Guides

Page Text Extraction

ComPDF Flutter SDK provides page text APIs for extracting text content from a PDF page. You can get all text from a page, extract text inside a rectangle, retrieve text lines, and get the text content for a specific line.

Get All Text From a Page

Use getAllText() to extract all text from the current page.

final CPDFPage page = document.pageAtIndex(0);
final String text = await page.getAllText();

print('Page text: $text');

If the page has no text layer, such as a scanned image-only PDF, the result is usually an empty string.

Get Text Inside a Rectangle

Use getTextInRect(rect) to extract text inside a rectangle on the current page.

final CPDFPage page = document.pageAtIndex(0);

const CPDFRectF rect = CPDFRectF(
  left: 40,
  top: 760,
  right: 560,
  bottom: 680,
);

final String text = await page.getTextInRect(rect);

print('Text in rectangle: $text');

The rect parameter uses the CPDFRectF structure. The values are page coordinates:

const CPDFRectF rect = CPDFRectF(
  left: 40,
  top: 760,
  right: 560,
  bottom: 680,
);

Get Text Lines From a Page

Use getTextLines() to retrieve all text lines from the current page.

final CPDFPage page = document.pageAtIndex(0);
final List<CPDFTextLine> lines = await page.getTextLines();

print('Line count: ${lines.length}');

Each text line is represented by CPDFTextLine:

class CPDFTextLine {
  final int pageIndex;
  final int lineIndex;
  final int location;
  final int length;
  final CPDFRectF rect;
}

Field description:

Field	Description
pageIndex	The zero-based page index where the line is located
lineIndex	The zero-based line index in the page line collection
location	The start character position of the line in the page text
length	The character length of the line
rect	The line bounding rectangle in page coordinates. It uses the same CPDFRectF format accepted by CPDFReaderWidgetController.setDisplayPageIndex(rectList: ...)

Get Text From a Specific Line

Use getTextByLine(line) to get the actual text content for a text line.

final CPDFPage page = document.pageAtIndex(0);
final List<CPDFTextLine> lines = await page.getTextLines();

if (lines.isNotEmpty) {
  final String firstLineText = await page.getTextByLine(lines.first);
  print('First line: $firstLineText');
}

The line should come from getTextLines() on the same page. Passing a line from another page to the current page returns a platform error.

Highlight a Text Line in CPDFReaderWidget

When you use CPDFReaderWidget, you can pass CPDFTextLine.rect to setDisplayPageIndex(rectList:) to highlight the line in the reader view.

final int pageIndex = await controller.getCurrentPageIndex();
final CPDFPage page = controller.document.pageAtIndex(pageIndex);
final List<CPDFTextLine> lines = await page.getTextLines();

if (lines.isNotEmpty) {
  final CPDFTextLine firstLine = lines.first;
  final String text = await page.getTextByLine(firstLine);

  await controller.setDisplayPageIndex(
    pageIndex: firstLine.pageIndex,
    rectList: [firstLine.rect],
  );

  print('Highlighted text: $text');
}

This is useful when you need to compare extracted text with its position on the page.

Complete Example

The following example extracts all page text, text inside a rectangle, the page line count, and the text of the first line.

import 'package:compdfkit_flutter/document/cpdf_document.dart';
import 'package:compdfkit_flutter/page/cpdf_page.dart';
import 'package:compdfkit_flutter/page/cpdf_text_line.dart';
import 'package:compdfkit_flutter/util/cpdf_rectf.dart';

Future<void> extractPageText(String filePath) async {
  final CPDFDocument document = await CPDFDocument.createInstance();
  await document.open(filePath);

  final CPDFPage page = document.pageAtIndex(0);

  final String allText = await page.getAllText();

  const CPDFRectF rect = CPDFRectF(
    left: 40,
    top: 760,
    right: 560,
    bottom: 680,
  );
  final String rectText = await page.getTextInRect(rect);

  final List<CPDFTextLine> lines = await page.getTextLines();
  final String firstLineText =
      lines.isNotEmpty ? await page.getTextByLine(lines.first) : '';

  print('All text length: ${allText.length}');
  print('Rectangle text: $rectText');
  print('Line count: ${lines.length}');
  print('First line: $firstLineText');
}

Notes

• Scanned PDFs or PDFs without a text layer may return an empty string or an empty array.
• getTextInRect(rect) and CPDFTextLine.rect use page coordinates, not screen coordinates.
• CPDFTextLine.rect can be passed directly to CPDFReaderWidgetController.setDisplayPageIndex(rectList: ...) to highlight the corresponding line.
• getTextByLine(line) should use a line returned by getTextLines() from the same page.
• Invalid page indexes return a platform error.
• If you need keyword search, continue using the existing CPDFTextSearcher.