src/PdfEncoder.Infrastructure/Pdf/PdfTextExtractor.cs - master - afanasevn/PdfEncoder

src/PdfEncoder.Infrastructure/Pdf/PdfTextExtractor.cs
94 строки3 KB
IBS\NAfanasev
DocumentContext local functional
01 июл 2026, 15:30
01 июл 2026, 15:30b4038c9
using PdfEncoder.Application.Abstractions;
using PdfEncoder.Domain.Models;
using UglyToad.PdfPig;
using UglyToad.PdfPig.AcroForms;
using UglyToad.PdfPig.Content;
using UglyToad.PdfPig.DocumentLayoutAnalysis.WordExtractor;

namespace PdfEncoder.Infrastructure.Pdf;

/// <summary>
/// Извлечение text layer и AcroForm через PdfPig.
/// </summary>
public sealed class PdfTextExtractor : IPdfTextExtractor
{
    /// <inheritdoc />
    public Task<PdfTextExtractionResult> ExtractAsync(
        ReadOnlyMemory<byte> content,
        IReadOnlyList<int> pageNumbers,
        CancellationToken ct)
    {
        ct.ThrowIfCancellationRequested();

        using var document = PdfDocument.Open(content);
        var textBlocks = new List<TextBlock>();
        var tables = new List<ExtractedTable>();
        var formFields = ExtractFormFields(document);

        foreach (var pageNumber in pageNumbers)
        {
            ct.ThrowIfCancellationRequested();
            if (pageNumber < 1 || pageNumber > document.NumberOfPages)
            {
                continue;
            }

            var page = document.GetPage(pageNumber);
            textBlocks.AddRange(ExtractTextBlocks(page, pageNumber));
            tables.AddRange(TableHeuristicExtractor.ExtractTables(page, pageNumber));
        }

        return Task.FromResult(new PdfTextExtractionResult
        {
            TextBlocks = textBlocks,
            Tables = tables,
            FormFields = formFields
        });
    }

    private static IReadOnlyList<TextBlock> ExtractTextBlocks(
        Page page,
        int pageNumber)
    {
        var blocks = new List<TextBlock>();
        foreach (var word in page.GetWords(NearestNeighbourWordExtractor.Instance))
        {
            var bbox = word.BoundingBox;
            blocks.Add(new TextBlock
            {
                PageNumber = pageNumber,
                Text = word.Text,
                BoundingBox = new BoundingBox
                {
                    X = bbox.Left,
                    Y = bbox.Bottom,
                    Width = bbox.Width,
                    Height = bbox.Height
                },
                Confidence = 1.0
            });
        }

        return blocks;
    }

    private static IReadOnlyList<FormField> ExtractFormFields(PdfDocument document)
    {
        if (!document.TryGetForm(out var form) || form is null)
        {
            return [];
        }

        return form.Fields
            .Select(field =>
            {
                var fieldValue = field.GetFieldValue();
                return new FormField
                {
                    Name = fieldValue.Key ?? field.Information.PartialName ?? field.ToString(),
                    Value = fieldValue.Value
                };
            })
            .ToList();
    }
}