How to Work with Text in TypeScript

This guide shows how to place and extract text in PDF documents with Aspose.PDF FOSS for TypeScript. Page.AddTextBlock() places styled, word-wrapped, and right-to-left text inside a bounding rectangle; Page.GetText() and Page.GetStructuredText() read text back out, either as a plain string or as position-aware blocks. It requires Node.js 22 or later.

Step-by-Step Guide

Step 1: Install the Package

asposefoss/pdf is not yet published — build from source until it ships. See the project README for build instructions.

Verify the installation by importing the Document class in a new TypeScript file — this line should resolve without error once the package is installed:

import { Document } from '@asposefoss/pdf';

Step 2: Import Required Classes

Import Document to open the file; AddTextBlock() and the read-back methods used below are called directly on the Page instances it returns:

import { Document } from '@asposefoss/pdf';

Step 3: Add a Formatted Text Block

Page.AddTextBlock(text, rect, options) wraps text inside rect, handling word wrapping, alignment, and glyph-width measurement. options covers font, fontSize, color, align, leading (line spacing), underline, strikethrough, background, and opacity:

const doc = Document.OpenFile('input.pdf');
const page = doc.Pages[0];

page.AddTextBlock(
  'This paragraph demonstrates automatic word wrapping at the right edge '
  + 'of the bounding rectangle. Words break on whitespace.',
  [60, 400, 480, 100],
  { font: 'Times-Roman', fontSize: 11, color: [0.1, 0.1, 0.1], align: 'left', leading: 15.4 },
);

page.AddTextBlock('Underlined and struck-through text.', [60, 640, 300, 20],
  { fontSize: 11, underline: true });

When the text overflows rect, AddTextBlock() returns the remaining text (or null if everything fit) — pass that remainder into a second call to continue the paragraph into another region:

const rest = page.AddTextBlock(longText, [72, 600, 200, 150], {
  font: 'Times-Roman', fontSize: 11, align: 'justify', valign: 'top', leading: 14,
});
if (rest) page.AddTextBlock(rest, [300, 600, 200, 150]); // continue into a 2nd column

Step 4: Add Right-to-Left and Embedded-Font Text

Pass an EmbeddedFont (from Document.AddFont() / Document.AddFontFile()) as font to draw Unicode text outside the 14 standard PDF fonts. Set shape: true and dir: 'rtl' to drive automatic BiDi and Arabic/Hebrew glyph shaping:

page.AddTextBlock('Русский: Здравствуй, мир!', [60, 300, 480, 16],
  { font: embeddedFont, fontSize: 11 });

page.AddTextBlock('שלום עולם', [60, 280, 435, 16],
  { font: embeddedFont, fontSize: 12, shape: true, dir: 'rtl', align: 'right' });

Step 5: Extract Plain Text

Page.GetText() returns the page’s full text content as a single string — useful for search-and-verify checks or lightweight text extraction:

const doc2 = Document.OpenFile('signed.pdf');
const pageText = doc2.Pages[0].GetText();
console.log(pageText.includes('Internal memo'));

Step 6: Get Position-Aware Structured Text

Page.GetStructuredText() returns an array of TextBlock entries, each carrying its own text and a quad describing where it sits on the page — useful for driving hand-authored tagging (see the Structure guide) or any workflow that needs to know where a run of text is located:

for (const block of page.GetStructuredText()) {
  const text = block.text.trim();
  if (text.length === 0) continue;
  console.log(text, block.quad);
}

Common Issues and Fixes

Page.AddTextBlock() clips text unexpectedly. Text is clipped to the bounding rect — check the returned remainder value (string | TextRun[] | null) and route it into a further AddTextBlock() call, as shown in Step 3, instead of assuming everything fit.

Right-to-left text renders in the wrong order. shape: true and dir: 'rtl' must both be set — dir alone selects alignment, while shape drives the BiDi reordering and Arabic/Hebrew glyph joining.

Page.GetText() returns text in a surprising order. It concatenates the page’s text content; for a version that preserves per-run position and grouping, use Page.GetStructuredText() instead.

A non-standard font renders as boxes or the wrong glyphs. The 14 standard PDF fonts (Helvetica, Times-Roman, Courier, and their bold/oblique variants) do not need embedding, but any other typeface must be loaded first through Document.AddFont() / Document.AddFontFile() and passed as the font option, not referenced by a bare string name.

Frequently Asked Questions

Does `AddTextBlock()` support multiple text runs with different styles in one call?

Yes — passing an array of TextRun-shaped objects instead of a plain string lets each run carry its own style within the same call.

Can I measure how much space a run of text will need before drawing it?

Page exposes a text-measurement method (MeasureText()) for this purpose, separate from the drawing methods covered here.

Is `GetText()` the same as what a PDF viewer’s text-selection shows?

GetText() reads the page’s underlying text content in the order it appears in the content stream, which usually — but not always — matches visual reading order; GetStructuredText() provides the per-block position data needed to reconstruct reading order explicitly.

Do word-wrapped paragraphs respect font metrics for different typefaces?

Yes — AddTextBlock() measures wrapping against the actual glyph widths of the font in use, whether a standard font or an EmbeddedFont.