Numbers and money

Decimal Field for Slint

KitDecimalField · Slint Kit 0.3.0

Numeric text input connected to DecimalValue in Rust.

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Try the component

Download the complete project, extract it and run cargo run --locked in its folder. Rust 1.92+; Slint Kit 0.3.0 from crates.io. You can also copy the four files below.

Edit the value, then press Enter or Accept. Rust accepts a valid draft and preserves the last accepted value on errors.

ui/app.slint

export { KitFormValidation, HtmlInputKind, NumberInputFormat, KitInputConstraints, KitValidationResult, KitValidityState } from "@kit/kit.slint";
import { KitDecimalField, KitButton, KitThemes, ValidationPresentation } from "@kit/kit.slint";
export component App inherits Window {
    title: "Decimal"; preferred-width: 520px; preferred-height: 320px;
    max-width: 100000px; max-height: 100000px; background: KitThemes.light.canvas;
    in-out property <string> draft; in property <string> error; in property <string> accepted;
    callback edited(string); callback commit(); callback blurred(); callback cancel();
    
    VerticalLayout {
        padding: 24px; spacing: 16px; alignment: start;
        control := KitDecimalField {
            required: true;
            label: "Decimal"; text <=> root.draft; error: root.error;
            validation: root.error != "" ? ValidationPresentation.invalid : ValidationPresentation.pristine;
            placeholder: "12.50";
            edited(value) => { root.edited(value); }
            commit-requested(value) => { root.commit(); }
            cancelled => { root.cancel(); }
            focus-observed(focused) => { if (!focused) { root.blurred(); } }
            
        }
        KitButton { text: "Accept"; activated => { root.commit(); } }
        Text { text: "Accepted: " + root.accepted; color: KitThemes.light.text-primary; wrap: word-wrap; }
    }
}

src/main.rs

use slint::ComponentHandle;
use slint_kit::*;
slint::include_modules!();
type Value = DecimalValue;
fn parse(text: &str) -> DraftValue<Value> {
    DecimalRules {
        locale: NumberLocale::EnCa,
        scale: DecimalScale::new(2).unwrap(),
        sign: SignPolicy::NonNegative,
        bounds: None,
    }
    .parse(text)
}
fn format(value: &Value) -> String {
    value.to_string()
}
fn main() -> Result<(), slint::PlatformError> {
    let app = App::new()?;
    slint_kit::init_form_validation!(self, app);
    let initial = DecimalValue::from_integer(12);
    app.set_accepted(format(&initial).into());
    let weak = app.as_weak();
    let field = FieldBinding::<Value, ()>::new(
        Some(initial),
        Ownership::Local,
        CommitPolicy::OnBlur,
        AbsencePolicy::Required,
        parse,
        format,
        |_| String::new(),
        move |view| {
            if let Some(app) = weak.upgrade() {
                app.set_draft(view.draft.into());
                app.set_error(view.error.into());
            }
        },
    );
    field.set_html_constraints(slint_kit::HtmlConstraints {
        kind: slint_kit::HtmlInputKind::Number, required: true,
        step: Some("any".into()),
        ..Default::default()
    });
    let weak = app.as_weak();
    field.on_intent(move |intent| {
        if let Some(app) = weak.upgrade() {
            if let FieldIntent::Commit(value) = intent {
                app.set_accepted(format(&value).into());
            }
        }
    });
    let binding = field.clone();
    app.on_edited(move |text| {
        let _ = binding.edited(&text);
    });
    let binding = field.clone();
    app.on_commit(move || {
        let _ = binding.commit(CommitTrigger::Submit);
    });
    let binding = field.clone();
    app.on_blurred(move || {
        let _ = binding.commit(CommitTrigger::Blur);
    });
    let binding = field.clone();
    app.on_cancel(move || binding.cancel());

    app.run()
}

[package]
name = "slint-kit-decimal-field-example"
version = "0.1.0"
edition = "2024"
rust-version = "1.92"
license = "GPL-3.0-or-later"
publish = false

[dependencies]
slint-kit = "=0.3.0"
slint = { version = "=1.18.1", default-features = false, features = ["std", "compat-1-18", "backend-winit", "renderer-skia", "accessibility"] }

[build-dependencies]
slint-kit-build = "=0.3.0"

[workspace]

fn main() {
    slint_kit_build::compile("ui/app.slint").expect("compile component example");
}

Files: Cargo.toml · build.rs · ui/app.slint · src/main.rs

Use FieldBinding with an explicit parser, formatter and commit policy. Nonnegative values with at most two decimal places; use a decimal point.

Draft text stays separate from the accepted typed value. Invalid or incomplete input shows an error without replacing that value.

View source ↗

Choose between built-in options and custom composition

Shared options

• label — built-in property; custom composition example
• description — built-in property; custom composition example
• error — built-in property; custom composition example

Visual composition

The file below produces the screenshot. For controller-driven components, it shows the displayed state without supplying the Rust wiring. Create a project.

Show the screenshot source

// SPDX-License-Identifier: GPL-3.0-or-later
// Display projections are fixtures. Validate accepted domain values in Rust.
import { KitDecimalField, KitTheme, KitThemes } from "@kit/kit.slint";

export component Example inherits Window {
    title: "KitDecimalField example";
    preferred-width: 420px;
    preferred-height: 180px;
    max-width: 100000px;
    max-height: 100000px;
    background: root.theme.canvas;
    in-out property <KitTheme> theme: KitThemes.light;
    in-out property <string> status;
    VerticalLayout {
        padding: 24px; spacing: 16px; alignment: start;
        Text { text: "Decimal Field"; color: root.theme.text-primary; font-size: 20px * root.theme.text-scale; font-weight: 600; }
        KitDecimalField { theme: root.theme; label: "Distance"; text: "12.75"; edited(value) => { root.status = "Draft: " + value; } }
        if root.status != "": Text { text: root.status; color: root.theme.text-secondary; font-size: 12px * root.theme.text-scale; wrap: word-wrap; }
    }
}

Download this example

Public API

Inherits KitIntegerField.

See also

• Integer Field
• Money Field