TextMeasurer

public class TextMeasurer(
    private val defaultFontFamilyResolver: FontFamily.Resolver,
    private val defaultDensity: Density,
    private val defaultLayoutDirection: LayoutDirection,
    private val cacheSize: Int = DefaultCacheSize,
)

Measures text to prepare it for drawing.

Create instances using rememberTextMeasurer in Composable contexts to inherit default composition locals.

Caches layout results internally using an LRU cache to optimize repeated measure calls.

Reuses the cached layout when changing only draw-affected parameters:

• TextStyle.color or TextStyle.brush
• TextStyle.shadow
• TextStyle.textDecoration
• TextStyle.drawStyle

This makes animating draw-only parameters highly efficient.

Layout-affecting changes like text, font size, or constraints calculate a new layout. These new layouts may evict older entries once the cache reaches capacity.

Provide FontFamily.Resolver, LayoutDirection, and Density during construction. TextMeasurer uses these as defaults when skipped in measure calls.

Parameters

Functions

measure

public fun measure(
        text: AnnotatedString,
        style: TextStyle = TextStyle.Default,
        overflow: TextOverflow = TextOverflow.Clip,
        softWrap: Boolean = true,
        maxLines: Int = Int.MAX_VALUE,
        placeholders: List<AnnotatedString.Range<Placeholder>> = listOf(),
        constraints: Constraints = Constraints(),
        layoutDirection: LayoutDirection = this.defaultLayoutDirection,
        density: Density = this.defaultDensity,
        fontFamilyResolver: FontFamily.Resolver = this.defaultFontFamilyResolver,
        skipCache: Boolean = false,
    ): TextLayoutResult

Creates a TextLayoutResult according to given parameters.

This function supports laying out text that consists of multiple paragraphs, includes placeholders, wraps around soft line breaks, and might overflow outside the specified size.

Most parameters for text affect the final text layout. One pixel change in constraints boundaries can displace a word to another line which would cause a chain reaction that completely changes how text is rendered.

On the other hand, some attributes only play a role when drawing the created text layout. For example text layout can be created completely in black color but we can apply TextStyle.color later in draw phase. This also means that animating text color shouldn't invalidate text layout.

Thus, textLayoutCache helps in the process of converting a set of text layout inputs to a text layout while ignoring non-layout-affecting attributes. Iterative calls that use the same input parameters should benefit from substantial performance improvements.

Parameters

measure

public fun measure(
        text: String,
        style: TextStyle = TextStyle.Default,
        overflow: TextOverflow = TextOverflow.Clip,
        softWrap: Boolean = true,
        maxLines: Int = Int.MAX_VALUE,
        constraints: Constraints = Constraints(),
        layoutDirection: LayoutDirection = this.defaultLayoutDirection,
        density: Density = this.defaultDensity,
        fontFamilyResolver: FontFamily.Resolver = this.defaultFontFamilyResolver,
        skipCache: Boolean = false,
    ): TextLayoutResult

Creates a TextLayoutResult according to given parameters.

This function supports laying out text that consists of multiple paragraphs, includes placeholders, wraps around soft line breaks, and might overflow outside the specified size.

Most parameters for text affect the final text layout. One pixel change in constraints boundaries can displace a word to another line which would cause a chain reaction that completely changes how text is rendered.

On the other hand, some attributes only play a role when drawing the created text layout. For example text layout can be created completely in black color but we can apply TextStyle.color later in draw phase. This also means that animating text color shouldn't invalidate text layout.

Thus, textLayoutCache helps in the process of converting a set of text layout inputs to a text layout while ignoring non-layout-affecting attributes. Iterative calls that use the same input parameters should benefit from substantial performance improvements.

Parameters