ASP.NET Core 8 API从PrintDocument迁移至Microsoft.Maui.Graphics的打印疑问

微软推荐使用Microsoft.Maui.Graphics的核心含义 #

PrintDocument是Windows专属API，无法在跨平台的ASP.NET Core环境中正常运行。微软推荐Microsoft.Maui.Graphics的逻辑是：它提供了跨平台的统一图形渲染能力，可以用一套代码生成打印所需的文本、图形、布局内容，再结合不同平台的打印触发机制完成打印。

MAUI本身的打印能力依赖底层平台的原生打印服务，而Microsoft.Maui.Graphics负责的是内容的跨平台绘制，而非直接提供打印调用接口。对于ASP.NET Core Web API这种服务端场景，有两种典型路径：

1. 跨平台路径：服务端用Microsoft.Maui.Graphics生成PDF/图片格式的可打印内容，返回给客户端，由客户端调用自身平台的打印功能（比如浏览器打印PDF、桌面应用调用系统打印API）。
2. Windows专属路径：如果API仅部署在Windows环境，可结合Microsoft.Maui.Graphics生成内容，再调用Windows原生打印API（如System.Printing）直接在服务端完成打印，兼容原有PrintDocument的使用逻辑，但失去跨平台特性。

跨平台打印内容生成POC #

这个示例通过Microsoft.Maui.Graphics生成测试打印内容并导出为PDF，API返回PDF文件后，可由客户端发起打印。

步骤1：安装依赖NuGet包 #

Install-Package Microsoft.Maui.Graphics
Install-Package Microsoft.Maui.Graphics.Skia

步骤2：代码实现 #

using Microsoft.Maui.Graphics;
using Microsoft.Maui.Graphics.Skia;
using System.IO;

public class PrintContentGenerator
{
    public byte[] GenerateTestPrintPage()
    {
        // A4纸尺寸（96DPI下约794x1123像素）
        int pageWidth = 794;
        int pageHeight = 1123;

        // 使用Skia渲染器创建画布
        using var bitmapContext = new SkiaBitmapExportContext(pageWidth, pageHeight, 96);
        ICanvas canvas = bitmapContext.Canvas;

        // 绘制页面背景
        canvas.FillColor = Colors.White;
        canvas.FillRectangle(0, 0, pageWidth, pageHeight);

        // 绘制标题
        canvas.Font = new Font("Arial", 24, FontWeight.Bold);
        canvas.TextColor = Colors.Black;
        canvas.DrawString("跨平台测试打印页", 50, 50, pageWidth - 100, HorizontalAlignment.Center);

        // 绘制正文文本
        canvas.Font = new Font("Arial", 12);
        canvas.DrawString("此内容由Microsoft.Maui.Graphics跨平台生成，可导出为PDF供客户端打印", 50, 150, pageWidth - 100, HorizontalAlignment.Left);

        // 绘制测试图形
        canvas.StrokeColor = Colors.DarkBlue;
        canvas.StrokeSize = 2;
        canvas.DrawRectangle(50, 200, pageWidth - 100, 120);
        canvas.DrawString("测试图形区域", 50, 240, pageWidth - 100, HorizontalAlignment.Center);

        // 导出为PDF字节数组
        using var stream = new MemoryStream();
        bitmapContext.WriteToStream(stream, ImageFormat.Pdf);
        return stream.ToArray();
    }
}

// API控制器
[ApiController]
[Route("api/print")]
public class PrintController : ControllerBase
{
    private readonly PrintContentGenerator _contentGenerator;

    public PrintController(PrintContentGenerator contentGenerator)
    {
        _contentGenerator = contentGenerator;
    }

    [HttpGet("generate-test-page")]
    public IActionResult GetTestPrintPage()
    {
        byte[] pdfBytes = _contentGenerator.GenerateTestPrintPage();
        return File(pdfBytes, "application/pdf", "TestPrintPage.pdf");
    }
}

Windows专属服务端直接打印POC #

如果你的API仅部署在Windows服务器，可结合Microsoft.Maui.Graphics生成内容，调用Windows原生打印API直接发起打印任务。

步骤1：安装依赖NuGet包 #

Install-Package Microsoft.Maui.Graphics
Install-Package Microsoft.Maui.Graphics.Skia
Install-Package System.Printing

步骤2：代码实现 #

using Microsoft.Maui.Graphics;
using Microsoft.Maui.Graphics.Skia;
using System.IO;
using System.Printing;
using System.Windows.Media;
using System.Windows.Media.Imaging;

public class WindowsPrintService
{
    public void SubmitTestPrintJob()
    {
        // 生成打印内容为Bitmap
        int pageWidth = 794;
        int pageHeight = 1123;
        using var bitmapContext = new SkiaBitmapExportContext(pageWidth, pageHeight, 96);
        ICanvas canvas = bitmapContext.Canvas;

        // 绘制内容（同跨平台示例）
        canvas.FillColor = Colors.White;
        canvas.FillRectangle(0, 0, pageWidth, pageHeight);
        canvas.Font = new Font("Arial", 24, FontWeight.Bold);
        canvas.DrawString("Windows服务端测试打印页", 50, 50, pageWidth - 100, HorizontalAlignment.Center);

        // 转换为WPF BitmapImage（适配Windows打印API）
        using var stream = new MemoryStream();
        bitmapContext.WriteToStream(stream, ImageFormat.Png);
        stream.Seek(0, SeekOrigin.Begin);
        var bitmapImage = new BitmapImage();
        bitmapImage.BeginInit();
        bitmapImage.StreamSource = stream;
        bitmapImage.EndInit();

        // 获取默认打印机队列
        PrintQueue printQueue = LocalPrintServer.GetDefaultPrintQueue();
        PrintTicket printTicket = printQueue.DefaultPrintTicket;

        // 创建打印视觉对象
        var visual = new DrawingVisual();
        using (DrawingContext dc = visual.RenderOpen())
        {
            // 适配打印机页面尺寸
            PageMediaSize pageSize = printTicket.PageMediaSize;
            dc.DrawImage(bitmapImage, new System.Windows.Rect(0, 0, pageSize.Width.Value, pageSize.Height.Value));
        }

        // 提交打印任务
        using var printDocument = new System.Windows.Documents.PrintDocument();
        printDocument.DocumentPaginator = new SinglePagePaginator(visual);
        printDocument.Print(printTicket);
    }
}

// 自定义单页分页器
public class SinglePagePaginator : System.Windows.Documents.DocumentPaginator
{
    private readonly Visual _printVisual;
    private readonly Size _pageSize;

    public SinglePagePaginator(Visual visual)
    {
        _printVisual = visual;
        _pageSize = new Size(8.5 * 96, 11 * 96); // 8.5x11英寸，96DPI
    }

    public override bool IsPageCountValid => true;
    public override int PageCount => 1;
    public override Size PageSize { get => _pageSize; set => _pageSize = value; }
    public override IDocumentPaginatorSource Source => null;

    public override DocumentPage GetPage(int pageNumber)
    {
        return new DocumentPage(_printVisual, PageSize, new Rect(PageSize), new Rect(PageSize));
    }
}

// API控制器
[ApiController]
[Route("api/print")]
public class PrintController : ControllerBase
{
    private readonly WindowsPrintService _printService;

    public PrintController(WindowsPrintService printService)
    {
        _printService = printService;
    }

    [HttpPost("print-test-page")]
    public IActionResult PrintTestPage()
    {
        if (!OperatingSystem.IsWindows())
        {
            return BadRequest("此打印功能仅支持Windows操作系统");
        }

        _printService.SubmitTestPrintJob();
        return Ok("打印任务已提交至默认打印机");
    }
}

内容的提问来源于stack exchange，提问作者Axel Samyn