TextEngine

Core text layout, line-wrapping, dimension measurement, and inline-content rendering engine.

Overview

TextEngine is the centralized subsystem responsible for measuring character widths, wrapping long text runs across multiple lines, aligning blocks horizontally/vertically, and laying out embedded inline spans (icons, textures, badges) alongside regular text.

Text and Content Measurement

Measurement methods compute line dimensions (measureLineWidth) and block heights (measureTextHeight) taking into account font ascent, descent, character code-points, and atomic inline spans. The minContentWidth method determines the minimum width required to display the longest word without clipping.

Line Wrapping

wrapLines() splits rich text across word boundaries to fit within a given maximum width (maxWidth). If single words exceed the available line width, they are broken at character boundaries to prevent line overflows.

Rendering and Inline Content

When rendering plain text runs, TextEngine delegates directly to RenderBackend. If inline spans exist, TextEngine computes exact coordinates for each atom and invokes its InlineContentRenderer with final screen bounds.

Measuring and Wrapping Rich Text

float maxWidth = 200.0f;
List<RichText> lines = TextEngine.wrapLines(context, richText, maxWidth);
float totalHeight = TextEngine.linesHeight(context, lines);

Drawing Aligned Text into Canvas

TextEngine.draw(context, richText, x, y, width, height, paint, transform,
    Alignment.CENTER, Alignment.CENTER);

API

TextEngine::measureLineWidth(String)

measureLineWidth(String)

Measures line width using approximate glyph spacing without active backend.

Parameter	Type	Description
text	String	Text to measure.

Returns float: Calculated line width in pixels..

TextEngine::minContentWidth(RichText)

minContentWidth(RichText)

Calculates the width of the longest unbreakable word in the rich text.

Parameter	Type	Description
text	RichText	Rich text to inspect.

Returns float: Minimum content width in pixels..

TextEngine::measureLineWidth(RenderContext, String)

measureLineWidth(RenderContext, String)

Measures string width using active render backend font metrics.

Parameter	Type	Description
context	RenderContext	Active render context.
text	String	Text string.

Returns float: Line width in pixels..

TextEngine::measureLineWidth(RenderContext, RichText)

measureLineWidth(RenderContext, RichText)

Measures rich text width taking inline spans and fonts into account.

Parameter	Type	Description
context	RenderContext	Active render context.
text	RichText	Rich text instance.

Returns float: Maximum line width in pixels..

TextEngine::measureLineWidth(RichText)

measureLineWidth(RichText)

Measures rich text width using font faces embedded in runs.

Parameter	Type	Description
text	RichText	Rich text instance.

Returns float: Line width in pixels..

TextEngine::measureTextHeight(RichText)

measureTextHeight(RichText)

Calculates total vertical height for all lines of rich text.

Parameter	Type	Description
text	RichText	Rich text instance.

Returns float: Total text height in pixels..

TextEngine::measureTextHeight(RenderContext, RichText)

measureTextHeight(RenderContext, RichText)

Calculates rich text height using active render backend font metrics.

Parameter	Type	Description
context	RenderContext	Active render context.
text	RichText	Rich text instance.

Returns float: Text height in pixels..

TextEngine::wrapLines(RichText, float)

wrapLines(RichText, float)

Splits rich text into wrapped lines fitting within the specified maximum width.

Parameter	Type	Description
text	RichText	Rich text to wrap.
maxWidth	float	Maximum line width.

Returns List: List of wrapped rich text lines..

TextEngine::wrapLines(RenderContext, RichText, float)

wrapLines(RenderContext, RichText, float)

Wraps rich text using backend font measurements.

Parameter	Type	Description
context	RenderContext	Active render context.
text	RichText	Rich text to wrap.
maxWidth	float	Maximum line width.

Returns List: List of wrapped rich text lines..

TextEngine::lineHeight(RichText)

lineHeight(RichText)

Calculates the height of a single rich text line based on runs and inline content.

Parameter	Type	Description
line	RichText	Line to evaluate.

Returns float: Line height in pixels..

TextEngine::lineHeight(RenderContext, RichText)

lineHeight(RenderContext, RichText)

Calculates line height using active render context metrics.

Parameter	Type	Description
context	RenderContext	Active render context.
line	RichText	Line to evaluate.

Returns float: Line height in pixels..

TextEngine::linesHeight(List)

linesHeight(List)

Calculates the combined height of multiple wrapped lines.

Parameter	Type	Description
lines	List	List of rich text lines.

Returns float: Combined height in pixels..

TextEngine::linesHeight(RenderContext, List)

linesHeight(RenderContext, List)

Calculates combined lines height using active render context.

Parameter	Type	Description
context	RenderContext	Active render context.
lines	List	List of rich text lines.

Returns float: Combined height in pixels..

TextEngine::draw(RenderContext, String, float, float, float, float, Paint, Transform, Alignment, Alignment)

draw(RenderContext, String, float, float, float, float, Paint, Transform, Alignment, Alignment)

Renders plain text aligned within the specified bounding box.

Parameter	Type	Description
context	RenderContext	Active render context.
text	String	Text string.
x	float	X coordinate.
y	float	Y coordinate.
width	float	Container width.
height	float	Container height.
paint	Paint	Paint styling.
transform	Transform	Optional transform.
horizontalAlignment	Alignment	Horizontal alignment.
verticalAlignment	Alignment	Vertical alignment.

TextEngine::draw(RenderContext, RichText, float, float, float, float, Paint, Transform, Alignment, Alignment)

draw(RenderContext, RichText, float, float, float, float, Paint, Transform, Alignment, Alignment)

Renders rich text with alignment and inline content support.

Parameter	Type	Description
context	RenderContext	Active render context.
text	RichText	Rich text instance.
x	float	X coordinate.
y	float	Y coordinate.
width	float	Container width.
height	float	Container height.
paint	Paint	Paint styling.
transform	Transform	Optional transform.
horizontalAlignment	Alignment	Horizontal alignment.
verticalAlignment	Alignment	Vertical alignment.

TextEngine::drawInline(DrawScope, RichText, float, float, float, float, Paint)

drawInline(DrawScope, RichText, float, float, float, float, Paint)

Lays out and draws rich text with inline content into a DrawScope.

Parameter	Type	Description
draw	DrawScope	Target draw scope.
text	RichText	Rich text instance.
x	float	X coordinate.
y	float	Y coordinate.
width	float	Container width.
height	float	Container height.
paint	Paint	Paint styling.

TextEngine::drawInline(DrawScope, RichText, float, float, float, float, Paint, float)

drawInline(DrawScope, RichText, float, float, float, float, Paint, float)

Lays out and draws rich text into a DrawScope with visual vertical offset.

Parameter	Type	Description
draw	DrawScope	Target draw scope.
text	RichText	Rich text instance.
x	float	X coordinate.
y	float	Y coordinate.
width	float	Container width.
height	float	Container height.
paint	Paint	Paint styling.
textVisualOffset	float	Vertical visual offset.

TextEngine::usesPositionalBrush(RichText)

usesPositionalBrush(RichText)

Checks whether any text run in the rich text uses a coordinate-dependent brush.

Parameter	Type	Description
text	RichText	Rich text instance.

Returns boolean: true if positional brush is present..

TextEngine::alignedStart(float, float, float, Alignment)

alignedStart(float, float, float, Alignment)

Calculates the starting coordinate of an item given available space and alignment.

Parameter	Type	Description
start	float	Base offset coordinate.
available	float	Total available dimension.
size	float	Item dimension.
alignment	Alignment	Alignment mode.

Returns float: Aligned start position..