Icon

A semantic icon name, such as Icon::Trash or Icon::Search. Components take an Icon and the backend chooses the artwork, which is Bootstrap Icons unless the host gives another set.

Import

use limn::{Element, Icon};

Icon is an enum, not a component: it has no render.

Usage

Pass an icon to the component that shows it, or paint one on its own with Element::icon, which draws it at 16 px in the element’s foreground.

fn view(palette: ComponentPalette) -> Element {
    Element::row(vec![
        Element::icon(Icon::Search).foreground(palette.muted),
        Button::new("open", "Open", palette).icon(Icon::Folder).render(),
    ])
}

The chosen item

let icon = if chosen { Icon::Folder.filled() } else { Icon::Folder };
Element::icon(icon).foreground(if chosen { palette.text } else { palette.muted })

filled() returns the solid form of an icon, for the active or chosen item of a list. An icon without one, such as Icon::Search, is returned as it is.

Larger

Element::icon(Icon::Folder).large_icon(48.0)

large_icon(px) draws a standalone icon larger than 16 px, up to 128, for thumbnails and empty states. Icons inside controls keep 16 px.

Smaller

Element::icon(Icon::Lock).small_icon(10.0)

small_icon(px) draws a standalone icon smaller than 16 px, down to SMALL_ICON_SIZE (8), such as a padlock over a corner of another icon or a speaker inside a small badge. The element measures the side it is drawn at.

Categories

Icon::Tree, FriedEgg, Gamepad, Car, Lightbulb and Flag, with Emoji and Heart, name the usual categories of an emoji picker: nature, food, activities, travel, objects and flags, people and symbols.

File types

Element::icon(file_icon("src/main.rs"))

file_icon(path) returns the artwork for a file’s type. These icons keep their own colors.

Artwork of your own

const LOGO: &str = include_str!("../assets/logo.svg");
Element::icon(Icon::Custom(LOGO)).foreground(palette.text)

Icon::Custom takes the source of an SVG drawn with currentColor. It is fitted to the icon’s square without distortion and tinted like any other icon.

Another icon set

fn lucide(icon: Icon) -> Option<&'static str> {
    match icon {
        Icon::Search => Some(include_str!("../assets/lucide/search.svg")),
        Icon::Trash => Some(include_str!("../assets/lucide/trash-2.svg")),
        _ => None,
    }
}

limn_egui::set_icon_pack(lucide);

A pack is a function from an Icon to the SVG that draws it, or None to leave that one to Bootstrap Icons, so it can replace a few icons or all of them. The artwork must draw with currentColor. Call set_icon_pack once on the UI thread when the window is created, before the first frame: an icon already drawn stays as it was. File type icons and Icon::Custom are not asked of the pack.

Platform-rendered icons

A host can render system artwork, such as SF Symbols on iOS, without converting it to SVG. Supply a function with this signature:

fn render_platform_icon(icon: Icon, pixels: u16) -> Option<eframe::egui::ColorImage>

Install it on the UI thread with limn_egui::set_icon_rasterizer(Some(render_platform_icon)). It receives the final physical pixel side, including display scaling. Return a square image of that exact size containing a white alpha mask; the painter applies the element’s color. Native premultiplied RGBA bytes can be converted with ColorImage::from_rgba_premultiplied.

Return None for an unsupported symbol or for application artwork that should remain unchanged. A missing or malformed image uses the configured SVG pack, then the usual bundled artwork. The rasterizer can explicitly handle Icon::Custom; file-type icons always keep their original colors.

The normal bounded texture cache reuses each icon at each physical size. Replacing the renderer, or removing it with set_icon_rasterizer(None), clears only cached icon textures and requests a repaint. Raster images and the application’s own artwork data remain in their separate caches.

See Icons in the component reference.