FontCollection.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Runtime.InteropServices;
using Gdip = System.Drawing.SafeNativeMethods.Gdip;

namespace System.Drawing.Text;

/// <summary>
/// When inherited, enumerates the FontFamily objects in a collection of fonts.
/// </summary>
public abstract class FontCollection : IDisposable
{
    internal IntPtr _nativeFontCollection;

    internal FontCollection() => _nativeFontCollection = IntPtr.Zero;

    /// <summary>
    /// Disposes of this <see cref='System.Drawing.Text.FontCollection'/>
    /// </summary>
    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing) { }

    /// <summary>
    /// Gets the array of <see cref='System.Drawing.FontFamily'/> objects associated
    /// with this <see cref='System.Drawing.Text.FontCollection'/>.
    /// </summary>
    public FontFamily[] Families
    {
        get
        {
            int numSought;
            int status = Gdip.GdipGetFontCollectionFamilyCount(new HandleRef(this, _nativeFontCollection), out numSought);
            Gdip.CheckStatus(status);

            var gpfamilies = new IntPtr[numSought];
            int numFound;
            status = Gdip.GdipGetFontCollectionFamilyList(new HandleRef(this, _nativeFontCollection), numSought, gpfamilies,
                                                         out numFound);
            Gdip.CheckStatus(status);

            Debug.Assert(numSought == numFound, "GDI+ can't give a straight answer about how many fonts there are");
            var families = new FontFamily[numFound];
            for (int f = 0; f < numFound; f++)
            {
                IntPtr native;
                Gdip.GdipCloneFontFamily(gpfamilies[f], out native);
                families[f] = new FontFamily(native);
            }

            return families;
        }
    }

    ~FontCollection() => Dispose(false);
}