1use metal::{MTLPixelFormat, TextureDescriptor, TextureRef};
 2
 3use super::atlas::{AllocId, AtlasAllocator};
 4use crate::{
 5    geometry::{rect::RectI, vector::Vector2I},
 6    ImageData,
 7};
 8use std::{collections::HashMap, mem};
 9
10pub struct ImageCache {
11    prev_frame: HashMap<usize, (AllocId, RectI)>,
12    curr_frame: HashMap<usize, (AllocId, RectI)>,
13    atlases: AtlasAllocator,
14}
15
16impl ImageCache {
17    pub fn new(device: metal::Device, size: Vector2I) -> Self {
18        let descriptor = TextureDescriptor::new();
19        descriptor.set_pixel_format(MTLPixelFormat::BGRA8Unorm);
20        descriptor.set_width(size.x() as u64);
21        descriptor.set_height(size.y() as u64);
22        Self {
23            prev_frame: Default::default(),
24            curr_frame: Default::default(),
25            atlases: AtlasAllocator::new(device, descriptor),
26        }
27    }
28
29    pub fn render(&mut self, image: &ImageData) -> (AllocId, RectI) {
30        let (alloc_id, atlas_bounds) = self
31            .prev_frame
32            .remove(&image.id)
33            .or_else(|| self.curr_frame.get(&image.id).copied())
34            .unwrap_or_else(|| self.atlases.upload(image.size(), image.as_bytes()));
35        self.curr_frame.insert(image.id, (alloc_id, atlas_bounds));
36        (alloc_id, atlas_bounds)
37    }
38
39    pub fn finish_frame(&mut self) {
40        mem::swap(&mut self.prev_frame, &mut self.curr_frame);
41        for (_, (id, _)) in self.curr_frame.drain() {
42            self.atlases.deallocate(id);
43        }
44    }
45
46    pub fn atlas_texture(&self, atlas_id: usize) -> Option<&TextureRef> {
47        self.atlases.texture(atlas_id)
48    }
49}