Add image/svg support to `iced_glow`

https://github.com/iced-rs/iced/issues/674

Uses image/svg support in `iced_graphics`. The is not currently using an
atlas, and uses one texture/draw per image. This should be good enough
for now; supporting images with glow is better than not supporting them,
and if something else performs better, that improvement can be made
without any change to the public API.

1 files changed, 23 insertions, 3 deletions

diff --git a/glow/src/backend.rs b/glow/src/backend.rs
index 21af2ecf..1ba70a49 100644
--- a/glow/src/backend.rs
+++ b/glow/src/backend.rs
@@ -1,3 +1,5 @@
+#[cfg(any(feature = "image_rs", feature = "svg"))]
+use crate::image;
 use crate::quad;
 use crate::text;
 use crate::{program, triangle};
@@ -15,6 +17,8 @@ use iced_native::{Font, Size};
 /// [`iced`]: https://github.com/iced-rs/iced
 #[derive(Debug)]
 pub struct Backend {
+    #[cfg(any(feature = "image_rs", feature = "svg"))]
+    image_pipeline: image::Pipeline,
     quad_pipeline: quad::Pipeline,
     text_pipeline: text::Pipeline,
     triangle_pipeline: triangle::Pipeline,
@@ -32,10 +36,14 @@ impl Backend {
 
         let shader_version = program::Version::new(gl);
 
+        #[cfg(any(feature = "image_rs", feature = "svg"))]
+        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 {
+            #[cfg(any(feature = "image_rs", feature = "svg"))]
+            image_pipeline,
             quad_pipeline,
             text_pipeline,
             triangle_pipeline,
@@ -70,6 +78,9 @@ impl Backend {
                 viewport_size.height,
             );
         }
+
+        #[cfg(any(feature = "image_rs", feature = "svg"))]
+        self.image_pipeline.trim_cache(gl);
     }
 
     fn flush(
@@ -112,6 +123,15 @@ impl Backend {
             );
         }
 
+        #[cfg(any(feature = "image_rs", feature = "svg"))]
+        if !layer.images.is_empty() {
+            let scaled = transformation
+                * Transformation::scale(scale_factor, scale_factor);
+
+            self.image_pipeline
+                .draw(gl, scaled, scale_factor, &layer.images);
+        }
+
         if !layer.text.is_empty() {
             for text in layer.text.iter() {
                 // Target physical coordinates directly to avoid blurry text
@@ -236,10 +256,10 @@ impl backend::Text for Backend {
     }
 }
 
-#[cfg(feature = "image")]
+#[cfg(feature = "image_rs")]
 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)
     }
 }