How can I dynamically split chunk of text into pages for jsPDF?

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05-10-2024

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Dynamically Splitting Text into Pages with jsPDF

Problem: You have a large chunk of text that needs to be formatted into a PDF document using jsPDF. However, you want to ensure that the text is split across multiple pages to avoid long, unreadable pages.

Rephrasing: Imagine you have a long story or article you want to print as a PDF. You don't want the whole thing squeezed onto a single page, making it hard to read. You want to break it into multiple pages, making it more manageable and visually appealing.

Solution: jsPDF itself doesn't automatically handle text splitting across pages. You need to implement this logic yourself. Here's how:

Understanding the Problem:

• Text Length: The length of your text will determine the number of pages required.
• Font Size and Line Height: The size and spacing of your text will affect how much text fits on a single page.
• Page Size: The chosen page size (e.g., A4, Letter) will influence the maximum space available for text.

Code Example:

import jsPDF from 'jspdf';

const doc = new jsPDF();
const text = "Your long text content here.";

const pageHeight = doc.internal.pageSize.getHeight();
const fontSize = 12; // Adjust as needed
const lineHeight = fontSize * 1.2; // Adjust for line spacing

let textY = 20; // Starting Y position on the page
let currentLine = 0;

for (const line of text.split("\n")) {
  const lineWidth = doc.getTextWidth(line);

  if (textY + lineHeight > pageHeight) { // Check for page overflow
    doc.addPage(); // Add a new page
    textY = 20; // Reset Y position
    currentLine = 0;
  }

  doc.text(line, 10, textY + (currentLine * lineHeight)); 
  textY += lineHeight;
  currentLine++;
}

doc.save('my_document.pdf'); 

Explanation:

1. Initialization: We create a new jsPDF document and define variables for page height, font size, line height, and starting text position.
2. Text Processing: We iterate over each line of the text, calculating its width.
3. Page Overflow Check: For every line, we check if adding the line would push the text beyond the page height.
4. New Page Creation: If overflow occurs, we add a new page to the document and reset the Y position and line counter.
5. Text Placement: We use doc.text to place each line on the current page, adjusting the Y position based on the line number and line height.

Enhancements and Considerations:

• Font Family: You can set the font family using doc.setFont('Arial', 'normal').
• Line Spacing: Adjust lineHeight to control the spacing between text lines.
• Margins: Add margins to your pages using doc.setMargins(left, top, right, bottom).
• Indentation: Apply indentation using doc.text(text, indentation, y, { align: 'left' }).
• Header/Footer: Add headers and footers for each page using doc.setFontSize(10).text('Header', 10, 10).
• Complex Formatting: Consider libraries like pdfmake or html2canvas for more intricate formatting and complex layout requirements.

Additional Value:

This approach allows you to dynamically adjust the text splitting based on the content, font size, and page size. It provides a flexible solution for creating well-formatted PDFs from large blocks of text.

References:

• jsPDF Documentation
• PDFMake
• html2canvas