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    /// An inline image. The layout engine reserves space for it.
80    ///
81    /// To retrieve the image pixel data, use the existing
82    /// [`TextDocument::resource(name)`](crate::TextDocument::resource) method.
83    Image {
84        name: String,
85        width: u32,
86        height: u32,
87        quality: u32,
88        format: TextFormat,
89        /// Character offset within the block (block-relative).
90        offset: usize,
91        /// Stable synthesized id for the underlying image anchor
92        /// (see [`synth_element_id`](common::format_runs::synth_element_id)).
93        element_id: u64,
94    },
95}
96
97// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
98// BlockSnapshot
99// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
100
101/// All layout-relevant data for one block, captured atomically.
102#[derive(Debug, Clone, PartialEq)]
103pub struct BlockSnapshot {
104    pub block_id: usize,
105    pub position: usize,
106    pub length: usize,
107    pub text: String,
108    pub fragments: Vec<FragmentContent>,
109    pub block_format: BlockFormat,
110    pub list_info: Option<ListInfo>,
111    /// Parent frame ID. Needed to know where this block lives in the
112    /// frame tree (e.g. main frame vs. a sub-frame or table cell frame).
113    pub parent_frame_id: Option<usize>,
114    /// If this block is inside a table cell, the cell coordinates.
115    /// Needed so the typesetter can propagate height changes to the
116    /// enclosing table row.
117    pub table_cell: Option<TableCellContext>,
118    /// Paint-only highlight overlay for this block.
119    ///
120    /// Non-empty **only** when the active syntax highlighter is paint-only
121    /// (colors / underline decorations, no metric changes). In that case
122    /// `fragments` carry the *base* formatting (no highlight merge) and the
123    /// layout engine applies these spans as a post-shape recolor — no
124    /// reshaping. When a metric-affecting highlighter is active, highlights
125    /// are merged into `fragments` as usual and this is empty.
126    pub paint_highlights: Vec<PaintHighlightSpan>,
127}
128
129/// A resolved paint-only highlight span for one character range of a block.
130///
131/// Char offsets are block-relative, matching [`HighlightSpan`](crate::HighlightSpan).
132/// Each color field is `None` when the highlight does not override it. This is
133/// the post-shape overlay counterpart of the merged-into-`fragments` path —
134/// it carries only attributes that do not change glyph metrics.
135#[derive(Debug, Clone, PartialEq, Eq)]
136pub struct PaintHighlightSpan {
137    pub start: usize,
138    pub length: usize,
139    pub foreground_color: Option<crate::Color>,
140    pub background_color: Option<crate::Color>,
141    pub underline_color: Option<crate::Color>,
142    pub underline_style: Option<crate::UnderlineStyle>,
143    pub font_underline: Option<bool>,
144    pub font_overline: Option<bool>,
145    pub font_strikeout: Option<bool>,
146}
147
148/// Snapshot-friendly reference to a table cell (plain IDs, no live handles).
149#[derive(Debug, Clone, PartialEq, Eq)]
150pub struct TableCellContext {
151    pub table_id: usize,
152    pub row: usize,
153    pub column: usize,
154}
155
156// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
157// ListInfo
158// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
159
160/// List membership and marker information for a block.
161#[derive(Debug, Clone, PartialEq, Eq)]
162pub struct ListInfo {
163    pub list_id: usize,
164    /// The list style (Disc, Decimal, LowerAlpha, etc.).
165    pub style: ListStyle,
166    /// Indentation level.
167    pub indent: u8,
168    /// Pre-formatted marker text: "•", "3.", "(c)", "IV.", etc.
169    pub marker: String,
170    /// 0-based index of this item within its list.
171    pub item_index: usize,
172}
173
174// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
175// TableCellRef
176// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
177
178/// Reference to a table cell that contains a block.
179#[derive(Clone)]
180pub struct TableCellRef {
181    pub table: TextTable,
182    pub row: usize,
183    pub column: usize,
184}
185
186// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
187// CellRange / SelectionKind
188// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
189
190/// A rectangular range of cells within a single table (inclusive bounds).
191#[derive(Debug, Clone, PartialEq, Eq)]
192pub struct CellRange {
193    pub table_id: usize,
194    pub start_row: usize,
195    pub start_col: usize,
196    pub end_row: usize,
197    pub end_col: usize,
198}
199
200impl CellRange {
201    /// Expand the range so that every merged cell whose span overlaps the
202    /// rectangle is fully included. `cells` is a slice of
203    /// `(row, col, row_span, col_span)` for every cell in the table.
204    ///
205    /// Uses fixed-point iteration (converges in 1-2 rounds for typical tables).
206    pub fn expand_for_spans(mut self, cells: &[(usize, usize, usize, usize)]) -> Self {
207        loop {
208            let mut expanded = false;
209            for &(row, col, rs, cs) in cells {
210                let cell_bottom = row + rs - 1;
211                let cell_right = col + cs - 1;
212                // Check overlap with current range
213                if row <= self.end_row
214                    && cell_bottom >= self.start_row
215                    && col <= self.end_col
216                    && cell_right >= self.start_col
217                {
218                    if row < self.start_row {
219                        self.start_row = row;
220                        expanded = true;
221                    }
222                    if cell_bottom > self.end_row {
223                        self.end_row = cell_bottom;
224                        expanded = true;
225                    }
226                    if col < self.start_col {
227                        self.start_col = col;
228                        expanded = true;
229                    }
230                    if cell_right > self.end_col {
231                        self.end_col = cell_right;
232                        expanded = true;
233                    }
234                }
235            }
236            if !expanded {
237                break;
238            }
239        }
240        self
241    }
242}
243
244/// Describes what kind of selection the cursor currently has.
245#[derive(Debug, Clone, PartialEq, Eq)]
246pub enum SelectionKind {
247    /// No selection (position == anchor).
248    None,
249    /// Normal text selection within a single cell or outside any table.
250    Text,
251    /// Rectangular cell selection within a table.
252    Cells(CellRange),
253    /// Selection crosses a table boundary (starts/ends outside the table).
254    /// The table portion is a rectangular cell range; `text_before` /
255    /// `text_after` indicate whether text outside the table is also selected.
256    Mixed {
257        cell_range: CellRange,
258        text_before: bool,
259        text_after: bool,
260    },
261}
262
263// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
264// Table format types
265// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
266
267/// Table-level formatting.
268#[derive(Debug, Clone, Default, PartialEq, Eq)]
269pub struct TableFormat {
270    pub border: Option<i32>,
271    pub cell_spacing: Option<i32>,
272    pub cell_padding: Option<i32>,
273    pub width: Option<i32>,
274    pub alignment: Option<Alignment>,
275}
276
277/// Cell-level formatting.
278#[derive(Debug, Clone, Default, PartialEq, Eq)]
279pub struct CellFormat {
280    pub padding: Option<i32>,
281    pub border: Option<i32>,
282    pub vertical_alignment: Option<CellVerticalAlignment>,
283    pub background_color: Option<String>,
284}
285
286/// Vertical alignment within a table cell.
287#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
288pub enum CellVerticalAlignment {
289    #[default]
290    Top,
291    Middle,
292    Bottom,
293}
294
295// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
296// Table and Cell Snapshots
297// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
298
299/// Consistent snapshot of a table's structure and all cell content.
300#[derive(Debug, Clone, PartialEq)]
301pub struct TableSnapshot {
302    pub table_id: usize,
303    pub rows: usize,
304    pub columns: usize,
305    pub column_widths: Vec<i32>,
306    pub format: TableFormat,
307    pub cells: Vec<CellSnapshot>,
308}
309
310/// Snapshot of one table cell including its block content.
311#[derive(Debug, Clone, PartialEq)]
312pub struct CellSnapshot {
313    pub row: usize,
314    pub column: usize,
315    pub row_span: usize,
316    pub column_span: usize,
317    pub format: CellFormat,
318    pub blocks: Vec<BlockSnapshot>,
319}
320
321// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
322// Flow Snapshots
323// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
324
325/// Consistent snapshot of the entire document flow, captured in a
326/// single lock acquisition.
327#[derive(Debug, Clone, PartialEq)]
328pub struct FlowSnapshot {
329    pub elements: Vec<FlowElementSnapshot>,
330}
331
332/// Snapshot of one flow element.
333// `Block` is by far the most common variant in a document flow, so boxing it
334// to shrink the enum would add a heap allocation on the hot path for no real
335// gain — the large-variant cost only bites the rare `Table`/`Frame` elements.
336#[allow(clippy::large_enum_variant)]
337#[derive(Debug, Clone, PartialEq)]
338pub enum FlowElementSnapshot {
339    Block(BlockSnapshot),
340    Table(TableSnapshot),
341    Frame(FrameSnapshot),
342}
343
344/// Snapshot of a sub-frame and its contents.
345#[derive(Debug, Clone, PartialEq)]
346pub struct FrameSnapshot {
347    pub frame_id: usize,
348    pub format: FrameFormat,
349    pub elements: Vec<FlowElementSnapshot>,
350}
351
352// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
353// FormatChangeKind
354// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
355
356/// What kind of formatting changed.
357#[derive(Debug, Clone, Copy, PartialEq, Eq)]
358pub enum FormatChangeKind {
359    /// Block-level: alignment, margins, indent, heading level.
360    /// Requires paragraph relayout.
361    Block,
362    /// Character-level: font, bold, italic, underline, color.
363    /// Requires reshaping but not necessarily reflow.
364    Character,
365    /// List-level: style, indent, prefix, suffix.
366    /// Requires marker relayout for list items.
367    List,
368}
text_document/flow.rs

text_document/
flow.rs
