Move image/svg handling into `iced_graphics`

The `TextureStore` trait is implemented by the atlas, and can also be
implemented in the glow renderer or in a software renderer.

The API here may be improved in the future, but API stability is
presumably not a huge issue since these types will only be used by
renderer backends.

5 files changed, 146 insertions, 49 deletions

diff --git a/graphics/Cargo.toml b/graphics/Cargo.toml
index 3b0e5236..749770f4 100644
--- a/graphics/Cargo.toml
+++ b/graphics/Cargo.toml
@@ -11,17 +11,33 @@ keywords = ["gui", "ui", "graphics", "interface", "widgets"]
 categories = ["gui"]
 
 [features]
+svg = ["resvg", "usvg", "tiny-skia"]
+image = ["png", "jpeg", "jpeg_rayon", "gif", "webp", "bmp"]
+png = ["image_rs/png"]
+jpeg = ["image_rs/jpeg"]
+jpeg_rayon = ["image_rs/jpeg_rayon"]
+gif = ["image_rs/gif"]
+webp = ["image_rs/webp"]
+pnm = ["image_rs/pnm"]
+ico = ["image_rs/ico"]
+bmp = ["image_rs/bmp"]
+hdr = ["image_rs/hdr"]
+dds = ["image_rs/dds"]
+farbfeld = ["image_rs/farbfeld"]
 canvas = ["lyon"]
 qr_code = ["qrcode", "canvas"]
 font-source = ["font-kit"]
 font-fallback = []
 font-icons = []
 opengl = []
+image_rs = ["kamadak-exif"]
 
 [dependencies]
 glam = "0.21.3"
+log = "0.4"
 raw-window-handle = "0.5"
 thiserror = "1.0"
+bitflags = "1.2"
 
 [dependencies.bytemuck]
 version = "1.4"
@@ -48,6 +64,28 @@ default-features = false
 version = "0.10"
 optional = true
 
+[dependencies.image_rs]
+version = "0.23"
+package = "image"
+default-features = false
+optional = true
+
+[dependencies.resvg]
+version = "0.18"
+optional = true
+
+[dependencies.usvg]
+version = "0.18"
+optional = true
+
+[dependencies.tiny-skia]
+version = "0.6"
+optional = true
+
+[dependencies.kamadak-exif]
+version = "0.5"
+optional = true
+
 [package.metadata.docs.rs]
 rustdoc-args = ["--cfg", "docsrs"]
 all-features = true
diff --git a/graphics/src/image.rs b/graphics/src/image.rs
new file mode 100644
index 00000000..f1153882
--- /dev/null
+++ b/graphics/src/image.rs
@@ -0,0 +1,34 @@
+//! Image loading and caching
+
+use std::fmt::Debug;
+
+#[cfg(feature = "image_rs")]
+pub mod raster;
+
+#[cfg(feature = "svg")]
+pub mod vector;
+
+/// Entry in the texture store
+pub trait TextureStoreEntry: Debug {
+    /// Width and height of the entry
+    fn size(&self) -> (u32, u32);
+}
+
+/// Stores cached image data for use in rendering
+pub trait TextureStore {
+    /// Entry in the texture store
+    type Entry: TextureStoreEntry;
+    /// State passed to upload/remove
+    type State<'a>;
+
+    /// Upload image data
+    fn upload(
+        &mut self,
+        width: u32,
+        height: u32,
+        data: &[u8],
+        state: &mut Self::State<'_>,
+    ) -> Option<Self::Entry>;
+    /// Remome image from store
+    fn remove(&mut self, entry: &Self::Entry, state: &mut Self::State<'_>);
+}
diff --git a/wgpu/src/image/raster.rs b/graphics/src/image/raster.rs
index 2b4d4af3..f9672dd5 100644
--- a/wgpu/src/image/raster.rs
+++ b/graphics/src/image/raster.rs
@@ -1,18 +1,27 @@
-use crate::image::atlas::{self, Atlas};
+//! Raster image loading and caching
+
 use iced_native::image;
 use std::collections::{HashMap, HashSet};
 
 use bitflags::bitflags;
 
+use super::{TextureStore, TextureStoreEntry};
+
+/// Entry in cache corresponding to an image handle
 #[derive(Debug)]
-pub enum Memory {
-    Host(::image_rs::ImageBuffer<::image_rs::Bgra<u8>, Vec<u8>>),
-    Device(atlas::Entry),
+pub enum Memory<T: TextureStore> {
+    /// Image data on host
+    Host(::image_rs::ImageBuffer<::image_rs::Rgba<u8>, Vec<u8>>),
+    /// Texture store entry
+    Device(T::Entry),
+    /// Image not found
     NotFound,
+    /// Invalid image data
     Invalid,
 }
 
-impl Memory {
+impl<T: TextureStore> Memory<T> {
+    /// Width and height of image
     pub fn dimensions(&self) -> (u32, u32) {
         match self {
             Memory::Host(image) => image.dimensions(),
@@ -23,21 +32,16 @@ impl Memory {
     }
 }
 
+/// Caches image raster data
 #[derive(Debug)]
-pub struct Cache {
-    map: HashMap<u64, Memory>,
+pub struct Cache<T: TextureStore> {
+    map: HashMap<u64, Memory<T>>,
     hits: HashSet<u64>,
 }
 
-impl Cache {
-    pub fn new() -> Self {
-        Self {
-            map: HashMap::new(),
-            hits: HashSet::new(),
-        }
-    }
-
-    pub fn load(&mut self, handle: &image::Handle) -> &mut Memory {
+impl<T: TextureStore> Cache<T> {
+    /// Load image
+    pub fn load(&mut self, handle: &image::Handle) -> &mut Memory<T> {
         if self.contains(handle) {
             return self.get(handle).unwrap();
         }
@@ -53,7 +57,7 @@ impl Cache {
                         })
                         .unwrap_or_else(Operation::empty);
 
-                    Memory::Host(operation.perform(image.to_bgra8()))
+                    Memory::Host(operation.perform(image.to_rgba8()))
                 } else {
                     Memory::NotFound
                 }
@@ -65,7 +69,7 @@ impl Cache {
                             .ok()
                             .unwrap_or_else(Operation::empty);
 
-                    Memory::Host(operation.perform(image.to_bgra8()))
+                    Memory::Host(operation.perform(image.to_rgba8()))
                 } else {
                     Memory::Invalid
                 }
@@ -91,19 +95,19 @@ impl Cache {
         self.get(handle).unwrap()
     }
 
+    /// Load image and upload raster data
     pub fn upload(
         &mut self,
         handle: &image::Handle,
-        device: &wgpu::Device,
-        encoder: &mut wgpu::CommandEncoder,
-        atlas: &mut Atlas,
-    ) -> Option<&atlas::Entry> {
+        state: &mut T::State<'_>,
+        store: &mut T,
+    ) -> Option<&T::Entry> {
         let memory = self.load(handle);
 
         if let Memory::Host(image) = memory {
             let (width, height) = image.dimensions();
 
-            let entry = atlas.upload(width, height, image, device, encoder)?;
+            let entry = store.upload(width, height, image, state)?;
 
             *memory = Memory::Device(entry);
         }
@@ -115,7 +119,8 @@ impl Cache {
         }
     }
 
-    pub fn trim(&mut self, atlas: &mut Atlas) {
+    /// Trim cache misses from cache
+    pub fn trim(&mut self, store: &mut T, state: &mut T::State<'_>) {
         let hits = &self.hits;
 
         self.map.retain(|k, memory| {
@@ -123,7 +128,7 @@ impl Cache {
 
             if !retain {
                 if let Memory::Device(entry) = memory {
-                    atlas.remove(entry);
+                    store.remove(entry, state);
                 }
             }
 
@@ -133,13 +138,13 @@ impl Cache {
         self.hits.clear();
     }
 
-    fn get(&mut self, handle: &image::Handle) -> Option<&mut Memory> {
+    fn get(&mut self, handle: &image::Handle) -> Option<&mut Memory<T>> {
         let _ = self.hits.insert(handle.id());
 
         self.map.get_mut(&handle.id())
     }
 
-    fn insert(&mut self, handle: &image::Handle, memory: Memory) {
+    fn insert(&mut self, handle: &image::Handle, memory: Memory<T>) {
         let _ = self.map.insert(handle.id(), memory);
     }
 
@@ -148,6 +153,15 @@ impl Cache {
     }
 }
 
+impl<T: TextureStore> Default for Cache<T> {
+    fn default() -> Self {
+        Self {
+            map: HashMap::new(),
+            hits: HashSet::new(),
+        }
+    }
+}
+
 bitflags! {
     struct Operation: u8 {
         const FLIP_HORIZONTALLY = 0b001;
diff --git a/wgpu/src/image/vector.rs b/graphics/src/image/vector.rs
index b08a0aa2..0062e2ce 100644
--- a/wgpu/src/image/vector.rs
+++ b/graphics/src/image/vector.rs
@@ -1,16 +1,22 @@
-use crate::image::atlas::{self, Atlas};
+//! Vector image loading and caching
 
 use iced_native::svg;
 
 use std::collections::{HashMap, HashSet};
 use std::fs;
 
+use super::TextureStore;
+
+/// Entry in cache corresponding to an svg handle
 pub enum Svg {
+    /// Parsed svg
     Loaded(usvg::Tree),
+    /// Svg not found or failed to parse
     NotFound,
 }
 
 impl Svg {
+    /// Viewport width and height
     pub fn viewport_dimensions(&self) -> (u32, u32) {
         match self {
             Svg::Loaded(tree) => {
@@ -23,24 +29,17 @@ impl Svg {
     }
 }
 
+/// Caches svg vector and raster data
 #[derive(Debug)]
-pub struct Cache {
+pub struct Cache<T: TextureStore> {
     svgs: HashMap<u64, Svg>,
-    rasterized: HashMap<(u64, u32, u32), atlas::Entry>,
+    rasterized: HashMap<(u64, u32, u32), T::Entry>,
     svg_hits: HashSet<u64>,
     rasterized_hits: HashSet<(u64, u32, u32)>,
 }
 
-impl Cache {
-    pub fn new() -> Self {
-        Self {
-            svgs: HashMap::new(),
-            rasterized: HashMap::new(),
-            svg_hits: HashSet::new(),
-            rasterized_hits: HashSet::new(),
-        }
-    }
-
+impl<T: TextureStore> Cache<T> {
+    /// Load svg
     pub fn load(&mut self, handle: &svg::Handle) -> &Svg {
         if self.svgs.contains_key(&handle.id()) {
             return self.svgs.get(&handle.id()).unwrap();
@@ -73,15 +72,15 @@ impl Cache {
         self.svgs.get(&handle.id()).unwrap()
     }
 
+    /// Load svg and upload raster data
     pub fn upload(
         &mut self,
         handle: &svg::Handle,
         [width, height]: [f32; 2],
         scale: f32,
-        device: &wgpu::Device,
-        encoder: &mut wgpu::CommandEncoder,
-        texture_atlas: &mut Atlas,
-    ) -> Option<&atlas::Entry> {
+        state: &mut T::State<'_>,
+        texture_store: &mut T,
+    ) -> Option<&T::Entry> {
         let id = handle.id();
 
         let (width, height) = (
@@ -125,12 +124,11 @@ impl Cache {
                 let mut rgba = img.take();
                 rgba.chunks_exact_mut(4).for_each(|rgba| rgba.swap(0, 2));
 
-                let allocation = texture_atlas.upload(
+                let allocation = texture_store.upload(
                     width,
                     height,
                     bytemuck::cast_slice(rgba.as_slice()),
-                    device,
-                    encoder,
+                    state,
                 )?;
                 log::debug!("allocating {} {}x{}", id, width, height);
 
@@ -144,7 +142,8 @@ impl Cache {
         }
     }
 
-    pub fn trim(&mut self, atlas: &mut Atlas) {
+    /// Load svg and upload raster data
+    pub fn trim(&mut self, texture_store: &mut T, state: &mut T::State<'_>) {
         let svg_hits = &self.svg_hits;
         let rasterized_hits = &self.rasterized_hits;
 
@@ -153,7 +152,7 @@ impl Cache {
             let retain = rasterized_hits.contains(k);
 
             if !retain {
-                atlas.remove(entry);
+                texture_store.remove(entry, state);
             }
 
             retain
@@ -163,6 +162,17 @@ impl Cache {
     }
 }
 
+impl<T: TextureStore> Default for Cache<T> {
+    fn default() -> Self {
+        Self {
+            svgs: HashMap::new(),
+            rasterized: HashMap::new(),
+            svg_hits: HashSet::new(),
+            rasterized_hits: HashSet::new(),
+        }
+    }
+}
+
 impl std::fmt::Debug for Svg {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
diff --git a/graphics/src/lib.rs b/graphics/src/lib.rs
index ec28ee58..d39dd90c 100644
--- a/graphics/src/lib.rs
+++ b/graphics/src/lib.rs
@@ -30,6 +30,7 @@ mod viewport;
 pub mod backend;
 pub mod font;
 pub mod gradient;
+pub mod image;
 pub mod layer;
 pub mod overlay;
 pub mod renderer;