免费PDF 转 EPUB

工作原理

A PDF is a fixed page: on a phone or an e-reader it is shrunk to fit and has to be zoomed and panned. This turns a text-based PDF into a reflowable EPUB 3 in your browser, rebuilding paragraphs and chapters from the page layout so the text wraps to any screen.

1. 1
   pdf.js reads the text and where it sits

   Each page's text runs are extracted with pdfjs-dist along with their coordinates and font size, and grouped into lines. A PDF whose pages have no text layer (a scan) is detected and pointed to OCR instead.
2. 2
   Page furniture is removed

   Text that repeats at the same height at the top or bottom of many pages — running headers and footers — is dropped, and so are bare page numbers.
3. 3
   Paragraphs and chapters are rebuilt

   Lines are joined into paragraphs using line spacing, first-line indents and sentence endings, and words hyphenated at a line end are rejoined. Lines set clearly larger than the body text become headings; the largest recurring heading size starts each chapter.
4. 4
   The EPUB is packaged

   JSZip writes an EPUB 3 with one XHTML file per chapter, a navigation document plus a toc.ncx for older readers, the title, author and language you set, and right-to-left page order for Arabic, Persian, Hebrew and Urdu. Images are added only if you ask.

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