48 files changed, 1422 insertions, 85 deletions

diff --git a/graphics/Cargo.toml b/graphics/Cargo.toml
new file mode 100644
index 00000000..8e078d75
--- /dev/null
+++ b/graphics/Cargo.toml
@@ -0,0 +1,37 @@
+[package]
+name = "iced_graphics"
+version = "0.1.0"
+authors = ["Héctor Ramón Jiménez <hector0193@gmail.com>"]
+edition = "2018"
+
+[features]
+canvas = ["lyon"]
+font-source = ["font-kit"]
+font-fallback = []
+font-icons = []
+opengl = []
+
+[dependencies]
+bytemuck = "1.2"
+glam = "0.8"
+raw-window-handle = "0.3"
+
+[dependencies.iced_native]
+version = "0.2"
+path = "../native"
+
+[dependencies.iced_style]
+version = "0.1"
+path = "../style"
+
+[dependencies.lyon]
+version = "0.15"
+optional = true
+
+[dependencies.font-kit]
+version = "0.6"
+optional = true
+
+[package.metadata.docs.rs]
+rustdoc-args = ["--cfg", "docsrs"]
+all-features = true
diff --git a/wgpu/src/text/icons.ttf b/graphics/fonts/Icons.ttf
index 1c832f86..1c832f86 100644
--- a/wgpu/src/text/icons.ttf
+++ b/graphics/fonts/Icons.ttf
diff --git a/wgpu/fonts/Lato-Regular.ttf b/graphics/fonts/Lato-Regular.ttf
index 33eba8b1..33eba8b1 100644
--- a/wgpu/fonts/Lato-Regular.ttf
+++ b/graphics/fonts/Lato-Regular.ttf
diff --git a/wgpu/fonts/OFL.txt b/graphics/fonts/OFL.txt
index dfca0da4..dfca0da4 100644
--- a/wgpu/fonts/OFL.txt
+++ b/graphics/fonts/OFL.txt
diff --git a/graphics/src/antialiasing.rs b/graphics/src/antialiasing.rs
new file mode 100644
index 00000000..34d94711
--- /dev/null
+++ b/graphics/src/antialiasing.rs
@@ -0,0 +1,26 @@
+/// An antialiasing strategy.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Antialiasing {
+    /// Multisample AA with 2 samples
+    MSAAx2,
+    /// Multisample AA with 4 samples
+    MSAAx4,
+    /// Multisample AA with 8 samples
+    MSAAx8,
+    /// Multisample AA with 16 samples
+    MSAAx16,
+}
+
+impl Antialiasing {
+    /// Returns the amount of samples of the [`Antialiasing`].
+    ///
+    /// [`Antialiasing`]: enum.Antialiasing.html
+    pub fn sample_count(self) -> u32 {
+        match self {
+            Antialiasing::MSAAx2 => 2,
+            Antialiasing::MSAAx4 => 4,
+            Antialiasing::MSAAx8 => 8,
+            Antialiasing::MSAAx16 => 16,
+        }
+    }
+}
diff --git a/graphics/src/backend.rs b/graphics/src/backend.rs
new file mode 100644
index 00000000..83510311
--- /dev/null
+++ b/graphics/src/backend.rs
@@ -0,0 +1,50 @@
+//! 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,
+        size: f32,
+        font: Font,
+        bounds: Size,
+    ) -> (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);
+}
diff --git a/wgpu/src/defaults.rs b/graphics/src/defaults.rs
index 11718a87..11718a87 100644
--- a/wgpu/src/defaults.rs
+++ b/graphics/src/defaults.rs
diff --git a/graphics/src/font.rs b/graphics/src/font.rs
new file mode 100644
index 00000000..bcc28857
--- /dev/null
+++ b/graphics/src/font.rs
@@ -0,0 +1,33 @@
+//! Find system fonts or use the built-in ones.
+#[cfg(feature = "font-source")]
+mod source;
+
+#[cfg(feature = "font-source")]
+#[cfg_attr(docsrs, doc(cfg(feature = "font-source")))]
+pub use source::Source;
+
+#[cfg(feature = "font-source")]
+#[cfg_attr(docsrs, doc(cfg(feature = "font-source")))]
+pub use font_kit::{
+    error::SelectionError as LoadError, family_name::FamilyName as Family,
+};
+
+/// A built-in fallback font, for convenience.
+#[cfg(feature = "font-fallback")]
+#[cfg_attr(docsrs, doc(cfg(feature = "font-fallback")))]
+pub const FALLBACK: &[u8] = include_bytes!("../fonts/Lato-Regular.ttf");
+
+/// A built-in icon font, for convenience.
+#[cfg(feature = "font-icons")]
+#[cfg_attr(docsrs, doc(cfg(feature = "font-icons")))]
+pub const ICONS: iced_native::Font = iced_native::Font::External {
+    name: "iced_wgpu icons",
+    bytes: include_bytes!("../fonts/Icons.ttf"),
+};
+
+/// The `char` representing a ✔ icon in the built-in [`ICONS`] font.
+///
+/// [`ICONS`]: const.ICONS.html
+#[cfg(feature = "font-icons")]
+#[cfg_attr(docsrs, doc(cfg(feature = "font-icons")))]
+pub const CHECKMARK_ICON: char = '\u{F00C}';
diff --git a/wgpu/src/text/font.rs b/graphics/src/font/source.rs
index 7346ccdb..917291ff 100644
--- a/wgpu/src/text/font.rs
+++ b/graphics/src/font/source.rs
@@ -1,18 +1,24 @@
-pub use font_kit::{
-    error::SelectionError as LoadError, family_name::FamilyName as Family,
-};
+use crate::font::{Family, LoadError};
 
+/// A font source that can find and load system fonts.
+#[allow(missing_debug_implementations)]
 pub struct Source {
     raw: font_kit::source::SystemSource,
 }
 
 impl Source {
+    /// Creates a new [`Source`].
+    ///
+    /// [`Source`]: struct.Source.html
     pub fn new() -> Self {
         Source {
             raw: font_kit::source::SystemSource::new(),
         }
     }
 
+    /// Finds and loads a font matching the set of provided family priorities.
+    ///
+    /// [`Source`]: struct.Source.html
     pub fn load(&self, families: &[Family]) -> Result<Vec<u8>, LoadError> {
         let font = self.raw.select_best_match(
             families,
diff --git a/graphics/src/layer.rs b/graphics/src/layer.rs
new file mode 100644
index 00000000..6aca738e
--- /dev/null
+++ b/graphics/src/layer.rs
@@ -0,0 +1,359 @@
+//! Organize rendering primitives into a flattened list of layers.
+use crate::image;
+use crate::svg;
+use crate::triangle;
+use crate::{
+    Background, Font, HorizontalAlignment, Point, Primitive, Rectangle, Size,
+    Vector, VerticalAlignment, Viewport,
+};
+
+/// A group of primitives that should be clipped together.
+#[derive(Debug, Clone)]
+pub struct Layer<'a> {
+    /// The clipping bounds of the [`Layer`].
+    ///
+    /// [`Layer`]: struct.Layer.html
+    pub bounds: Rectangle,
+
+    /// The quads of the [`Layer`].
+    ///
+    /// [`Layer`]: struct.Layer.html
+    pub quads: Vec<Quad>,
+
+    /// The triangle meshes of the [`Layer`].
+    ///
+    /// [`Layer`]: struct.Layer.html
+    pub meshes: Vec<Mesh<'a>>,
+
+    /// The text of the [`Layer`].
+    ///
+    /// [`Layer`]: struct.Layer.html
+    pub text: Vec<Text<'a>>,
+
+    /// The images of the [`Layer`].
+    ///
+    /// [`Layer`]: struct.Layer.html
+    pub images: Vec<Image>,
+}
+
+impl<'a> Layer<'a> {
+    /// Creates a new [`Layer`] with the given clipping bounds.
+    ///
+    /// [`Layer`]: struct.Layer.html
+    pub fn new(bounds: Rectangle) -> Self {
+        Self {
+            bounds,
+            quads: Vec::new(),
+            meshes: Vec::new(),
+            text: Vec::new(),
+            images: Vec::new(),
+        }
+    }
+
+    /// Creates a new [`Layer`] for the provided overlay text.
+    ///
+    /// This can be useful for displaying debug information.
+    ///
+    /// [`Layer`]: struct.Layer.html
+    pub fn overlay(lines: &'a [impl AsRef<str>], viewport: &Viewport) -> Self {
+        let mut overlay =
+            Layer::new(Rectangle::with_size(viewport.logical_size()));
+
+        for (i, line) in lines.iter().enumerate() {
+            let text = Text {
+                content: line.as_ref(),
+                bounds: Rectangle::new(
+                    Point::new(11.0, 11.0 + 25.0 * i as f32),
+                    Size::INFINITY,
+                ),
+                color: [0.9, 0.9, 0.9, 1.0],
+                size: 20.0,
+                font: Font::Default,
+                horizontal_alignment: HorizontalAlignment::Left,
+                vertical_alignment: VerticalAlignment::Top,
+            };
+
+            overlay.text.push(text);
+
+            overlay.text.push(Text {
+                bounds: text.bounds + Vector::new(-1.0, -1.0),
+                color: [0.0, 0.0, 0.0, 1.0],
+                ..text
+            });
+        }
+
+        overlay
+    }
+
+    /// Distributes the given [`Primitive`] and generates a list of layers based
+    /// on its contents.
+    ///
+    /// [`Primitive`]: ../enum.Primitive.html
+    pub fn generate(
+        primitive: &'a Primitive,
+        viewport: &Viewport,
+    ) -> Vec<Self> {
+        let first_layer =
+            Layer::new(Rectangle::with_size(viewport.logical_size()));
+
+        let mut layers = vec![first_layer];
+
+        Self::process_primitive(&mut layers, Vector::new(0.0, 0.0), primitive);
+
+        layers
+    }
+
+    fn process_primitive(
+        layers: &mut Vec<Self>,
+        translation: Vector,
+        primitive: &'a Primitive,
+    ) {
+        match primitive {
+            Primitive::None => {}
+            Primitive::Group { primitives } => {
+                // TODO: Inspect a bit and regroup (?)
+                for primitive in primitives {
+                    Self::process_primitive(layers, translation, primitive)
+                }
+            }
+            Primitive::Text {
+                content,
+                bounds,
+                size,
+                color,
+                font,
+                horizontal_alignment,
+                vertical_alignment,
+            } => {
+                let layer = layers.last_mut().unwrap();
+
+                layer.text.push(Text {
+                    content,
+                    bounds: *bounds + translation,
+                    size: *size,
+                    color: color.into_linear(),
+                    font: *font,
+                    horizontal_alignment: *horizontal_alignment,
+                    vertical_alignment: *vertical_alignment,
+                });
+            }
+            Primitive::Quad {
+                bounds,
+                background,
+                border_radius,
+                border_width,
+                border_color,
+            } => {
+                let layer = layers.last_mut().unwrap();
+
+                // TODO: Move some of these computations to the GPU (?)
+                layer.quads.push(Quad {
+                    position: [
+                        bounds.x + translation.x,
+                        bounds.y + translation.y,
+                    ],
+                    size: [bounds.width, bounds.height],
+                    color: match background {
+                        Background::Color(color) => color.into_linear(),
+                    },
+                    border_radius: *border_radius as f32,
+                    border_width: *border_width as f32,
+                    border_color: border_color.into_linear(),
+                });
+            }
+            Primitive::Mesh2D { buffers, size } => {
+                let layer = layers.last_mut().unwrap();
+
+                let bounds = Rectangle::new(
+                    Point::new(translation.x, translation.y),
+                    *size,
+                );
+
+                // Only draw visible content
+                if let Some(clip_bounds) = layer.bounds.intersection(&bounds) {
+                    layer.meshes.push(Mesh {
+                        origin: Point::new(translation.x, translation.y),
+                        buffers,
+                        clip_bounds,
+                    });
+                }
+            }
+            Primitive::Clip {
+                bounds,
+                offset,
+                content,
+            } => {
+                let layer = layers.last_mut().unwrap();
+                let translated_bounds = *bounds + translation;
+
+                // Only draw visible content
+                if let Some(clip_bounds) =
+                    layer.bounds.intersection(&translated_bounds)
+                {
+                    let clip_layer = Layer::new(clip_bounds);
+                    let new_layer = Layer::new(layer.bounds);
+
+                    layers.push(clip_layer);
+                    Self::process_primitive(
+                        layers,
+                        translation
+                            - Vector::new(offset.x as f32, offset.y as f32),
+                        content,
+                    );
+                    layers.push(new_layer);
+                }
+            }
+            Primitive::Translate {
+                translation: new_translation,
+                content,
+            } => {
+                Self::process_primitive(
+                    layers,
+                    translation + *new_translation,
+                    &content,
+                );
+            }
+            Primitive::Cached { cache } => {
+                Self::process_primitive(layers, translation, &cache);
+            }
+            Primitive::Image { handle, bounds } => {
+                let layer = layers.last_mut().unwrap();
+
+                layer.images.push(Image::Raster {
+                    handle: handle.clone(),
+                    bounds: *bounds + translation,
+                });
+            }
+            Primitive::Svg { handle, bounds } => {
+                let layer = layers.last_mut().unwrap();
+
+                layer.images.push(Image::Vector {
+                    handle: handle.clone(),
+                    bounds: *bounds + translation,
+                });
+            }
+        }
+    }
+}
+
+/// A colored rectangle with a border.
+///
+/// This type can be directly uploaded to GPU memory.
+#[derive(Debug, Clone, Copy)]
+#[repr(C)]
+pub struct Quad {
+    /// The position of the [`Quad`].
+    ///
+    /// [`Quad`]: struct.Quad.html
+    pub position: [f32; 2],
+
+    /// The size of the [`Quad`].
+    ///
+    /// [`Quad`]: struct.Quad.html
+    pub size: [f32; 2],
+
+    /// The color of the [`Quad`], in __linear RGB__.
+    ///
+    /// [`Quad`]: struct.Quad.html
+    pub color: [f32; 4],
+
+    /// The border color of the [`Quad`], in __linear RGB__.
+    ///
+    /// [`Quad`]: struct.Quad.html
+    pub border_color: [f32; 4],
+
+    /// The border radius of the [`Quad`].
+    ///
+    /// [`Quad`]: struct.Quad.html
+    pub border_radius: f32,
+
+    /// The border width of the [`Quad`].
+    ///
+    /// [`Quad`]: struct.Quad.html
+    pub border_width: f32,
+}
+
+/// A mesh of triangles.
+#[derive(Debug, Clone, Copy)]
+pub struct Mesh<'a> {
+    /// The origin of the vertices of the [`Mesh`].
+    ///
+    /// [`Mesh`]: struct.Mesh.html
+    pub origin: Point,
+
+    /// The vertex and index buffers of the [`Mesh`].
+    ///
+    /// [`Mesh`]: struct.Mesh.html
+    pub buffers: &'a triangle::Mesh2D,
+
+    /// The clipping bounds of the [`Mesh`].
+    ///
+    /// [`Mesh`]: struct.Mesh.html
+    pub clip_bounds: Rectangle<f32>,
+}
+
+/// A paragraph of text.
+#[derive(Debug, Clone, Copy)]
+pub struct Text<'a> {
+    /// The content of the [`Text`].
+    ///
+    /// [`Text`]: struct.Text.html
+    pub content: &'a str,
+
+    /// The layout bounds of the [`Text`].
+    ///
+    /// [`Text`]: struct.Text.html
+    pub bounds: Rectangle,
+
+    /// The color of the [`Text`], in __linear RGB_.
+    ///
+    /// [`Text`]: struct.Text.html
+    pub color: [f32; 4],
+
+    /// The size of the [`Text`].
+    ///
+    /// [`Text`]: struct.Text.html
+    pub size: f32,
+
+    /// The font of the [`Text`].
+    ///
+    /// [`Text`]: struct.Text.html
+    pub font: Font,
+
+    /// The horizontal alignment of the [`Text`].
+    ///
+    /// [`Text`]: struct.Text.html
+    pub horizontal_alignment: HorizontalAlignment,
+
+    /// The vertical alignment of the [`Text`].
+    ///
+    /// [`Text`]: struct.Text.html
+    pub vertical_alignment: VerticalAlignment,
+}
+
+/// A raster or vector image.
+#[derive(Debug, Clone)]
+pub enum Image {
+    /// A raster image.
+    Raster {
+        /// The handle of a raster image.
+        handle: image::Handle,
+
+        /// The bounds of the image.
+        bounds: Rectangle,
+    },
+    /// A vector image.
+    Vector {
+        /// The handle of a vector image.
+        handle: svg::Handle,
+
+        /// The bounds of the image.
+        bounds: Rectangle,
+    },
+}
+
+#[allow(unsafe_code)]
+unsafe impl bytemuck::Zeroable for Quad {}
+
+#[allow(unsafe_code)]
+unsafe impl bytemuck::Pod for Quad {}
diff --git a/graphics/src/lib.rs b/graphics/src/lib.rs
new file mode 100644
index 00000000..b6dda132
--- /dev/null
+++ b/graphics/src/lib.rs
@@ -0,0 +1,40 @@
+//! A bunch of backend-agnostic types that can be leveraged to build a renderer
+//! for [`iced`].
+//!
+//! [`iced`]: https://github.com/hecrj/iced
+#![deny(missing_docs)]
+#![deny(missing_debug_implementations)]
+#![deny(unused_results)]
+#![deny(unsafe_code)]
+#![forbid(rust_2018_idioms)]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+mod antialiasing;
+mod defaults;
+mod primitive;
+mod renderer;
+mod transformation;
+mod viewport;
+mod widget;
+
+pub mod backend;
+pub mod font;
+pub mod layer;
+pub mod triangle;
+pub mod window;
+
+#[doc(no_inline)]
+pub use widget::*;
+
+pub use antialiasing::Antialiasing;
+pub use backend::Backend;
+pub use defaults::Defaults;
+pub use layer::Layer;
+pub use primitive::Primitive;
+pub use renderer::Renderer;
+pub use transformation::Transformation;
+pub use viewport::Viewport;
+
+pub use iced_native::{
+    Background, Font, HorizontalAlignment, Point, Rectangle, Size, Vector,
+    VerticalAlignment,
+};
diff --git a/wgpu/src/primitive.rs b/graphics/src/primitive.rs
index e73227ef..95dbf7dd 100644
--- a/wgpu/src/primitive.rs
+++ b/graphics/src/primitive.rs
@@ -82,13 +82,13 @@ pub enum Primitive {
     ///
     /// It can be used to render many kinds of geometry freely.
     Mesh2D {
+        /// The vertex and index buffers of the mesh
+        buffers: triangle::Mesh2D,
+
         /// The size of the drawable region of the mesh.
         ///
         /// Any geometry that falls out of this region will be clipped.
         size: Size,
-
-        /// The vertex and index buffers of the mesh
-        buffers: triangle::Mesh2D,
     },
     /// A cached primitive.
     ///
diff --git a/graphics/src/renderer.rs b/graphics/src/renderer.rs
new file mode 100644
index 00000000..c9360f3a
--- /dev/null
+++ b/graphics/src/renderer.rs
@@ -0,0 +1,98 @@
+use crate::{Backend, Defaults, Primitive};
+use iced_native::layout::{self, Layout};
+use iced_native::mouse;
+use iced_native::{Background, Color, Element, Point, Widget};
+
+/// A backend-agnostic renderer that supports all the built-in widgets.
+#[derive(Debug)]
+pub struct Renderer<B: Backend> {
+    backend: B,
+}
+
+impl<B: Backend> Renderer<B> {
+    /// Creates a new [`Renderer`] from the given [`Backend`].
+    ///
+    /// [`Renderer`]: struct.Renderer.html
+    /// [`Backend`]: backend/trait.Backend.html
+    pub fn new(backend: B) -> Self {
+        Self { backend }
+    }
+
+    /// Returns a reference to the [`Backend`] of the [`Renderer`].
+    ///
+    /// [`Renderer`]: struct.Renderer.html
+    /// [`Backend`]: backend/trait.Backend.html
+    pub fn backend(&self) -> &B {
+        &self.backend
+    }
+
+    /// Returns a mutable reference to the [`Backend`] of the [`Renderer`].
+    ///
+    /// [`Renderer`]: struct.Renderer.html
+    /// [`Backend`]: backend/trait.Backend.html
+    pub fn backend_mut(&mut self) -> &mut B {
+        &mut self.backend
+    }
+}
+
+impl<B> iced_native::Renderer for Renderer<B>
+where
+    B: Backend,
+{
+    type Output = (Primitive, mouse::Interaction);
+    type Defaults = Defaults;
+
+    fn layout<'a, Message>(
+        &mut self,
+        element: &Element<'a, Message, Self>,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        let layout = element.layout(self, limits);
+
+        self.backend.trim_measurements();
+
+        layout
+    }
+}
+
+impl<B> layout::Debugger for Renderer<B>
+where
+    B: Backend,
+{
+    fn explain<Message>(
+        &mut self,
+        defaults: &Defaults,
+        widget: &dyn Widget<Message, Self>,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        color: Color,
+    ) -> Self::Output {
+        let (primitive, cursor) =
+            widget.draw(self, defaults, layout, cursor_position);
+
+        let mut primitives = Vec::new();
+
+        explain_layout(layout, color, &mut primitives);
+        primitives.push(primitive);
+
+        (Primitive::Group { primitives }, cursor)
+    }
+}
+
+fn explain_layout(
+    layout: Layout<'_>,
+    color: Color,
+    primitives: &mut Vec<Primitive>,
+) {
+    primitives.push(Primitive::Quad {
+        bounds: layout.bounds(),
+        background: Background::Color(Color::TRANSPARENT),
+        border_radius: 0,
+        border_width: 1,
+        border_color: [0.6, 0.6, 0.6, 0.5].into(),
+    });
+
+    for child in layout.children() {
+        explain_layout(child, color, primitives);
+    }
+}
diff --git a/wgpu/src/transformation.rs b/graphics/src/transformation.rs
index ff3b1d00..ff3b1d00 100644
--- a/wgpu/src/transformation.rs
+++ b/graphics/src/transformation.rs
diff --git a/graphics/src/triangle.rs b/graphics/src/triangle.rs
new file mode 100644
index 00000000..ce879ffc
--- /dev/null
+++ b/graphics/src/triangle.rs
@@ -0,0 +1,32 @@
+//! Draw geometry using meshes of triangles.
+
+/// A set of [`Vertex2D`] and indices representing a list of triangles.
+///
+/// [`Vertex2D`]: struct.Vertex2D.html
+#[derive(Clone, Debug)]
+pub struct Mesh2D {
+    /// The vertices of the mesh
+    pub vertices: Vec<Vertex2D>,
+
+    /// The list of vertex indices that defines the triangles of the mesh.
+    ///
+    /// Therefore, this list should always have a length that is a multiple of
+    /// 3.
+    pub indices: Vec<u32>,
+}
+
+/// A two-dimensional vertex with some color in __linear__ RGBA.
+#[derive(Copy, Clone, Debug)]
+#[repr(C)]
+pub struct Vertex2D {
+    /// The vertex position
+    pub position: [f32; 2],
+    /// The vertex color in __linear__ RGBA.
+    pub color: [f32; 4],
+}
+
+#[allow(unsafe_code)]
+unsafe impl bytemuck::Zeroable for Vertex2D {}
+
+#[allow(unsafe_code)]
+unsafe impl bytemuck::Pod for Vertex2D {}
diff --git a/graphics/src/viewport.rs b/graphics/src/viewport.rs
new file mode 100644
index 00000000..66122e6d
--- /dev/null
+++ b/graphics/src/viewport.rs
@@ -0,0 +1,70 @@
+use crate::{Size, Transformation};
+
+/// A viewing region for displaying computer graphics.
+#[derive(Debug)]
+pub struct Viewport {
+    physical_size: Size<u32>,
+    logical_size: Size<f32>,
+    scale_factor: f64,
+    projection: Transformation,
+}
+
+impl Viewport {
+    /// Creates a new [`Viewport`] with the given physical dimensions and scale
+    /// factor.
+    ///
+    /// [`Viewport`]: struct.Viewport.html
+    pub fn with_physical_size(size: Size<u32>, scale_factor: f64) -> Viewport {
+        Viewport {
+            physical_size: size,
+            logical_size: Size::new(
+                (size.width as f64 / scale_factor) as f32,
+                (size.height as f64 / scale_factor) as f32,
+            ),
+            scale_factor,
+            projection: Transformation::orthographic(size.width, size.height),
+        }
+    }
+
+    /// Returns the physical size of the [`Viewport`].
+    ///
+    /// [`Viewport`]: struct.Viewport.html
+    pub fn physical_size(&self) -> Size<u32> {
+        self.physical_size
+    }
+
+    /// Returns the physical width of the [`Viewport`].
+    ///
+    /// [`Viewport`]: struct.Viewport.html
+    pub fn physical_width(&self) -> u32 {
+        self.physical_size.height
+    }
+
+    /// Returns the physical height of the [`Viewport`].
+    ///
+    /// [`Viewport`]: struct.Viewport.html
+    pub fn physical_height(&self) -> u32 {
+        self.physical_size.height
+    }
+
+    /// Returns the logical size of the [`Viewport`].
+    ///
+    /// [`Viewport`]: struct.Viewport.html
+    pub fn logical_size(&self) -> Size<f32> {
+        self.logical_size
+    }
+
+    /// Returns the scale factor of the [`Viewport`].
+    ///
+    /// [`Viewport`]: struct.Viewport.html
+    pub fn scale_factor(&self) -> f64 {
+        self.scale_factor
+    }
+
+    /// Returns the projection transformation of the [`Viewport`].
+    ///
+    /// [`Viewport`]: struct.Viewport.html
+    pub fn projection(&self) -> Transformation {
+        self.projection
+    }
+}
diff --git a/graphics/src/widget.rs b/graphics/src/widget.rs
new file mode 100644
index 00000000..1f6d6559
--- /dev/null
+++ b/graphics/src/widget.rs
@@ -0,0 +1,59 @@
+//! Use the widgets supported out-of-the-box.
+//!
+//! # Re-exports
+//! For convenience, the contents of this module are available at the root
+//! module. Therefore, you can directly type:
+//!
+//! ```
+//! use iced_graphics::{button, Button};
+//! ```
+pub mod button;
+pub mod checkbox;
+pub mod container;
+pub mod image;
+pub mod pane_grid;
+pub mod progress_bar;
+pub mod radio;
+pub mod scrollable;
+pub mod slider;
+pub mod svg;
+pub mod text_input;
+
+mod column;
+mod row;
+mod space;
+mod text;
+
+#[doc(no_inline)]
+pub use button::Button;
+#[doc(no_inline)]
+pub use checkbox::Checkbox;
+#[doc(no_inline)]
+pub use container::Container;
+#[doc(no_inline)]
+pub use pane_grid::PaneGrid;
+#[doc(no_inline)]
+pub use progress_bar::ProgressBar;
+#[doc(no_inline)]
+pub use radio::Radio;
+#[doc(no_inline)]
+pub use scrollable::Scrollable;
+#[doc(no_inline)]
+pub use slider::Slider;
+#[doc(no_inline)]
+pub use text_input::TextInput;
+
+pub use column::Column;
+pub use image::Image;
+pub use row::Row;
+pub use space::Space;
+pub use svg::Svg;
+pub use text::Text;
+
+#[cfg(feature = "canvas")]
+#[cfg_attr(docsrs, doc(cfg(feature = "canvas")))]
+pub mod canvas;
+
+#[cfg(feature = "canvas")]
+#[doc(no_inline)]
+pub use canvas::Canvas;
diff --git a/wgpu/src/renderer/widget/button.rs b/graphics/src/widget/button.rs
index eb225038..aeb862d5 100644
--- a/wgpu/src/renderer/widget/button.rs
+++ b/graphics/src/widget/button.rs
@@ -1,9 +1,29 @@
-use crate::{button::StyleSheet, defaults, Defaults, Primitive, Renderer};
+//! Allow your users to perform actions by pressing a button.
+//!
+//! A [`Button`] has some local [`State`].
+//!
+//! [`Button`]: type.Button.html
+//! [`State`]: struct.State.html
+use crate::defaults::{self, Defaults};
+use crate::{Backend, Primitive, Renderer};
+use iced_native::mouse;
 use iced_native::{
-    mouse, Background, Color, Element, Layout, Point, Rectangle, Vector,
+    Background, Color, Element, Layout, Point, Rectangle, Vector,
 };
 
-impl iced_native::button::Renderer for Renderer {
+pub use iced_native::button::State;
+pub use iced_style::button::{Style, StyleSheet};
+
+/// A widget that produces a message when clicked.
+///
+/// This is an alias of an `iced_native` button with an `iced_wgpu::Renderer`.
+pub type Button<'a, Message, Backend> =
+    iced_native::Button<'a, Message, Renderer<Backend>>;
+
+impl<B> iced_native::button::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     const DEFAULT_PADDING: u16 = 5;
 
     type Style = Box<dyn StyleSheet>;
diff --git a/graphics/src/widget/canvas.rs b/graphics/src/widget/canvas.rs
new file mode 100644
index 00000000..d393a5c5
--- /dev/null
+++ b/graphics/src/widget/canvas.rs
@@ -0,0 +1,236 @@
+//! Draw 2D graphics for your users.
+//!
+//! A [`Canvas`] widget can be used to draw different kinds of 2D shapes in a
+//! [`Frame`]. It can be used for animation, data visualization, game graphics,
+//! and more!
+//!
+//! [`Canvas`]: struct.Canvas.html
+//! [`Frame`]: struct.Frame.html
+use crate::{Backend, Defaults, Primitive, Renderer};
+use iced_native::{
+    layout, mouse, Clipboard, Element, Hasher, Layout, Length, Point, Size,
+    Vector, Widget,
+};
+use std::hash::Hash;
+use std::marker::PhantomData;
+
+pub mod path;
+
+mod cache;
+mod cursor;
+mod event;
+mod fill;
+mod frame;
+mod geometry;
+mod program;
+mod stroke;
+mod text;
+
+pub use cache::Cache;
+pub use cursor::Cursor;
+pub use event::Event;
+pub use fill::Fill;
+pub use frame::Frame;
+pub use geometry::Geometry;
+pub use path::Path;
+pub use program::Program;
+pub use stroke::{LineCap, LineJoin, Stroke};
+pub use text::Text;
+
+/// A widget capable of drawing 2D graphics.
+///
+/// [`Canvas`]: struct.Canvas.html
+///
+/// # Examples
+/// The repository has a couple of [examples] showcasing how to use a
+/// [`Canvas`]:
+///
+/// - [`clock`], an application that uses the [`Canvas`] widget to draw a clock
+/// and its hands to display the current time.
+/// - [`game_of_life`], an interactive version of the Game of Life, invented by
+/// John Conway.
+/// - [`solar_system`], an animated solar system drawn using the [`Canvas`] widget
+/// and showcasing how to compose different transforms.
+///
+/// [examples]: https://github.com/hecrj/iced/tree/master/examples
+/// [`clock`]: https://github.com/hecrj/iced/tree/master/examples/clock
+/// [`game_of_life`]: https://github.com/hecrj/iced/tree/master/examples/game_of_life
+/// [`solar_system`]: https://github.com/hecrj/iced/tree/master/examples/solar_system
+///
+/// ## Drawing a simple circle
+/// If you want to get a quick overview, here's how we can draw a simple circle:
+///
+/// ```no_run
+/// # mod iced {
+/// #     pub use iced_graphics::canvas;
+/// #     pub use iced_native::{Color, Rectangle};
+/// # }
+/// use iced::canvas::{self, Canvas, Cursor, Fill, Frame, Geometry, Path, Program};
+/// use iced::{Color, Rectangle};
+///
+/// // First, we define the data we need for drawing
+/// #[derive(Debug)]
+/// struct Circle {
+///     radius: f32,
+/// }
+///
+/// // Then, we implement the `Program` trait
+/// impl Program<()> for Circle {
+///     fn draw(&self, bounds: Rectangle, _cursor: Cursor) -> Vec<Geometry>{
+///         // We prepare a new `Frame`
+///         let mut frame = Frame::new(bounds.size());
+///
+///         // We create a `Path` representing a simple circle
+///         let circle = Path::circle(frame.center(), self.radius);
+///
+///         // And fill it with some color
+///         frame.fill(&circle, Fill::Color(Color::BLACK));
+///
+///         // Finally, we produce the geometry
+///         vec![frame.into_geometry()]
+///     }
+/// }
+///
+/// // Finally, we simply use our `Circle` to create the `Canvas`!
+/// let canvas = Canvas::new(Circle { radius: 50.0 });
+/// ```
+#[derive(Debug)]
+pub struct Canvas<Message, P: Program<Message>> {
+    width: Length,
+    height: Length,
+    program: P,
+    phantom: PhantomData<Message>,
+}
+
+impl<Message, P: Program<Message>> Canvas<Message, P> {
+    const DEFAULT_SIZE: u16 = 100;
+
+    /// Creates a new [`Canvas`].
+    ///
+    /// [`Canvas`]: struct.Canvas.html
+    pub fn new(program: P) -> Self {
+        Canvas {
+            width: Length::Units(Self::DEFAULT_SIZE),
+            height: Length::Units(Self::DEFAULT_SIZE),
+            program,
+            phantom: PhantomData,
+        }
+    }
+
+    /// Sets the width of the [`Canvas`].
+    ///
+    /// [`Canvas`]: struct.Canvas.html
+    pub fn width(mut self, width: Length) -> Self {
+        self.width = width;
+        self
+    }
+
+    /// Sets the height of the [`Canvas`].
+    ///
+    /// [`Canvas`]: struct.Canvas.html
+    pub fn height(mut self, height: Length) -> Self {
+        self.height = height;
+        self
+    }
+}
+
+impl<Message, P, B> Widget<Message, Renderer<B>> for Canvas<Message, P>
+where
+    P: Program<Message>,
+    B: Backend,
+{
+    fn width(&self) -> Length {
+        self.width
+    }
+
+    fn height(&self) -> Length {
+        self.height
+    }
+
+    fn layout(
+        &self,
+        _renderer: &Renderer<B>,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        let limits = limits.width(self.width).height(self.height);
+        let size = limits.resolve(Size::ZERO);
+
+        layout::Node::new(size)
+    }
+
+    fn on_event(
+        &mut self,
+        event: iced_native::Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        messages: &mut Vec<Message>,
+        _renderer: &Renderer<B>,
+        _clipboard: Option<&dyn Clipboard>,
+    ) {
+        let bounds = layout.bounds();
+
+        let canvas_event = match event {
+            iced_native::Event::Mouse(mouse_event) => {
+                Some(Event::Mouse(mouse_event))
+            }
+            _ => None,
+        };
+
+        let cursor = Cursor::from_window_position(cursor_position);
+
+        if let Some(canvas_event) = canvas_event {
+            if let Some(message) =
+                self.program.update(canvas_event, bounds, cursor)
+            {
+                messages.push(message);
+            }
+        }
+    }
+
+    fn draw(
+        &self,
+        _renderer: &mut Renderer<B>,
+        _defaults: &Defaults,
+        layout: Layout<'_>,
+        cursor_position: Point,
+    ) -> (Primitive, mouse::Interaction) {
+        let bounds = layout.bounds();
+        let translation = Vector::new(bounds.x, bounds.y);
+        let cursor = Cursor::from_window_position(cursor_position);
+
+        (
+            Primitive::Translate {
+                translation,
+                content: Box::new(Primitive::Group {
+                    primitives: self
+                        .program
+                        .draw(bounds, cursor)
+                        .into_iter()
+                        .map(Geometry::into_primitive)
+                        .collect(),
+                }),
+            },
+            self.program.mouse_interaction(bounds, cursor),
+        )
+    }
+
+    fn hash_layout(&self, state: &mut Hasher) {
+        struct Marker;
+        std::any::TypeId::of::<Marker>().hash(state);
+
+        self.width.hash(state);
+        self.height.hash(state);
+    }
+}
+
+impl<'a, Message, P, B> From<Canvas<Message, P>>
+    for Element<'a, Message, Renderer<B>>
+where
+    Message: 'static,
+    P: Program<Message> + 'a,
+    B: Backend,
+{
+    fn from(canvas: Canvas<Message, P>) -> Element<'a, Message, Renderer<B>> {
+        Element::new(canvas)
+    }
+}
diff --git a/wgpu/src/widget/canvas/cache.rs b/graphics/src/widget/canvas/cache.rs
index 4b28d164..4b28d164 100644
--- a/wgpu/src/widget/canvas/cache.rs
+++ b/graphics/src/widget/canvas/cache.rs
diff --git a/wgpu/src/widget/canvas/cursor.rs b/graphics/src/widget/canvas/cursor.rs
index 456760ea..456760ea 100644
--- a/wgpu/src/widget/canvas/cursor.rs
+++ b/graphics/src/widget/canvas/cursor.rs
diff --git a/wgpu/src/widget/canvas/event.rs b/graphics/src/widget/canvas/event.rs
index ad11f51e..ad11f51e 100644
--- a/wgpu/src/widget/canvas/event.rs
+++ b/graphics/src/widget/canvas/event.rs
diff --git a/wgpu/src/widget/canvas/fill.rs b/graphics/src/widget/canvas/fill.rs
index a2010e45..a2010e45 100644
--- a/wgpu/src/widget/canvas/fill.rs
+++ b/graphics/src/widget/canvas/fill.rs
diff --git a/wgpu/src/widget/canvas/frame.rs b/graphics/src/widget/canvas/frame.rs
index 5262ab4e..48d28d95 100644
--- a/wgpu/src/widget/canvas/frame.rs
+++ b/graphics/src/widget/canvas/frame.rs
@@ -304,11 +304,11 @@ impl Frame {
     pub fn into_geometry(mut self) -> Geometry {
         if !self.buffers.indices.is_empty() {
             self.primitives.push(Primitive::Mesh2D {
-                size: self.size,
                 buffers: triangle::Mesh2D {
                     vertices: self.buffers.vertices,
                     indices: self.buffers.indices,
                 },
+                size: self.size,
             });
         }
 
diff --git a/wgpu/src/widget/canvas/geometry.rs b/graphics/src/widget/canvas/geometry.rs
index 4cadee39..4cadee39 100644
--- a/wgpu/src/widget/canvas/geometry.rs
+++ b/graphics/src/widget/canvas/geometry.rs
diff --git a/wgpu/src/widget/canvas/path.rs b/graphics/src/widget/canvas/path.rs
index c26bf187..c26bf187 100644
--- a/wgpu/src/widget/canvas/path.rs
+++ b/graphics/src/widget/canvas/path.rs
diff --git a/wgpu/src/widget/canvas/path/arc.rs b/graphics/src/widget/canvas/path/arc.rs
index 343191f1..343191f1 100644
--- a/wgpu/src/widget/canvas/path/arc.rs
+++ b/graphics/src/widget/canvas/path/arc.rs
diff --git a/wgpu/src/widget/canvas/path/builder.rs b/graphics/src/widget/canvas/path/builder.rs
index 6511fa52..6511fa52 100644
--- a/wgpu/src/widget/canvas/path/builder.rs
+++ b/graphics/src/widget/canvas/path/builder.rs
diff --git a/wgpu/src/widget/canvas/program.rs b/graphics/src/widget/canvas/program.rs
index 725d9d72..725d9d72 100644
--- a/wgpu/src/widget/canvas/program.rs
+++ b/graphics/src/widget/canvas/program.rs
diff --git a/wgpu/src/widget/canvas/stroke.rs b/graphics/src/widget/canvas/stroke.rs
index 5b6fc56a..5b6fc56a 100644
--- a/wgpu/src/widget/canvas/stroke.rs
+++ b/graphics/src/widget/canvas/stroke.rs
diff --git a/wgpu/src/widget/canvas/text.rs b/graphics/src/widget/canvas/text.rs
index c4cae30e..c4cae30e 100644
--- a/wgpu/src/widget/canvas/text.rs
+++ b/graphics/src/widget/canvas/text.rs
diff --git a/wgpu/src/renderer/widget/checkbox.rs b/graphics/src/widget/checkbox.rs
index 0340bf62..cb7fd2cf 100644
--- a/wgpu/src/renderer/widget/checkbox.rs
+++ b/graphics/src/widget/checkbox.rs
@@ -1,9 +1,22 @@
-use crate::{checkbox::StyleSheet, Primitive, Renderer};
-use iced_native::{
-    checkbox, mouse, HorizontalAlignment, Rectangle, VerticalAlignment,
-};
+//! Show toggle controls using checkboxes.
+use crate::backend::{self, Backend};
+use crate::{Primitive, Renderer};
+use iced_native::checkbox;
+use iced_native::mouse;
+use iced_native::{HorizontalAlignment, Rectangle, VerticalAlignment};
 
-impl checkbox::Renderer for Renderer {
+pub use iced_style::checkbox::{Style, StyleSheet};
+
+/// A box that can be checked.
+///
+/// This is an alias of an `iced_native` checkbox with an `iced_wgpu::Renderer`.
+pub type Checkbox<Message, Backend> =
+    iced_native::Checkbox<Message, Renderer<Backend>>;
+
+impl<B> checkbox::Renderer for Renderer<B>
+where
+    B: Backend + backend::Text,
+{
     type Style = Box<dyn StyleSheet>;
 
     const DEFAULT_SIZE: u16 = 20;
@@ -35,8 +48,8 @@ impl checkbox::Renderer for Renderer {
             Primitive::Group {
                 primitives: if is_checked {
                     let check = Primitive::Text {
-                        content: crate::text::CHECKMARK_ICON.to_string(),
-                        font: crate::text::BUILTIN_ICONS,
+                        content: B::CHECKMARK_ICON.to_string(),
+                        font: B::ICON_FONT,
                         size: bounds.height * 0.7,
                         bounds: Rectangle {
                             x: bounds.center_x(),
diff --git a/wgpu/src/renderer/widget/row.rs b/graphics/src/widget/column.rs
index d0b7ef09..6c7235c7 100644
--- a/wgpu/src/renderer/widget/row.rs
+++ b/graphics/src/widget/column.rs
@@ -1,11 +1,20 @@
-use crate::{Primitive, Renderer};
-use iced_native::{mouse, row, Element, Layout, Point};
+use crate::{Backend, Primitive, Renderer};
+use iced_native::column;
+use iced_native::mouse;
+use iced_native::{Element, Layout, Point};
 
-impl row::Renderer for Renderer {
+/// A container that distributes its contents vertically.
+pub type Column<'a, Message, Backend> =
+    iced_native::Column<'a, Message, Renderer<Backend>>;
+
+impl<B> column::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     fn draw<Message>(
         &mut self,
         defaults: &Self::Defaults,
-        children: &[Element<'_, Message, Self>],
+        content: &[Element<'_, Message, Self>],
         layout: Layout<'_>,
         cursor_position: Point,
     ) -> Self::Output {
@@ -13,7 +22,7 @@ impl row::Renderer for Renderer {
 
         (
             Primitive::Group {
-                primitives: children
+                primitives: content
                     .iter()
                     .zip(layout.children())
                     .map(|(child, layout)| {
diff --git a/wgpu/src/renderer/widget/container.rs b/graphics/src/widget/container.rs
index 30cc3f07..070cb48b 100644
--- a/wgpu/src/renderer/widget/container.rs
+++ b/graphics/src/widget/container.rs
@@ -1,7 +1,22 @@
-use crate::{container, defaults, Defaults, Primitive, Renderer};
+//! Decorate content and apply alignment.
+use crate::container;
+use crate::defaults::{self, Defaults};
+use crate::{Backend, Primitive, Renderer};
 use iced_native::{Background, Color, Element, Layout, Point, Rectangle};
 
-impl iced_native::container::Renderer for Renderer {
+pub use iced_style::container::{Style, StyleSheet};
+
+/// An element decorating some content.
+///
+/// This is an alias of an `iced_native` container with a default
+/// `Renderer`.
+pub type Container<'a, Message, Backend> =
+    iced_native::Container<'a, Message, Renderer<Backend>>;
+
+impl<B> iced_native::container::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     type Style = Box<dyn container::StyleSheet>;
 
     fn draw<Message>(
diff --git a/wgpu/src/renderer/widget/image.rs b/graphics/src/widget/image.rs
index c4c04984..30f446e8 100644
--- a/wgpu/src/renderer/widget/image.rs
+++ b/graphics/src/widget/image.rs
@@ -1,9 +1,18 @@
+//! Display images in your user interface.
+use crate::backend::{self, Backend};
 use crate::{Primitive, Renderer};
-use iced_native::{image, mouse, Layout};
+use iced_native::image;
+use iced_native::mouse;
+use iced_native::Layout;
 
-impl image::Renderer for Renderer {
+pub use iced_native::image::{Handle, Image};
+
+impl<B> image::Renderer for Renderer<B>
+where
+    B: Backend + backend::Image,
+{
     fn dimensions(&self, handle: &image::Handle) -> (u32, u32) {
-        self.image_pipeline.dimensions(handle)
+        self.backend().dimensions(handle)
     }
 
     fn draw(
diff --git a/wgpu/src/renderer/widget/pane_grid.rs b/graphics/src/widget/pane_grid.rs
index 2253e4af..56af683d 100644
--- a/wgpu/src/renderer/widget/pane_grid.rs
+++ b/graphics/src/widget/pane_grid.rs
@@ -1,11 +1,36 @@
-use crate::{Primitive, Renderer};
-use iced_native::{
-    mouse,
-    pane_grid::{self, Axis, Pane},
-    Element, Layout, Point, Rectangle, Vector,
+//! Let your users split regions of your application and organize layout dynamically.
+//!
+//! [![Pane grid - Iced](https://thumbs.gfycat.com/MixedFlatJellyfish-small.gif)](https://gfycat.com/mixedflatjellyfish)
+//!
+//! # Example
+//! The [`pane_grid` example] showcases how to use a [`PaneGrid`] with resizing,
+//! drag and drop, and hotkey support.
+//!
+//! [`pane_grid` example]: https://github.com/hecrj/iced/tree/0.1/examples/pane_grid
+//! [`PaneGrid`]: type.PaneGrid.html
+use crate::{Backend, Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::pane_grid;
+use iced_native::{Element, Layout, Point, Rectangle, Vector};
+
+pub use iced_native::pane_grid::{
+    Axis, Direction, DragEvent, Focus, KeyPressEvent, Pane, ResizeEvent, Split,
+    State,
 };
 
-impl pane_grid::Renderer for Renderer {
+/// A collection of panes distributed using either vertical or horizontal splits
+/// to completely fill the space available.
+///
+/// [![Pane grid - Iced](https://thumbs.gfycat.com/MixedFlatJellyfish-small.gif)](https://gfycat.com/mixedflatjellyfish)
+///
+/// This is an alias of an `iced_native` pane grid with an `iced_wgpu::Renderer`.
+pub type PaneGrid<'a, Message, Backend> =
+    iced_native::PaneGrid<'a, Message, Renderer<Backend>>;
+
+impl<B> pane_grid::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     fn draw<Message>(
         &mut self,
         defaults: &Self::Defaults,
diff --git a/wgpu/src/renderer/widget/progress_bar.rs b/graphics/src/widget/progress_bar.rs
index 2baeeb14..48acb3c1 100644
--- a/wgpu/src/renderer/widget/progress_bar.rs
+++ b/graphics/src/widget/progress_bar.rs
@@ -1,7 +1,26 @@
-use crate::{progress_bar::StyleSheet, Primitive, Renderer};
-use iced_native::{mouse, progress_bar, Color, Rectangle};
+//! Allow your users to visually track the progress of a computation.
+//!
+//! A [`ProgressBar`] has a range of possible values and a current value,
+//! as well as a length, height and style.
+//!
+//! [`ProgressBar`]: type.ProgressBar.html
+use crate::{Backend, Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::progress_bar;
+use iced_native::{Color, Rectangle};
 
-impl progress_bar::Renderer for Renderer {
+pub use iced_style::progress_bar::{Style, StyleSheet};
+
+/// A bar that displays progress.
+///
+/// This is an alias of an `iced_native` progress bar with an
+/// `iced_wgpu::Renderer`.
+pub type ProgressBar<Backend> = iced_native::ProgressBar<Renderer<Backend>>;
+
+impl<B> progress_bar::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     type Style = Box<dyn StyleSheet>;
 
     const DEFAULT_HEIGHT: u16 = 30;
diff --git a/wgpu/src/renderer/widget/radio.rs b/graphics/src/widget/radio.rs
index cee0deb6..dd8b5f17 100644
--- a/wgpu/src/renderer/widget/radio.rs
+++ b/graphics/src/widget/radio.rs
@@ -1,10 +1,25 @@
-use crate::{radio::StyleSheet, Primitive, Renderer};
-use iced_native::{mouse, radio, Background, Color, Rectangle};
+//! Create choices using radio buttons.
+use crate::{Backend, Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::radio;
+use iced_native::{Background, Color, Rectangle};
+
+pub use iced_style::radio::{Style, StyleSheet};
+
+/// A circular button representing a choice.
+///
+/// This is an alias of an `iced_native` radio button with an
+/// `iced_wgpu::Renderer`.
+pub type Radio<Message, Backend> =
+    iced_native::Radio<Message, Renderer<Backend>>;
 
 const SIZE: f32 = 28.0;
 const DOT_SIZE: f32 = SIZE / 2.0;
 
-impl radio::Renderer for Renderer {
+impl<B> radio::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     type Style = Box<dyn StyleSheet>;
 
     const DEFAULT_SIZE: u16 = SIZE as u16;
diff --git a/wgpu/src/renderer/widget/column.rs b/graphics/src/widget/row.rs
index b853276d..4c1dbadc 100644
--- a/wgpu/src/renderer/widget/column.rs
+++ b/graphics/src/widget/row.rs
@@ -1,7 +1,16 @@
-use crate::{Primitive, Renderer};
-use iced_native::{column, mouse, Element, Layout, Point};
+use crate::{Backend, Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::row;
+use iced_native::{Element, Layout, Point};
 
-impl column::Renderer for Renderer {
+/// A container that distributes its contents horizontally.
+pub type Row<'a, Message, Backend> =
+    iced_native::Row<'a, Message, Renderer<Backend>>;
+
+impl<B> row::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     fn draw<Message>(
         &mut self,
         defaults: &Self::Defaults,
diff --git a/wgpu/src/renderer/widget/scrollable.rs b/graphics/src/widget/scrollable.rs
index 8a400b82..b149db0a 100644
--- a/wgpu/src/renderer/widget/scrollable.rs
+++ b/graphics/src/widget/scrollable.rs
@@ -1,10 +1,27 @@
-use crate::{Primitive, Renderer};
-use iced_native::{mouse, scrollable, Background, Color, Rectangle, Vector};
+//! Navigate an endless amount of content with a scrollbar.
+use crate::{Backend, Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::scrollable;
+use iced_native::{Background, Color, Rectangle, Vector};
+
+pub use iced_native::scrollable::State;
+pub use iced_style::scrollable::{Scrollbar, Scroller, StyleSheet};
+
+/// A widget that can vertically display an infinite amount of content
+/// with a scrollbar.
+///
+/// This is an alias of an `iced_native` scrollable with a default
+/// `Renderer`.
+pub type Scrollable<'a, Message, Backend> =
+    iced_native::Scrollable<'a, Message, Renderer<Backend>>;
 
 const SCROLLBAR_WIDTH: u16 = 10;
 const SCROLLBAR_MARGIN: u16 = 2;
 
-impl scrollable::Renderer for Renderer {
+impl<B> scrollable::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     type Style = Box<dyn iced_style::scrollable::StyleSheet>;
 
     fn scrollbar(
diff --git a/wgpu/src/renderer/widget/slider.rs b/graphics/src/widget/slider.rs
index 220feace..b00cde9a 100644
--- a/wgpu/src/renderer/widget/slider.rs
+++ b/graphics/src/widget/slider.rs
@@ -1,12 +1,30 @@
-use crate::{
-    slider::{HandleShape, StyleSheet},
-    Primitive, Renderer,
-};
-use iced_native::{mouse, slider, Background, Color, Point, Rectangle};
+//! Display an interactive selector of a single value from a range of values.
+//!
+//! A [`Slider`] has some local [`State`].
+//!
+//! [`Slider`]: struct.Slider.html
+//! [`State`]: struct.State.html
+use crate::{Backend, Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::slider;
+use iced_native::{Background, Color, Point, Rectangle};
+
+pub use iced_native::slider::State;
+pub use iced_style::slider::{Handle, HandleShape, Style, StyleSheet};
+
+/// An horizontal bar and a handle that selects a single value from a range of
+/// values.
+///
+/// This is an alias of an `iced_native` slider with an `iced_wgpu::Renderer`.
+pub type Slider<'a, Message, Backend> =
+    iced_native::Slider<'a, Message, Renderer<Backend>>;
 
 const HANDLE_HEIGHT: f32 = 22.0;
 
-impl slider::Renderer for Renderer {
+impl<B> slider::Renderer for Renderer<B>
+where
+    B: Backend,
+{
     type Style = Box<dyn StyleSheet>;
 
     fn height(&self) -> u32 {
diff --git a/graphics/src/widget/space.rs b/graphics/src/widget/space.rs
new file mode 100644
index 00000000..1f31eabe
--- /dev/null
+++ b/graphics/src/widget/space.rs
@@ -0,0 +1,15 @@
+use crate::{Backend, Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::space;
+use iced_native::Rectangle;
+
+pub use iced_native::Space;
+
+impl<B> space::Renderer for Renderer<B>
+where
+    B: Backend,
+{
+    fn draw(&mut self, _bounds: Rectangle) -> Self::Output {
+        (Primitive::None, mouse::Interaction::default())
+    }
+}
diff --git a/wgpu/src/renderer/widget/svg.rs b/graphics/src/widget/svg.rs
index f6d6d0ba..8b5ed66a 100644
--- a/wgpu/src/renderer/widget/svg.rs
+++ b/graphics/src/widget/svg.rs
@@ -1,9 +1,16 @@
+//! Display vector graphics in your application.
+use crate::backend::{self, Backend};
 use crate::{Primitive, Renderer};
 use iced_native::{mouse, svg, Layout};
 
-impl svg::Renderer for Renderer {
+pub use iced_native::svg::{Handle, Svg};
+
+impl<B> svg::Renderer for Renderer<B>
+where
+    B: Backend + backend::Svg,
+{
     fn dimensions(&self, handle: &svg::Handle) -> (u32, u32) {
-        self.image_pipeline.viewport_dimensions(handle)
+        self.backend().viewport_dimensions(handle)
     }
 
     fn draw(
diff --git a/wgpu/src/renderer/widget/text.rs b/graphics/src/widget/text.rs
index 4605ed06..327f8e29 100644
--- a/wgpu/src/renderer/widget/text.rs
+++ b/graphics/src/widget/text.rs
@@ -1,12 +1,23 @@
+//! Write some text for your users to read.
+use crate::backend::{self, Backend};
 use crate::{Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::text;
 use iced_native::{
-    mouse, text, Color, Font, HorizontalAlignment, Rectangle, Size,
-    VerticalAlignment,
+    Color, Font, HorizontalAlignment, Rectangle, Size, VerticalAlignment,
 };
 
+/// A paragraph of text.
+///
+/// This is an alias of an `iced_native` text with an `iced_wgpu::Renderer`.
+pub type Text<Backend> = iced_native::Text<Renderer<Backend>>;
+
 use std::f32;
 
-impl text::Renderer for Renderer {
+impl<B> text::Renderer for Renderer<B>
+where
+    B: Backend + backend::Text,
+{
     type Font = Font;
 
     const DEFAULT_SIZE: u16 = 20;
@@ -18,7 +29,7 @@ impl text::Renderer for Renderer {
         font: Font,
         bounds: Size,
     ) -> (f32, f32) {
-        self.text_pipeline
+        self.backend()
             .measure(content, f32::from(size), font, bounds)
     }
 
diff --git a/wgpu/src/renderer/widget/text_input.rs b/graphics/src/widget/text_input.rs
index 57be6692..893197d1 100644
--- a/wgpu/src/renderer/widget/text_input.rs
+++ b/graphics/src/widget/text_input.rs
@@ -1,14 +1,32 @@
-use crate::{text_input::StyleSheet, Primitive, Renderer};
-
+//! Display fields that can be filled with text.
+//!
+//! A [`TextInput`] has some local [`State`].
+//!
+//! [`TextInput`]: struct.TextInput.html
+//! [`State`]: struct.State.html
+use crate::backend::{self, Backend};
+use crate::{Primitive, Renderer};
+use iced_native::mouse;
+use iced_native::text_input::{self, cursor};
 use iced_native::{
-    mouse,
-    text_input::{self, cursor},
     Background, Color, Font, HorizontalAlignment, Point, Rectangle, Size,
     Vector, VerticalAlignment,
 };
 use std::f32;
 
-impl text_input::Renderer for Renderer {
+pub use iced_native::text_input::State;
+pub use iced_style::text_input::{Style, StyleSheet};
+
+/// A field that can be filled with text.
+///
+/// This is an alias of an `iced_native` text input with an `iced_wgpu::Renderer`.
+pub type TextInput<'a, Message, Backend> =
+    iced_native::TextInput<'a, Message, Renderer<Backend>>;
+
+impl<B> text_input::Renderer for Renderer<B>
+where
+    B: Backend + backend::Text,
+{
     type Style = Box<dyn StyleSheet>;
 
     fn default_size(&self) -> u16 {
@@ -17,19 +35,10 @@ impl text_input::Renderer for Renderer {
     }
 
     fn measure_value(&self, value: &str, size: u16, font: Font) -> f32 {
-        let (mut width, _) = self.text_pipeline.measure(
-            value,
-            f32::from(size),
-            font,
-            Size::INFINITY,
-        );
-
-        let spaces_around = value.len() - value.trim().len();
+        let backend = self.backend();
 
-        if spaces_around > 0 {
-            let space_width = self.text_pipeline.space_width(size as f32);
-            width += spaces_around as f32 * space_width;
-        }
+        let (width, _) =
+            backend.measure(value, f32::from(size), font, Size::INFINITY);
 
         width
     }
@@ -241,14 +250,17 @@ impl text_input::Renderer for Renderer {
     }
 }
 
-fn measure_cursor_and_scroll_offset(
-    renderer: &Renderer,
+fn measure_cursor_and_scroll_offset<B>(
+    renderer: &Renderer<B>,
     text_bounds: Rectangle,
     value: &text_input::Value,
     size: u16,
     cursor_index: usize,
     font: Font,
-) -> (f32, f32) {
+) -> (f32, f32)
+where
+    B: Backend + backend::Text,
+{
     use iced_native::text_input::Renderer;
 
     let text_before_cursor = value.until(cursor_index).to_string();
diff --git a/graphics/src/window.rs b/graphics/src/window.rs
new file mode 100644
index 00000000..3e74db5f
--- /dev/null
+++ b/graphics/src/window.rs
@@ -0,0 +1,10 @@
+//! Draw graphics to window surfaces.
+mod compositor;
+
+#[cfg(feature = "opengl")]
+mod gl_compositor;
+
+pub use compositor::Compositor;
+
+#[cfg(feature = "opengl")]
+pub use gl_compositor::GLCompositor;
diff --git a/native/src/window/backend.rs b/graphics/src/window/compositor.rs
index 892d4bb9..d5920c95 100644
--- a/native/src/window/backend.rs
+++ b/graphics/src/window/compositor.rs
@@ -1,14 +1,14 @@
-use crate::mouse;
-
+use crate::Viewport;
+use iced_native::mouse;
 use raw_window_handle::HasRawWindowHandle;
 
-/// A graphics backend that can render to windows.
-pub trait Backend: Sized {
+/// A graphics compositor that can draw to windows.
+pub trait Compositor: Sized {
     /// The settings of the backend.
     type Settings: Default;
 
     /// The iced renderer of the backend.
-    type Renderer: crate::Renderer;
+    type Renderer: iced_native::Renderer;
 
     /// The surface of the backend.
     type Surface;
@@ -16,7 +16,7 @@ pub trait Backend: Sized {
     /// The swap chain of the backend.
     type SwapChain;
 
-    /// Creates a new [`Backend`] and an associated iced renderer.
+    /// Creates a new [`Backend`].
     ///
     /// [`Backend`]: trait.Backend.html
     fn new(settings: Self::Settings) -> (Self, Self::Renderer);
@@ -48,8 +48,8 @@ pub trait Backend: Sized {
         &mut self,
         renderer: &mut Self::Renderer,
         swap_chain: &mut Self::SwapChain,
-        output: &<Self::Renderer as crate::Renderer>::Output,
-        scale_factor: f64,
+        viewport: &Viewport,
+        output: &<Self::Renderer as iced_native::Renderer>::Output,
         overlay: &[T],
     ) -> mouse::Interaction;
 }
diff --git a/graphics/src/window/gl_compositor.rs b/graphics/src/window/gl_compositor.rs
new file mode 100644
index 00000000..542213b5
--- /dev/null
+++ b/graphics/src/window/gl_compositor.rs
@@ -0,0 +1,67 @@
+use crate::{Size, Viewport};
+use iced_native::mouse;
+
+use core::ffi::c_void;
+
+/// A basic OpenGL compositor.
+///
+/// A compositor is responsible for initializing a renderer and managing window
+/// surfaces.
+///
+/// For now, this compositor only deals with a single global surface
+/// for drawing. However, the trait will most likely change in the near future
+/// to handle multiple surfaces at once.
+///
+/// If you implement an OpenGL renderer, you can implement this trait to ease
+/// integration with existing windowing shells, like `iced_glutin`.
+pub trait GLCompositor: Sized {
+    /// The renderer of the [`Compositor`].
+    ///
+    /// This should point to your renderer type, which could be a type alias
+    /// of the [`Renderer`] provided in this crate with with a specific
+    /// [`Backend`].
+    ///
+    /// [`Compositor`]: trait.Compositor.html
+    /// [`Renderer`]: ../struct.Renderer.html
+    /// [`Backend`]: ../backend/trait.Backend.html
+    type Renderer: iced_native::Renderer;
+
+    /// The settings of the [`Compositor`].
+    ///
+    /// It's up to you to decide the configuration supported by your renderer!
+    type Settings: Default;
+
+    /// Creates a new [`Compositor`] and [`Renderer`] with the given
+    /// [`Settings`] and an OpenGL address loader function.
+    ///
+    /// [`Compositor`]: trait.Compositor.html
+    /// [`Renderer`]: #associatedtype.Renderer
+    /// [`Backend`]: ../backend/trait.Backend.html
+    #[allow(unsafe_code)]
+    unsafe fn new(
+        settings: Self::Settings,
+        loader_function: impl FnMut(&str) -> *const c_void,
+    ) -> (Self, Self::Renderer);
+
+    /// Returns the amount of samples that should be used when configuring
+    /// an OpenGL context for this [`Compositor`].
+    ///
+    /// [`Compositor`]: trait.Compositor.html
+    fn sample_count(settings: &Self::Settings) -> u32;
+
+    /// Resizes the viewport of the [`Compositor`].
+    ///
+    /// [`Compositor`]: trait.Compositor.html
+    fn resize_viewport(&mut self, physical_size: Size<u32>);
+
+    /// Draws the provided output with the given [`Renderer`].
+    ///
+    /// [`Compositor`]: trait.Compositor.html
+    fn draw<T: AsRef<str>>(
+        &mut self,
+        renderer: &mut Self::Renderer,
+        viewport: &Viewport,
+        output: &<Self::Renderer as iced_native::Renderer>::Output,
+        overlay: &[T],
+    ) -> mouse::Interaction;
+}