在 PdfSharp 中使用私有字体
在 PdfSharp 中使用私有字体
在 PdfSharp 1.5 中提供了在 Web 服务器上使用私有字体的示例，见：http://www.pdfsharp.net/wiki/(X(1)S(mg0wojiafv2wdqhklvachrti))/FontResolver-sample.ashx。
注意：FontResolver 是一个全局对象，应用于 PdfSharp 库的所有消费者。也被 MigraDoc 库用于创建 PDF 文档。
1. 私有字体
JetBrain 是一套适合程序员使用的字体，我从 https://www.jetbrains.com/lp/mono/ 下载了它，下载下来的文件是一个 Zip 包，解压之后，里面是多个 TrueType 格式的字体文件，文件名的氛围两部分组成，以中划线分隔，前面都是 JetBrainsMono，后面是字体的风格。例如，对于普通的字体来说，就是 JetBrainsMono-Regular.ttf 这个字体文件。粗体对应的字体文件是 JetBrainsMono-Bold.ttf，而斜体对应的字体文件是 JetBrains-Mono-Italic.ttf。
我还下载了一个微软雅慧的 TrueType 字体文件。名称为 YaHei.ttf。通过它来使用中文字体。
字体族和字体
这里有两个概念：字体家族 Font Family 和 字体 Font Face。
Font Family 是一套字体的名称，例如，对于 JetBrains Mono 字体家族来说，这就是一套字体的名称。而一套字体内部，有包括了普通字体，粗体，斜体等等多种具体的字体。这些最终的字体称为 Font Face。
当使用字体的时候，我们需要提供字体家族的名称，具体对应的样式，它们组合起来，我们可以得到实际使用的字体文件，最终得到 TrueType 字体数据。
下面的示例将展示如何使用这两种字体。
2. IFontResolver 接口
PdfSharp 通过 IFontResolver 接口定义了如何获取字体。该接口定义如下。见：https://github.com/empira/PDFsharp/blob/master/src/PdfSharp/Fonts/IFontResolver.cs
namespace PdfSharp.Fonts
{
/// <summary>
/// Provides functionality that converts a requested typeface into a physical font.
/// </summary>
public interface IFontResolver
{
/// <summary>
/// Converts specified information about a required typeface into a specific font.
/// </summary>
/// <param name="familyName">Name of the font family.</param>
/// <param name="isBold">Set to <c>true</c> when a bold fontface is required.</param>
/// <param name="isItalic">Set to <c>true</c> when an italic fontface is required.</param>
/// <returns>Information about the physical font, or null if the request cannot be satisfied.</returns>
FontResolverInfo ResolveTypeface(string familyName, bool isBold, bool isItalic);
//FontResolverInfo ResolveTypeface(Typeface); TODO in PDFsharp 2.0
/// <summary>
/// Gets the bytes of a physical font with specified face name.
/// </summary>
/// <param name="faceName">A face name previously retrieved by ResolveTypeface.</param>
byte[] GetFont(string faceName);
}
}
接口定义了两个方法。
2.1 ResolveTypeface
获得字体信息。将需要使用的特定字体信息表示为一个 FontResolverInfo 对象。需要提供字体家族名称，是否粗体，是否泄题。
对于字体来说，我们需要提供一个字体族的名称来代表一类字体，在内部，我们需要针对每种具体的字形，定义出针对每种字形的字符串名称。通过字符串常量定义出来。
/// <summary>
/// The font family names that can be used in the constructor of XFont.
/// Used in the first parameter of ResolveTypeface.
/// Family names are given in lower case because the implementation of JetBrainsMonoFontResolver ignores case.
/// </summary>
static class FamilyNames
{
public const string JetBrainsMonoRegular = "JetBrains Mono";
public const string HansRegular = "Hans";
}
内部在实际使用字体的时候，使用的是字形名称。对于字形信息，定义如下的字符串常量。
/// <summary>
/// The internal names that uniquely identify a font's type faces (i.e. a physical font file).
/// Used in the first parameter of the FontResolverInfo constructor.
/// </summary>
static class FaceNames
{
public const string JetBrainsMonoRegular = "JetBrainsMono-Regular";
public const string JetBrainsMonoBold = "JetBrainsMono-Bold";
public const string JetBrainsMonoBoldItalic = "JetBrainsMono-Bold-Italic";
public const string HansRegular = "SourceHanSerif";
}
在 ResolveTypeface() 方法内部，需要实现将字体族名称和样式的组合对应到实际的字形映射。
针对对应的字体族名称，以及所希望使用的字体样式，来找到对应的字形名称。
public FontResolverInfo ResolveTypeface(string familyName, bool isBold, bool isItalic)
{
// Note: PDFsharp calls ResolveTypeface only once for each unique combination
// of familyName, isBold, and isItalic.
string lowerFamilyName = familyName.ToLowerInvariant();
// Looking for a JetBrains Mono font?
if (lowerFamilyName.StartsWith("jetBrains mono") || lowerFamilyName.StartsWith("hans"))
{
// Bold simulation is not recommended, but used here for demonstration.
bool simulateBold = false;
// Since Segoe WP typefaces do not contain any italic font
// always simulate italic if it is requested.
bool simulateItalic = false;
string faceName;
// In this sample family names are case sensitive. You can relax this in your own implementation
// and make them case insensitive.
switch (familyName)
{
case FamilyNames.JetBrainsMonoRegular:
faceName = FaceNames.JetBrainsMonoRegular;
break;
case FamilyNames.HansRegular:
faceName = FaceNames.HansRegular;
break;
default:
Debug.Assert(false, "Unknown JetBrains Mono font: " + lowerFamilyName);
goto case FamilyNames.JetBrainsMonoRegular; // Alternatively throw an exception in this case.
}
// Tell the caller the effective typeface name and whether bold or italic should be simulated.
return new FontResolverInfo(faceName, simulateBold, simulateItalic);
}
// Return null means that the typeface cannot be resolved and PDFsharp stops working.
// Alternatively forward call to PlatformFontResolver.
return PlatformFontResolver.ResolveTypeface(familyName, isBold, isItalic);
}
使用系统字体
如果没有提供对应的私有字体，使用平台所提供的字体。
return PlatformFontResolver.ResolveTypeface(familyName, isBold, isItalic);
2.2 GetFont()
根据字符串格式的字体名称，获得 TrueType 字体数据。注意这里使用的是字体名称而不是字体族名称。实际返回的是 TrueType 字体数据。
public byte[] GetFont(string faceName)
{
// Note: PDFsharp never calls GetFont twice with the same face name.
// Return the bytes of a font.
switch (faceName)
{
case FaceNames.JetBrainsMonoBold:
return FontDataHelper.JetBrainsMonoBold;
case FaceNames.JetBrainsMonoRegular:
return FontDataHelper.JetBrainsMonoRegular;
case FaceNames.HansRegular:
return FontDataHelper.HanSerif;
}
// PDFsharp never calls GetFont with a face name that was not returned by ResolveTypeface.
throw new ArgumentException(String.Format("Invalid typeface name '{0}'", faceName));
}
3. 实现
using PdfSharp.Fonts;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
/*
* An sample at: https://github.com/empira/PDFsharp-samples/blob/master/samples/core/FontResolver/SegoeWpFontResolver.cs
*/
namespace pdfSharpStarter.PrivateFonts
{
public class JetBrainsMonoFontResolver : IFontResolver
{
/// <summary>
/// The font family names that can be used in the constructor of XFont.
/// Used in the first parameter of ResolveTypeface.
/// Family names are given in lower case because the implementation of JetBrainsMonoFontResolver ignores case.
/// </summary>
static class FamilyNames
{
public const string JetBrainsMonoRegular = "JetBrains Mono";
public const string HansRegular = "Hans";
}
/// <summary>
/// The internal names that uniquely identify a font's type faces (i.e. a physical font file).
/// Used in the first parameter of the FontResolverInfo constructor.
/// </summary>
static class FaceNames
{
public const string JetBrainsMonoRegular = "JetBrainsMono-Regular";
public const string JetBrainsMonoBold = "JetBrainsMono-Bold";
public const string JetBrainsMonoBoldItalic = "JetBrainsMono-Bold-Italic";
public const string HansRegular = "SourceHanSerif";
}
/// <summary>
/// Converts specified information about a required typeface into a specific font.
/// </summary>
/// <param name="familyName">Name of the font family.</param>
/// <param name="isBold">Set to <c>true</c> when a bold fontface is required.</param>
/// <param name="isItalic">Set to <c>true</c> when an italic fontface is required.</param>
/// <returns>
/// Information about the physical font, or null if the request cannot be satisfied.
/// </returns>
public FontResolverInfo ResolveTypeface(string familyName, bool isBold, bool isItalic)
{
// Note: PDFsharp calls ResolveTypeface only once for each unique combination
// of familyName, isBold, and isItalic.
string lowerFamilyName = familyName.ToLowerInvariant();
// Looking for a JetBrains Mono font?
if (lowerFamilyName.StartsWith("jetBrains mono") || lowerFamilyName.StartsWith("hans"))
{
// Bold simulation is not recommended, but used here for demonstration.
bool simulateBold = false;
// Since Segoe WP typefaces do not contain any italic font
// always simulate italic if it is requested.
bool simulateItalic = false;
string faceName;
// In this sample family names are case sensitive. You can relax this in your own implementation
// and make them case insensitive.
switch (familyName)
{
case FamilyNames.JetBrainsMonoRegular:
faceName = FaceNames.JetBrainsMonoRegular;
break;
case FamilyNames.HansRegular:
faceName = FaceNames.HansRegular;
break;
default:
Debug.Assert(false, "Unknown JetBrains Mono font: " + lowerFamilyName);
goto case FamilyNames.JetBrainsMonoRegular; // Alternatively throw an exception in this case.
}
// Tell the caller the effective typeface name and whether bold or italic should be simulated.
return new FontResolverInfo(faceName, simulateBold, simulateItalic);
}
// Return null means that the typeface cannot be resolved and PDFsharp stops working.
// Alternatively forward call to PlatformFontResolver.
return PlatformFontResolver.ResolveTypeface(familyName, isBold, isItalic);
}
public byte[] GetFont(string faceName)
{
// Note: PDFsharp never calls GetFont twice with the same face name.
// Return the bytes of a font.
switch (faceName)
{
case FaceNames.JetBrainsMonoBold:
return FontDataHelper.JetBrainsMonoBold;
case FaceNames.JetBrainsMonoRegular:
return FontDataHelper.JetBrainsMonoRegular;
case FaceNames.HansRegular:
return FontDataHelper.HanSerif;
}
// PDFsharp never calls GetFont with a face name that was not returned by ResolveTypeface.
throw new ArgumentException(String.Format("Invalid typeface name '{0}'", faceName));
}
}
}
辅助类
这里使用了嵌入到程序集内的资源。
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
namespace pdfSharpStarter.PrivateFonts
{
/*
* pdfSharpStarter.Resources.ttf.JetBrainsMono-Bold.ttf
* pdfSharpStarter.Resources.ttf.JetBrainsMono-Light.ttf
* pdfSharpStarter.Resources.ttf.JetBrainsMono-Regular.ttf
*/
public static class FontDataHelper
{
public static byte[] JetBrainsMonoRegular
{
get { return LoadFontData("pdfSharpStarter.Resources.ttf.JetBrainsMono-Regular.ttf"); }
}
public static byte[] JetBrainsMonoBold
{
get { return LoadFontData("pdfSharpStarter.Resources.ttf.JetBrainsMono-Bold.ttf"); }
}
public static byte[] HanSerif
{
get { return LoadFontData("pdfSharpStarter.Resources.YaHei.ttf"); }
}
static byte[] LoadFontData(string name)
{
Assembly assembly = typeof(FontDataHelper).Assembly;
using (Stream stream = assembly.GetManifestResourceStream(name))
{
if (stream == null)
throw new ArgumentException("No resource with name " + name);
var count = (int)stream.Length;
var data = new byte[count];
stream.Read(data, 0, count);
return data;
}
}
}
}
4. 使用私有字体
注册
// REgister font resolver before start using PDFSharp
PdfSharp.Fonts.GlobalFontSettings.FontResolver
= new PrivateFonts.JetBrainsMonoFontResolver();
使用字体
下面创建了 2 种字体进行绘制。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace pdfSharpStarter.PrivateFonts
{
/*
* REgister font resolver before start using PDFSharp
*
* PdfSharp.Fonts.GlobalFontSettings.FontResolver
* = new PrivateFonts.JetBrainsMonoFontResolver();
*/
public class PrivateFontsSample
{
public static void Demo()
{
// Create a new PDF document.
var document = new PdfSharp.Pdf.PdfDocument();
document.Info.Title = "Font Resolver Sample";
// Create an empty page in this document.
var page = document.AddPage();
page.Size = PdfSharp.PageSize.A4;
// Get an XGraphics object for drawing on this PDF page.
var gfx = PdfSharp.Drawing.XGraphics.FromPdfPage(page);
// Create some fonts.
const double fontSize = 24;
PdfSharp.Drawing.XPdfFontOptions options
= new PdfSharp.Drawing.XPdfFontOptions(
PdfSharp.Pdf.PdfFontEncoding.Unicode);
var font = new PdfSharp.Drawing.XFont("JetBrains Mono", fontSize, PdfSharp.Drawing.XFontStyle.Regular, options);
var cfont = new PdfSharp.Drawing.XFont("Hans", fontSize, PdfSharp.Drawing.XFontStyle.Regular, options);
// Draw the text.
const double x = 40;
double y = 50;
const string ctext = "字体：JetBrains Mono";
gfx.DrawString(ctext, cfont, PdfSharp.Drawing.XBrushes.Black, x, y);
y += 60;
const string text1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
gfx.DrawString(text1, font, PdfSharp.Drawing.XBrushes.Black, x, y);
y += 60;
const string text2 = "abcdefghijklmnopqrstuvwxyz";
gfx.DrawString(text2, font, PdfSharp.Drawing.XBrushes.Black, x, y);
y += 60;
const string text3 = "0123456789";
gfx.DrawString(text3, font, PdfSharp.Drawing.XBrushes.Black, x, y);
y += 60;
// Save the document...
const string filename = "../../../Output/FontResolver_tempfile.pdf";
document.Save(filename);
// ...and start a viewer.
}
}
}
