Pre-Wrap Mode

Pre-wrap mode preserves whitespace characters that are normally collapsed. Use it for editor-like text where spaces, tabs, and newlines should be visible and affect layout.

Enabling Pre-Wrap

iOS

let prepared = Pretext.prepare(editorText, font: font, options: PrepareOptions(whiteSpace: .preWrap))
let result = Pretext.layout(prepared, maxWidth: editorWidth, lineHeight: 20)

Android

val prepared = Pretext.prepare(editorText, measurer, PrepareOptions(WhiteSpaceMode.PreWrap))
val result = Pretext.layout(prepared, maxWidth = editorWidth, lineHeight = 20f)

Behavior Differences

Character	Normal mode	Pre-wrap mode
Space " "	Collapsed, zero-width at line end	Visible width, wrappable
Tab \t	Collapsed to space	Advances to next tab stop
Newline \n	Collapsed to space	Hard line break
Multiple spaces " "	Collapsed to single space	Each space has visible width

Tab Stops

Tabs advance to the next tab stop position. Tab stops are spaced at 8 times the space width (matching the default browser tab-size: 8):

"Hello\tWorld"
 ↓
 Hello···World     (tab fills to next 8-space boundary)

The tab width depends on the current line position — a tab at position 0 advances 8 spaces, but a tab at position 3 advances only 5 spaces (to reach the next multiple of 8).

Hard Breaks

In pre-wrap mode, \n characters force a new line regardless of available width. The text is split into "chunks" at hard break boundaries, and each chunk is laid out independently.

"Line one\nLine two\n\nLine four"
 ↓
 Line one
 Line two
 (empty line)
 Line four

Empty lines between consecutive \n characters are preserved and contribute to the total height.

Use Cases

• Text editors: Measuring textarea content with preserved formatting
• Code display: Indentation and blank lines matter
• Chat with formatting: Messages that include intentional line breaks and spacing
• Pre-formatted content: Content pasted from external sources