client/Services/Printing/RawPrintJobExecutor.cs

using CloudPrint.Client.Helpers;
using CloudPrint.Client.Models;
using System.IO;

namespace CloudPrint.Client.Services.Printing;

public sealed class RawPrintJobExecutor : IPrintJobExecutor
{
    public bool CanHandle(PrintJob job) => true;

    public async Task ExecuteAsync(PrintJob job, IProgress<int>? progress, CancellationToken cancellationToken = default)
    {
        PrintFileGuards.EnsurePrintableFile(job);

        if (!WindowsPrintApi.OpenPrinter(job.PrinterName, out var printerHandle, IntPtr.Zero))
        {
            throw new InvalidOperationException($"打开打印机失败：{job.PrinterName}");
        }

        try
        {
            var docInfo = new WindowsPrintApi.DocInfo
            {
                DocumentName = string.IsNullOrWhiteSpace(job.FileName) ? job.JobNo : job.FileName,
                DataType = "RAW"
            };

            var windowsJobId = WindowsPrintApi.StartDocPrinter(printerHandle, 1, docInfo);
            if (windowsJobId == 0)
            {
                throw new InvalidOperationException("启动打印文档失败");
            }

            job.WindowsJobId = windowsJobId;
            job.WindowsJobStatus = "已提交到 Windows 打印队列";

            try
            {
                if (!WindowsPrintApi.StartPagePrinter(printerHandle))
                {
                    throw new InvalidOperationException("启动打印页面失败");
                }

                try
                {
                    await WriteFileToPrinterAsync(printerHandle, job.FilePath, progress, cancellationToken).ConfigureAwait(true);
                }
                finally
                {
                    WindowsPrintApi.EndPagePrinter(printerHandle);
                }
            }
            finally
            {
                WindowsPrintApi.EndDocPrinter(printerHandle);
            }
        }
        finally
        {
            WindowsPrintApi.ClosePrinter(printerHandle);
        }
    }

    private static async Task WriteFileToPrinterAsync(IntPtr printerHandle, string filePath, IProgress<int>? progress, CancellationToken cancellationToken)
    {
        const int bufferSize = 64 * 1024;
        var buffer = new byte[bufferSize];
        var fileInfo = new FileInfo(filePath);
        long totalWritten = 0;

        await using var stream = File.OpenRead(filePath);
        while (true)
        {
            cancellationToken.ThrowIfCancellationRequested();
            var read = await stream.ReadAsync(buffer.AsMemory(0, buffer.Length), cancellationToken).ConfigureAwait(true);
            if (read == 0)
            {
                break;
            }

            var chunk = read == buffer.Length ? buffer : buffer[..read];
            if (!WindowsPrintApi.WritePrinter(printerHandle, chunk, read, out var written) || written != read)
            {
                throw new InvalidOperationException("写入打印机失败");
            }

            totalWritten += written;
            var percent = fileInfo.Length == 0 ? 100 : (int)Math.Min(99, totalWritten * 100 / fileInfo.Length);
            progress?.Report(percent);
        }

        progress?.Report(100);
    }
}