YD_Event.Admin/YD_Event.Application/Certificate/CertificateFontHelper.cs

using QuestPDF.Fluent;
using QuestPDF.Helpers;
using QuestPDF.Infrastructure;
using System.Runtime.InteropServices;
using Microsoft.Extensions.Logging;

namespace YD_Event.Application.Certificate;

/// <summary>
/// 证书字体助手 - 可靠的中文字体处理
/// </summary>
public static class CertificateFontHelper
{
    private static bool _fontConfigured = false;
    private static readonly object _lock = new();
    private static string _selectedFont = null;

    /// <summary>
    /// 配置 QuestPDF 中文字体
    /// </summary>
    public static void ConfigureFonts(ILogger logger)
    {
        if (_fontConfigured) return;

        lock (_lock)
        {
            if (_fontConfigured) return;

            try
            {
                logger.LogInformation("开始配置 QuestPDF 中文字体...");

                // 设置许可证
                QuestPDF.Settings.License = LicenseType.Community;

                // 检测并选择中文字体
                _selectedFont = FindAvailableChineseFont(logger);

                if (!string.IsNullOrEmpty(_selectedFont))
                {
                    logger.LogInformation($"成功选中中文字体: {_selectedFont}");
                }
                else
                {
                    logger.LogWarning("未找到中文字体，将使用默认字体");
                }

                _fontConfigured = true;
                logger.LogInformation("QuestPDF 字体配置完成");
            }
            catch (Exception ex)
            {
                logger.LogError(ex, "配置字体时出错");
            }
        }
    }

    /// <summary>
    /// 查找可用的中文字体
    /// </summary>
    private static string FindAvailableChineseFont(ILogger logger)
    {
        var fontList = GetFontCandidates();

        foreach (var font in fontList)
        {
            try
            {
                logger.LogDebug($"尝试字体: {font}");
                if (TestFont(font))
                {
                    logger.LogInformation($"字体可用: {font}");
                    return font;
                }
            }
            catch (Exception ex)
            {
                logger.LogDebug(ex, $"字体测试失败: {font}");
            }
        }

        return null;
    }

    /// <summary>
    /// 获取字体候选列表（按优先级排序）
    /// </summary>
    private static string[] GetFontCandidates()
    {
        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
        {
            return new[]
            {
                "Microsoft YaHei",      // 微软雅黑
                "SimHei",              // 黑体
                "SimSun",              // 宋体
                "Microsoft YaHei UI",
                "Segoe UI",
                "Arial Unicode MS"
            };
        }
        else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
        {
            return new[]
            {
                "WenQuanYi Zen Hei",
                "WenQuanYi Micro Hei",
                "Noto Sans CJK SC",
                "Noto Sans SC",
                "DejaVu Sans",
                "Droid Sans Fallback"
            };
        }
        else
        {
            return new[]
            {
                "PingFang SC",         // macOS
                "Heiti SC",
                "STSong",
                "Arial Unicode MS"
            };
        }
    }

    /// <summary>
    /// 测试字体是否可用
    /// </summary>
    private static bool TestFont(string fontName)
    {
        try
        {
            using var stream = new MemoryStream();
            
            Document.Create(container =>
            {
                container.Page(page =>
                {
                    page.DefaultTextStyle(x => x.FontFamily(fontName));
                    page.Content().Text("测试中文 Test");
                });
            }).GeneratePdf(stream);

            return stream.Length > 0;
        }
        catch
        {
            return false;
        }
    }

    /// <summary>
    /// 获取选中的字体
    /// </summary>
    public static string GetSelectedFont()
    {
        return _selectedFont;
    }

    /// <summary>
    /// 应用字体到文本样式
    /// </summary>
    public static TextStyle ApplyFont(TextStyle style)
    {
        if (!string.IsNullOrEmpty(_selectedFont))
        {
            try
            {
                return style.FontFamily(_selectedFont);
            }
            catch
            {
                // 如果字体应用失败，使用默认字体
            }
        }
        return style;
    }
}