migrations/egui
1
0
Fork 0
mirror of https://github.com/emilk/egui.git synced 2026-08-31 13:50:04 -04:00
Code Activity

New text layout (#682)

Browse Source 
This PR introduces a completely rewritten text layout engine which is simpler and more powerful. It allows mixing different text styles (heading, body, etc) and formats (color, underlining, strikethrough, …) in the same layout pass, and baked into the same `Galley`.

This opens up the door to having a syntax-highlighed code editor, or a WYSIWYG markdown editor.

One major change is the color is now baked in at layout time. However, many widgets changes text color on hovered. But we need to do the text layout before we know if it is hovered. Therefor the painter has an option to override the text color of a galley.


## Performance
Text layout alone is about 20% slower, but a lot of that is because more tessellation is done upfront. Text tessellation is now a lot faster, but text layout + tessellation still lands at a net loss of 5-10% in performance. There are however a few tricks to speed it up (like using `smallvec`) which I am saving for later. Text layout is also cached, meaning that in most cases (when all text isn't changing each frame) text tessellation is actually more important (and that's more than 2x faster!).

Sadly, the actual text cache lookup is significantly slower (300ns -> 600ns). That's because the `TextLayoutJob` is a lot bigger (it has more options, like underlining, fonts etc), so it is slower to hash and compare. I have an idea how to speed this up, but I need to do some other work before I can implement that.

All in all, the performance impact on `demo_with_tesselate__realistic` is about 5-6% in the red. Not great; not terrible. The benefits are worth it, but I also think with some work I can get that down significantly, hopefully down to the old levels.
This commit is contained in:
Emil Ernerfeldt
2021-09-03 18:18:00 +02:00
committed by GitHub
parent 36cffd7b84
commit de1a1ba9b2
43 changed files with 2204 additions and 1295 deletions
Download Patch File Download Diff File Expand all files Collapse all files

152
epaint/src/text/fonts.rs
View File

@@ -10,7 +10,7 @@ use crate::{
mutex::Mutex,
text::{
font::{Font, FontImpl},
Galley,
Galley, LayoutJob,
},
Texture, TextureAtlas,
};
@@ -315,69 +315,58 @@ impl Fonts {
self.fonts[&text_style].row_height()
}
/// Will line break at `\n`.
/// Layout some text.
/// This is the most advanced layout function.
/// See also [`Self::layout`], [`Self::layout_no_wrap`] and
/// [`Self::layout_delayed_color`].
///
/// Always returns at least one row.
pub fn layout_no_wrap(&self, text_style: TextStyle, text: String) -> Arc<Galley> {
self.layout_multiline(text_style, text, f32::INFINITY)
}
/// Typeset the given text onto one row.
/// Any `\n` will show up as the replacement character.
/// Always returns exactly one `Row` in the `Galley`.
///
/// Most often you probably want `\n` to produce a new row,
/// and so [`Self::layout_no_wrap`] may be a better choice.
pub fn layout_single_line(&self, text_style: TextStyle, text: String) -> Arc<Galley> {
self.galley_cache.lock().layout(
&self.fonts,
LayoutJob {
text_style,
text,
layout_params: LayoutParams::SingleLine,
},
)
/// The implementation uses memoization so repeated calls are cheap.
pub fn layout_job(&self, job: impl Into<Arc<LayoutJob>>) -> Arc<Galley> {
self.galley_cache.lock().layout(self, job.into())
}
/// Will wrap text at the given width and line break at `\n`.
///
/// Always returns at least one row.
pub fn layout_multiline(
/// The implementation uses memoization so repeated calls are cheap.
pub fn layout(
&self,
text_style: TextStyle,
text: String,
max_width_in_points: f32,
text_style: TextStyle,
color: crate::Color32,
wrap_width: f32,
) -> Arc<Galley> {
self.layout_multiline_with_indentation_and_max_width(
text_style,
text,
0.0,
max_width_in_points,
)
let job = LayoutJob::simple(text, text_style, color, wrap_width);
self.layout_job(job)
}
/// * `first_row_indentation`: extra space before the very first character (in points).
/// * `max_width_in_points`: wrapping width.
/// Will line break at `\n`.
///
/// Always returns at least one row.
pub fn layout_multiline_with_indentation_and_max_width(
/// The implementation uses memoization so repeated calls are cheap.
pub fn layout_no_wrap(
&self,
text_style: TextStyle,
text: String,
first_row_indentation: f32,
max_width_in_points: f32,
text_style: TextStyle,
color: crate::Color32,
) -> Arc<Galley> {
self.galley_cache.lock().layout(
&self.fonts,
LayoutJob {
text_style,
text,
layout_params: LayoutParams::Multiline {
first_row_indentation: first_row_indentation.into(),
max_width_in_points: max_width_in_points.into(),
},
},
)
let job = LayoutJob::simple(text, text_style, color, f32::INFINITY);
self.layout_job(job)
}
/// Like [`Self::layout`], made for when you want to pick a color for the text later.
///
/// The implementation uses memoization so repeated calls are cheap.
pub fn layout_delayed_color(
&self,
text: String,
text_style: TextStyle,
wrap_width: f32,
) -> Arc<Galley> {
self.layout_job(LayoutJob::simple(
text,
text_style,
crate::Color32::TEMPORARY_COLOR,
wrap_width,
))
}
pub fn num_galleys_in_cache(&self) -> usize {
@@ -386,7 +375,7 @@ impl Fonts {
/// Must be called once per frame to clear the [`Galley`] cache.
pub fn end_frame(&self) {
self.galley_cache.lock().end_frame()
self.galley_cache.lock().end_frame();
}
}
@@ -401,22 +390,6 @@ impl std::ops::Index<TextStyle> for Fonts {
// ----------------------------------------------------------------------------
#[derive(Clone, Copy, Eq, PartialEq, Hash)]
enum LayoutParams {
SingleLine,
Multiline {
first_row_indentation: ordered_float::OrderedFloat<f32>,
max_width_in_points: ordered_float::OrderedFloat<f32>,
},
}
#[derive(Clone, Eq, PartialEq, Hash)]
struct LayoutJob {
text_style: TextStyle,
layout_params: LayoutParams,
text: String,
}
struct CachedGalley {
/// When it was last used
last_used: u32,
@@ -427,41 +400,26 @@ struct CachedGalley {
struct GalleyCache {
/// Frame counter used to do garbage collection on the cache
generation: u32,
cache: AHashMap<LayoutJob, CachedGalley>,
cache: AHashMap<Arc<LayoutJob>, CachedGalley>,
}
impl GalleyCache {
fn layout(&mut self, fonts: &BTreeMap<TextStyle, Font>, job: LayoutJob) -> Arc<Galley> {
if let Some(cached) = self.cache.get_mut(&job) {
cached.last_used = self.generation;
cached.galley.clone()
} else {
let LayoutJob {
text_style,
layout_params,
text,
} = job.clone();
let font = &fonts[&text_style];
let galley = match layout_params {
LayoutParams::SingleLine => font.layout_single_line(text),
LayoutParams::Multiline {
first_row_indentation,
max_width_in_points,
} => font.layout_multiline_with_indentation_and_max_width(
text,
first_row_indentation.into_inner(),
max_width_in_points.into_inner(),
),
};
let galley = Arc::new(galley);
self.cache.insert(
job,
CachedGalley {
fn layout(&mut self, fonts: &Fonts, job: Arc<LayoutJob>) -> Arc<Galley> {
match self.cache.entry(job.clone()) {
std::collections::hash_map::Entry::Occupied(entry) => {
let cached = entry.into_mut();
cached.last_used = self.generation;
cached.galley.clone()
}
std::collections::hash_map::Entry::Vacant(entry) => {
let galley = super::layout(fonts, job);
let galley = Arc::new(galley);
entry.insert(CachedGalley {
last_used: self.generation,
galley: galley.clone(),
},
);
galley
});
galley
}
}
}