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//! Image handling.
use std::collections::{hash_map::Entry, HashMap};
use std::fmt::{self, Debug, Formatter};
use std::io;
use std::path::Path;
use std::rc::Rc;
use image::io::Reader as ImageReader;
use image::{DynamicImage, GenericImageView, ImageFormat};
use serde::{Deserialize, Serialize};
use crate::loading::{FileHash, Loader};
/// A unique identifier for a loaded image.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[derive(Serialize, Deserialize)]
pub struct ImageId(u32);
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 const fn from_raw(v: u32) -> Self {
Self(v)
}
/// Convert into the raw underlying value.
pub const fn into_raw(self) -> u32 {
self.0
}
}
/// Storage for loaded and decoded images.
pub struct ImageStore {
loader: Rc<dyn Loader>,
files: HashMap<FileHash, ImageId>,
images: Vec<Image>,
on_load: Option<Box<dyn Fn(ImageId, &Image)>>,
}
impl ImageStore {
/// Create a new, empty image store.
pub fn new(loader: Rc<dyn Loader>) -> Self {
Self {
loader,
files: HashMap::new(),
images: vec![],
on_load: None,
}
}
/// 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));
}
/// Load and decode an image file from a path.
pub fn load(&mut self, path: &Path) -> io::Result<ImageId> {
let hash = self.loader.resolve(path)?;
Ok(*match self.files.entry(hash) {
Entry::Occupied(entry) => entry.into_mut(),
Entry::Vacant(entry) => {
let buffer = self.loader.load(path)?;
let image = Image::parse(&buffer)?;
let id = ImageId(self.images.len() as u32);
if let Some(callback) = &self.on_load {
callback(id, &image);
}
self.images.push(image);
entry.insert(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 this store's [`load()`](Self::load)
/// method.
#[track_caller]
pub fn get(&self, id: ImageId) -> &Image {
&self.images[id.0 as usize]
}
}
/// 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]) -> io::Result<Self> {
let cursor = io::Cursor::new(data);
let reader = ImageReader::new(cursor).with_guessed_format()?;
let format = reader.format().ok_or_else(|| {
io::Error::new(io::ErrorKind::InvalidData, "unknown image format")
})?;
let buf = reader
.decode()
.map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))?;
Ok(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()
}
}
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