wordcraft/crates/layout/src/lib.rs

//! WordCraft layout: turns a [`Document`] into pages.
//!
//! - [`para`]: one paragraph → lines (shaping, first-fit line breaking, tabs, list labels,
//!   alignment). Results are memoised per paragraph revision in a [`LayoutCache`].
//! - [`layout`]: sections → pages and columns; tables; keep/widow rules; page breaks; headers
//!   and footers; page-number fields.
//! - [`display`]: a page → draw items (glyph runs, rules, fills, images) for the renderers.
//! - [`hit`]: point ↔ position, caret geometry, line navigation, selection rectangles.
#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]

pub mod balloons;
mod contour;
pub mod display;
pub mod fields;
pub mod hit;
pub mod kinsoku;
pub mod math;
pub mod outline;
pub mod para;
pub mod styleref;
mod table;
mod textbox;
mod vertical;
pub mod wordart;
mod work;

use std::collections::{HashMap, HashSet};
use std::hash::{Hash, Hasher};
use std::sync::Arc;

use wordcraft_doc::numbering::{Counters, Level};
use wordcraft_doc::para::{Anchor, Float, FloatAlign, InlineObject, Wrap, WrapText};
use wordcraft_doc::props::{Border, CharProps, HeightRule, Rgb, TableFloat, TextDirection};
use wordcraft_doc::section::{HeaderSet, SectionProps, SectionStart};
use wordcraft_doc::{Block, Blocks, Document, Paragraph, Path, StoryRef};
use wordcraft_geom::{Point, Rect, Spin};

pub use fields::FieldCtx;
pub use hit::VisualStep;
pub use para::{LineEnd, ParaLayout};
pub use table::{autofit_widths, cell_margins, measure_table_columns};

mod boxes;
mod cache;
mod ctx;
mod floats;
mod flow;
mod headers;
mod notes;
mod page;
mod pass;
mod placed;
mod table_flow;

#[cfg(test)]
use boxes::{BOX_INSET_X, BOX_INSET_Y};
use boxes::{BoxContext, BoxLayout, Edges, fit_box, layout_box, push_para};
pub use cache::LayoutCache;
use cache::{MAX_TOTAL_PASSES, Totals};
#[cfg(test)]
use ctx::picture_outline;
use ctx::{Ctx, Pass};
use floats::{EarlyFloats, MAX_REWRAP_PASSES, merge_early};
pub use floats::{is_floating, shape_figure_alt};
#[cfg(test)]
use floats::{left_out_objects, wrap_area};
#[cfg(test)]
use headers::MAX_HEADER_ITEMS;
pub use notes::DECOR_STORY;
pub(crate) use notes::NOTE_SEP_W;
use notes::{MAX_NOTE_PASSES, footnote_pages};
#[cfg(test)]
use notes::{NOTE_SEP, note_numbers};
use page::item_bottom;
use pass::layout_pass;
pub use pass::now_ms;
pub use placed::{HfSlot, Placed, turn_point, turn_rect, unturn_point};

/// How the document is viewed.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Default, serde::Serialize, serde::Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum ViewMode {
    #[default]
    Print,
    /// One page as wide as the window, no page breaks.
    Web,
    /// Draft: like web, page breaks shown as rules.
    Draft,
    /// Reading: reflow into viewport-height narrow pages, navigated horizontally.
    Read,
    /// Outline: like draft, the body as an outline of its headings ([`outline`]).
    Outline,
}

/// How digits look on screen (Word › File › Options › Advanced › Numeral).
///
/// Display only: the document text keeps the typed codepoints, so find, spelling, copying and
/// the saved file all see the original digits. Only ASCII digits are substituted: Arabic-Indic
/// (U+0660–U+0669) and Extended Arabic-Indic digits (U+06F0–U+06F9, Persian/Urdu ۰۱۲۳…) always
/// show as typed, so fonts that ligate them (e.g. the end-of-ayah mark U+06DD) keep working.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Default, serde::Serialize, serde::Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum NumeralMode {
    /// Western digits everywhere (`0123456789`); the default, today's behaviour.
    #[default]
    Arabic,
    /// Eastern Arabic-Indic digits everywhere (`٠١٢٣٤٥٦٧٨٩`).
    Hindi,
    /// Hindi digits in and around right-to-left text, Western digits elsewhere (numbers take
    /// an even bidi level, so the surrounding text decides).
    Context,
    /// Hindi digits when the system locale is an Arabic-script language, else Western digits.
    /// Call [`NumeralMode::resolve`] before laying out.
    System,
}

impl NumeralMode {
    /// Short UI label (Word's option names).
    pub fn label(self) -> &'static str {
        match self {
            NumeralMode::Arabic => "Arabic",
            NumeralMode::Hindi => "Hindi",
            NumeralMode::Context => "Context",
            NumeralMode::System => "System",
        }
    }

    /// Parse a command value (`"arabic" | "hindi" | "context" | "system"`, any case).
    pub fn parse(s: &str) -> Option<NumeralMode> {
        match s.to_lowercase().as_str() {
            "arabic" => Some(NumeralMode::Arabic),
            "hindi" => Some(NumeralMode::Hindi),
            "context" => Some(NumeralMode::Context),
            "system" => Some(NumeralMode::System),
            _ => None,
        }
    }

    /// Resolve `System` against the system locale (a BCP 47 or POSIX tag such as `ar-EG` or
    /// `fa_IR.UTF-8`, found by the shell: layout never reads the environment). Hindi digits for
    /// Arabic-script languages, else Western; unknown locale = Western. Other modes pass through.
    pub fn resolve(self, system_locale: Option<&str>) -> NumeralMode {
        if self != NumeralMode::System {
            return self;
        }
        if system_locale.is_some_and(hindi_locale) { NumeralMode::Hindi } else { NumeralMode::Arabic }
    }

    /// The displayed form of `c` in a run shaped with direction `rtl`.
    ///
    /// One character maps to exactly one character, so shaped text stays codepoint-aligned
    /// with the document text (only byte offsets shift). A `System` mode that was not
    /// resolved falls back to Western digits.
    pub fn map(self, c: char, rtl: bool) -> char {
        let hindi = match self {
            NumeralMode::Arabic => false,
            NumeralMode::Hindi => true,
            NumeralMode::Context => rtl,
            NumeralMode::System => false,
        };
        if hindi { if c.is_ascii_digit() { char::from_u32(0x660 + (c as u32 - '0' as u32)).unwrap_or(c) } else { c } } else { c }
    }
}

/// Does locale `tag` use Hindi digits (Arabic, Persian, Urdu, Pashto, Sindhi, Kurdish)?
fn hindi_locale(tag: &str) -> bool {
    let lang = tag.split(['_', '-', '.', '@']).next().unwrap_or_default().to_ascii_lowercase();
    matches!(lang.as_str(), "ar" | "fa" | "ur" | "ps" | "sd" | "ku" | "ckb")
}

#[derive(Clone, Debug, Default)]
pub struct LayoutOptions {
    pub view: ViewMode,
    /// Width of the window in Web/Draft views, points.
    pub web_width: f32,
    /// Page height in Reading Mode (document points).
    pub read_height: f32,
    /// Transient read-only line-spacing override; ignored by print/export views.
    pub read_line_spacing: Option<f32>,
    pub show_hidden: bool,
    /// Final text ("No Markup"): tracked deletions take no space and draw nothing.
    pub hide_deleted: bool,
    /// Tracked deletions that take no space and draw nothing although markup is shown: those
    /// Track Changes Options mark Hidden (deletions, or moved-away text). `hide_deleted` and
    /// `deletions_in_balloons` leave every deletion out whatever this says.
    pub hide_marked: HideDeleted,
    /// Show revisions in balloons: tracked deletions in the body take no space and draw nothing
    /// (the editor shows them in balloons beside the page). Headers, footers, notes and text
    /// boxes get no balloons, so their deletions stay inline.
    pub deletions_in_balloons: bool,
    /// Check spelling as you type (squiggles).
    pub proofing: bool,
    /// How digits look on screen (display only; the text is untouched). Callers resolve
    /// `System` ([`NumeralMode::resolve`]); an unresolved `System` shows Western digits.
    pub numeral: NumeralMode,
    /// Print Markup (PDF, print, page images): widen each page by [`balloons::MARKUP_AREA`]
    /// and show the comments there in balloons joined to their anchors, as Word prints them.
    /// The editor draws its own interactive balloons and leaves this off.
    pub comment_balloons: bool,
    /// Show field codes (`{ PAGE }`, shaded) instead of field results (View › Field Codes, Alt+F9).
    /// A field whose own `code` flag is set shows the other one.
    pub field_codes: bool,
    /// Outline view: what's collapsed and shown (used when `view` is [`ViewMode::Outline`]).
    pub outline: Option<outline::OutlineView>,
    /// What the spelling check skips, and whether grammar is marked too (File › Options › Proofing).
    pub proof: ProofOptions,
    /// The word being typed, which gets no spelling squiggle until the caret leaves it (#1552).
    pub typing_word: Option<TypingWord>,
    /// Document file name for FILENAME fields ([`FieldCtx::filename`]).
    pub filename: Option<Arc<str>>,
    /// Document full path for FILENAME \p fields ([`FieldCtx::filepath`]).
    pub filepath: Option<Arc<str>>,
}

/// The word being typed ([`LayoutOptions::typing_word`]): the paragraph by its revision
/// ([`Paragraph::rev`]) and the word's byte range in it.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct TypingWord {
    pub rev: u64,
    pub start: usize,
    pub end: usize,
}

/// File › Options › Proofing choices that change the squiggles.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct ProofOptions {
    /// Mark grammar errors as you type.
    pub grammar: bool,
    pub spelling: wordcraft_proof::Options,
}

impl Default for ProofOptions {
    fn default() -> Self {
        ProofOptions { grammar: true, spelling: wordcraft_proof::Options::default() }
    }
}

impl LayoutOptions {
    /// Which tracked deletions in `story` take no space and draw nothing.
    pub fn hides_deleted(&self, story: StoryRef) -> HideDeleted {
        if self.hide_deleted || (self.deletions_in_balloons && story == StoryRef::Body) { HideDeleted::ALL } else { self.hide_marked }
    }
}

/// Which tracked deletions are left out of the layout: ordinary ones, and the text a tracked
/// move took away (the source of a move, `w:moveFrom`).
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
pub struct HideDeleted {
    pub plain: bool,
    pub moved_from: bool,
}

impl HideDeleted {
    pub const ALL: HideDeleted = HideDeleted { plain: true, moved_from: true };
    /// Whether any deletion is left out.
    pub fn any(self) -> bool {
        self.plain || self.moved_from
    }
    /// Whether text deleted by revision `del` (`None`: not deleted) is left out.
    pub fn hides(self, doc: &Document, del: Option<u32>) -> bool {
        del.is_some() && if doc.move_name(del).is_some() { self.moved_from } else { self.plain }
    }
}

/// One laid-out page.
#[derive(Clone, Debug, Default)]
pub struct Page {
    pub w: f32,
    pub h: f32,
    /// Index into `Document::sections()`.
    pub section: usize,
    /// Page number as displayed (after section restarts).
    pub number: u32,
    pub items: Vec<Placed>,
    /// Header / footer items (drawn dimmed while editing the body).
    pub header: Vec<Placed>,
    pub footer: Vec<Placed>,
    /// The body text area (margins).
    pub body: Rect,
    pub header_story: Option<u32>,
    pub footer_story: Option<u32>,
    /// Which of its section's headers/footers this page shows (first page, even page or the
    /// default), whether or not the section has one: double-clicking an empty header area
    /// creates that one (#960).
    pub hf_slot: HfSlot,
    /// Top-level body block index at the start of the page.
    pub first_block: usize,
    /// Width of the markup area on the right of `w` that holds comment balloons (Print Markup,
    /// [`LayoutOptions::comment_balloons`]); 0 without one. The document page is `w - markup` wide.
    pub markup: f32,
    /// The top-level body tables placed on this page as floating tables (`w:tblpPr`): a click
    /// outside one doesn't land in its cells ([`DocLayout::hit`]).
    pub float_tables: Vec<Path>,
}

/// The whole layout.
#[derive(Clone, Debug, Default)]
pub struct DocLayout {
    pub pages: Vec<Page>,
    /// Index: (story, paragraph path) → (page, item index) of each placed piece, in order.
    pub index: HashMap<(StoryRef, Path), Vec<(usize, usize)>>,
    /// Layout time, milliseconds.
    pub ms: f64,
    /// Text box stories laid out (each time a box's text was).
    pub text_boxes: usize,
}

/// Lay out the whole document.
pub fn layout(doc: &Document, cache: &mut LayoutCache, opts: &LayoutOptions) -> DocLayout {
    let t0 = now_ms();
    // Page totals shown in the body (`NUMPAGES`, `SECTIONPAGES`) are known only after
    // paginating: lay out again with the totals found until they hold (bounded). Footnotes
    // numbered again on each page likewise settle over a few more passes.
    let per_page = opts.view == ViewMode::Print
        && doc.sections().iter().any(|(_, s)| doc.note_options(s, false).num_restart == wordcraft_doc::section::NoteRestart::EachPage);
    let mut note_pages = HashMap::new();
    let mut note_passes = 1;
    let mut totals = Totals::first_guess(doc.sections().len());
    let mut passes = 0;
    let (mut early, mut rewraps) = (EarlyFloats::new(), 0);
    let mut l = loop {
        match layout_pass(doc, cache, opts, &note_pages, &totals, passes < MAX_TOTAL_PASSES, (&early, rewraps < MAX_REWRAP_PASSES)) {
            Pass::Again(t) => {
                totals = t;
                passes += 1;
            }
            Pass::Rewrap(found) => {
                merge_early(&mut early, found);
                rewraps += 1;
            }
            Pass::Done(l) => {
                if per_page && note_passes < MAX_NOTE_PASSES {
                    // Number each page's footnotes from where the pass before placed them, until they stay.
                    let placed = footnote_pages(doc, &l.pages);
                    if placed != note_pages {
                        note_pages = placed;
                        note_passes += 1;
                        continue;
                    }
                }
                break l;
            }
        }
    };
    l.ms = now_ms() - t0;
    l
}

#[cfg(test)]
thread_local! {
    /// How many wrap relays (#1374) the layouts on this thread made: tests check none happen
    /// without something new to wrap around.
    static WRAP_RELAYS: std::cell::Cell<usize> = const { std::cell::Cell::new(0) };
}

#[cfg(test)]
mod tests;