C#：检查字体中是否有不支持的字符/字形

Question

我正在开发一个翻译软件插件（C#、.NET 2.0），它在模拟设备显示屏中显示翻译后的文本。 我必须检查所有翻译的文本是否可以使用指定字体（Windows TTF）显示。 但我没有找到任何方法来检查字体是否有不受支持的字形。 有人有想法吗？

谢谢

Answer 1

您是否仅限于 .NET 2.0？在.NET 3.0或更高版本中，有GlyphTypeface类，它可以加载字体文件并公开CharacterToGlyphMap属性，我相信它可以做你想要的事情。

在 .NET 2.0 中，我认为您必须依赖 PInvoke。尝试类似的方法：

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

[DllImport("gdi32.dll", EntryPoint = "GetGlyphIndicesW")]
private static extern uint GetGlyphIndices([In] IntPtr hdc, [In] [MarshalAs(UnmanagedType.LPTStr)] string lpsz, int c, [Out] ushort[] pgi, uint fl);

[DllImport("gdi32.dll")]
private static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);

private const uint GGI_MARK_NONEXISTING_GLYPHS = 0x01;

// Create a dummy Graphics object to establish a device context
private Graphics _graphics = Graphics.FromImage(new Bitmap(1, 1));

public bool DoesGlyphExist(char c, Font font)
{
  // Get a device context from the dummy Graphics 
  IntPtr hdc = _graphics.GetHdc();
  ushort[] glyphIndices;

  try {
    IntPtr hfont = font.ToHfont();

    // Load the font into the device context
    SelectObject(hdc, hfont);

    string testString = new string(c, 1);
    glyphIndices = new ushort[testString.Length];

    GetGlyphIndices(hdc, testString, testString.Length, glyphIndices, GGI_MARK_NONEXISTING_GLYPHS);

  } finally {

    // Clean up our mess
    _graphics.ReleaseHdc(hdc);
  }

  // 0xffff is the value returned for a missing glyph
  return (glyphIndices[0] != 0xffff);
}

private void Test()
{
  Font f = new Font("Courier New", 10);

  // Glyph for A is found -- returns true
  System.Diagnostics.Debug.WriteLine(DoesGlyphExist('A', f).ToString()); 

  // Glyph for ಠ is not found -- returns false
  System.Diagnostics.Debug.WriteLine(DoesGlyphExist((char) 0xca0, f).ToString()); 
}