egui/crates/egui_extras/src/loaders/image_loader.rs

114 lines
3.3 KiB
Rust

use egui::{
ahash::HashMap,
load::{BytesPoll, ImageLoadResult, ImageLoader, ImagePoll, LoadError, SizeHint},
mutex::Mutex,
ColorImage,
};
use std::{mem::size_of, path::Path, sync::Arc};
type Entry = Result<Arc<ColorImage>, String>;
#[derive(Default)]
pub struct ImageCrateLoader {
cache: Mutex<HashMap<String, Entry>>,
}
impl ImageCrateLoader {
pub const ID: &str = egui::generate_loader_id!(ImageCrateLoader);
}
fn is_supported_uri(uri: &str) -> bool {
let Some(ext) = Path::new(uri).extension().and_then(|ext| ext.to_str()) else {
// `true` because if there's no extension, assume that we support it
return true;
};
ext != "svg"
}
fn is_unsupported_mime(mime: &str) -> bool {
mime.contains("svg")
}
impl ImageLoader for ImageCrateLoader {
fn id(&self) -> &str {
Self::ID
}
fn load(&self, ctx: &egui::Context, uri: &str, _: SizeHint) -> ImageLoadResult {
// three stages of guessing if we support loading the image:
// 1. URI extension
// 2. Mime from `BytesPoll::Ready`
// 3. image::guess_format
// (1)
if !is_supported_uri(uri) {
return Err(LoadError::NotSupported);
}
let mut cache = self.cache.lock();
if let Some(entry) = cache.get(uri).cloned() {
match entry {
Ok(image) => Ok(ImagePoll::Ready { image }),
Err(err) => Err(LoadError::Custom(err)),
}
} else {
match ctx.try_load_bytes(uri) {
Ok(BytesPoll::Ready { bytes, mime, .. }) => {
// (2 and 3)
if mime.as_deref().is_some_and(is_unsupported_mime)
|| image::guess_format(&bytes).is_err()
{
return Err(LoadError::NotSupported);
}
crate::log_trace!("started loading {uri:?}");
let result = crate::image::load_image_bytes(&bytes).map(Arc::new);
crate::log_trace!("finished loading {uri:?}");
cache.insert(uri.into(), result.clone());
match result {
Ok(image) => Ok(ImagePoll::Ready { image }),
Err(err) => Err(LoadError::Custom(err)),
}
}
Ok(BytesPoll::Pending { size }) => Ok(ImagePoll::Pending { size }),
Err(err) => Err(err),
}
}
}
fn forget(&self, uri: &str) {
let _ = self.cache.lock().remove(uri);
}
fn forget_all(&self) {
self.cache.lock().clear();
}
fn byte_size(&self) -> usize {
self.cache
.lock()
.values()
.map(|result| match result {
Ok(image) => image.pixels.len() * size_of::<egui::Color32>(),
Err(err) => err.len(),
})
.sum()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn check_support() {
assert!(is_supported_uri("https://test.png"));
assert!(is_supported_uri("test.jpeg"));
assert!(is_supported_uri("http://test.gif"));
assert!(is_supported_uri("test.webp"));
assert!(is_supported_uri("file://test"));
assert!(!is_supported_uri("test.svg"));
}
}