
            {
                int readIconCount = 0;
                IntPtr[] hDummy  = new IntPtr[1] {IntPtr.Zero};
                IntPtr[] hIconEx = new IntPtr[1] {IntPtr.Zero};

try
                {
                    if(large)
                        readIconCount = ExtractIconEx(file,0, hIconEx, hDummy, 1);
                    else
                        readIconCount = ExtractIconEx(file,0, hDummy, hIconEx, 1);

if(readIconCount > 0 && hIconEx[0] != IntPtr.Zero)
                    {
                        // GET FIRST EXTRACTED ICON
                        Icon extractedIcon = (Icon)Icon.FromHandle(hIconEx[0]).Clone();

return extractedIcon;
                    }
                    else // NO ICONS READ
                        return null;
                }
                catch(Exception ex)
                {
                    /* EXTRACT ICON ERROR */

// BUBBLE UP
                    throw new ApplicationException("Could not extract icon", ex);
                }
                finally
                {
                    // RELEASE RESOURCES
                    foreach(IntPtr ptr in hIconEx)
                        if(ptr != IntPtr.Zero)
                            DestroyIcon(ptr);

foreach(IntPtr ptr in hDummy)
                        if(ptr != IntPtr.Zero)
                            DestroyIcon(ptr);
                }
            }
        }
	}
 }

!!!!Sample Code (VB Version of above):
 Imports System.Runtime.InteropServices
 Imports System.Drawing

Module IconExtract
    <DllImport("shell32.dll", CharSet:=CharSet.Auto)> _
    Function ExtractIconEx(ByVal szFileName As String, _
            ByVal nIconIndex As Integer, _
            ByVal phiconLarge() As IntPtr, _
            ByVal phiconSmall() As IntPtr, _
            ByVal nIcons As Integer) As Integer
    End Function
    <DllImport("user32.dll", EntryPoint:="DestroyIcon", SetLastError:=True)> _
    Function DestroyIcon(ByVal hIcon As IntPtr) As Integer
    End Function

Public Function WriteIconOut(ByVal iconsrcpath As String, ByVal icondestpath As String)
        Dim iconsrc As Icon = ExtractIconFromExe(iconsrcpath, True)
        iconsrc.Save(System.IO.File.OpenWrite(icondestpath))
    End Function

Public Function ExtractIconFromExe(ByVal f As String, ByVal large As Boolean) As Icon
        Dim readIconCount As Integer = 0
        Dim hDummy As IntPtr() = New IntPtr(0) {IntPtr.Zero}
        Dim hIconEx As IntPtr() = New IntPtr(0) {IntPtr.Zero}

Try
            If (large) Then
                readIconCount = ExtractIconEx(f, 0, hIconEx, hDummy, 1)
            Else
                readIconCount = ExtractIconEx(f, 0, hDummy, hIconEx, 1)
            End If

If (readIconCount > 0 AndAlso Not hIconEx(0).Equals(IntPtr.Zero)) Then
                ' GET FIRST EXTRACTED ICON
                Dim extractedIcon As Icon = Icon.FromHandle(hIconEx(0)).Clone()
                Return extractedIcon
            Else ' NO ICONS READ
                Return Nothing
            End If
        Catch ex As Exception
            ' EXTRACT ICON ERROR 
            ' BUBBLE UP
            Throw New ApplicationException("Could not extract icon", ex)
        Finally
            'RELEASE RESOURCES
            For Each ptr As IntPtr In hIconEx
                If (Not ptr.Equals(IntPtr.Zero)) Then
                    DestroyIcon(ptr)
                End If
            Next ptr

For Each ptr As IntPtr In hDummy
                If Not (ptr.Equals(IntPtr.Zero)) Then
                    DestroyIcon(ptr)
                End If
            Next ptr
        End Try
    End Function
 End Module

!!!!Alternative Managed API:
Icon.ExtractAssociatedIcon(sFile)

Documentation: ExtractIconEx@msdn on MSDN