Module layout 

Page-Aware Layout Engine

This is the heart of Forme and the reason it exists.

The Problem With Every Other Engine

Most PDF renderers do this:

1. Lay out all content on an infinitely tall canvas
2. Slice the canvas into pages
3. Try to fix the things that broke at slice points

Step 3 is where everything falls apart. Flexbox layouts collapse because the flex algorithm ran on the pre-sliced dimensions. Table rows get split in the wrong places. Headers don’t repeat. Content gets “mashed together.”

How Forme Works

Forme never creates an infinite canvas. The layout algorithm is:

1. Open a page with known dimensions and remaining space
2. Place each child node. Before placing, ask: “does this fit?”
3. If it fits: place it, reduce remaining space
4. If it doesn’t fit and is unbreakable: start a new page, place it there
5. If it doesn’t fit and is breakable: place what fits, split the rest to a new page, and RE-RUN flex layout on both fragments
6. For tables: when splitting, clone the header rows onto the new page

The key insight in step 5: when a flex container splits across pages, BOTH fragments get their own independent flex layout pass. This is why react-pdf’s flex breaks on page wrap — it runs flex once on the whole container and then slices, so the flex calculations are wrong on both halves. We run flex AFTER splitting.

Modules

flex

Flex Layout Utilities

grid

CSS Grid Layout

page_break

Page Break Decisions

Structs

BookmarkEntry

A bookmark entry collected during layout.

ElementInfo

Layout metadata for a single positioned element (hierarchical).

ElementStyleInfo

Serializable snapshot of ResolvedStyle for the inspector panel.

LayoutElement

A positioned element on a page.

LayoutEngine

The main layout engine.

LayoutInfo

Complete layout metadata for all pages.

LayoutPage

A fully laid-out page ready for PDF serialization.

PageInfo

Layout metadata for a single page.

PositionedGlyph

TextLine

Enums

DrawCommand

What to actually draw for this element.

FormFieldType

Configuration for an interactive PDF form field.

Constants

PAGE_NUMBER_SENTINEL

Sentinel character for {{pageNumber}} placeholder. A single char that is atomic (can’t be split by line breaking), measured as the width of “00”, and recognized by the PDF serializer for replacement.

TOTAL_PAGES_SENTINEL

Sentinel character for {{totalPages}} placeholder.