vectorcraft/crates/doc/src/text.rs

//! Text objects (model only; layout and glyph outlines live in `vectorcraft-text`).

use serde::{Deserialize, Serialize};
use vectorcraft_color::{Color, Paint};
use vectorcraft_geom::{Affine, PathData, Point, Rect};

use crate::appearance::{Appearance, AppearanceItem, Dash, FillLayer, LineCap, LineJoin, StrokeLayer};

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
pub enum Justify {
    #[default]
    Left,
    Center,
    Right,
    JustifyLeft,
    JustifyCenter,
    JustifyRight,
    JustifyAll,
}

/// Character attributes (the Character panel).
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct CharStyle {
    pub font_family: String,
    #[serde(default = "regular")]
    pub font_style: String,
    /// Size in points.
    pub size: f64,
    /// Leading in points; None = Auto (120% of size).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub leading: Option<f64>,
    /// Tracking in 1/1000 em.
    #[serde(default)]
    pub tracking: f64,
    /// Kerning: None = Auto (metrics), Some(v) = manual in 1/1000 em.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub kerning: Option<f64>,
    #[serde(default)]
    pub baseline_shift: f64,
    #[serde(default = "hundred")]
    pub h_scale: f64,
    #[serde(default = "hundred")]
    pub v_scale: f64,
    #[serde(default)]
    pub rotation: f64,
    pub fill: Paint,
    #[serde(default)]
    pub stroke: Paint,
    #[serde(default)]
    pub stroke_width: f64,
    #[serde(default)]
    pub underline: bool,
    #[serde(default)]
    pub strikethrough: bool,
    #[serde(default)]
    pub all_caps: bool,
    /// OpenType features that differ from the defaults (OpenType panel), as tags: `"dlig"` turns
    /// a feature on, `"-liga"` off.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub features: Vec<String>,
    /// Character style (Character Styles panel) these attributes come from; None = Normal.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub style_name: Option<String>,
    /// Overprint Fill / Overprint Stroke of these characters (see [`crate::FillLayer::overprint`]).
    #[serde(default, skip_serializing_if = "crate::skip::is_default")]
    pub overprint_fill: bool,
    #[serde(default, skip_serializing_if = "crate::skip::is_default")]
    pub overprint_stroke: bool,
    /// Cap, join, miter limit and dashes of the character stroke (Stroke panel, with type
    /// selected); defaults as for object strokes.
    #[serde(default, skip_serializing_if = "crate::skip::is_default")]
    pub stroke_cap: LineCap,
    #[serde(default, skip_serializing_if = "crate::skip::is_default")]
    pub stroke_join: LineJoin,
    #[serde(default = "ten", skip_serializing_if = "is_ten")]
    pub stroke_miter_limit: f64,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub stroke_dash: Option<Dash>,
    /// Superscript or subscript (Character panel).
    #[serde(default, skip_serializing_if = "crate::skip::is_default")]
    pub position: CharPosition,
    /// Small Caps (Character panel): lowercase letters drawn as capitals at this percentage of the
    /// size (Document Setup → Type → Small Caps); None = off.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub small_caps: Option<f64>,
}

/// Superscript or subscript proportions in percent of the font size (Document Setup → Type).
#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
pub struct ScriptMetrics {
    /// Glyph size.
    pub size: f64,
    /// Baseline offset: up for superscript, down for subscript.
    pub position: f64,
}

impl ScriptMetrics {
    pub const DEFAULT: Self = Self { size: 58.3, position: 33.3 };
}

impl Default for ScriptMetrics {
    fn default() -> Self {
        Self::DEFAULT
    }
}

/// Character position (Character panel Superscript / Subscript). The proportions are the
/// document's when the position is applied, and follow later Document Setup changes.
#[derive(Clone, Copy, Debug, Default, PartialEq, Serialize, Deserialize)]
#[serde(tag = "kind", rename_all = "camelCase")]
pub enum CharPosition {
    #[default]
    Normal,
    Superscript(ScriptMetrics),
    Subscript(ScriptMetrics),
}

impl CharPosition {
    /// Glyph scale and baseline shift (points, positive = up) for text of `size` points.
    pub fn scale_shift(self, size: f64) -> (f64, f64) {
        match self {
            CharPosition::Normal => (1.0, 0.0),
            CharPosition::Superscript(m) => (m.size / 100.0, m.position / 100.0 * size),
            CharPosition::Subscript(m) => (m.size / 100.0, -m.position / 100.0 * size),
        }
    }
    /// `normal`, `superscript` or `subscript`.
    pub fn id(self) -> &'static str {
        match self {
            CharPosition::Normal => "normal",
            CharPosition::Superscript(_) => "superscript",
            CharPosition::Subscript(_) => "subscript",
        }
    }
}

fn ten() -> f64 {
    10.0
}
fn is_ten(v: &f64) -> bool {
    *v == 10.0
}
fn regular() -> String {
    "Regular".into()
}
fn hundred() -> f64 {
    100.0
}

impl Default for CharStyle {
    fn default() -> Self {
        Self {
            font_family: "Source Sans 3".into(),
            font_style: "Regular".into(),
            size: 12.0,
            leading: None,
            tracking: 0.0,
            kerning: None,
            baseline_shift: 0.0,
            h_scale: 100.0,
            v_scale: 100.0,
            rotation: 0.0,
            fill: Paint::solid(Color::BLACK),
            stroke: Paint::None,
            stroke_width: 0.0,
            underline: false,
            strikethrough: false,
            all_caps: false,
            features: vec![],
            style_name: None,
            overprint_fill: false,
            overprint_stroke: false,
            stroke_cap: LineCap::Butt,
            stroke_join: LineJoin::Miter,
            stroke_miter_limit: 10.0,
            stroke_dash: None,
            position: CharPosition::Normal,
            small_caps: None,
        }
    }
}

impl CharStyle {
    pub fn effective_leading(&self) -> f64 {
        self.leading.unwrap_or(self.size * 1.2)
    }
    /// Do the characters draw a stroke (a paint and a positive weight)?
    pub fn has_stroke(&self) -> bool {
        !self.stroke.is_none() && self.stroke_width > 0.0
    }
    /// The character stroke as a stroke layer (paint, weight, cap, join, miter limit, dashes and
    /// overprint), so type strokes share the object strokes' geometry, rendering and export.
    pub fn stroke_layer(&self) -> StrokeLayer {
        StrokeLayer {
            overprint: self.overprint_stroke,
            cap: self.stroke_cap,
            join: self.stroke_join,
            miter_limit: self.stroke_miter_limit,
            dash: self.stroke_dash.clone(),
            ..StrokeLayer::new(self.stroke.clone(), self.stroke_width)
        }
    }
    /// Take the paint, weight, cap, join, miter limit and dashes of `st` as the character stroke
    /// (the options characters have no use for, such as alignment and arrowheads, are dropped).
    pub fn set_stroke_layer(&mut self, st: &StrokeLayer) {
        self.stroke = st.paint.clone();
        self.stroke_width = st.width;
        self.stroke_cap = st.cap;
        self.stroke_join = st.join;
        self.stroke_miter_limit = st.miter_limit;
        self.stroke_dash = st.dash.clone();
    }
    /// The character fill as a fill layer, overprinting as the characters do.
    fn fill_layer(&self) -> FillLayer {
        FillLayer { overprint: self.overprint_fill, ..FillLayer::new(self.fill.clone()) }
    }
    /// The characters' paint as an object appearance (their outlines'): the fill, plus the
    /// stroke when it draws one, overprinting as the characters do.
    pub fn appearance(&self) -> Appearance {
        let mut a = Appearance { items: vec![AppearanceItem::Fill(self.fill_layer())], ..Default::default() };
        if self.has_stroke() {
            a.items.push(AppearanceItem::Stroke(self.stroke_layer()));
        }
        a
    }
    /// The characters' paint as the basic fill and stroke rows (the stroke row even when it has
    /// no paint): the appearance the Eyedropper and graphic styles take from type.
    pub fn basic_appearance(&self) -> Appearance {
        Appearance { items: vec![AppearanceItem::Fill(self.fill_layer()), AppearanceItem::Stroke(self.stroke_layer())], ..Default::default() }
    }
}

/// Tab stop alignment (Tabs panel).
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum TabAlign {
    #[default]
    Left,
    Center,
    Right,
    /// Aligns on the first `align_on` character (a decimal point by default).
    Decimal,
}

/// A tab stop, measured from the left edge of the text (area type: the frame's left edge).
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct TabStop {
    pub position: f64,
    #[serde(default)]
    pub align: TabAlign,
    /// Leader characters repeated across the tab's gap (e.g. ". ").
    #[serde(default, skip_serializing_if = "String::is_empty")]
    pub leader: String,
    /// Decimal tabs align on this character.
    #[serde(default = "default_align_on")]
    pub align_on: char,
}

fn default_align_on() -> char {
    '.'
}

/// Distance between default tab stops when no explicit stop applies (½ inch).
pub const DEFAULT_TAB_INTERVAL: f64 = 36.0;

/// Paragraph attributes (the Paragraph panel).
#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
pub struct ParaStyle {
    #[serde(default)]
    pub justify: Justify,
    #[serde(default)]
    pub left_indent: f64,
    #[serde(default)]
    pub right_indent: f64,
    #[serde(default)]
    pub first_line_indent: f64,
    #[serde(default)]
    pub space_before: f64,
    #[serde(default)]
    pub space_after: f64,
    #[serde(default)]
    pub hyphenate: bool,
    /// Tab stops (Tabs panel), sorted by position.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub tabs: Vec<TabStop>,
    /// Paragraph style (Paragraph Styles panel) these attributes come from; None = Normal.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub style_name: Option<String>,
}

/// Area Type Options "First Baseline" offset.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum FirstBaseline {
    /// The tallest glyph ascent touches the frame top (Illustrator's default).
    #[default]
    Ascent,
    CapHeight,
    XHeight,
    /// The first line's leading.
    Leading,
    /// Exactly `first_baseline_min` below the top.
    Fixed,
}

/// Text Wrap Options of a wrap object (Object → Text Wrap).
#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
#[serde(default)]
pub struct TextWrap {
    /// Distance kept between the text and the object, in points (Illustrator's default 6 pt).
    pub offset: f64,
    /// Invert Wrap: text flows inside the object instead of around it.
    pub invert: bool,
}

impl Default for TextWrap {
    fn default() -> Self {
        Self { offset: 6.0, invert: false }
    }
}

/// A resolved wrap shape on an area text object: the outline of a wrap object in text space.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct WrapShape {
    pub path: PathData,
    #[serde(flatten)]
    pub wrap: TextWrap,
}

/// Type on a Path effect: how each glyph is oriented on the path (Type → Type on a Path).
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum PathEffect {
    /// Glyphs rotate with the path (the default).
    #[default]
    Rainbow,
    /// Vertical edges stay vertical; the baseline follows the path.
    Skew,
    /// Horizontal edges stay horizontal; vertical edges are perpendicular to the path.
    #[serde(rename = "3dRibbon")]
    Ribbon3d,
    /// No rotation: the left end of each glyph's baseline sits on the path.
    StairStep,
    /// The baseline centre sits on the path and glyphs point away from the path's centre.
    Gravity,
}

impl PathEffect {
    pub const ALL: [PathEffect; 5] = [PathEffect::Rainbow, PathEffect::Skew, PathEffect::Ribbon3d, PathEffect::StairStep, PathEffect::Gravity];
    pub fn id(self) -> &'static str {
        match self {
            PathEffect::Rainbow => "rainbow",
            PathEffect::Skew => "skew",
            PathEffect::Ribbon3d => "3dRibbon",
            PathEffect::StairStep => "stairStep",
            PathEffect::Gravity => "gravity",
        }
    }
    pub fn parse(s: &str) -> Option<Self> {
        let k = s.to_ascii_lowercase().replace([' ', '-', '_'], "");
        Self::ALL.into_iter().find(|e| e.id().to_ascii_lowercase() == k || (k == "ribbon3d" && *e == PathEffect::Ribbon3d))
    }
}

/// Area Type Options: rows and columns, gutters, inset and first baseline of area type.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
#[serde(default, rename_all = "camelCase")]
pub struct AreaOptions {
    pub rows: usize,
    pub columns: usize,
    /// Gutter between rows/columns in points.
    pub gutter: f64,
    /// Inset from the frame edges in points.
    pub inset: f64,
    pub first_baseline: FirstBaseline,
    /// Minimum first-baseline offset in points.
    pub first_baseline_min: f64,
}

impl Default for AreaOptions {
    fn default() -> Self {
        Self { rows: 1, columns: 1, gutter: 18.0, inset: 0.0, first_baseline: FirstBaseline::Ascent, first_baseline_min: 0.0 }
    }
}

/// A named character or paragraph style: the attributes it sets (a subset of [`CharStyle`] or
/// [`ParaStyle`] fields, by their serialized names). Text using it records the name.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct TextStyleDef {
    pub name: String,
    #[serde(default)]
    pub attrs: serde_json::Map<String, serde_json::Value>,
}

/// A run of text sharing one character style.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct TextRun {
    pub text: String,
    pub style: CharStyle,
}

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
#[serde(tag = "kind", rename_all = "lowercase")]
pub enum TextKind {
    /// Point type: anchored at the baseline origin of the first line.
    Point,
    /// Area type flowed inside `frame` (document coordinates, untransformed by `xf`).
    Area { frame: PathData },
    /// Type on a path, starting at `start` (0..1 of the path length).
    OnPath { path: PathData, start: f64 },
}

/// A text object. `runs` split into paragraphs at `\n`.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct TextObject {
    pub kind: TextKind,
    /// Maps text space (origin = first baseline start for point type) to the document.
    pub xf: Affine,
    pub runs: Vec<TextRun>,
    #[serde(default)]
    pub para: ParaStyle,
    /// Area Type Options (area type only).
    #[serde(default, skip_serializing_if = "crate::skip::is_default")]
    pub area: AreaOptions,
    /// Type on a Path effect (type on a path only).
    #[serde(default, rename = "pathEffect", skip_serializing_if = "crate::skip::is_default")]
    pub path_effect: PathEffect,
    /// Wrap objects above this area type, resolved by the engine after each edit (text space).
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub wrap: Vec<WrapShape>,
    /// Cached layout bounds in text space, filled in by the layout engine (not serialized).
    #[serde(skip)]
    pub cached_bounds: Option<Rect>,
}

impl TextObject {
    pub fn point(origin: Point, text: &str, style: CharStyle) -> Self {
        Self {
            kind: TextKind::Point,
            xf: Affine::translate(origin.to_vec2()),
            runs: vec![TextRun { text: text.into(), style }],
            para: ParaStyle::default(),
            area: AreaOptions::default(),
            path_effect: PathEffect::default(),
            wrap: Vec::new(),
            cached_bounds: None,
        }
    }
    pub fn plain_text(&self) -> String {
        self.runs.iter().map(|r| r.text.as_str()).collect()
    }
    pub fn first_style(&self) -> CharStyle {
        self.runs.first().map(|r| r.style.clone()).unwrap_or_default()
    }
    /// Approximate bounds when no layout cache is available (0.55 em average advance).
    pub fn estimate_bounds(&self) -> Rect {
        let st = self.first_style();
        let text = self.plain_text();
        let lines: Vec<&str> = text.split('\n').collect();
        let w = lines.iter().map(|l| l.chars().count()).max().unwrap_or(0) as f64 * st.size * 0.55;
        let lead = st.effective_leading();
        Rect::new(0.0, -st.size * 0.8, w.max(1.0), -st.size * 0.8 + lead * lines.len().max(1) as f64)
    }
    pub fn bounds(&self) -> Option<Rect> {
        match &self.kind {
            TextKind::Area { frame } => frame.bounds().map(|b| self.xf.transform_rect_bbox(b)),
            TextKind::OnPath { path, .. } => path.bounds().map(|b| self.xf.transform_rect_bbox(b)),
            TextKind::Point => Some(self.xf.transform_rect_bbox(self.cached_bounds.unwrap_or_else(|| self.estimate_bounds()))),
        }
    }
    pub fn transform(&mut self, a: Affine) {
        self.xf = a * self.xf;
    }
    /// Scale the character strokes' weights and dashes by `s` (they are drawn in text space, so
    /// `1 / scale` keeps their weight through a transform that scales the type).
    pub fn scale_char_strokes(&mut self, s: f64) {
        for r in &mut self.runs {
            r.style.stroke_width *= s;
            if let Some(d) = &mut r.style.stroke_dash {
                d.scale(s);
            }
        }
    }
    /// Layout bounds in text space (the layout cache, else the estimate): the box an unplaced run
    /// gradient fits, as the renderers lay it out.
    pub fn local_bounds(&self) -> Rect {
        self.cached_bounds.unwrap_or_else(|| self.estimate_bounds())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn point_text_basics() {
        let t = TextObject::point(Point::new(10.0, 20.0), "Hello", CharStyle::default());
        assert_eq!(t.plain_text(), "Hello");
        let b = t.bounds().unwrap();
        assert!(b.x0 >= 10.0 - 1e-9 && b.y1 > 20.0);
        assert_eq!(CharStyle::default().effective_leading(), 14.399999999999999);
    }
}