text_document/
flow.rs

1//! Flow types for document traversal and layout engine support.
2//!
3//! The layout engine processes [`FlowElement`]s in order to build its layout
4//! tree. Snapshot types capture consistent views for thread-safe reads.
5
6use crate::text_block::TextBlock;
7use crate::text_frame::TextFrame;
8use crate::text_table::TextTable;
9use crate::{Alignment, BlockFormat, FrameFormat, ListStyle, TextFormat};
10
11// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
12// FlowElement
13// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
14
15/// An element in the document's visual flow.
16///
17/// The layout engine processes these in order to build its layout tree.
18/// Obtained from [`TextDocument::flow()`](crate::TextDocument::flow) or
19/// [`TextFrame::flow()`].
20#[derive(Clone)]
21pub enum FlowElement {
22    /// A paragraph or heading. Layout as a text block.
23    Block(TextBlock),
24
25    /// A table at this position in the flow. Layout as a grid.
26    /// The anchor frame's `table` field identifies the table entity.
27    Table(TextTable),
28
29    /// A non-table sub-frame (float, sidebar, blockquote).
30    /// Contains its own nested flow, accessible via
31    /// [`TextFrame::flow()`].
32    Frame(TextFrame),
33}
34
35impl FlowElement {
36    /// Snapshot this element into a thread-safe, plain-data representation.
37    ///
38    /// Dispatches to [`TextBlock::snapshot()`], [`TextTable::snapshot()`],
39    /// or [`TextFrame::snapshot()`] as appropriate.
40    pub fn snapshot(&self) -> FlowElementSnapshot {
41        match self {
42            FlowElement::Block(b) => FlowElementSnapshot::Block(b.snapshot()),
43            FlowElement::Table(t) => FlowElementSnapshot::Table(t.snapshot()),
44            FlowElement::Frame(f) => FlowElementSnapshot::Frame(f.snapshot()),
45        }
46    }
47}
48
49// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
50// FragmentContent
51// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
52
53/// A contiguous run of content with uniform formatting within a block.
54///
55/// Offsets are **block-relative**: `offset` is the character position
56/// within the block where this fragment starts (0 = block start).
57#[derive(Debug, Clone, PartialEq, Eq)]
58pub enum FragmentContent {
59    /// A text run. The layout engine shapes these into glyphs.
60    Text {
61        text: String,
62        format: TextFormat,
63        /// Character offset within the block (block-relative).
64        offset: usize,
65        /// Character count.
66        length: usize,
67        /// Stable synthesized id for the underlying format run
68        /// (see [`synth_element_id`](common::format_runs::synth_element_id)).
69        /// Survives edits that don't delete the run (character insertions
70        /// inside the run keep the same id). Used by accessibility layers
71        /// to build stable `NodeId`s for AccessKit `TextRun` children.
72        element_id: u64,
73        /// Unicode word starts within `text`, expressed as character
74        /// indices (not byte offsets). Computed per UAX #29 via
75        /// `unicode-segmentation`. Fed directly into AccessKit's
76        /// `set_word_starts` on the corresponding `Role::TextRun`.
77        word_starts: Vec<u8>,
78    },
79    /// A footnote reference. The layout engine draws `marker` at this position
80    /// and reserves what those glyphs advance to.
81    ///
82    /// Occupies exactly **one** character of the document however many glyphs
83    /// `marker` shapes to — the same `U+FFFC` an image occupies. The two facts
84    /// are what make the reference atomic to the caret: a layout engine must
85    /// map every glyph of the marker back to this one offset.
86    FootnoteReference {
87        /// Identifies the note. Stable, stored, and never shown.
88        label: String,
89        /// What to draw — a number, usually. **Presentation only**: derived from
90        /// document order, or supplied by the host, and never part of the
91        /// document. Storing it would mean rewriting the author's prose every
92        /// time a note was inserted above this one.
93        marker: String,
94        format: TextFormat,
95        /// Character offset within the block (block-relative).
96        offset: usize,
97        /// Stable synthesized id for the underlying reference anchor.
98        element_id: u64,
99    },
100    /// An inline image. The layout engine reserves space for it.
101    ///
102    /// To retrieve the image pixel data, use the existing
103    /// [`TextDocument::resource(name)`](crate::TextDocument::resource) method.
104    Image {
105        name: String,
106        /// Alternative text describing the image. May be empty.
107        ///
108        /// Carried through to layout so an accessibility layer can name the
109        /// image without a second lookup, in the same way `word_starts` is
110        /// precomputed for text runs.
111        alt: String,
112        width: u32,
113        height: u32,
114        quality: u32,
115        format: TextFormat,
116        /// Character offset within the block (block-relative).
117        offset: usize,
118        /// Stable synthesized id for the underlying image anchor
119        /// (see [`synth_element_id`](common::format_runs::synth_element_id)).
120        element_id: u64,
121    },
122}
123
124// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
125// BlockSnapshot
126// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
127
128/// All layout-relevant data for one block, captured atomically.
129#[derive(Debug, Clone, PartialEq)]
130pub struct BlockSnapshot {
131    pub block_id: usize,
132    pub position: usize,
133    pub length: usize,
134    pub text: String,
135    pub fragments: Vec<FragmentContent>,
136    pub block_format: BlockFormat,
137    pub list_info: Option<ListInfo>,
138    /// Parent frame ID. Needed to know where this block lives in the
139    /// frame tree (e.g. main frame vs. a sub-frame or table cell frame).
140    pub parent_frame_id: Option<usize>,
141    /// If this block is inside a table cell, the cell coordinates.
142    /// Needed so the typesetter can propagate height changes to the
143    /// enclosing table row.
144    pub table_cell: Option<TableCellContext>,
145    /// Paint-only highlight overlay for this block.
146    ///
147    /// Non-empty **only** when the active syntax highlighter is paint-only
148    /// (colors / underline decorations, no metric changes). In that case
149    /// `fragments` carry the *base* formatting (no highlight merge) and the
150    /// layout engine applies these spans as a post-shape recolor — no
151    /// reshaping. When a metric-affecting highlighter is active, highlights
152    /// are merged into `fragments` as usual and this is empty.
153    pub paint_highlights: Vec<PaintHighlightSpan>,
154}
155
156/// A resolved paint-only highlight span for one character range of a block.
157///
158/// Char offsets are block-relative, matching [`HighlightSpan`](crate::HighlightSpan).
159/// Each color field is `None` when the highlight does not override it. This is
160/// the post-shape overlay counterpart of the merged-into-`fragments` path —
161/// it carries only attributes that do not change glyph metrics.
162#[derive(Debug, Clone, PartialEq, Eq)]
163pub struct PaintHighlightSpan {
164    pub start: usize,
165    pub length: usize,
166    pub foreground_color: Option<crate::Color>,
167    pub background_color: Option<crate::Color>,
168    pub underline_color: Option<crate::Color>,
169    pub underline_style: Option<crate::UnderlineStyle>,
170    pub font_underline: Option<bool>,
171    pub font_overline: Option<bool>,
172    pub font_strikeout: Option<bool>,
173}
174
175/// Snapshot-friendly reference to a table cell (plain IDs, no live handles).
176#[derive(Debug, Clone, PartialEq, Eq)]
177pub struct TableCellContext {
178    pub table_id: usize,
179    pub row: usize,
180    pub column: usize,
181}
182
183// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
184// ListInfo
185// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
186
187/// List membership and marker information for a block.
188#[derive(Debug, Clone, PartialEq, Eq)]
189pub struct ListInfo {
190    pub list_id: usize,
191    /// The list style (Disc, Decimal, LowerAlpha, etc.).
192    pub style: ListStyle,
193    /// Indentation level.
194    pub indent: u8,
195    /// Pre-formatted marker text: "•", "3.", "(c)", "IV.", etc.
196    pub marker: String,
197    /// 0-based index of this item within its list.
198    pub item_index: usize,
199}
200
201// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
202// TableCellRef
203// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
204
205/// Reference to a table cell that contains a block.
206#[derive(Clone)]
207pub struct TableCellRef {
208    pub table: TextTable,
209    pub row: usize,
210    pub column: usize,
211}
212
213// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
214// FrameRef
215// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
216
217/// Reference to the frame that immediately encloses the cursor's block.
218/// `depth` is the nesting level (1 for a direct child of the root).
219/// `is_blockquote` is true iff `fmt_is_blockquote` is `Some(true)`.
220#[derive(Clone, Debug, PartialEq, Eq)]
221pub struct FrameRef {
222    pub frame_id: usize,
223    pub parent_frame_id: Option<usize>,
224    pub is_blockquote: bool,
225    pub depth: usize,
226}
227
228// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
229// CellRange / SelectionKind
230// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
231
232/// A rectangular range of cells within a single table (inclusive bounds).
233#[derive(Debug, Clone, PartialEq, Eq)]
234pub struct CellRange {
235    pub table_id: usize,
236    pub start_row: usize,
237    pub start_col: usize,
238    pub end_row: usize,
239    pub end_col: usize,
240}
241
242impl CellRange {
243    /// Expand the range so that every merged cell whose span overlaps the
244    /// rectangle is fully included. `cells` is a slice of
245    /// `(row, col, row_span, col_span)` for every cell in the table.
246    ///
247    /// Uses fixed-point iteration (converges in 1-2 rounds for typical tables).
248    pub fn expand_for_spans(mut self, cells: &[(usize, usize, usize, usize)]) -> Self {
249        loop {
250            let mut expanded = false;
251            for &(row, col, rs, cs) in cells {
252                let cell_bottom = row + rs - 1;
253                let cell_right = col + cs - 1;
254                // Check overlap with current range
255                if row <= self.end_row
256                    && cell_bottom >= self.start_row
257                    && col <= self.end_col
258                    && cell_right >= self.start_col
259                {
260                    if row < self.start_row {
261                        self.start_row = row;
262                        expanded = true;
263                    }
264                    if cell_bottom > self.end_row {
265                        self.end_row = cell_bottom;
266                        expanded = true;
267                    }
268                    if col < self.start_col {
269                        self.start_col = col;
270                        expanded = true;
271                    }
272                    if cell_right > self.end_col {
273                        self.end_col = cell_right;
274                        expanded = true;
275                    }
276                }
277            }
278            if !expanded {
279                break;
280            }
281        }
282        self
283    }
284}
285
286/// Describes what kind of selection the cursor currently has.
287#[derive(Debug, Clone, PartialEq, Eq)]
288pub enum SelectionKind {
289    /// No selection (position == anchor).
290    None,
291    /// Normal text selection within a single cell or outside any table.
292    Text,
293    /// Rectangular cell selection within a table.
294    Cells(CellRange),
295    /// Selection crosses a table boundary (starts/ends outside the table).
296    /// The table portion is a rectangular cell range; `text_before` /
297    /// `text_after` indicate whether text outside the table is also selected.
298    Mixed {
299        cell_range: CellRange,
300        text_before: bool,
301        text_after: bool,
302    },
303}
304
305// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
306// Table format types
307// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
308
309/// Table-level formatting.
310#[derive(Debug, Clone, Default, PartialEq, Eq)]
311pub struct TableFormat {
312    pub border: Option<i32>,
313    pub cell_spacing: Option<i32>,
314    pub cell_padding: Option<i32>,
315    pub width: Option<i32>,
316    pub alignment: Option<Alignment>,
317}
318
319/// Cell-level formatting.
320#[derive(Debug, Clone, Default, PartialEq, Eq)]
321pub struct CellFormat {
322    pub padding: Option<i32>,
323    pub border: Option<i32>,
324    pub vertical_alignment: Option<CellVerticalAlignment>,
325    pub background_color: Option<String>,
326}
327
328/// Vertical alignment within a table cell.
329#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
330pub enum CellVerticalAlignment {
331    #[default]
332    Top,
333    Middle,
334    Bottom,
335}
336
337// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
338// Table and Cell Snapshots
339// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
340
341/// Consistent snapshot of a table's structure and all cell content.
342#[derive(Debug, Clone, PartialEq)]
343pub struct TableSnapshot {
344    pub table_id: usize,
345    pub rows: usize,
346    pub columns: usize,
347    pub column_widths: Vec<i32>,
348    pub format: TableFormat,
349    pub cells: Vec<CellSnapshot>,
350}
351
352/// Snapshot of one table cell including its block content.
353#[derive(Debug, Clone, PartialEq)]
354pub struct CellSnapshot {
355    pub row: usize,
356    pub column: usize,
357    pub row_span: usize,
358    pub column_span: usize,
359    pub format: CellFormat,
360    pub blocks: Vec<BlockSnapshot>,
361}
362
363// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
364// Flow Snapshots
365// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
366
367/// Consistent snapshot of the entire document flow, captured in a
368/// single lock acquisition.
369#[derive(Debug, Clone, PartialEq)]
370pub struct FlowSnapshot {
371    pub elements: Vec<FlowElementSnapshot>,
372}
373
374/// Snapshot of one flow element.
375// `Block` is by far the most common variant in a document flow, so boxing it
376// to shrink the enum would add a heap allocation on the hot path for no real
377// gain — the large-variant cost only bites the rare `Table`/`Frame` elements.
378#[allow(clippy::large_enum_variant)]
379#[derive(Debug, Clone, PartialEq)]
380pub enum FlowElementSnapshot {
381    Block(BlockSnapshot),
382    Table(TableSnapshot),
383    Frame(FrameSnapshot),
384}
385
386/// Snapshot of a sub-frame and its contents.
387#[derive(Debug, Clone, PartialEq)]
388pub struct FrameSnapshot {
389    pub frame_id: usize,
390    pub format: FrameFormat,
391    pub elements: Vec<FlowElementSnapshot>,
392}
393
394// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
395// FormatChangeKind
396// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
397
398/// What kind of formatting changed.
399#[derive(Debug, Clone, Copy, PartialEq, Eq)]
400pub enum FormatChangeKind {
401    /// Block-level: alignment, margins, indent, heading level.
402    /// Requires paragraph relayout.
403    Block,
404    /// Character-level: font, bold, italic, underline, color.
405    /// Requires reshaping but not necessarily reflow.
406    Character,
407    /// List-level: style, indent, prefix, suffix.
408    /// Requires marker relayout for list items.
409    List,
410}
text_document/flow.rs

text_document/
flow.rs
