Write documentation for iced_graphics

graphics/src/backend.rs

@@ -1,15 +1,33 @@
+//! Write a graphics backend.
 use iced_native::image;
 use iced_native::svg;
 use iced_native::{Font, Size};
 
+/// The graphics backend of a [`Renderer`].
+///
+/// [`Renderer`]: ../struct.Renderer.html
 pub trait Backend {
+    /// Trims the measurements cache.
+    ///
+    /// This method is currently necessary to properly trim the text cache in
+    /// `iced_wgpu` and `iced_glow` because of limitations in the text rendering
+    /// pipeline. It will be removed in the future.
     fn trim_measurements(&mut self) {}
 }
 
+/// A graphics backend that supports text rendering.
 pub trait Text {
+    /// The icon font of the backend.
     const ICON_FONT: Font;
+
+    /// The `char` representing a ✔ icon in the [`ICON_FONT`].
+    ///
+    /// [`ICON_FONT`]: #associatedconst.ICON_FONt
     const CHECKMARK_ICON: char;
 
+    /// Measures the text contents with the given size and font,
+    /// returning the size of a laid out paragraph that fits in the provided
+    /// bounds.
     fn measure(
         &self,
         contents: &str,
@@ -19,10 +37,14 @@ pub trait Text {
     ) -> (f32, f32);
 }
 
+/// A graphics backend that supports image rendering.
 pub trait Image {
+    /// Returns the dimensions of the provided image.
     fn dimensions(&self, handle: &image::Handle) -> (u32, u32);
 }
 
+/// A graphics backend that supports SVG rendering.
 pub trait Svg {
+    /// Returns the viewport dimensions of the provided SVG.
     fn viewport_dimensions(&self, handle: &svg::Handle) -> (u32, u32);
 }