Text

All text is shown by text elements: text(..) in Rust, <Text> in TSX. A text element is one paragraph, typeset by the platform’s text engine (CoreText on Apple platforms, StaticLayout on Android) on the engine thread when it is laid out, and only drawn on the main thread. Nested text elements are spans of the same paragraph, not separate views.

text("By continuing you agree to the ")
    .text_size(px(16.0))
    .line_height(px(24.0))
    .text_color(rgb(0x1f2328))
    .child(
        text("Terms of service")
            .text_color(rgb(0x0969da))
            .underline()
            .on_press(open_terms),
    )
    .child(".")

<Text style={{ fontSize: 16, lineHeight: 24, color: "#1f2328" }}>
  By continuing you agree to the{" "}
  <Text style={{ color: "#0969da", textDecorationLine: "underline" }} onPress={openTerms}>
    Terms of service
  </Text>
  .
</Text>

The element itself is documented on text; this page is about using it.

#Strings and whitespace

In Rust, a text’s content is a string, shown as written: \n breaks the line. Content that reads signals is a closure, and the text updates when they change. In TSX, JSX text follows the same rules as in React: each line is trimmed, lines that are only whitespace are dropped, and the remaining lines are joined with a single space. Whitespace within one line is kept, so {first} {last} keeps its space. Use {" "} for a space at the start or end of a line, and {"\n"} for a line break:

text(move || format!("Hello, {}!\nWelcome back.", name.get()))

<Text>
  Hello,
  {name()}!{"\n"}
  Welcome back.
</Text>

Expressions in text follow what they read: text(move || format!("{} items", count.get())) and <Text>{count()} items</Text> update when count changes.

#Spans and inheritance

A text inside a text is a span. It inherits the text style of its parent and overrides what it sets:

text("")
    .text_size(px(17.0))
    .text_color(rgb(0x1f2328))
    .child(text("Light ").font_weight(FontWeight::LIGHT))
    .child(text("Bold ").font_weight(FontWeight::BOLD))
    .child(text("Italic ").italic())
    .child(text("Spaced").letter_spacing(px(4.0)))

<Text style={{ fontSize: 17, color: "#1f2328" }}>
  <Text style={{ fontWeight: "300" }}>Light </Text>
  <Text style={{ fontWeight: "700" }}>Bold </Text>
  <Text style={{ fontStyle: "italic" }}>Italic </Text>
  <Text style={{ letterSpacing: 4 }}>Spaced</Text>
</Text>

Text styles also pass down from views, as in CSS: view().text_color(white()).text_sm() in Rust and <View class="text-white text-sm"> in TSX style the text and input elements inside them.

#Links

A span with a press handler (.on_press(..) or .on_long_press(..); onPress or onLongPress) is a link: a press on its characters goes to the span, a press elsewhere to the paragraph. Links in nested spans work too.

text("Read the ")
    .on_press(move || tapped.set("the sentence"))
    .child(text("terms").text_color(rgb(0x0969da)).on_press(move || tapped.set("terms")))
    .child(" first.")

<Text onPress={() => log("the sentence")}>
  Read the <Text style={{ color: "#0969da" }} onPress={() => open(termsUrl)}>terms</Text> first.
</Text>

#Backgrounds of spans

A span’s background color and corner radius paint a box behind its characters on each line it reaches, as tall as its font; the text lays out the same and copies whole, so inline code is a span (Text element):

text("Run ")
    .child(text(" npm test ").font_family("ui-monospace").bg(rgb(0xeff1f3)).rounded(px(4.0)))
    .child(" first.")

<Text>
  Run <Text style={{ fontFamily: "ui-monospace", backgroundColor: "#eff1f3", borderRadius: 4 }}> npm test </Text> first.
</Text>

#Views and images inside text

Any element other than a text inside a text is laid out inline, on the baseline, and wraps with the words. It can take presses of its own:

text("Made with ")
    .text_size(px(16.0))
    .line_height(px(26.0))
    .child(image(LOGO).size(px(18.0)))
    .child(" nsh. Status ")
    .child(
        view()
            .bg(rgb(0x1a7f37))
            .rounded(px(9.0))
            .px(px(7.0))
            .h(px(18.0))
            .justify_center()
            .child(text("LIVE").text_color(white()).text_size(px(11.0)).font_weight(FontWeight::BOLD)),
    )

<Text style={{ fontSize: 16, lineHeight: 26 }}>
  Made with <Image src={logo} style={{ width: 18, height: 18 }} /> nsh. Status{" "}
  <View style={{ backgroundColor: "#1a7f37", borderRadius: 9, paddingHorizontal: 7, height: 18, justifyContent: "center" }}>
    <Text style={{ color: "#ffffff", fontSize: 11, fontWeight: "700" }}>LIVE</Text>
  </View>
</Text>

Inline elements cut off by numberOfLines or an ellipsis are hidden; copying the text leaves them out.

The style key verticalAlign places an inline element in its line, as CSS’s vertical-align places an image: "baseline" (the default) stands its bottom on the baseline, "text-top" and "text-bottom" put its top or bottom at the top or bottom of the text’s font, and "middle" centers it half the font’s x height above the baseline. The line grows to hold the element wherever it reaches past the font. An icon at the start of a paragraph that should line up with the text’s bottom, as Android’s ImageSpan draws it, takes "text-bottom". The classes are align-baseline, align-text-top, align-text-bottom and align-middle; in Rust .align_text_bottom() and the others of the same names.

<Text style={{ fontSize: 16 }}>
  <Image src={badge} style={{ width: 16, height: 16, verticalAlign: "text-bottom" }} /> Verified seller
</Text>

#Text styles

A text element is also a view: it takes backgrounds, borders, corners, padding and the other view styles.

text(move || format!("{:.2}", price.get())).text_size(px(18.0)).tabular_nums()
text("Typo").underline().text_decoration_wavy().text_decoration_color(rgb(0xcf222e))
text("Shadow")
    .text_size(px(26.0))
    .font_weight(FontWeight::EXTRA_BOLD)
    .text_color(white())
    .text_shadow_color(rgba(0x00000099))
    .text_shadow_offset(point(px(2.0), px(2.0)))
    .text_shadow_radius(px(4.0))

<Text style={{ fontSize: 18, fontVariant: ["tabular-nums"] }}>{price().toFixed(2)}</Text>
<Text style={{ textDecorationLine: "underline", textDecorationStyle: "wavy", textDecorationColor: "#cf222e" }}>Typo</Text>
<Text style={{ fontSize: 26, fontWeight: "800", color: "#ffffff", textShadowColor: "rgba(0,0,0,0.6)", textShadowOffset: { width: 2, height: 2 }, textShadowRadius: 4 }}>
  Shadow
</Text>

tabular-nums gives every digit the same width, which keeps counters and prices from jittering as they change.

#Truncation

text(long_description).number_of_lines(2)
text(file_path).number_of_lines(1).ellipsize_mode(EllipsizeMode::Middle)

<Text numberOfLines={2}>{longDescription}</Text>
<Text numberOfLines={1} ellipsizeMode="middle">{filePath}</Text>

text(move || total.get())
    .number_of_lines(1)
    .shrink_to_fit(0.5)
    .text_size(px(48.0))
    .w(px(200.0))

<Text numberOfLines={1} adjustsFontSizeToFit minimumFontScale={0.5} style={{ fontSize: 48, width: 200 }}>
  {total()}
</Text>

The Tailwind classes truncate and line-clamp-* do the same and lose to the props when both are set.

#System text size

Text follows the user’s text size setting (Dynamic Type on iOS, font size on Android) by default.

font_scale() in Rust and fontScale() from nsh/device in TSX are the current scale, and change when the user changes the setting. Inputs take allowFontScaling and maxFontSizeMultiplier too.

text("Tab label").max_font_size_multiplier(1.3).text_size(px(13.0))

<Text maxFontSizeMultiplier={1.3} style={{ fontSize: 13 }}>Tab label</Text>

Prefer limiting the scale over turning it off: large text is an accessibility setting people rely on.

#Selection

selectable (.selectable(true)) lets the user select and copy the text, as in the system’s own text views: a long press selects the word under the finger, the handles move the selection’s ends, and the edit menu offers Copy and Select All (iOS adds Look Up, Translate and Share; Android Share). A selection stays inside one text block. The style key selectionColor (.selection_color(..), selection:text-*) colors the highlight and the handles. The class select-text does the same as selectable.

In desktop browsers text is selectable by default, as on a web page, except inside interactive elements (views with press or touch handlers, such as buttons and pressable rows); selectable={false} (.selectable(false)) or the class select-none keeps a text unselectable there. Phone and tablet browsers follow the native rule.

text(order_number).selectable(true).selection_color(rgb(0x7c3aed))

<Text selectable style={{ selectionColor: "#7c3aed" }}>{orderNumber}</Text>

To copy from code (a Copy button), use set_clipboard(..) in Rust or nsh/clipboard in TSX.

#onTextLayout

onTextLayout (the TextLayout event in Rust) reports the laid-out lines after each layout, in the text’s content box:

text(move || body.get()).on(EventKind::TextLayout, move |e: &EventPayload| {
    if let EventPayload::TextLayout(laid_out) = e {
        lines.set(laid_out.len());
    }
})

<Text
  onTextLayout={(e) => {
    lines.set(e.lines.length);
    console.log(e.lines.map((l) => `${l.text} (${l.bounds.size.width.toFixed(0)}pt)`));
  }}
>
  {body()}
</Text>

Each line has text, x, y, width, height, ascender, descender, capHeight and xHeight (cap_height and x_height in Rust). Use it to show a “Read more” button only when text was cut, or to align other content with a baseline.

#Accessibility

A text element is read by screen readers as its content. Give a role to text that acts as a heading (.role(AccessibilityRole::Header), role="header") and to links (AccessibilityRole::Link, role="link"). See Accessibility.

#Related

• Fonts: custom fonts and weights.
• text element: every prop.
• Forms and keyboard: text input.