Typography

ChatTypography controls two SDK typography layers:

1. Font sizes — 6 semantic tokens (big, medium, mediumUpper, regular, small, error). These are ChatTypography(...) constructor parameters, each is a ChatFontStyle instance.
2. Custom fonts — 20 TTF substitution points (*FontPath: String?). These are var properties in the class body; set them after creating the object (via apply { ... } or direct assignment), not through the constructor. Paths are relative to app/src/main/assets/.

Only what is listed here

The tables below list all SDK-configurable fonts and sizes. If you find a field in the SDK code that is not in these lists, it is not part of the public API and cannot be changed.

Font sizes

Field	Type	Default size	Description
big	ChatFontStyle	20 sp (R.dimen.ecc_text_big)	Large font (titles, accents)
mediumUpper	ChatFontStyle	18 sp (R.dimen.ecc_text_medium_upper)	Slightly larger than medium
medium	ChatFontStyle	16 sp (R.dimen.ecc_text_medium)	Medium font
regular	ChatFontStyle	14 sp (R.dimen.ecc_text_regular)	Main SDK font (message text)
small	ChatFontStyle	12 sp (R.dimen.ecc_text_small)	Small font (timestamps, captions)
error	ChatFontStyle	11 sp (R.dimen.ecc_error_text_size)	Font for error messages

ChatFontStyle stores the size as a dimen resource reference in sp units (which preserves accessibility scaling at the system level) — changes to the system font scale automatically scale all 6 semantic tokens.

Custom fonts — 20 substitution points

All fields are String? with a default of null (system font is used). The value is a path relative to app/src/main/assets/, for example "fonts/Roboto-Regular.ttf".

Field	Description
defaultFontRegularPath	Default font (Regular)
defaultFontBoldPath	Default bold font
defaultFontLightPath	Default thin font
toolbarTitleFontPath	Toolbar title
toolbarSubtitleFontPath	Toolbar subtitle
placeholderTitleFontPath	Welcome screen title
placeholderSubtitleFontPath	Welcome screen subtitle
quoteHeaderFontPath	Quote header
quoteAuthorFontPath	Quote author
quoteMessageFontPath	Quoted message text
quoteTimeFontPath	Quote timestamp
inputQuotedMessageFontPath	Quoted message in the input field
bubbleMessageFontPath	Chat message text
bubbleTimeFontPath	Chat timestamp
messageHeaderFontPath	Date/time headers between messages
typingFontPath	Typing indicator
scheduleAlertFontPath	Schedule notice
systemMessageFontPath	System messages
emptyMediaAndFilesHeaderFontPath	Empty "Media and files" list header
emptyMediaAndFilesDescriptionFontPath	Empty "Media and files" list description

Basic setup

val typography = ChatTypography().apply {
    // Global defaults — fill all other fields if they are null
    defaultFontRegularPath = "fonts/MyFont-Regular.ttf"
    defaultFontBoldPath = "fonts/MyFont-Bold.ttf"
    defaultFontLightPath = "fonts/MyFont-Light.ttf"

    // Per-element overrides
    toolbarTitleFontPath = "fonts/MyFont-Medium.ttf"
    bubbleMessageFontPath = "fonts/MyFont-Regular.ttf"
}

val theme = ChatTheme(
    applicationContext,
    typography = typography
)

Global defaults + per-element override

First set defaultFontRegularPath / defaultFontBoldPath / defaultFontLightPath — this covers 95% of the surface. Then add *FontPath only for elements that need a different font.

TypefaceCache does not render the file if the path is invalid

The SDK caches Typeface through an internal TypefaceCache. If the file at the given path is missing from assets/, the SDK silently falls back to the system font — no exception. Check the list of files in app/src/main/assets/fonts/ before release.

Full brand kit

Overriding both fonts and sizes. Semantic tokens are set via the constructor; *FontPath fields — via apply { ... }.

Resources live in the app, the fontSize type is strictly @DimenRes

R.dimen.brand_text_* and R.color.brand_* below are placeholders. Declare them in your app's app/src/main/res/values/dimens.xml (or the corresponding colors.xml) before the build, otherwise you'll get an Unresolved reference.

ChatFontStyle.fontSize: Int? is declared without the @DimenRes annotation, but in most SDK pipelines the value is processed via Resources.getDimension(...) (see TextViewFabric, InputViewFabric). Pass only an R.dimen.* identifier. A literal in sp (fontSize = 22) will lead either to Resources$NotFoundException or to an incorrect size (for example, in spannable text where the value is applied as a raw pixel size).

val brandTypography = ChatTypography(
    big = ChatFontStyle(fontSize = R.dimen.brand_text_big),         // e.g., 22 sp
    regular = ChatFontStyle(fontSize = R.dimen.brand_text_regular), // e.g., 15 sp
    small = ChatFontStyle(fontSize = R.dimen.brand_text_small)      // e.g., 13 sp
).apply {
    defaultFontRegularPath = "fonts/Brand-Regular.ttf"
    defaultFontBoldPath = "fonts/Brand-Bold.ttf"
    defaultFontLightPath = "fonts/Brand-Light.ttf"
    toolbarTitleFontPath = "fonts/Brand-Medium.ttf"
}

val theme = ChatTheme(
    applicationContext,
    colors = brandColors,
    images = brandImages,
    typography = brandTypography
)

A detailed scenario of building light and dark themes is in Themes.

Related sections

• Design system: overview — how ChatTheme, ChatColors, ChatImages, ChatTypography are organized.
• Screen components — where the listed fonts appear on screen.
• Colors — ChatColors table.
• Images — ChatImages fields.
• Themes — how ChatTypography is integrated into ChatTheme.
• Flows — screen-specific customization.
• Accessibility — sp units and Dynamic Type.
• Known limitations — parameters with server-side priority.