pdfboss-text 0.7.1

Font loading, encodings, ToUnicode CMaps and text extraction for pdfboss
Documentation 
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//! Text extraction for pdfboss: font loading, encodings, ToUnicode CMaps,
//! and positional layout.

mod cmap;
mod extract;
mod font;

use pdfboss_core::{Document, Page, Result};

/// A positioned run of extracted text.
#[derive(Debug, Clone, PartialEq)]
pub struct TextSpan {
    /// The decoded text.
    pub text: String,
    /// Device-space x coordinate of the span origin.
    pub x: f32,
    /// Device-space y coordinate of the span baseline.
    pub y: f32,
    /// Effective font size.
    pub size: f32,
    /// Font resource name.
    pub font: String,
}

/// Extracts the page's text with positional layout applied: spans grouped
/// into lines, lines ordered top to bottom and joined with `\n`, spaces
/// inserted at horizontal gaps.
pub fn extract_text(doc: &Document, page: &Page) -> Result<String> {
    let spans = extract::page_spans(doc, page)?;
    Ok(extract::layout(&spans))
}

/// Extracts the page's raw text spans (position, size and font per span),
/// before any layout pass.
pub fn extract_spans(doc: &Document, page: &Page) -> Result<Vec<TextSpan>> {
    Ok(extract::page_spans(doc, page)?
        .into_iter()
        .map(|s| TextSpan {
            text: s.text,
            x: s.x,
            y: s.y,
            size: s.size,
            font: s.font,
        })
        .collect())
}

#[cfg(test)]
mod tests {
    use super::*;
    use pdfboss_testkit::{multi_page_doc, simple_doc, PdfBuilder};

    fn page_text(doc: &Document, index: usize) -> String {
        let page = doc.page(index).unwrap();
        extract_text(doc, &page).unwrap()
    }

    #[test]
    fn simple_doc_exact_text() {
        let doc = Document::load(simple_doc("Hello, world!")).unwrap();
        assert_eq!(page_text(&doc, 0), "Hello, world!");
    }

    #[test]
    fn multi_page_doc_per_page() {
        let doc = Document::load(multi_page_doc(&["Page one", "Page two", "Page three"])).unwrap();
        assert_eq!(doc.page_count(), 3);
        assert_eq!(page_text(&doc, 0), "Page one");
        assert_eq!(page_text(&doc, 1), "Page two");
        assert_eq!(page_text(&doc, 2), "Page three");
    }

    #[test]
    fn differences_remap_in_extraction() {
        let mut b = PdfBuilder::new();
        b.object(1, "<< /Type /Catalog /Pages 2 0 R >>");
        b.object(2, "<< /Type /Pages /Kids [3 0 R] /Count 1 >>");
        b.object(
            3,
            "<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] \
             /Resources << /Font << /F1 5 0 R >> >> /Contents 4 0 R >>",
        );
        b.stream(4, "", b"BT /F1 12 Tf 72 720 Td (AB) Tj ET");
        b.object(
            5,
            "<< /Type /Font /Subtype /Type1 /BaseFont /Custom \
             /Encoding << /BaseEncoding /WinAnsiEncoding \
             /Differences [65 /alpha] >> >>",
        );
        let doc = Document::load(b.build(1)).unwrap();
        assert_eq!(page_text(&doc, 0), "\u{3B1}B");
    }

    #[test]
    fn type0_font_with_tounicode_stream() {
        let mut b = PdfBuilder::new();
        b.object(1, "<< /Type /Catalog /Pages 2 0 R >>");
        b.object(2, "<< /Type /Pages /Kids [3 0 R] /Count 1 >>");
        b.object(
            3,
            "<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] \
             /Resources << /Font << /F1 5 0 R >> >> /Contents 4 0 R >>",
        );
        b.stream(4, "", b"BT /F1 12 Tf 72 720 Td <00010001> Tj ET");
        b.object(
            5,
            "<< /Type /Font /Subtype /Type0 /BaseFont /X /Encoding /Identity-H \
             /DescendantFonts [6 0 R] /ToUnicode 7 0 R >>",
        );
        b.object(
            6,
            "<< /Type /Font /Subtype /CIDFontType2 /BaseFont /X /DW 600 >>",
        );
        b.stream(
            7,
            "",
            b"1 begincodespacerange <0000> <FFFF> endcodespacerange\n\
              1 beginbfchar <0001> <03A9> endbfchar",
        );
        let doc = Document::load(b.build(1)).unwrap();
        assert_eq!(page_text(&doc, 0), "\u{3A9}\u{3A9}");
    }

    #[test]
    fn form_xobject_recursion() {
        let mut b = PdfBuilder::new();
        b.object(1, "<< /Type /Catalog /Pages 2 0 R >>");
        b.object(2, "<< /Type /Pages /Kids [3 0 R] /Count 1 >>");
        b.object(
            3,
            "<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] \
             /Resources << /Font << /F1 5 0 R >> /XObject << /Fx 6 0 R >> >> \
             /Contents 4 0 R >>",
        );
        b.stream(4, "", b"BT /F1 12 Tf 72 720 Td (out) Tj ET /Fx Do");
        b.object(
            5,
            "<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica \
             /Encoding /WinAnsiEncoding >>",
        );
        // No own /Resources: falls back to the page's, so /F1 resolves.
        b.stream(
            6,
            "/Type /XObject /Subtype /Form /BBox [0 0 612 792] \
             /Matrix [1 0 0 1 0 -20]",
            b"BT /F1 12 Tf 72 720 Td (in) Tj ET",
        );
        let doc = Document::load(b.build(1)).unwrap();
        assert_eq!(page_text(&doc, 0), "out\nin");
        let page = doc.page(0).unwrap();
        let spans = extract_spans(&doc, &page).unwrap();
        assert_eq!(spans.len(), 2);
        assert!((spans[1].y - 700.0).abs() < 1e-3); // form matrix applied
    }

    #[test]
    fn extract_spans_sane_positions() {
        let doc = Document::load(simple_doc("Hi")).unwrap();
        let page = doc.page(0).unwrap();
        let spans = extract_spans(&doc, &page).unwrap();
        assert_eq!(spans.len(), 1);
        let s = &spans[0];
        assert_eq!(s.text, "Hi");
        assert!((s.x - 72.0).abs() < 1e-3);
        assert!((s.y - 720.0).abs() < 1e-3);
        assert!((s.size - 12.0).abs() < 1e-3);
        assert_eq!(s.font, "F1");
    }

    #[test]
    fn extract_spans_ordering_multi_line() {
        let doc = Document::load(pdfboss_testkit::doc_with_graphics(
            "BT /F1 12 Tf 72 720 Td (top) Tj 0 -40 Td (bottom) Tj ET",
        ))
        .unwrap();
        let page = doc.page(0).unwrap();
        let spans = extract_spans(&doc, &page).unwrap();
        assert_eq!(spans.len(), 2);
        assert!(spans[0].y > spans[1].y);
        assert_eq!(spans[0].text, "top");
        assert_eq!(spans[1].text, "bottom");
        assert!(spans.iter().all(|s| s.size > 0.0 && s.x >= 0.0));
    }

    #[test]
    fn committed_fixture_files() {
        let dir = concat!(env!("CARGO_MANIFEST_DIR"), "/../../tests/fixtures");
        let hello = std::fs::read(format!("{dir}/hello.pdf")).unwrap();
        let doc = Document::load(hello).unwrap();
        assert_eq!(page_text(&doc, 0), "Hello, world!");

        let three = std::fs::read(format!("{dir}/three-pages.pdf")).unwrap();
        let doc = Document::load(three).unwrap();
        assert_eq!(doc.page_count(), 3);
        assert_eq!(page_text(&doc, 0), "Page one");
        assert_eq!(page_text(&doc, 1), "Page two");
        assert_eq!(page_text(&doc, 2), "Page three");

        let xs = std::fs::read(format!("{dir}/xref-stream.pdf")).unwrap();
        let doc = Document::load(xs).unwrap();
        assert_eq!(page_text(&doc, 0), "Hello, world!");
    }
}