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use crate::core::{Font, Size};
use crate::text;
use rustc_hash::{FxHashMap, FxHashSet};
use std::collections::hash_map;
use std::hash::{BuildHasher, Hash, Hasher};
#[allow(missing_debug_implementations)]
#[derive(Default)]
pub struct Cache {
entries: FxHashMap<KeyHash, Entry>,
aliases: FxHashMap<KeyHash, KeyHash>,
recently_used: FxHashSet<KeyHash>,
hasher: HashBuilder,
}
#[cfg(not(target_arch = "wasm32"))]
type HashBuilder = twox_hash::RandomXxHashBuilder64;
#[cfg(target_arch = "wasm32")]
type HashBuilder = std::hash::BuildHasherDefault<twox_hash::XxHash64>;
impl Cache {
pub fn new() -> Self {
Self::default()
}
pub fn get(&self, key: &KeyHash) -> Option<&Entry> {
self.entries.get(key)
}
pub fn allocate(
&mut self,
font_system: &mut cosmic_text::FontSystem,
key: Key<'_>,
) -> (KeyHash, &mut Entry) {
let hash = key.hash(self.hasher.build_hasher());
if let Some(hash) = self.aliases.get(&hash) {
let _ = self.recently_used.insert(*hash);
return (*hash, self.entries.get_mut(hash).unwrap());
}
if let hash_map::Entry::Vacant(entry) = self.entries.entry(hash) {
let metrics = cosmic_text::Metrics::new(
key.size,
key.line_height.max(f32::MIN_POSITIVE),
);
let mut buffer = cosmic_text::Buffer::new(font_system, metrics);
buffer.set_size(
font_system,
key.bounds.width,
key.bounds.height.max(key.line_height),
);
buffer.set_text(
font_system,
key.content,
text::to_attributes(key.font),
text::to_shaping(key.shaping),
);
let bounds = text::measure(&buffer);
let _ = entry.insert(Entry {
buffer,
min_bounds: bounds,
});
for bounds in [
bounds,
Size {
width: key.bounds.width,
..bounds
},
] {
if key.bounds != bounds {
let _ = self.aliases.insert(
Key { bounds, ..key }.hash(self.hasher.build_hasher()),
hash,
);
}
}
}
let _ = self.recently_used.insert(hash);
(hash, self.entries.get_mut(&hash).unwrap())
}
pub fn trim(&mut self) {
self.entries
.retain(|key, _| self.recently_used.contains(key));
self.aliases
.retain(|_, value| self.recently_used.contains(value));
self.recently_used.clear();
}
}
#[derive(Debug, Clone, Copy)]
pub struct Key<'a> {
pub content: &'a str,
pub size: f32,
pub line_height: f32,
pub font: Font,
pub bounds: Size,
pub shaping: text::Shaping,
}
impl Key<'_> {
fn hash<H: Hasher>(self, mut hasher: H) -> KeyHash {
self.content.hash(&mut hasher);
self.size.to_bits().hash(&mut hasher);
self.line_height.to_bits().hash(&mut hasher);
self.font.hash(&mut hasher);
self.bounds.width.to_bits().hash(&mut hasher);
self.bounds.height.to_bits().hash(&mut hasher);
self.shaping.hash(&mut hasher);
hasher.finish()
}
}
pub type KeyHash = u64;
#[allow(missing_debug_implementations)]
pub struct Entry {
pub buffer: cosmic_text::Buffer,
pub min_bounds: Size,
}
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