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//! Image handling.
use std::collections::{hash_map::Entry, HashMap};
use std::fmt::{self, Debug, Formatter};
use std::io::Cursor;
use std::rc::Rc;
use image::io::Reader as ImageReader;
use image::{DynamicImage, GenericImageView, ImageFormat};
use serde::{Deserialize, Serialize};
use crate::loading::{FileId, Loader};
/// A loaded image.
pub struct Image {
/// The original format the image was encoded in.
pub format: ImageFormat,
/// The decoded image.
pub buf: DynamicImage,
}
impl Image {
/// Parse an image from raw data in a supported format (PNG or JPEG).
///
/// The image format is determined automatically.
pub fn parse(data: &[u8]) -> Option<Self> {
let cursor = Cursor::new(data);
let reader = ImageReader::new(cursor).with_guessed_format().ok()?;
let format = reader.format()?;
let buf = reader.decode().ok()?;
Some(Self { format, buf })
}
/// The width of the image.
pub fn width(&self) -> u32 {
self.buf.width()
}
/// The height of the image.
pub fn height(&self) -> u32 {
self.buf.height()
}
}
impl Debug for Image {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.debug_struct("Image")
.field("format", &self.format)
.field("color", &self.buf.color())
.field("width", &self.width())
.field("height", &self.height())
.finish()
}
}
/// Caches decoded images.
pub struct ImageCache {
loader: Rc<dyn Loader>,
images: HashMap<ImageId, Image>,
on_load: Option<Box<dyn Fn(ImageId, &Image)>>,
}
impl ImageCache {
/// Create a new, empty image cache.
pub fn new(loader: Rc<dyn Loader>) -> Self {
Self {
loader,
images: HashMap::new(),
on_load: None,
}
}
/// Load and decode an image file from a path.
pub fn load(&mut self, file: FileId) -> Option<ImageId> {
let id = ImageId(file.into_raw());
if let Entry::Vacant(entry) = self.images.entry(id) {
let buffer = self.loader.load_file(file)?;
let image = Image::parse(&buffer)?;
if let Some(callback) = &self.on_load {
callback(id, &image);
}
entry.insert(image);
}
Some(id)
}
/// Get a reference to a loaded image.
///
/// This panics if no image with this id was loaded. This function should
/// only be called with ids returned by [`load()`](Self::load).
#[track_caller]
pub fn get(&self, id: ImageId) -> &Image {
&self.images[&id]
}
/// Register a callback which is invoked each time an image is loaded.
pub fn on_load<F>(&mut self, f: F)
where
F: Fn(ImageId, &Image) + 'static,
{
self.on_load = Some(Box::new(f));
}
}
/// A unique identifier for a loaded image.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
pub struct ImageId(u64);
impl ImageId {
/// Create an image id from the raw underlying value.
///
/// This should only be called with values returned by
/// [`into_raw`](Self::into_raw).
pub fn from_raw(v: u64) -> Self {
Self(v)
}
/// Convert into the raw underlying value.
pub fn into_raw(self) -> u64 {
self.0
}
}
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