How to Extract Text with Formatting from PDFs Using iTextSharp?

Extract formatted text using iTextSharp

Introduction:

iTextSharp is a powerful library for manipulating and generating PDF documents, but it is sometimes difficult to extract text with the desired format. This article provides a method to extract text and formatting information from PDF using iTextSharp.

Custom extraction strategy:

To extract formatted text, you can create a custom ITextExtractionStrategy implementation. This policy defines how text rendering information is handled.

Code snippet:

The following code defines a custom strategy that tracks changes in baseline, font name, and font size and generates HTML with appropriate styling:

<code>public class TextWithFontExtractionStategy : iTextSharp.text.pdf.parser.ITextExtractionStrategy
{
    // ... (此处省略)

    public void RenderText(iTextSharp.text.pdf.parser.TextRenderInfo renderInfo)
    {
        // 确定字体属性
        string curFont = renderInfo.GetFont().PostscriptFontName;
        if (renderInfo.GetTextRenderMode() == (int)TextRenderMode.FillThenStrokeText)
        {
            curFont += "-Bold";
        }

        // 检查基线、字体或字体大小的变化
        Vector curBaseline = renderInfo.GetBaseline().GetStartPoint();
        Single curFontSize = renderInfo.GetAscentLine().GetEndPoint()[Vector.I2] - curBaseline[Vector.I2];
        if ((this.lastBaseLine == null) || (curBaseline[Vector.I2] != lastBaseLine[Vector.I2]) ||
            (curFontSize != lastFontSize) || (curFont != lastFont))
        {
            // 生成带有更新样式的HTML span
            result.AppendFormat("</code>

Usage:

To use a custom strategy, you can specify it when extracting text:

<code>PdfReader reader = new PdfReader("MyDocument.pdf");
TextWithFontExtractionStategy strategy = new TextWithFontExtractionStategy();
string textWithFormatting = PdfTextExtractor.GetTextFromPage(reader, 1, strategy);</code>

Output:

The

textWithFormatting variable will contain the extracted text with HTML tags reflecting the formatting information, including font and font size.

Conclusion:

This custom extraction strategy allows you to extract PDF text with the desired format. This is a powerful tool that can be used to accurately reproduce text and styles in PDF documents.

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