Merge branch 'master' into improvement/update-wgpu_glyph

29 files changed, 581 insertions, 65 deletions

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 5799dba7..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 {
@@ -17,12 +35,10 @@ impl text_input::Renderer for Renderer {
     }
 
     fn measure_value(&self, value: &str, size: u16, font: Font) -> f32 {
-        let (width, _) = self.text_pipeline.measure(
-            value,
-            f32::from(size),
-            font,
-            Size::INFINITY,
-        );
+        let backend = self.backend();
+
+        let (width, _) =
+            backend.measure(value, f32::from(size), font, Size::INFINITY);
 
         width
     }
@@ -234,14 +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();