Reflow content into new margins in the middle of a page.

Documents with asymmetric margins (a wide outer margin for margin notes, figures, or a classic book layout) sometimes need a stretch of content to use a different layout — for example exercise blocks laid out in two columns across the full symmetric width, or normal text resuming at the wide book margin after such a block. riffle reflows that content starting exactly where it appears, without forcing a page break, and keeps the new margins for the pages that follow.

The idea of reflowing content mid-page comes from meander.typ. This package focuses on the asymmetric ⇄ symmetric direction, on the multi-page asymmetric case that could previously fail to converge, and on mixed CJK/Latin reflow.

The name stays with the river metaphor: a riffle is the short stretch of a stream where the current changes character — here, the stretch of a page where the layout changes course.

Installation

The package is available on Typst Universe:

#import "@preview/riffle:0.1.0": column-flow, single-flow, asymmetric-flow

Quick start

#import "@preview/riffle:0.1.0": column-flow

#set page(margin: (inside: 1.75cm, outside: 6.45cm))
#set par(first-line-indent: (amount: 2em, all: true), justify: true)

// ... text on the current asymmetric page ...

#v(1em)

#column-flow(
  [
    第一段内容。#footnote[第一条脚注。]

    第二段内容。
  ],
  gutter: 14pt,
  footnote-entry: (indent: 0em, size: 9pt),
)

The call reflows the content into two columns across the symmetric content width, right where it appears, and the following pages use symmetric margins.

Functions

All three:

• start at the current position and never insert a page break before the reflowed content;
• lay the reflowed content flush to the bottom of the available height;
• pull footnotes out of the flow and render them at the bottom of the reflowed block, preserving numbering and refs;
• switch the margins of the following pages to the new layout;
• are context functions, so they measure the current page themselves.

Set par.first-line-indent if you want first-line indentation inside the reflowed content.

column-flow

#column-flow(content, gutter: 4%, count: 2, footnote-entry: none)

• content (content): the content to reflow. Paragraph breaks are honored.
• gutter (length, default 4% of the reflow width): gap between columns.
• count (int, default 2): number of columns.
• footnote-entry (none, dictionary, or function): styling for the manually laid-out footnote entries. none uses Typst’s defaults, a dictionary is used as footnote.entry configuration (such as indent, size, leading, clearance, gap, separator, style), and a function is shorthand for (style: function).

single-flow

#single-flow(content, footnote-entry: none)

• content (content): the content to reflow.
• footnote-entry (none, dictionary, or function): as in column-flow.

asymmetric-flow

#asymmetric-flow(content, margin, footnote-entry: none)

• content (content): the content to reflow.
• margin (auto, length, or dictionary): the asymmetric horizontal margin to switch to, e.g. (inside: 1cm, outside: 3cm) or (left: 1cm, right: 3cm). inside/outside are resolved against the current page parity, like page.margin. Only the horizontal margins are taken from margin; the top and bottom margins of the current page are preserved.
• footnote-entry (none, dictionary, or function): as in column-flow.

Compatibility and CJK

• Content-processing packages should be applied to the content before it is passed in, because the functions split and rebuild content. For example, with cjk-unbreak:

  #import "@preview/cjk-unbreak:0.2.3": remove-cjk-break-space
  
  #column-flow(remove-cjk-break-space[
    中文与英文混排 content ...
  ])
  

• CJK and mixed scripts are supported: the splitter is aware of Han characters, CJK punctuation and spaces, so Chinese, Japanese and Korean text, as well as mixed CJK/Latin reflow, works. Use a CJK-capable font and enable justification and indentation:

  #set text(font: ("New Computer Modern", "SimSun"), lang: "zh")
  #set par(first-line-indent: (amount: 2em, all: true), justify: true)
  

• Layout packages have not been tested. The functions build their own fixed-height grid/block structure and change page.margin, so packages that also control pagination, columns or page geometry may conflict. Packages that only decorate content generally work. Footnote styling is rendered manually, so use the footnote-entry parameter if a package restyles footnote.entry.

• Margin-note packages (e.g. marginalia, a common combination): because the flow functions manage the page and change page.margin mid-page, do not wrap the output of a flow function in marginalia.wideblock, and do not use marginalia.wideblock/marginalia.header for headers or footers. Instead, align the header/footer from page.margin so that they follow the margins the flow sets (the manual shows a minimal example). An empty marginalia.wideblock may still be used to keep margin notes from overflowing into the body text.

Documentation

• Manual (English)
• 手册（中文）
• README（中文）

The examples in the manuals are rendered on small pages with boundary guide lines: the blue dashed line marks the symmetric content boundary and the orange dashed line the asymmetric one.

License

Licensed under the MIT license.