Let the Resource Allocator decode the images

We pass the encoded image data into the resource allocator now instead
of trying to decode the image in the scene manager. This way the
renderer has the ability to support all sorts of image formats that we
might not support. For example, this would also allow the renderer to
decode GIFs itself and thus properly animate them.

src/rendering/mod.rs

@@ -444,26 +444,11 @@ impl<A: ResourceAllocator> RenderContext<'_, A> {
     }
 
     fn create_icon(&mut self, image_data: &[u8]) -> Option<Icon<A::Image>> {
-        #[cfg(feature = "image")]
-        {
-            if image_data.is_empty() {
-                return None;
-            }
-
-            let image = image::load_from_memory(image_data).ok()?.to_rgba8();
-
-            Some(Icon {
-                aspect_ratio: image.width() as f32 / image.height() as f32,
-                image: self
-                    .handles
-                    .create_image(image.width(), image.height(), &image),
-            })
-        }
-        #[cfg(not(feature = "image"))]
-        {
-            let _ = image_data;
-            None
-        }
+        let (image, aspect_ratio) = self.handles.create_image(image_data)?;
+        Some(Icon {
+            aspect_ratio,
+            image,
+        })
     }
 
     fn scale(&mut self, factor: f32) {

src/rendering/resource/allocation.rs

@@ -59,10 +59,11 @@ pub trait ResourceAllocator {
         builder.finish()
     }
 
-    /// Creates an image out of the image data provided. The image's resolution
-    /// is provided as well. The data is an array of RGBA8 encoded pixels (red,
-    /// green, blue, alpha with each channel being an u8).
-    fn create_image(&mut self, width: u32, height: u32, data: &[u8]) -> Self::Image;
+    /// Creates an image out of the image data provided. The data represents the
+    /// image in its original file format. It needs to be parsed in order to be
+    /// visualized. The parsed image as well as the aspect ratio (width /
+    /// height) are returned in case the image was parsed successfully.
+    fn create_image(&mut self, data: &[u8]) -> Option<(Self::Image, f32)>;
 
     /// Creates a font from the font description provided. It is expected that
     /// the the font description is used in a font matching algorithm to find
@@ -191,8 +192,8 @@ impl<A: ResourceAllocator> ResourceAllocator for &mut A {
         MutPathBuilder((*self).path_builder())
     }
 
-    fn create_image(&mut self, width: u32, height: u32, data: &[u8]) -> Self::Image {
-        (*self).create_image(width, height, data)
+    fn create_image(&mut self, data: &[u8]) -> Option<(Self::Image, f32)> {
+        (*self).create_image(data)
     }
 
     fn create_font(&mut self, font: Option<&Font>, kind: FontKind) -> Self::Font {

src/rendering/resource/handles.rs

@@ -78,9 +78,9 @@ impl<A: ResourceAllocator> ResourceAllocator for Handles<A> {
         self.next(circle)
     }
 
-    fn create_image(&mut self, width: u32, height: u32, data: &[u8]) -> Self::Image {
-        let image = self.allocator.create_image(width, height, data);
-        self.next(image)
+    fn create_image(&mut self, data: &[u8]) -> Option<(Self::Image, f32)> {
+        let (image, aspect_ratio) = self.allocator.create_image(data)?;
+        Some((self.next(image), aspect_ratio))
     }
 
     fn create_font(&mut self, font: Option<&Font>, kind: super::FontKind) -> Self::Font {

src/rendering/software.rs

@@ -25,7 +25,7 @@ pub use image::{self, RgbaImage};
 struct SkiaBuilder(PathBuilder);
 
 type SkiaPath = Option<UnsafeRc<Path>>;
-type SkiaImage = Option<UnsafeRc<Pixmap>>;
+type SkiaImage = UnsafeRc<Pixmap>;
 type SkiaFont = Font<SkiaPath>;
 type SkiaLabel = Label<SkiaPath>;
 
@@ -87,16 +87,27 @@ impl ResourceAllocator for SkiaAllocator {
         path_builder()
     }
 
-    fn create_image(&mut self, width: u32, height: u32, data: &[u8]) -> Self::Image {
-        let mut image = Pixmap::new(width, height)?;
-        for (d, &[r, g, b, a]) in image
-            .pixels_mut()
-            .iter_mut()
-            .zip(bytemuck::cast_slice::<_, [u8; 4]>(data))
+    fn create_image(&mut self, data: &[u8]) -> Option<(Self::Image, f32)> {
+        #[cfg(feature = "image")]
         {
-            *d = tiny_skia::ColorU8::from_rgba(r, g, b, a).premultiply();
+            let src = image::load_from_memory(data).ok()?.to_rgba8();
+            let (width, height) = (src.width(), src.height());
+            // FIXME: Turn the image into a Pixmap directly. We should not need
+            // to allocate a new Pixmap here.
+            let mut dst = Pixmap::new(width, height)?;
+            for (d, &[r, g, b, a]) in dst
+                .pixels_mut()
+                .iter_mut()
+                .zip(bytemuck::cast_slice::<u8, [u8; 4]>(&src))
+            {
+                *d = tiny_skia::ColorU8::from_rgba(r, g, b, a).premultiply();
+            }
+            Some((UnsafeRc::new(dst), width as f32 / height as f32))
+        }
+        #[cfg(not(feature = "image"))]
+        {
+            None
         }
-        Some(UnsafeRc::new(image))
     }
 
     fn create_font(&mut self, font: Option<&settings::Font>, kind: FontKind) -> Self::Font {
@@ -397,28 +408,26 @@ fn render_layer(
                 }
             }
             Entity::Image(image, transform) => {
-                if let Some(image) = image.as_deref() {
-                    canvas.fill_path(
-                        rectangle,
-                        &Paint {
-                            shader: Pattern::new(
-                                image.as_ref(),
-                                SpreadMode::Pad,
-                                FilterQuality::Bilinear,
-                                1.0,
-                                tiny_skia::Transform::from_scale(
-                                    1.0 / image.width() as f32,
-                                    1.0 / image.height() as f32,
-                                ),
+                canvas.fill_path(
+                    rectangle,
+                    &Paint {
+                        shader: Pattern::new(
+                            image.as_ref(),
+                            SpreadMode::Pad,
+                            FilterQuality::Bilinear,
+                            1.0,
+                            tiny_skia::Transform::from_scale(
+                                1.0 / image.width() as f32,
+                                1.0 / image.height() as f32,
                             ),
-                            anti_alias: true,
-                            ..Default::default()
-                        },
-                        FillRule::Winding,
-                        convert_transform(transform),
-                        None,
-                    );
-                }
+                        ),
+                        anti_alias: true,
+                        ..Default::default()
+                    },
+                    FillRule::Winding,
+                    convert_transform(transform),
+                    None,
+                );
             }
             Entity::Label(label, shader, transform) => {
                 let label = label.read().unwrap();
@@ -622,13 +631,11 @@ fn calculate_bounds(layer: &[Entity<SkiaPath, SkiaImage, SkiaLabel>]) -> (f32, f
                     }
                 }
             }
-            Entity::Image(image, transform) => {
-                if image.is_some() {
-                    for y in [0.0, 1.0] {
-                        let transformed_y = transform.transform_y(y);
-                        min_y = min_y.min(transformed_y);
-                        max_y = max_y.max(transformed_y);
-                    }
+            Entity::Image(_, transform) => {
+                for y in [0.0, 1.0] {
+                    let transformed_y = transform.transform_y(y);
+                    min_y = min_y.min(transformed_y);
+                    max_y = max_y.max(transformed_y);
                 }
             }
             Entity::Label(label, _, transform) => {