lib8: implement layer blending

src/lib8.rs

@@ -2,6 +2,16 @@ use palette::encoding::srgb::Srgb;
 
 use rgb::RGB8;
 
+pub trait Rgb8Blend {
+    fn saturating_add(&self, b: Self) -> Self;
+}
+
+impl Rgb8Blend for RGB8 {
+    fn saturating_add(&self, b: Self) -> Self {
+        RGB8::new(self.r.saturating_add(b.r), self.g.saturating_add(b.g), self.b.saturating_add(b.b))
+    }
+}
+
 pub trait IntoRgb8 {
     fn into_rgb8(self) -> RGB8;
 }

src/platform/embedded_graphics_lib.rs

@@ -103,7 +103,7 @@ impl<T: LedPixelShape, S: Surface> Display<S> for EmbeddedDisplay<Ws2812DrawTarg
                 let mut pixel = RGB8::new(0, 0, 0);
                 for surface in self.surfaces.iter() {
                     surface.with_shader(|shader| {
-                        pixel = shader.draw(virtCoords.clone());
+                        pixel = pixel.saturating_add(shader.draw(virtCoords.clone()));
                     })
                 }
                 self.total_mw += pixel.as_milliwatts();