Typography Diagnostics

Sappar's built-in quality analyzer continuously evaluates your book's typography and helps you produce cleaner, more professional pages.

How It Works

Sappar includes a Typography Diagnostics Panel in the Inspector sidebar that continuously evaluates the typographic quality of your book. Every time the layout engine updates the document, Sappar automatically analyzes the resulting pages and assigns a quality score from 0 to 100. No manual action is required.

What the Panel Detects

The diagnostics system analyzes several categories of typographic issues across your entire book.

Spacing

Spacing issues affect the visual texture of a page and are one of the most common causes of poor typography. The analyzer detects:

Loose lines with excessive word spacing
Badly spaced lines
Severe spacing problems
Inconsistent spacing patterns across a page

Hyphenation

Hyphenation is necessary in justified text, but excessive hyphenation can make pages difficult to read. The diagnostics engine flags:

Two consecutive hyphenated lines
Three consecutive hyphenated lines
Four or more consecutive hyphenated lines
High hyphen density within a page region

Rivers

Rivers occur when inter-word spaces align vertically across multiple lines, forming visible streams of white space down a paragraph. The system detects both weak and strong vertical rivers by analyzing the alignment of word spacing across consecutive lines.

Page Break Issues

Professional book layout avoids certain pagination problems that interrupt reading flow. The analyzer detects:

Widows — single lines stranded at the top of a page
Orphans — single lines stranded at the bottom of a page
Spread widows across facing pages
Chapter-opening widows

Layout Fallbacks

In rare situations the layout engine may fall back to simpler line breaking when optimal breaking cannot be achieved. The diagnostics system reports lines that required greedy breaking instead of optimal layout, and emergency breaks where no valid breakpoint was available.

Note Layout fallback events are uncommon. When they do occur, they usually indicate a very narrow text column or an unusually long word.

Paragraph Shape

The analyzer checks paragraph endings and flags short final lines, which can create visually awkward paragraph shapes.

Typography Quality Score

All detected issues contribute to a typographic quality score displayed in the Inspector.

Score	Quality
95–100	Excellent
90–94	Good
70–89	Fair
Below 70	Needs Attention

The score provides a quick overview of the overall typographic quality of the current layout.

What You See in the Inspector

In the Inspector sidebar, the Quality section displays:

A score badge in the collapsed section header
A color-coded progress bar indicating the quality tier
A summary of detected issues grouped by category — rivers, widows, spacing, and hyphenation
A per-chapter breakdown of typographic scores
Individual issue rows listing the page number, issue type, and severity indicator

Chapters without issues are summarized as a clean count.

Click-to-Navigate

Selecting any issue in the diagnostics panel automatically scrolls the preview to the relevant page. This lets you quickly inspect the flagged area and decide whether adjustments are necessary.

Tip Not every flagged issue needs fixing. The diagnostics panel highlights areas worth reviewing — use your judgment to decide which issues affect readability.

Performance

Typography diagnostics run with no noticeable performance impact. The analysis occurs during the layout process and reads metrics already produced by the layout engine. The Inspector simply displays cached results — no additional layout passes or font shaping are required.

Technical Overview

Internally, the diagnostics system analyzes metrics produced by Sappar's layout engine during pagination.

Knuth–Plass line breaking → Paragraph quality metrics → Post-pagination analysis → Book diagnostics report → Inspector panel

Because the diagnostics operate on existing layout data, the feature provides detailed typography analysis without additional rendering cost.

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