Rendering pages

docboss render report.docx --page 1 -o page.png            # one page, 72 dpi
docboss render report.docx --scale 2 -o 'page-%d.png'      # every page at 144 dpi
docboss render report.docx --page 1 -o page.jpg --jpeg-quality 85
docboss render legacy.doc -o 'legacy-%d.ppm'

The -o extension picks the format: .png, .ppm, .bmp or .jpg/.jpeg. %d in the path is replaced by the page number; without --page every page is rendered, laid out once and painted on all cores. --scale is pixels per point, so 1.0 is 72 dpi and 2.0 is 144 dpi.

What layout does

docboss lays a document out the way Word does rather than the way a browser would:

• Paragraph and run properties are resolved through document defaults, the style chain, table styles, list levels and direct formatting.
• Lines break at Unicode line-break opportunities with soft hyphens honored, and are aligned or justified; line spacing follows the paragraph's rule (auto, exact, at least) with Word's extra leading on single spacing.
• Tab stops, leaders and default tabs; list labels with their hanging indents.
• Keep with next, keep lines together, widow and orphan control, page breaks before.
• Tables: grid widths, merged cells in both directions, cell margins, borders and shading, rows split across pages, header rows repeated on each page.
• Sections with their own page size, margins and columns; headers and footers for first, even and default pages, with PAGE and NUMPAGES fields in the section's number format.
• Footnotes at the bottom of the page they are referenced on; inline and floating images.

Fonts come from the machine and from the document; see Installation for where docboss looks and which substitutes it uses. docboss fonts report.docx prints each font the document names and the face it resolved to.

Python

from pathlib import Path

import docboss

doc = docboss.Document("report.docx")
print(doc.page_count(), "pages")
Path("first.png").write_bytes(doc.render(0, scale=2.0))
Path("last.jpg").write_bytes(doc.render(-1, format="jpeg", jpeg_quality=85))
for index, png in enumerate(doc.render_pages(scale=1.5)):
    Path(f"page-{index + 1}.png").write_bytes(png)

render_pages renders every page (or the indexes given in pages=) in parallel and returns the encoded images in page order. Layout is computed once per document and cached, so rendering pages one by one costs no second layout.

Rust

use docboss_render::Format;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let doc = docboss_core::open("report.docx")?;
    let layout = docboss_layout::layout_document(&doc);
    for (index, page) in docboss_render::render_pages(&layout, 2.0).into_iter().enumerate() {
        std::fs::write(format!("page-{}.png", index + 1), page?.encode(Format::Png)?)?;
    }
    Ok(())
}

docboss_layout::layout takes an explicit FontDatabase when several documents should share one; layout_document builds one for the document, including its embedded fonts. Each laid-out page holds positioned glyph runs, rectangles, lines and images in points, so a program can inspect geometry without rasterizing.

What is not drawn

Text boxes, shapes with their preset and custom geometry, groups, canvases, gradient fills, SmartArt (from its saved drawing), charts (from their cached values), Office Math, WMF and EMF pictures and page borders are drawn, and body text wraps around floating images, text frames and floating tables (square, tight, through and top and bottom); text in table cells, text frames, headers and footers does not wrap around the floats there. Picture and pattern fills and shape effects are not drawn, 3-D, radar, stock, surface, bubble and bar-of-pie charts show an empty frame, and TIFF pictures draw a placeholder rectangle; docboss diagnostics report.docx --layout reports them and everything else layout approximated.