260 lines
8 KiB
Rust
260 lines
8 KiB
Rust
use std::{borrow::Cow, ops::Range, sync::Arc};
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use crate::{
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color::Color,
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fonts::{HighlightStyle, TextStyle},
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geometry::{
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rect::RectF,
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vector::{vec2f, Vector2F},
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},
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json::{ToJson, Value},
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text_layout::{Line, RunStyle, ShapedBoundary},
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DebugContext, Element, Event, EventContext, FontCache, LayoutContext, PaintContext,
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SizeConstraint, TextLayoutCache,
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};
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use serde_json::json;
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pub struct Text {
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text: String,
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style: TextStyle,
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soft_wrap: bool,
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highlights: Vec<(Range<usize>, HighlightStyle)>,
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}
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pub struct LayoutState {
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shaped_lines: Vec<Line>,
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wrap_boundaries: Vec<Vec<ShapedBoundary>>,
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line_height: f32,
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}
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impl Text {
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pub fn new(text: String, style: TextStyle) -> Self {
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Self {
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text,
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style,
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soft_wrap: true,
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highlights: Vec::new(),
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}
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}
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pub fn with_default_color(mut self, color: Color) -> Self {
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self.style.color = color;
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self
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}
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pub fn with_highlights(mut self, runs: Vec<(Range<usize>, HighlightStyle)>) -> Self {
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self.highlights = runs;
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self
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}
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pub fn with_soft_wrap(mut self, soft_wrap: bool) -> Self {
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self.soft_wrap = soft_wrap;
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self
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}
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}
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impl Element for Text {
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type LayoutState = LayoutState;
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type PaintState = ();
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fn layout(
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&mut self,
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constraint: SizeConstraint,
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cx: &mut LayoutContext,
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) -> (Vector2F, Self::LayoutState) {
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// Convert the string and highlight ranges into an iterator of highlighted chunks.
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let mut offset = 0;
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let mut highlight_ranges = self.highlights.iter().peekable();
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let chunks = std::iter::from_fn(|| {
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let result;
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if let Some((range, highlight_style)) = highlight_ranges.peek() {
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if offset < range.start {
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result = Some((&self.text[offset..range.start], None));
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offset = range.start;
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} else {
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result = Some((&self.text[range.clone()], Some(*highlight_style)));
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highlight_ranges.next();
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offset = range.end;
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}
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} else if offset < self.text.len() {
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result = Some((&self.text[offset..], None));
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offset = self.text.len();
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} else {
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result = None;
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}
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result
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});
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// Perform shaping on these highlighted chunks
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let shaped_lines = layout_highlighted_chunks(
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chunks,
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&self.style,
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cx.text_layout_cache,
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&cx.font_cache,
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usize::MAX,
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self.text.matches('\n').count() + 1,
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);
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// If line wrapping is enabled, wrap each of the shaped lines.
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let font_id = self.style.font_id;
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let mut line_count = 0;
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let mut max_line_width = 0_f32;
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let mut wrap_boundaries = Vec::new();
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let mut wrapper = cx.font_cache.line_wrapper(font_id, self.style.font_size);
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for (line, shaped_line) in self.text.lines().zip(&shaped_lines) {
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if self.soft_wrap {
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let boundaries = wrapper
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.wrap_shaped_line(line, shaped_line, constraint.max.x())
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.collect::<Vec<_>>();
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line_count += boundaries.len() + 1;
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wrap_boundaries.push(boundaries);
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} else {
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line_count += 1;
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}
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max_line_width = max_line_width.max(shaped_line.width());
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}
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let line_height = cx.font_cache.line_height(self.style.font_size);
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let size = vec2f(
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max_line_width
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.ceil()
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.max(constraint.min.x())
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.min(constraint.max.x()),
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(line_height * line_count as f32).ceil(),
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);
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(
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size,
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LayoutState {
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shaped_lines,
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wrap_boundaries,
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line_height,
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},
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)
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}
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fn paint(
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&mut self,
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bounds: RectF,
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visible_bounds: RectF,
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layout: &mut Self::LayoutState,
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cx: &mut PaintContext,
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) -> Self::PaintState {
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let mut origin = bounds.origin();
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let empty = Vec::new();
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for (ix, line) in layout.shaped_lines.iter().enumerate() {
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let wrap_boundaries = layout.wrap_boundaries.get(ix).unwrap_or(&empty);
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let boundaries = RectF::new(
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origin,
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vec2f(
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bounds.width(),
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(wrap_boundaries.len() + 1) as f32 * layout.line_height,
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),
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);
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if boundaries.intersects(visible_bounds) {
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if self.soft_wrap {
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line.paint_wrapped(
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origin,
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visible_bounds,
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layout.line_height,
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wrap_boundaries.iter().copied(),
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cx,
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);
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} else {
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line.paint(origin, visible_bounds, layout.line_height, cx);
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}
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}
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origin.set_y(boundaries.max_y());
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}
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}
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fn dispatch_event(
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&mut self,
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_: &Event,
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_: RectF,
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_: RectF,
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_: &mut Self::LayoutState,
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_: &mut Self::PaintState,
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_: &mut EventContext,
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) -> bool {
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false
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}
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fn debug(
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&self,
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bounds: RectF,
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_: &Self::LayoutState,
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_: &Self::PaintState,
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_: &DebugContext,
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) -> Value {
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json!({
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"type": "Text",
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"bounds": bounds.to_json(),
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"text": &self.text,
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"style": self.style.to_json(),
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})
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}
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}
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/// Perform text layout on a series of highlighted chunks of text.
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pub fn layout_highlighted_chunks<'a>(
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chunks: impl Iterator<Item = (&'a str, Option<HighlightStyle>)>,
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text_style: &'a TextStyle,
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text_layout_cache: &'a TextLayoutCache,
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font_cache: &'a Arc<FontCache>,
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max_line_len: usize,
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max_line_count: usize,
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) -> Vec<Line> {
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let mut layouts = Vec::with_capacity(max_line_count);
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let mut line = String::new();
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let mut styles = Vec::new();
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let mut row = 0;
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let mut line_exceeded_max_len = false;
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for (chunk, highlight_style) in chunks.chain([("\n", Default::default())]) {
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for (ix, mut line_chunk) in chunk.split('\n').enumerate() {
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if ix > 0 {
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layouts.push(text_layout_cache.layout_str(&line, text_style.font_size, &styles));
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line.clear();
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styles.clear();
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row += 1;
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line_exceeded_max_len = false;
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if row == max_line_count {
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return layouts;
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}
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}
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if !line_chunk.is_empty() && !line_exceeded_max_len {
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let text_style = if let Some(style) = highlight_style {
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text_style
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.clone()
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.highlight(style, font_cache)
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.map(Cow::Owned)
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.unwrap_or_else(|_| Cow::Borrowed(text_style))
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} else {
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Cow::Borrowed(text_style)
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};
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if line.len() + line_chunk.len() > max_line_len {
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let mut chunk_len = max_line_len - line.len();
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while !line_chunk.is_char_boundary(chunk_len) {
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chunk_len -= 1;
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}
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line_chunk = &line_chunk[..chunk_len];
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line_exceeded_max_len = true;
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}
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line.push_str(line_chunk);
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styles.push((
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line_chunk.len(),
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RunStyle {
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font_id: text_style.font_id,
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color: text_style.color,
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underline: text_style.underline,
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},
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));
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}
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}
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}
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layouts
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}
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