* 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>
- fix for https://github.com/rerun-io/reality/pull/1075
The galleys row size was calculated by looking at the last glyphs pos_x,
which got changed to be rounded to integers when we added subpixel
binning. This introduced a subtle bug which caused the width of galleys
to be slightly off.
This PR fixes this by looking at the actual cursor position instead,
which is not rounded.
Also added a test to ensure this is correct. Previously, for the second
and last line, the `x` was too close to the `0`.
<img width="48" height="67" alt="image"
src="https://github.com/user-attachments/assets/a69a4cc3-b3f3-4553-ab92-73cb2e7a358c"
/>
---------
Co-authored-by: lucasmerlin <8009393+lucasmerlin@users.noreply.github.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>
This adds a new mode, `UPDATE_SNAPSHOTS=force`, which will lower the
threshold to zero, overwriting every image that is not _exactly_ the
same.
Most comparisons has a threshold because different GPUs render slightly
differently. However, setting that threshold accurately can be hard.
Sometimes a test will pass locally, but fail on CI. In those cases you
want to force an update of the failing test. You can use
`UPDATE_SNAPSHOTS=force` for that.
And sometimes a small change _should_ update all images, but the change
is so tiny that it falls under the threshold. Still, you want to make a
point of showing that these images have changes. You can use
`UPDATE_SNAPSHOTS=force` for that.
Continuation of #5713
**Silently breaking changes:**
- Menus now close on click by default, this is configurable via
`PopupCloseBehavior`
**Additional additions:**
- `Button::right_text`
- `StyleModifier`
This is a rewrite of the egui menus, with the following goals:
- submenu buttons should work everywhere, in a popup, context menu,
area, in some random Ui
- remove the menu state from Ui
- should work just like the previous menu
- ~proper support for keyboard navigation~
- It's better now but requires further work to be perfect
- support `PopupCloseBehavior`
* Closes#4607
* [x] I have followed the instructions in the PR template
This introduces new `Tooltip` and `Popup` structs that unify and extend
the old popups and tooltips.
`Popup` handles the positioning and optionally stores state on whether
the popup is open (for click based popups like `ComboBox`, menus,
context menus).
`Tooltip` is based on `Popup` and handles state of whether the tooltip
should be shown (which turns out to be quite complex to handles all the
edge cases).
Both `Popup` and `Tooltip` can easily be constructed from a `Response`
and then customized via builder methods.
This also introduces `PositionAlign`, for aligning something outside of
a `Rect` (in contrast to `Align2` for aligning inside a `Rect`). But I
don't like the name, any suggestions? Inspired by [mui's tooltip
positioning](https://mui.com/material-ui/react-tooltip/#positioned-tooltips).
* Part of #4607
* [x] I have followed the instructions in the PR template
TODOs:
- [x] Automatic tooltip positioning based on available space
- [x] Review / fix / remove all code TODOs
- [x] ~Update the helper fns on `Response` to be consistent in naming
and parameters (Some use tooltip, some hover_ui, some take &self, some
take self)~ actually, I think the naming and parameter make sense on
second thought
- [x] Make sure all old code is marked deprecated
For discussion during review:
- the following check in `show_tooltip_for` still necessary?:
```rust
let is_touch_screen = ctx.input(|i| i.any_touches());
let allow_placing_below = !is_touch_screen; // There is a finger below. TODO: Needed?
```
