Files
deckcraft/crates/render/src/text_draw.rs
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Dylan M. Taylor 23ac4f7efd Fonts: bound font-controlled work in enumeration, outlines and carets (#1701)
* Fonts: bound font-controlled work in enumeration, outlines and carets

An embedded font could make each lookup do far more than real fonts need:
- enumerating a collection read up to 256 faces times 1024 named instances,
  each then built with its own shaper; now 4096 per file across all faces,
  with a set for the duplicate-style check instead of a scan;
- composite and VARC glyphs could expand one dense outline without limit,
  and the outline cache only counted entries; outlines now stop at 32768
  path elements (drawing nothing past it) and the cache is also bounded by
  the elements it holds;
- the 64-caret limit applied after filtering, so a ligature lookup could
  read every caret record; it now applies to the records read.

* address review: bound thread-local glyph cache by path elements
2026-11-03 20:39:57 -05:00

435 lines
18 KiB
Rust

use super::geometry::{blur, color, pre_translate, scale_of};
use super::opts::ParaState;
use super::{
Affine, Arc, BezPath, Ctx, FontDb, HashMap, Opts, PhType, Rect, RenderContext, Rgba, Shape, TextBody, Vec2, colr, paint, peniko, resolve,
};
/// The prompt shown in an empty placeholder, formatted like its content would be.
pub(crate) fn prompt_body(rctx: &Ctx, s: &Shape, kind: PhType) -> TextBody {
// Layout/master prompt text when the layout supplies a custom one.
let (lp, _) = resolve::parents(rctx, s);
let custom = lp.and_then(|l| l.ph.as_ref().filter(|p| p.has_custom_prompt).and(l.text.as_ref())).filter(|t| !t.is_empty());
if let Some(t) = custom {
return t.clone();
}
if matches!(rctx.owner, resolve::Owner::Layout | resolve::Owner::Master) {
return TextBody::default();
}
let txt = kind.prompt();
if txt.is_empty() || kind.is_footer_kind() {
return TextBody::default();
}
let mut t = TextBody::from_text(txt);
if matches!(kind, PhType::Picture | PhType::Chart | PhType::Table | PhType::Media | PhType::Diagram | PhType::ClipArt) {
t.body.anchor = Some(deckcraft_model::text::Anchor::Bottom);
if let Some(p) = t.paragraphs.first_mut() {
p.props.align = Some(deckcraft_model::text::Align::Center);
p.props.bullet = Some(deckcraft_model::text::Bullet::None);
p.props.margin_left = Some(0.0);
p.props.indent = Some(0.0);
for r in &mut p.runs {
r.props.size = Some(14.0);
}
}
}
t
}
/// Most path elements this thread's glyph cache retains. Its entries are shared with the font
/// cache, but they stay alive here after that cache evicts them, so they are bounded by elements.
const GLYPH_CACHE_MAX_ELEMENTS: usize = 1 << 22;
thread_local! {
/// The cached outlines, and the path elements they hold.
static GLYPH_CACHE: std::cell::RefCell<(HashMap<(u32, u32), Arc<BezPath>>, usize)> = std::cell::RefCell::new((HashMap::new(), 0));
}
pub(crate) fn glyph(face: &deckcraft_fonts::FontFace, gid: u32) -> Arc<BezPath> {
let key = (face.id(), gid);
if let Some(p) = GLYPH_CACHE.with(|c| c.borrow().0.get(&key).cloned()) {
return p;
}
let p = FontDb::global().outline(face, gid);
GLYPH_CACHE.with(|c| {
let mut c = c.borrow_mut();
let n = p.elements().len();
if c.0.len() > 200_000 || c.1.saturating_add(n) > GLYPH_CACHE_MAX_ELEMENTS {
c.0.clear();
c.1 = 0;
}
c.1 += n;
c.0.insert(key, p.clone());
});
p
}
/// Draw a text body into shape space `m` within the text rect `opts.rect`.
pub fn draw_text(ctx: &mut RenderContext, rctx: &Ctx, s: &Shape, body: &TextBody, m: Affine, opts: &Opts) {
let l = deckcraft_text::layout(rctx, s, body, opts);
draw_layout(ctx, &l, opts.rect, m);
}
/// Add transient list markers to an editor layout, using the document's own bullet glyphs.
pub(crate) fn preview_empty_bullets(l: &mut deckcraft_text::TextLayout) {
for mut run in l.empty_bullets.drain(..) {
run.color = Rgba::rgb(0xB3, 0xB3, 0xB3);
run.alpha = 1.0;
l.runs.push(run);
}
}
/// Where text laid out in text rect `tr` is drawn, for a shape drawn with `m` (shape-local →
/// output): `m`, without mirroring, then the layout's `rotation` about the rect's centre.
///
/// Flips mirror a shape's geometry, never its text. When `m` reflects (flipH or flipV, the shape's
/// own or a group's) the text rect keeps its mirrored place and the text is mirrored back about
/// the rect's centre: a flipH shape's text stays readable and a flipV shape's text is turned 180°
/// (both flips: 180°), as in PowerPoint. Rendering, hit testing and the caret all use this.
pub fn text_transform(m: Affine, tr: Rect, rotation: f64) -> Affine {
let c = tr.center().to_vec2();
let mut t = m;
if m.determinant() < 0.0 && c.is_finite() {
t = t * Affine::translate(c) * Affine::scale_non_uniform(-1.0, 1.0) * Affine::translate(-c);
}
if rotation != 0.0 && rotation.is_finite() && c.is_finite() {
t = t * Affine::translate(c) * Affine::rotate(rotation.to_radians()) * Affine::translate(-c);
}
t
}
/// The WordArt warp of `s`'s text over its text rectangle `tr`, if it has one DeckCraft draws.
pub fn text_warp(rctx: &Ctx, s: &Shape, tr: Rect) -> Option<deckcraft_geom::warp::Warp> {
let bp = resolve::body(rctx, s);
let name = bp.warp.as_deref()?;
deckcraft_geom::warp::warp(name, &bp.warp_adj, tr)
}
/// Draw an already laid-out text block.
pub fn draw_layout(ctx: &mut RenderContext, l: &deckcraft_text::TextLayout, tr: Rect, m: Affine) {
draw_layout_with(ctx, l, tr, m, &[]);
}
/// Draw a laid-out text block with per-paragraph animation states.
pub fn draw_layout_with(ctx: &mut RenderContext, l: &deckcraft_text::TextLayout, tr: Rect, m: Affine, paras: &[(usize, ParaState)]) {
let para = |i: usize| paras.iter().find(|(p, _)| *p == i).map(|(_, s)| *s).unwrap_or_default();
let m = text_transform(m, tr, l.rotation);
let lines_of = LineIndex::new(l);
let deco = |ctx: &mut RenderContext, d: &deckcraft_text::Deco| {
let ps = para(d.para);
if !ps.visible || ps.opacity <= 0.001 {
return;
}
ctx.set_transform(m * Affine::translate(ps.offset));
ctx.set_paint(color(d.color, ps.opacity));
fill_deco(ctx, d);
};
for d in l.decos.iter().filter(|d| d.behind) {
deco(ctx, d);
}
// Text shadows, then glows, under all the text.
for pass in [TextEffect::Shadow, TextEffect::Glow] {
for run in &l.runs {
let ps = para(run.para);
if ps.visible && ps.opacity > 0.001 {
text_effect(ctx, run, pass, m * Affine::translate(ps.offset), ps.opacity);
}
}
}
for run in &l.runs {
if (run.alpha <= 0.0 || run.color.a == 0) && run.outline.is_none() {
continue;
}
let ps = para(run.para);
if !ps.visible || ps.opacity <= 0.001 {
continue;
}
let m = m * Affine::translate(ps.offset);
// A gradient fill starts over on every line and spans that line's text (from its top to
// its bottom, from its first to its last character), as in PowerPoint.
let mut grads: Vec<(usize, peniko::Gradient)> = Vec::new();
for (gid, x, y) in &run.glyphs {
let at = m * glyph_place(run, *gid, *x, *y);
let Some(g) = run.gradient.as_ref().filter(|g| !g.stops.is_empty()) else {
draw_glyph(ctx, run, *gid, at, ps.opacity);
continue;
};
let li = lines_of.line_at(run.para, *y);
if !grads.iter().any(|(i, _)| *i == li) {
let scheme = deckcraft_color::ColorScheme { name: String::new(), colors: [Rgba::BLACK; 12] };
let stops = g.stops.iter().map(|s| (s.pos, s.color.resolve(&scheme, None))).collect();
let bounds = l.lines.get(li).and_then(line_bounds).unwrap_or(tr);
grads.push((li, paint::gradient(&g.shape, stops, bounds, run.alpha * ps.opacity)));
}
let fill = grads.iter().find(|(i, _)| *i == li).map(|(_, g)| (g, Affine::translate((-*x, -*y))));
draw_glyph_with(ctx, run, *gid, at, ps.opacity, fill);
}
}
for d in l.decos.iter().filter(|d| !d.behind) {
deco(ctx, d);
}
}
/// Where glyph `gid` of `run` with its pen at (`x`, `y`) is drawn, in text space: there, turned a
/// quarter turn back about its em box's centre when it stands upright in vertical text.
pub(crate) fn glyph_place(run: &deckcraft_text::GlyphRun, gid: u32, x: f64, y: f64) -> Affine {
let at = Affine::translate((x, y));
match run.upright_centre(gid, x, y) {
Some((cx, cy)) => Affine::translate((cx, cy)) * Affine::rotate(-std::f64::consts::FRAC_PI_2) * Affine::translate((-cx, -cy)) * at,
None => at,
}
}
/// Fill an underline, strikethrough or highlight with the current paint and transform: its box,
/// its dashes, or its zigzag stroked.
pub(crate) fn fill_deco(ctx: &mut RenderContext, d: &deckcraft_text::Deco) {
if let Some((pts, w)) = d.wave() {
let mut path = BezPath::new();
for (i, p) in pts.iter().enumerate() {
if i == 0 {
path.move_to(*p);
} else {
path.line_to(*p);
}
}
ctx.set_stroke(kurbo::Stroke::new(w.max(0.01)));
ctx.stroke_path(&path);
return;
}
for r in d.pieces() {
ctx.fill_rect(&r);
}
}
/// Finds the line of a paragraph holding a glyph on baseline `y` without scanning the paragraph's
/// lines for every glyph. A paragraph whose lines are ordered top to bottom (every layout the text
/// crate produces) is searched by bisection; any other falls back to a scan with the same answer.
pub(crate) struct LineIndex<'a> {
l: &'a deckcraft_text::TextLayout,
/// Per paragraph: its lines' tops, bottoms and baselines all rise with the line index.
ordered: Vec<bool>,
}
impl<'a> LineIndex<'a> {
pub(crate) fn new(l: &'a deckcraft_text::TextLayout) -> Self {
let ordered = l
.para_lines
.iter()
.map(|&(first, count)| {
let end = first.saturating_add(count).min(l.lines.len());
l.lines.get(first..end).is_some_and(|ls| {
ls.iter().all(|a| a.top <= a.bottom)
&& ls.windows(2).all(|w| w[0].top <= w[1].top && w[0].bottom <= w[1].bottom && w[0].baseline <= w[1].baseline)
})
})
.collect();
LineIndex { l, ordered }
}
/// The nearest line baseline to `y` among `lines` (the first of equals), as an index into `lines`.
fn nearest(lines: &[deckcraft_text::LineInfo], y: f64) -> Option<usize> {
let i = lines.partition_point(|li| li.baseline < y);
let best = match (i.checked_sub(1), lines.get(i)) {
(Some(p), Some(n)) => {
if (lines[p].baseline - y).abs() <= (n.baseline - y).abs() {
p
} else {
i
}
}
(Some(p), None) => p,
(None, Some(_)) => i,
(None, None) => return None,
};
let b = lines[best].baseline;
Some(lines.partition_point(|li| li.baseline < b))
}
/// The paragraph's lines when they are ordered, with the index of the first.
fn ordered_lines(&self, para: usize) -> Option<(usize, &[deckcraft_text::LineInfo])> {
let &(first, count) = self.l.para_lines.get(para)?;
let end = first.saturating_add(count).min(self.l.lines.len());
(self.ordered[para] && first < end).then(|| (first, &self.l.lines[first..end]))
}
/// The line of paragraph `para` holding a glyph on baseline `y` (the nearest baseline).
pub(crate) fn line_at(&self, para: usize, y: f64) -> usize {
if let Some((first, ls)) = self.ordered_lines(para) {
return Self::nearest(ls, y).map_or(0, |i| first + i);
}
line_at_scan(self.l, para, y)
}
/// The first line of paragraph `para` whose box holds `y`, else the nearest baseline's line.
pub(crate) fn line_of(&self, para: usize, y: f64) -> Option<usize> {
let Some((first, ls)) = self.ordered_lines(para) else { return crate::warp::line_of_scan(self.l, para, y) };
let i = ls.partition_point(|li| li.bottom + 0.01 < y);
if ls.get(i).is_some_and(|li| y >= li.top - 0.01) {
return Some(first + i);
}
Self::nearest(ls, y).map(|i| first + i)
}
}
/// The line of paragraph `para` holding a glyph on baseline `y` (the nearest baseline), by scanning.
fn line_at_scan(l: &deckcraft_text::TextLayout, para: usize, y: f64) -> usize {
if let Some(&(first, count)) = l.para_lines.get(para) {
if count == 0 {
return 0;
}
let end = (first + count).min(l.lines.len());
if first < end {
return l.lines[first..end]
.iter()
.enumerate()
.min_by(|a, b| (a.1.baseline - y).abs().total_cmp(&(b.1.baseline - y).abs()))
.map(|(i, _)| first + i)
.unwrap_or(0);
}
}
l.lines
.iter()
.enumerate()
.filter(|(_, li)| li.para == para)
.min_by(|a, b| (a.1.baseline - y).abs().total_cmp(&(b.1.baseline - y).abs()))
.map(|(i, _)| i)
.unwrap_or(0)
}
/// The box a line's text covers: its top and bottom, its first and last caret.
pub(crate) fn line_bounds(li: &deckcraft_text::LineInfo) -> Option<Rect> {
let (x0, x1) = li.caret_x.iter().fold((f64::INFINITY, f64::NEG_INFINITY), |(a, b), x| (a.min(*x), b.max(*x)));
let r = Rect::new(x0, li.top, x1, li.bottom);
(r.is_finite() && r.width() > 0.0 && r.height() > 0.0).then_some(r)
}
#[derive(Clone, Copy, PartialEq)]
enum TextEffect {
Shadow,
Glow,
}
/// Draw `run`'s shadow or glow (if it has one) under its glyphs, placed by `m`.
fn text_effect(ctx: &mut RenderContext, run: &deckcraft_text::GlyphRun, which: TextEffect, m: Affine, opacity: f64) {
let Some(fx) = run.effects else { return };
let k = run.size / run.face.upem.max(1.0);
let skew = if run.fake_italic { Affine::new([1.0, 0.0, -0.2, 1.0, 0.0, 0.0]) } else { Affine::IDENTITY };
let px = scale_of(m);
let (c, sigma, offset, grow) = match (which, fx.shadow, fx.glow) {
(TextEffect::Shadow, Some(s), _) => (s.color, s.blur * 0.5 * px, Vec2::new(s.dx, s.dy), 0.0),
// Measured on PowerPoint's export: a text glow of radius r is solid to about a third of r
// past the glyph's edge and fades out by about two thirds of r.
(TextEffect::Glow, _, Some((gc, r))) => (gc, r * 0.15 * px, Vec2::ZERO, r * 0.68),
_ => return,
};
let alpha = (c.a as f64 / 255.0) * opacity;
if alpha <= 0.0 {
return;
}
ctx.set_transform(Affine::IDENTITY);
ctx.push_layer(None, None, Some(alpha as f32), None, Some(blur(sigma)));
ctx.set_paint(color(c.with_alpha(255), 1.0));
for (gid, x, y) in &run.glyphs {
let path = glyph(&run.face, *gid);
if path.elements().is_empty() {
continue;
}
// The offset is in slide space: a shadow falls the same way whatever the text's rotation.
let at = pre_translate(m * glyph_place(run, *gid, *x, *y), offset * px) * skew * Affine::scale(k);
ctx.set_transform(at);
ctx.fill_path(&path);
if grow > 0.0 {
ctx.set_stroke(kurbo::Stroke::new(grow / k.max(1e-9)).with_join(kurbo::Join::Round));
ctx.stroke_path(&path);
}
}
ctx.pop_layer();
}
/// Draw glyph `gid` of `run` with its origin (on the baseline) mapped by `at`, faded by `opacity`.
pub(crate) fn draw_glyph(ctx: &mut RenderContext, run: &deckcraft_text::GlyphRun, gid: u32, at: Affine, opacity: f64) {
draw_glyph_with(ctx, run, gid, at, opacity, None);
}
/// [`draw_glyph`], filled with `fill` (a gradient laid out in the text's space, and the map from
/// the glyph's origin to that space) instead of the run's colour.
fn draw_glyph_with(
ctx: &mut RenderContext,
run: &deckcraft_text::GlyphRun,
gid: u32,
at: Affine,
opacity: f64,
fill: Option<(&peniko::Gradient, Affine)>,
) {
let alpha = run.alpha * opacity;
if (alpha <= 0.0 || run.color.a == 0) && run.outline.is_none() {
return;
}
let k = run.size / run.face.upem.max(1.0);
// Colour glyphs (emoji) paint their own colours; an outline (text outline effect) still
// strokes the plain glyph below.
if alpha > 0.0 && run.outline.is_none() && run.face.is_color() && colr::paint(ctx, &run.face, gid, at, k, run.color, alpha) {
return;
}
let path = glyph(&run.face, gid);
if path.elements().is_empty() {
return;
}
let skew = if run.fake_italic { Affine::new([1.0, 0.0, -0.2, 1.0, 0.0, 0.0]) } else { Affine::IDENTITY };
ctx.set_transform(at * skew * Affine::scale(k));
if let Some((g, to_text)) = fill
&& alpha > 0.0
{
ctx.set_paint(g.clone());
ctx.set_paint_transform((skew * Affine::scale(k)).inverse() * to_text);
ctx.fill_path(&path);
ctx.reset_paint_transform();
} else if alpha > 0.0 && run.color.a > 0 {
ctx.set_paint(color(run.color, alpha));
ctx.fill_path(&path);
if run.fake_bold {
ctx.set_stroke(kurbo::Stroke::new(run.face.upem * 0.025).with_join(kurbo::Join::Round));
ctx.stroke_path(&path);
}
}
if let Some((oc, ow)) = run.outline {
ctx.set_paint(color(oc, opacity));
ctx.set_stroke(kurbo::Stroke::new(ow / k.max(1e-9)).with_join(kurbo::Join::Round));
ctx.stroke_path(&path);
}
}
#[cfg(test)]
mod line_index_tests {
use super::*;
use deckcraft_text::{LineInfo, TextLayout};
fn layout(ordered: bool) -> TextLayout {
let line = |para, top: f64| LineInfo { para, top, baseline: top + 8.0, bottom: top + 10.0, ..Default::default() };
let mut lines: Vec<LineInfo> = (0..40).map(|i| line(usize::from(i >= 25), f64::from(i) * 10.0)).collect();
if !ordered {
lines.swap(3, 7);
}
TextLayout { lines, para_lines: vec![(0, 25), (25, 15)], ..Default::default() }
}
#[test]
fn bisection_matches_the_scan() {
for ordered in [true, false] {
let l = layout(ordered);
let idx = LineIndex::new(l_ref(&l));
assert_eq!(idx.ordered, vec![ordered, true]);
for para in 0..2 {
for k in -20..450 {
let y = f64::from(k) * 0.9;
assert_eq!(idx.line_at(para, y), line_at_scan(&l, para, y), "line_at {para} {y}");
assert_eq!(idx.line_of(para, y), crate::warp::line_of_scan(&l, para, y), "line_of {para} {y}");
}
}
}
}
fn l_ref(l: &TextLayout) -> &TextLayout {
l
}
}