* Related to #56 (Improve text — tracking issue)
## Summary
This PR integrates [harfrust](https://crates.io/crates/harfrust) (a
pure-Rust port of HarfBuzz) into epaint's text layout pipeline,
replacing the character-by-character glyph positioning with proper
OpenType text shaping.
### What this enables
- **GPOS kerning**: most modern fonts only ship kerning in GPOS tables
(not the legacy `kern` table). Pairs like "AV", "VA", "AT" are now
properly tightened.
- **GSUB substitutions**: ligatures (fi, fl), contextual alternates, and
other OpenType features.
- **Combining marks**: diacritics (e.g. ɔ̃) are positioned via anchor
tables instead of being rendered as standalone replacement glyphs.
### Before/After
#### Kerning, etc.
<img width="838" height="726" alt="before_main"
src="https://github.com/user-attachments/assets/f0f26d5f-b117-43a6-b39c-ea40d2e73836"
/>
<img width="838" height="726" alt="after_harfrust"
src="https://github.com/user-attachments/assets/d983e5da-486c-4f39-bd4f-5782a90c6b39"
/>
#### Ligatures
<img width="1117" height="698" alt="before_closeup"
src="https://github.com/user-attachments/assets/7a3b08b4-cf6f-45b7-98ba-07c473cd3b02"
/>
<img width="1117" height="698" alt="after_closeup"
src="https://github.com/user-attachments/assets/6cfc5f21-d32f-4f09-be0c-59c8c553d44f"
/>
### Architecture
The shaping integrates into the existing pipeline without changing the
public API:
1. **`Font::segment_into_runs`** — segments text into contiguous runs by
font face (grapheme-cluster aware, never splits combining sequences)
2. **`FontFace::shape_text`** — calls harfrust to shape each run,
returning glyph IDs + positioned advances/offsets
3. **`layout_shaped_run`** — emits `Glyph` structs from the shaping
output, with NOTDEF fallback to other font faces for missing glyphs
4. **Buffer recycling** — `FontsImpl` pools a `harfrust::UnicodeBuffer`
to avoid per-layout allocations
### Disclaimer
I'm far from being a good Rust programmer. Claude Code did most of the
heavy lifting here. I did my best and used my limited knowledge to avoid
making too many mistakes. If this PR isn't up to quality standards,
please don't hesitate to close it.
## Test plan
- [x] `cargo test -p epaint` — all 18 text tests pass, including 6 new
ones
- [x] `cargo clippy -p epaint --all-features` — clean
- [x] `cargo fmt` — clean
- [ ] Snapshot tests need regeneration (expected: shaping changes glyph
positions)
- New tests added:
- `test_gpos_kerning` — verifies GPOS kerning tightens "AV", "VA", "AT"
pairs
- `test_combining_diacritics` — combining tilde doesn't add extra width
- `test_shaping_basic_latin` — sanity check for Latin text
- `test_shaping_empty_string` — empty input doesn't panic
- `test_shaping_multiple_newlines` — newline splitting works correctly
- `test_shaping_mixed_font_fallback` — Latin + emoji in same string
---------
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
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* Closes N/A
* [x] I have followed the instructions in the PR template
This was mostly from last month, but I never got around to submitting
it.
This PR adds font variation coordinates to the `TextFormat` struct, and
uses them when rendering text. The coordinates are stored in a
`SmallVec`; I've chosen to store up to 2 inline, which makes it take up
24 bytes (the minimum possible for a `SmallVec`). The variation axis
tags are stored as the `font_types::Tag` type, which I've chosen to
re-export from `epaint::text`.
The variation coordinates are resolved to a `skrifa::Location` during
font rendering/scaling, and are cached in the same way as all the other
scaled metrics. I've renamed the `ScaledMetrics` struct to
`StyledMetrics`, since it now also contains the resolved variation
coordinates. I haven't benchmarked the performance of text layout with
variation coordinates, but the existing text layout performance is
unchanged.
I've replaced the API for manually overriding a font's weight
(https://github.com/emilk/egui/pull/7790) with an API for manually
overriding any variation coordinates via `FontTweak`. This should
support the same use case as #7790 while being substantially more
flexible.
I have *not* yet added any higher-level API for mapping style attributes
(weight, width, slant, etc) to variation coordinates or to different
font faces within a single family. That's a pretty huge can of worms,
and it'd involve rethinking the split between `FontId` and `TextFormat`
(and whether `FontId` is so big that we should provide a way to reuse
it). This API is intentionally pretty low-level for now.
Likewise, I've intentionally not used variation coordinates when
computing a font's row height. I can't think of any fonts that change
their vertical metrics depending on variation axes, so this should be
fine for now.
---------
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
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* Closes N/A
* [x] I have followed the instructions in the PR template
I'll probably come back to this and clean it up a bit. This PR
reimplements ab_glyph's functionality on top of Skrifa, a somewhat
lower-level font API that's being used in Chrome now.
Skrifa doesn't perform rasterization itself, so I'm using
[vello_cpu](https://github.com/linebender/vello) from the Linebender
project for rasterization. It's still in its early days, but I believe
it's already quite fast. It also supports color and gradient fills, so
color emoji support will be easier.
Skrifa also supports font hinting, which should make text look a bit
nicer / less blurry.
Here's the current ab_glyph rendering:
<img width="1592" height="1068" alt="image"
src="https://github.com/user-attachments/assets/2385b66e-23f8-4c6e-b8c2-ea90e0eea4e4"
/>
Here's Skrifa *without* hinting--it looks almost identical, but there
are some subpixel differences, probably due to rasterizer behavior:
<img width="1592" height="1068" alt="image"
src="https://github.com/user-attachments/assets/a815f3e9-65ac-4940-bc00-571177bef53d"
/>
Here's Skrifa *with* hinting:
<img width="1592" height="1068" alt="image"
src="https://github.com/user-attachments/assets/d6cc0669-3537-4377-bba9-ed5ef09664db"
/>
Hinting does make the horizontal strokes look a bit bolder, which makes
me wonder once again about increasing the font weight from "light" to
"regular".
---------
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
* related #7494
Removes the `deadlock_detection` feature, since we now have a more
primitive panic-after-30s deadlock detection which works well enough and
even detects kinds of deadlocks that the `deadlock_detection` feature
never supported.
## What
(written by @emilk)
When editing long text (thousands of line), egui would previously
re-layout the entire text on each edit. This could be slow.
With this PR, we instead split the text into paragraphs (split on `\n`)
and then cache each such paragraph. When editing text then, only the
changed paragraph needs to be laid out again.
Still, there is overhead from splitting the text, hashing each
paragraph, and then joining the results, so the runtime complexity is
still O(N).
In our benchmark, editing a 2000 line string goes from ~8ms to ~300 ms,
a speedup of ~25x.
In the future, we could also consider laying out each paragraph in
parallel, to speed up the initial layout of the text.
## Details
This is an ~~almost complete~~ implementation of the approach described
by emilk [in this
comment](<https://github.com/emilk/egui/issues/3086#issuecomment-1724205777>),
excluding CoW semantics for `LayoutJob` (but including them for `Row`).
It supersedes the previous unsuccessful attempt here:
https://github.com/emilk/egui/pull/4000.
Draft because:
- [X] ~~Currently individual rows will have `ends_with_newline` always
set to false.
This breaks selection with Ctrl+A (and probably many other things)~~
- [X] ~~The whole block for doing the splitting and merging should
probably become a function (I'll do that later).~~
- [X] ~~I haven't run the check script, the tests, and haven't made sure
all of the examples build (although I assume they probably don't rely on
Galley internals).~~
- [x] ~~Layout is sometimes incorrect (missing empty lines, wrapping
sometimes makes text overlap).~~
- A lot of text-related code had to be changed so this needs to be
properly tested to ensure no layout issues were introduced, especially
relating to the now row-relative coordinate system of `Row`s. Also this
requires that we're fine making these very breaking changes.
It does significantly improve the performance of rendering large blocks
of text (if they have many newlines), this is the test program I used to
test it (adapted from <https://github.com/emilk/egui/issues/3086>):
<details>
<summary>code</summary>
```rust
use eframe::egui::{self, CentralPanel, TextEdit};
use std::fmt::Write;
fn main() -> Result<(), eframe::Error> {
let options = eframe::NativeOptions {
..Default::default()
};
eframe::run_native(
"editor big file test",
options,
Box::new(|_cc| Ok(Box::<MyApp>::new(MyApp::new()))),
)
}
struct MyApp {
text: String,
}
impl MyApp {
fn new() -> Self {
let mut string = String::new();
for line_bytes in (0..50000).map(|_| (0u8..50)) {
for byte in line_bytes {
write!(string, " {byte:02x}").unwrap();
}
write!(string, "\n").unwrap();
}
println!("total bytes: {}", string.len());
MyApp { text: string }
}
}
impl eframe::App for MyApp {
fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
CentralPanel::default().show(ctx, |ui| {
let start = std::time::Instant::now();
egui::ScrollArea::vertical().show(ui, |ui| {
let code_editor = TextEdit::multiline(&mut self.text)
.code_editor()
.desired_width(f32::INFINITY)
.desired_rows(40);
let response = code_editor.show(ui).response;
if response.changed() {
println!("total bytes now: {}", self.text.len());
}
});
let end = std::time::Instant::now();
let time_to_update = end - start;
if time_to_update.as_secs_f32() > 0.5 {
println!("Long update took {:.3}s", time_to_update.as_secs_f32())
}
});
}
}
```
</details>
I think the way to proceed would be to make a new type, something like
`PositionedRow`, that would wrap an `Arc<Row>` but have a separate `pos`
~~and `ends_with_newline`~~ (that would mean `Row` only holds a `size`
instead of a `rect`). This type would of course have getters that would
allow you to easily get a `Rect` from it and probably a `Deref` to the
underlying `Row`.
~~I haven't done this yet because I wanted to get some opinions whether
this would be an acceptable API first.~~ This is now implemented, but of
course I'm still open to discussion about this approach and whether it's
what we want to do.
Breaking changes (currently):
- The `Galley::rows` field has a different type.
- There is now a `PlacedRow` wrapper for `Row`.
- `Row` now uses a coordinate system relative to itself instead of the
`Galley`.
* Closes <https://github.com/emilk/egui/issues/3086>
* [X] I have followed the instructions in the PR template
---------
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Hey! I am not sure if this is something that's been considered before
and decided against (I couldn't find any PR's or issues).
This change removes the internal profiling macros in library crates and
the `puffin` feature and replaces it with similar functions in the
[profiling](https://github.com/aclysma/profiling) crate. This crate
provides a layer of abstraction over various profiler instrumentation
crates and allows library users to pick their favorite (supported)
profiler.
An additional benefit for puffin users is that dependencies of egui are
included in the instrumentation output too (mainly wgpu which uses the
profiling crate), so more details might be available when profiling.
A breaking change is that instead of using the `puffin` feature on egui,
users that want to profile the crate with puffin instead have to enable
the `profile-with-puffin` feature on the profiling crate. Similarly they
could instead choose to use `profile-with-tracy` etc.
I tried to add a 'tracy' feature to egui_demo_app in order to showcase ,
however the /scripts/check.sh currently breaks on mutually exclusive
features (which this introduces), so I decided against including it for
the initial PR. I'm happy to iterate more on this if there is interest
in taking this PR though.
Screenshot showing the additional info for wgpu now available when using
puffin
You can see this feature in action
[here](https://docs.rs/sysinfo/latest/src/sysinfo/common/system.rs.html#46)
or on any of dtolnay's crates and many others. I found myself going
through your project code recently on docs.rs and I was a bit sad I
couldn't have this feature enabled. This should fix it at next release.
:)
This allows license checking tools to omit the OFL and UFL licenses when
`default_fonts` are turned off.
There was some discussion of versioning on the original issue; I have
chosen to label this version as `0.28.1` to match the other crates.
Happy to adjust the version as needed.
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* Closes <https://github.com/emilk/egui/issues/2321>
* [X] I have followed the instructions in the PR template
---------
Co-authored-by: Alex Pinkus <pinkus@amazon.com>
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* The PR title is what ends up in the changelog, so make it descriptive!
* If applicable, add a screenshot or gif.
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Inspired by:
44d65f41ac/Cargo.toml (L65)
I took the liberty of removing that comment since I *think* that I got
all "relevant" ones (showing up more than once, sort of).
Removes `egui_assert` etc and replaces it with normal `debug_assert`
calls.
Previously you could opt-in to more runtime checks using feature flags.
Now these extra runtime checks are always enabled for debug builds.
You are most likely to encounter them if you use negative sizes or NaNs
or other similar bugs.
These usually indicate bugs in user space.
* Closes https://github.com/emilk/egui/issues/3941
Workspace dependencies can be annoying.
If you don't set them to `default-features=false`, then you cannot opt
out of their default features anywhere else, and get warnings if you
try.
So you set `default-features=false`, and then you need to manually opt
in to the default features everywhere else.
Or, as in my case, don't.
I don't have the energy to do this tonight, so I'll just revert.
* Part of https://github.com/emilk/egui/issues/1485
This adds a `rayon` feature to `epaint` and `egui` to parallelize
tessellation of large shapes, such as high-resolution plot lines.
* Replace tracing crate with log
It's just so much simpler to use
* Add `bacon wasm` job
* eframe: add a WebLogger for piping log events to the web console
* split out ecolor crate
* split up ecolor crate in lots of modules
* add changelog notes
* add readme to ecolor
* put clippy::manual_range_contains on cranky allow list
* fix hex color issues
* doc fixes
* more hex_color fixes
* Document features
* Rename hex_color module to avoid warning
* Sort the feature names
* fix link in CHANGELOG.md
* better wording
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
* Use total_cmp for clamping DragValue
* Added test for clamping
* Increase MSRV in all crates
* Increased rust version for github actions and lib.rs
* Inversed ranges are now working properply with clamp_to_range
* Added more tests
