Enumerating active fonts in C# using DLL call to EnumFontFamiliesEx has me schtumped

Question

My ultimate goal is to list all active fonts on a windows computer. For example, if you start WordPad or Word, you will see them all. Some of these fonts comes from the windows\fonts folder, but not all. Some are registered dynamically using the gdi32.dll call AddFontResource(...). Now, you would think C# had support for retrieving this entire list, and if so, let me know, please!

However, after spending many hours on this, the regular C# calls to get installed system fonts retrieve just some of all the fonts that are actually active. InstalledFontCollection.Families, for example, does NOT find any of the fonts added with AddFontResource (It finds about 25% of the fonts listed in wordpad !)

While I want to do this in C#, it appears I have to use some more gdi32.dll calls. Thus started my EnumFontFamiliesEx issue.

I have managed to get the following code working to the point that I am getting a bunch of callbacks with fonts. However, the structure ENUMLOGFONTEX seems to be corrupted, and for example lpelfe.elfFullName usually contains a couple of square characters, never a real name. Maybe I have made a mistake in the marshalling, or the struct definition, not really sure. I've tried many iterations and endless googling, but to no avail.

Any help would be very much appreciated.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Windows.Media;
using System.Runtime.InteropServices;
using Microsoft.Win32;


namespace FontRetriever
{
public partial class TestForm : Form
{

    [DllImport("gdi32.dll")]
    static extern int EnumFontFamiliesEx(IntPtr hdc,
    [In] IntPtr pLogfont,
    EnumFontExDelegate lpEnumFontFamExProc,
    IntPtr lParam,
    uint dwFlags);

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public class LOGFONT
    {
        public int lfHeight;
        public int lfWidth;
        public int lfEscapement;
        public int lfOrientation;
        public FontWeight lfWeight;
        [MarshalAs(UnmanagedType.U1)]
        public bool lfItalic;
        [MarshalAs(UnmanagedType.U1)]
        public bool lfUnderline;
        [MarshalAs(UnmanagedType.U1)]
        public bool lfStrikeOut;
        public FontCharSet lfCharSet;
        public FontPrecision lfOutPrecision;
        public FontClipPrecision lfClipPrecision;
        public FontQuality lfQuality;
        public FontPitchAndFamily lfPitchAndFamily;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string lfFaceName;
    }

    public enum FontWeight : int
    {
        FW_DONTCARE = 0,
        FW_THIN = 100,
        FW_EXTRALIGHT = 200,
        FW_LIGHT = 300,
        FW_NORMAL = 400,
        FW_MEDIUM = 500,
        FW_SEMIBOLD = 600,
        FW_BOLD = 700,
        FW_EXTRABOLD = 800,
        FW_HEAVY = 900,
    }
    public enum FontCharSet : byte
    {
        ANSI_CHARSET = 0,
        DEFAULT_CHARSET = 1,
        SYMBOL_CHARSET = 2,
        SHIFTJIS_CHARSET = 128,
        HANGEUL_CHARSET = 129,
        HANGUL_CHARSET = 129,
        GB2312_CHARSET = 134,
        CHINESEBIG5_CHARSET = 136,
        OEM_CHARSET = 255,
        JOHAB_CHARSET = 130,
        HEBREW_CHARSET = 177,
        ARABIC_CHARSET = 178,
        GREEK_CHARSET = 161,
        TURKISH_CHARSET = 162,
        VIETNAMESE_CHARSET = 163,
        THAI_CHARSET = 222,
        EASTEUROPE_CHARSET = 238,
        RUSSIAN_CHARSET = 204,
        MAC_CHARSET = 77,
        BALTIC_CHARSET = 186,
    }
    public enum FontPrecision : byte
    {
        OUT_DEFAULT_PRECIS = 0,
        OUT_STRING_PRECIS = 1,
        OUT_CHARACTER_PRECIS = 2,
        OUT_STROKE_PRECIS = 3,
        OUT_TT_PRECIS = 4,
        OUT_DEVICE_PRECIS = 5,
        OUT_RASTER_PRECIS = 6,
        OUT_TT_ONLY_PRECIS = 7,
        OUT_OUTLINE_PRECIS = 8,
        OUT_SCREEN_OUTLINE_PRECIS = 9,
        OUT_PS_ONLY_PRECIS = 10,
    }
    public enum FontClipPrecision : byte
    {
        CLIP_DEFAULT_PRECIS = 0,
        CLIP_CHARACTER_PRECIS = 1,
        CLIP_STROKE_PRECIS = 2,
        CLIP_MASK = 0xf,
        CLIP_LH_ANGLES = (1 << 4),
        CLIP_TT_ALWAYS = (2 << 4),
        CLIP_DFA_DISABLE = (4 << 4),
        CLIP_EMBEDDED = (8 << 4),
    }
    public enum FontQuality : byte
    {
        DEFAULT_QUALITY = 0,
        DRAFT_QUALITY = 1,
        PROOF_QUALITY = 2,
        NONANTIALIASED_QUALITY = 3,
        ANTIALIASED_QUALITY = 4,
        CLEARTYPE_QUALITY = 5,
        CLEARTYPE_NATURAL_QUALITY = 6,
    }
    [Flags]
    public enum FontPitchAndFamily : byte
    {
        DEFAULT_PITCH = 0,
        FIXED_PITCH = 1,
        VARIABLE_PITCH = 2,
        FF_DONTCARE = (0 << 4),
        FF_ROMAN = (1 << 4),
        FF_SWISS = (2 << 4),
        FF_MODERN = (3 << 4),
        FF_SCRIPT = (4 << 4),
        FF_DECORATIVE = (5 << 4),
    }

    [StructLayout(LayoutKind.Sequential)]
    public class NEWTEXTMETRICEX
    {
        //public const int LF_FACESIZE = 32;
        public int tmHeight;
        public int tmAscent;
        public int tmDescent;
        public int tmInternalLeading;
        public int tmExternalLeading;
        public int tmAveCharWidth;
        public int tmMaxCharWidth;
        public int tmWeight;
        public int tmOverhang;
        public int tmDigitizedAspectX;
        public int tmDigitizedAspectY;
        public char tmFirstChar;
        public char tmLastChar;
        public char tmDefaultChar;
        public char tmBreakChar;
        public byte tmItalic;
        public byte tmUnderlined;
        public byte tmStruckOut;
        public byte tmPitchAndFamily;
        public byte tmCharSet;
    }



    private const byte DEFAULT_CHARSET = 1;
    private const byte SHIFTJIS_CHARSET = 128;
    private const byte JOHAB_CHARSET = 130;
    private const byte EASTEUROPE_CHARSET = 238;

    private const byte DEFAULT_PITCH = 0;
    private const byte FIXED_PITCH = 1;
    private const byte VARIABLE_PITCH = 2;
    private const byte FF_DONTCARE = (0 << 4);
    private const byte FF_ROMAN = (1 << 4);
    private const byte FF_SWISS = (2 << 4);
    private const byte FF_MODERN = (3 << 4);
    private const byte FF_SCRIPT = (4 << 4);
    private const byte FF_DECORATIVE = (5 << 4);


    public TestForm()
    {
        InitializeComponent();
    }


    private int cnt = 0;


    private void TestForm_Load(object sender, EventArgs e)
    {
        LOGFONT lf = CreateLogFont("");

        IntPtr plogFont = Marshal.AllocHGlobal(Marshal.SizeOf(lf));
        Marshal.StructureToPtr(lf, plogFont, true);

        int ret = 0;
        try
        {
            Graphics G = pictureBox1.CreateGraphics();
            IntPtr P = G.GetHdc();

            del1 = new EnumFontExDelegate(callback1);
            ret = EnumFontFamiliesEx(P, plogFont, del1, IntPtr.Zero, 0);

            System.Diagnostics.Trace.WriteLine("EnumFontFamiliesEx = " + ret.ToString());
        }
        catch
        {
            System.Diagnostics.Trace.WriteLine("Exception");
        }
    }



    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct ENUMLOGFONTEX
    {
        public LOGFONT elfLogFont;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
        public string elfFullName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string elfStyle;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string elfScript;
    }

    public delegate int EnumFontExDelegate(ref ENUMLOGFONTEX lpelfe, IntPtr lpntme, int FontType, int lParam);
    public EnumFontExDelegate del1;


    public int callback1(ref ENUMLOGFONTEX lpelfe, IntPtr lpntme, int FontType, int lParam)
    {
        try
        {
            ++cnt;

            Font F = Font.FromLogFont(lpelfe.elfLogFont);
            Console.WriteLine(F.Name + "   " + lpelfe.elfFullName);


        }
        catch
        {
            System.Diagnostics.Trace.WriteLine("What happened?");
        }
        return cnt;
    }


    public static LOGFONT CreateLogFont(string fontname)
    {
        LOGFONT lf = new LOGFONT();
        lf.lfHeight = 0;
        lf.lfWidth = 0;
        lf.lfEscapement = 0;
        lf.lfOrientation = 0;
        lf.lfWeight = 0;
        lf.lfItalic = false;
        lf.lfUnderline = false;
        lf.lfStrikeOut = false;
        lf.lfCharSet = FontCharSet.DEFAULT_CHARSET;
        lf.lfOutPrecision = 0;
        lf.lfClipPrecision = 0;
        lf.lfQuality = 0;
        lf.lfPitchAndFamily = FontPitchAndFamily.FF_DONTCARE;
        lf.lfFaceName = "";


        return lf;
    }

}    

}

Answer 1

Adding CharSet=CharSet.Auto to your DllImport attribute on EnumFontFamiliesEx should take care of the problem. Like Merlyn hints at, it's a ANSI/Unicode mismatch problem.

And don't forget to free the memory you allocate with Marshal.AllocHGlobal.

Answer 2

Thanks for the answer Mattias. It turned out I had a couple of issues, and I got some answers from other forums as well that helped resolve them. So here is the final code for all to enjoy.

[DllImport("gdi32.dll", CharSet = CharSet.Auto)]
static extern int EnumFontFamiliesEx(IntPtr hdc,
                                [In] IntPtr pLogfont,
                                EnumFontExDelegate lpEnumFontFamExProc,
                                IntPtr lParam,
                                uint dwFlags);


[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public class LOGFONT
    {

        public int lfHeight;
        public int lfWidth;
        public int lfEscapement;
        public int lfOrientation;
        public FontWeight lfWeight;
        [MarshalAs(UnmanagedType.U1)]
        public bool lfItalic;
        [MarshalAs(UnmanagedType.U1)]
        public bool lfUnderline;
        [MarshalAs(UnmanagedType.U1)]
        public bool lfStrikeOut;
        public FontCharSet lfCharSet;
        public FontPrecision lfOutPrecision;
        public FontClipPrecision lfClipPrecision;
        public FontQuality lfQuality;
        public FontPitchAndFamily lfPitchAndFamily;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string lfFaceName;
    }


public enum FontWeight : int
    {
        FW_DONTCARE = 0,
        FW_THIN = 100,
        FW_EXTRALIGHT = 200,
        FW_LIGHT = 300,
        FW_NORMAL = 400,
        FW_MEDIUM = 500,
        FW_SEMIBOLD = 600,
        FW_BOLD = 700,
        FW_EXTRABOLD = 800,
        FW_HEAVY = 900,
    }
    public enum FontCharSet : byte
    {
        ANSI_CHARSET = 0,
        DEFAULT_CHARSET = 1,
        SYMBOL_CHARSET = 2,
        SHIFTJIS_CHARSET = 128,
        HANGEUL_CHARSET = 129,
        HANGUL_CHARSET = 129,
        GB2312_CHARSET = 134,
        CHINESEBIG5_CHARSET = 136,
        OEM_CHARSET = 255,
        JOHAB_CHARSET = 130,
        HEBREW_CHARSET = 177,
        ARABIC_CHARSET = 178,
        GREEK_CHARSET = 161,
        TURKISH_CHARSET = 162,
        VIETNAMESE_CHARSET = 163,
        THAI_CHARSET = 222,
        EASTEUROPE_CHARSET = 238,
        RUSSIAN_CHARSET = 204,
        MAC_CHARSET = 77,
        BALTIC_CHARSET = 186,
    }
    public enum FontPrecision : byte
    {
        OUT_DEFAULT_PRECIS = 0,
        OUT_STRING_PRECIS = 1,
        OUT_CHARACTER_PRECIS = 2,
        OUT_STROKE_PRECIS = 3,
        OUT_TT_PRECIS = 4,
        OUT_DEVICE_PRECIS = 5,
        OUT_RASTER_PRECIS = 6,
        OUT_TT_ONLY_PRECIS = 7,
        OUT_OUTLINE_PRECIS = 8,
        OUT_SCREEN_OUTLINE_PRECIS = 9,
        OUT_PS_ONLY_PRECIS = 10,
    }
    public enum FontClipPrecision : byte
    {
        CLIP_DEFAULT_PRECIS = 0,
        CLIP_CHARACTER_PRECIS = 1,
        CLIP_STROKE_PRECIS = 2,
        CLIP_MASK = 0xf,
        CLIP_LH_ANGLES = (1 << 4),
        CLIP_TT_ALWAYS = (2 << 4),
        CLIP_DFA_DISABLE = (4 << 4),
        CLIP_EMBEDDED = (8 << 4),
    }
    public enum FontQuality : byte
    {
        DEFAULT_QUALITY = 0,
        DRAFT_QUALITY = 1,
        PROOF_QUALITY = 2,
        NONANTIALIASED_QUALITY = 3,
        ANTIALIASED_QUALITY = 4,
        CLEARTYPE_QUALITY = 5,
        CLEARTYPE_NATURAL_QUALITY = 6,
    }
    [Flags]
    public enum FontPitchAndFamily : byte
    {
        DEFAULT_PITCH = 0,
        FIXED_PITCH = 1,
        VARIABLE_PITCH = 2,
        FF_DONTCARE = (0 << 4),
        FF_ROMAN = (1 << 4),
        FF_SWISS = (2 << 4),
        FF_MODERN = (3 << 4),
        FF_SCRIPT = (4 << 4),
        FF_DECORATIVE = (5 << 4),
    }

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct NEWTEXTMETRIC
    {
        public int tmHeight;
        public int tmAscent;
        public int tmDescent;
        public int tmInternalLeading;
        public int tmExternalLeading;
        public int tmAveCharWidth;
        public int tmMaxCharWidth;
        public int tmWeight;
        public int tmOverhang;
        public int tmDigitizedAspectX;
        public int tmDigitizedAspectY;
        public char tmFirstChar;
        public char tmLastChar;
        public char tmDefaultChar;
        public char tmBreakChar;
        public byte tmItalic;
        public byte tmUnderlined;
        public byte tmStruckOut;
        public byte tmPitchAndFamily;
        public byte tmCharSet;
        int ntmFlags;
        int ntmSizeEM;
        int ntmCellHeight;
        int ntmAvgWidth;
    }
    public struct FONTSIGNATURE
    {
        [MarshalAs(UnmanagedType.ByValArray)]
        int[] fsUsb;
        [MarshalAs(UnmanagedType.ByValArray)]
        int[] fsCsb;
    }
    public struct NEWTEXTMETRICEX
    {
        NEWTEXTMETRIC ntmTm;
        FONTSIGNATURE ntmFontSig;
    }

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct ENUMLOGFONTEX
    {
        public LOGFONT elfLogFont;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
        public string elfFullName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string elfStyle;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string elfScript;
    }

    private const byte DEFAULT_CHARSET = 1;
    private const byte SHIFTJIS_CHARSET = 128;
    private const byte JOHAB_CHARSET = 130;
    private const byte EASTEUROPE_CHARSET = 238;

    private const byte DEFAULT_PITCH = 0;
    private const byte FIXED_PITCH = 1;
    private const byte VARIABLE_PITCH = 2;
    private const byte FF_DONTCARE = (0 << 4);
    private const byte FF_ROMAN = (1 << 4);
    private const byte FF_SWISS = (2 << 4);
    private const byte FF_MODERN = (3 << 4);
    private const byte FF_SCRIPT = (4 << 4);
    private const byte FF_DECORATIVE = (5 << 4);

…

private void TestForm_Load(object sender, EventArgs e)
    {
        LOGFONT lf = CreateLogFont("");

        IntPtr plogFont = Marshal.AllocHGlobal(Marshal.SizeOf(lf));
        Marshal.StructureToPtr(lf, plogFont, true);

        int ret = 0;
        try
        {
            Graphics G = pictureBox1.CreateGraphics();
            IntPtr P = G.GetHdc();

            del1 = new EnumFontExDelegate(callback1);
            ret = EnumFontFamiliesEx(P, plogFont, del1, IntPtr.Zero, 0);

            System.Diagnostics.Trace.WriteLine("EnumFontFamiliesEx = " + ret.ToString());

            G.ReleaseHdc(P);
        }
        catch
        {
            System.Diagnostics.Trace.WriteLine("Error!");
        }
        finally
        {
            Marshal.DestroyStructure(plogFont, typeof(LOGFONT));

        }
    }

public delegate int EnumFontExDelegate(ref ENUMLOGFONTEX lpelfe, ref NEWTEXTMETRICEX lpntme, int FontType, int lParam);
    public EnumFontExDelegate del1;


    public int callback1(ref ENUMLOGFONTEX lpelfe, ref NEWTEXTMETRICEX lpntme, int FontType, int lParam)
    {
        try
        { 
        // Do something cool
        }
        catch (Exception e)
        {
            System.Diagnostics.Trace.WriteLine(e.ToString());
        }
        return cnt;
    }

public static LOGFONT CreateLogFont(string fontname)
    {
        LOGFONT lf = new LOGFONT();
        lf.lfHeight = 0;
        lf.lfWidth = 0;
        lf.lfEscapement = 0;
        lf.lfOrientation = 0;
        lf.lfWeight = 0;
        lf.lfItalic = false;
        lf.lfUnderline = false;
        lf.lfStrikeOut = false;
        lf.lfCharSet = FontCharSet.DEFAULT_CHARSET;
        lf.lfOutPrecision = 0;
        lf.lfClipPrecision = 0;
        lf.lfQuality = 0;
        lf.lfPitchAndFamily =  FontPitchAndFamily.FF_DONTCARE;
        lf.lfFaceName = "";


        return lf;
    }