Reading Text from Specified Area in C# and .NET

In the world of document processing, especially on a large scale, extracting specific text from a PDF document can be an important task. Whether it's data extraction, form field analysis, or content filtering, the ability to accurately identify and extract text from a specific rectangular area in a PDF file can simplify many workflows. In this article, you will learn about the process of extracting text from a custom rectangle using C# and .Net the SautinSoft.Pdf library.

Step-by-step guide:

  1. Add SautinSoft.PDF from NuGet.
  2. Load the PDF document.
  3. Define a rectangular area by coordinates.
  4. Extract the text from the specified rectangular area.
  5. Output the extracted text to the console.

Input file:

PDF coordinates:

Output result:

Complete code

using System;
using System.IO;
using SautinSoft;
using SautinSoft.Pdf;
using SautinSoft.Pdf.Content;

class Program
{
    /// <summary>
    /// Reading text
    /// </summary>
    /// <remarks>
    /// Details: https://sautinsoft.com/products/pdf/help/net/developer-guide/reading-text-from-specific-rectangular-area.php
    /// </remarks>
    static void Main()
    {
        // Before starting this example, please get a free 100-day trial key:
        // https://sautinsoft.com/start-for-free/

        // Apply the key here:
        // PdfDocument.SetLicense("...");

        string pdfFile = Path.GetFullPath(@"..\..\..\simple text.pdf");
        var pageIndex = 0;
        double areaLeft = 200, areaRight = 520, areaBottom = 510, areaTop = 720;
        using (var document = PdfDocument.Load(pdfFile))
        {
            // Retrieve first page object.
            var page = document.Pages[pageIndex];
            // Retrieve text content elements that are inside specified area on the first page.
            var contentEnumerator = page.Content.Elements.All(page.Transform).GetEnumerator();
            while (contentEnumerator.MoveNext())
            {
                if (contentEnumerator.Current.ElementType == PdfContentElementType.Text)
                {
                    var textElement = (PdfTextContent)contentEnumerator.Current;
                    var bounds = textElement.Bounds;
                    contentEnumerator.Transform.Transform(bounds);

                    if (bounds.Left > areaLeft && bounds.Right < areaRight &&
                    bounds.Bottom > areaBottom && bounds.Top < areaTop)
                    {
                        // Read the text of an element located in a given area
                        Console.Write(textElement.ToString());
                    }
                }
            }
        }
    }
}

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Option Infer On

Imports System
Imports System.IO
Imports SautinSoft
Imports SautinSoft.Pdf
Imports SautinSoft.Pdf.Content

Friend Class Program
	''' <summary>
	''' Reading text
	''' </summary>
	''' <remarks>
	''' Details: https://sautinsoft.com/products/pdf/help/net/developer-guide/reading-text-from-specific-rectangular-area.php
	''' </remarks>
	Shared Sub Main()
		' Before starting this example, please get a free license:
		' https://sautinsoft.com/start-for-free/

		' Apply the key here:
		' PdfDocument.SetLicense("...");

		Dim pdfFile As String = Path.GetFullPath("..\..\..\simple text.pdf")
		Dim pageIndex = 0
		Dim areaLeft As Double = 200, areaRight As Double = 520, areaBottom As Double = 510, areaTop As Double = 720
		Using document = PdfDocument.Load(pdfFile)
			' Retrieve first page object.
			Dim page = document.Pages(pageIndex)
			' Retrieve text content elements that are inside specified area on the first page.
			Dim contentEnumerator = page.Content.Elements.All(page.Transform).GetEnumerator()
			Do While contentEnumerator.MoveNext()
				If contentEnumerator.Current.ElementType = PdfContentElementType.Text Then
					Dim textElement = CType(contentEnumerator.Current, PdfTextContent)
					Dim bounds = textElement.Bounds
					contentEnumerator.Transform.Transform(bounds)

					If bounds.Left > areaLeft AndAlso bounds.Right < areaRight AndAlso bounds.Bottom > areaBottom AndAlso bounds.Top < areaTop Then
						' Read the text of an element located in a given area
						Console.Write(textElement.ToString())
					End If
				End If
			Loop
		End Using
	End Sub
End Class

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