Makepad Font Skill

Version: makepad-widgets (dev branch) | Last Updated: 2026-01-19

Check for updates: https://crates.io/crates/makepad-widgets

You are an expert at Makepad text and font rendering. Help users by:

• Font configuration: Font families, sizes, styles
• Text layout: Understanding text layouter and shaping
• Text rendering: GPU-based text rendering with SDF

Documentation

Refer to the local files for detailed documentation:

• ./references/font-system.md - Font module structure and APIs

IMPORTANT: Documentation Completeness Check

Before answering questions, Claude MUST:

1. Read the relevant reference file(s) listed above
2. If file read fails or file is empty:
   • Inform user: "本地文档不完整，建议运行 /sync-crate-skills makepad --force 更新文档"
   • Still answer based on SKILL.md patterns + built-in knowledge
3. If reference file exists, incorporate its content into the answer

Text Module Structure

draw/src/text/
├── font.rs           # Font handle and metrics
├── font_atlas.rs     # GPU texture atlas for glyphs
├── font_face.rs      # Font face data
├── font_family.rs    # Font family management
├── fonts.rs          # Built-in fonts
├── glyph_outline.rs  # Glyph vector outlines
├── glyph_raster_image.rs # Rasterized glyph images
├── layouter.rs       # Text layout engine
├── rasterizer.rs     # Glyph rasterization
├── sdfer.rs          # Signed distance field generator
├── selection.rs      # Text selection/cursor
├── shaper.rs         # Text shaping (harfbuzz)

Using Fonts in DSL

Text Style

<Label> {
    text: "Hello World"
    draw_text: {
        text_style: {
            font: { path: dep("crate://self/resources/fonts/MyFont.ttf") }
            font_size: 16.0
            line_spacing: 1.5
            letter_spacing: 0.0
        }
        color: #FFFFFF
    }
}

Theme Fonts

<Label> {
    text: "Styled Text"
    draw_text: {
        text_style: <THEME_FONT_REGULAR> {
            font_size: (THEME_FONT_SIZE_P)
        }
    }
}

Font Definition in DSL

live_design! {
    // Define font path
    FONT_REGULAR = {
        font: { path: dep("crate://self/resources/fonts/Regular.ttf") }
    }

    FONT_BOLD = {
        font: { path: dep("crate://self/resources/fonts/Bold.ttf") }
    }

    // Use in widget
    <Label> {
        draw_text: {
            text_style: <FONT_REGULAR> {
                font_size: 14.0
            }
        }
    }
}

Layouter API

pub struct Layouter {
    loader: Loader,
    cache_size: usize,
    cached_params: VecDeque<OwnedLayoutParams>,
    cached_results: HashMap<OwnedLayoutParams, Rc<LaidoutText>>,
}

impl Layouter {
    pub fn new(settings: Settings) -> Self;
    pub fn rasterizer(&self) -> &Rc<RefCell<Rasterizer>>;
    pub fn is_font_family_known(&self, id: FontFamilyId) -> bool;
    pub fn define_font_family(&mut self, id: FontFamilyId, definition: FontFamilyDefinition);
    pub fn define_font(&mut self, id: FontId, definition: FontDefinition);
    pub fn get_or_layout(&mut self, params: impl LayoutParams) -> Rc<LaidoutText>;
}

Layout Parameters

pub struct OwnedLayoutParams {
    pub text: Substr,
    pub spans: Box<[Span]>,
    pub options: LayoutOptions,
}

pub struct Span {
    pub style: Style,
    pub len: usize,
}

pub struct Style {
    pub font_family_id: FontFamilyId,
    pub font_size_in_pts: f32,
    pub color: Option<Color>,
}

pub struct LayoutOptions {
    pub max_width_in_lpxs: Option<f32>,  // Max width for wrapping
    pub wrap: bool,                       // Enable word wrap
    pub first_row_indent_in_lpxs: f32,    // First line indent
}

Rasterizer Settings

pub struct Settings {
    pub loader: loader::Settings,
    pub cache_size: usize,  // Default: 4096
}

pub struct rasterizer::Settings {
    pub sdfer: sdfer::Settings {
        padding: 4,     // SDF padding
        radius: 8.0,    // SDF radius
        cutoff: 0.25,   // SDF cutoff
    },
    pub grayscale_atlas_size: Size::new(4096, 4096),
    pub color_atlas_size: Size::new(2048, 2048),
}

DrawText Widget

<View> {
    // Label is a simple text widget
    <Label> {
        text: "Simple Label"
        draw_text: {
            color: #FFFFFF
            text_style: {
                font_size: 14.0
            }
        }
    }

    // TextFlow for rich text
    <TextFlow> {
        <Bold> { text: "Bold text" }
        <Italic> { text: "Italic text" }
        <Link> {
            text: "Click here"
            href: "https://example.com"
        }
    }
}

Text Properties

When Answering Questions

1. Makepad uses SDF (Signed Distance Field) for crisp text at any scale
2. Fonts are loaded once and cached in GPU texture atlases
3. Text shaping uses harfbuzz for proper glyph positioning
4. Use dep("crate://...") for embedded font resources
5. Default font cache size is 4096 glyphs
6. Atlas sizes: 4096x4096 for grayscale, 2048x2048 for color (emoji)

When to Use

Use this skill when tackling tasks related to its primary domain or functionality as described above.

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.