Text & typography

label(...) renders native text. Its font is chosen from a semantic (logical) style that maps to each platform’s own text styles, so a Day app matches the OS’s typography and inherits its accessibility text scaling automatically.

use day::prelude::*;

label("Chapter One").font(Font::Title)                 // a semantic style
label("A quiet caption").font(Font::Footnote)
label("Read me").font(Font::Body).bold()               // weight
label("Whispered").italic()                            // slant
label(tr("price")).color(Color::hex(0x27AE60))         // color
label("Everything")
    .font(Font::Title2)
    .weight(FontWeight::Heavy)
    .italic()
    .color(Color::hex(0x8E44AD))
label("18 pt").font(Font::System(18.0))                // a custom size (still accessibility-scaled)

Semantic styles (Font)

Largest → smallest, mirroring SwiftUI’s Font.TextStyle:

LargeTitle, Title, Title2, Title3, Headline, Subheadline, Body (default), Callout, Footnote, Caption, Caption2. Plus System(pt) for a custom point size, and Custom("Family", pt) for a bundled custom font referenced by family name (ship the file in the project’s resource/fonts/ directory; see docs/resources.md §18.4 for the packaging and naming rules).

Each maps to the platform’s native text style where one exists, so sizes and weights match the OS:

Weight & style

• .weight(FontWeight::Semibold): UltraLight, Thin, Light, Regular, Medium, Semibold, Bold, Heavy, Black (matching UIFont.Weight). .bold() is shorthand for .weight(FontWeight::Bold).
• .italic(): slants the text.
• A weight override keeps the style’s accessibility-scaled size (on iOS the weighted font is wrapped in UIFontMetrics so it also scales with Dynamic Type).

Color

.color(Color) sets the text color; omit it to use the platform’s default label color (which adapts to light/dark). Colors are given as Color::hex(0xRRGGBB) or Color::rgba(r, g, b, a).

Custom sizes and accessibility

Font::System(pt) takes an explicit point size, but it is still scaled by the platform’s accessibility text-size setting (iOS runs it through UIFontMetrics, Android uses sp, GTK uses the text-scaling factor, web-dom expresses it as pt/16 rem so it rides the browser’s font-size preference), so a hard-coded size never turns into a fixed, unreadable pixel size.

Font::Custom("Family", pt) scales the same way; a bundled font never opts out of accessibility sizing.

Selectable text

Text is not user-selectable by default on any backend: a label, a button’s caption, and a table cell all match each platform’s native behavior, where static text can’t be selected. Opt a piece in with .selectable():

label("Order #A1B2-C3D4").selectable()   // the reader can select and copy it

It applies to the piece’s own widget, so on a container it makes every label within selectable. The modifier routes to Toolkit::set_selectable, honored where the toolkit has a native affordance:

Selection visuals and the copy shortcut are the platform’s own. It’s unmanaged: set once at mount, and it survives Day’s own text updates.

The showcase’s Text page is a live specimen of every style, weight, italic, color, custom size, the three bundled custom fonts, and a .selectable() line.