WIP glow image rendering support

#674

This works, but duplicates code from `iced_wgpu` that should ideally be
shared, and the cache never evicts.

The next step here is to work on an API design to move some of the image
loading and caching logic from the backend to `iced_graphics` (or
elsewhere?).

Cargo.toml

@@ -15,7 +15,7 @@ resolver = "2"
 [features]
 default = ["wgpu"]
 # Enables the `Image` widget
-image = ["iced_wgpu/image", "image_rs"]
+image = ["iced_wgpu/image", "iced_glow/image", "image_rs"]
 # Enables the `Svg` widget
 svg = ["iced_wgpu/svg"]
 # Enables the `Canvas` widget

glow/Cargo.toml

@@ -8,11 +8,22 @@ license = "MIT AND OFL-1.1"
 repository = "https://github.com/iced-rs/iced"
 
 [features]
+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 = ["iced_graphics/canvas"]
 qr_code = ["iced_graphics/qr_code"]
 default_system_font = ["iced_graphics/font-source"]
 # Not supported yet!
-image = []
 svg = []
 
 [dependencies]
@@ -22,6 +33,8 @@ glyph_brush = "0.7"
 euclid = "0.22"
 bytemuck = "1.4"
 log = "0.4"
+kamadak-exif = "0.5"
+bitflags = "1.2"
 
 [dependencies.iced_native]
 version = "0.5"
@@ -32,6 +45,12 @@ version = "0.3"
 path = "../graphics"
 features = ["font-fallback", "font-icons", "opengl"]
 
+[dependencies.image_rs]
+version = "0.23"
+package = "image"
+default-features = false
+optional = true
+
 [package.metadata.docs.rs]
 rustdoc-args = ["--cfg", "docsrs"]
 all-features = true

glow/src/backend.rs

@@ -1,3 +1,4 @@
+use crate::image;
 use crate::program;
 use crate::quad;
 use crate::text;
@@ -16,6 +17,7 @@ use iced_native::{Font, Size};
 /// [`iced`]: https://github.com/iced-rs/iced
 #[derive(Debug)]
 pub struct Backend {
+    image_pipeline: image::Pipeline,
     quad_pipeline: quad::Pipeline,
     text_pipeline: text::Pipeline,
     triangle_pipeline: triangle::Pipeline,
@@ -33,10 +35,12 @@ impl Backend {
 
         let shader_version = program::Version::new(gl);
 
+        let image_pipeline = image::Pipeline::new(gl, &shader_version);
         let quad_pipeline = quad::Pipeline::new(gl, &shader_version);
         let triangle_pipeline = triangle::Pipeline::new(gl, &shader_version);
 
         Self {
+            image_pipeline,
             quad_pipeline,
             text_pipeline,
             triangle_pipeline,
@@ -113,6 +117,20 @@ impl Backend {
             );
         }
 
+        #[cfg(feature = "image")]
+        if !layer.images.is_empty() {
+            let scaled = transformation
+                * Transformation::scale(scale_factor, scale_factor);
+
+            self.image_pipeline.draw(
+                gl,
+                target_height,
+                scaled,
+                scale_factor,
+                &layer.images,
+            );
+        }
+
         if !layer.text.is_empty() {
             for text in layer.text.iter() {
                 // Target physical coordinates directly to avoid blurry text
@@ -239,8 +257,8 @@ impl backend::Text for Backend {
 
 #[cfg(feature = "image")]
 impl backend::Image for Backend {
-    fn dimensions(&self, _handle: &iced_native::image::Handle) -> (u32, u32) {
-        (50, 50)
+    fn dimensions(&self, handle: &iced_native::image::Handle) -> (u32, u32) {
+        self.image_pipeline.dimensions(handle)
     }
 }