Merge pull request #1748 from iced-rs/feature/software-renderer

Software renderer, runtime renderer fallback, and core consolidation

41 files changed, 397 insertions, 207 deletions

diff --git a/core/Cargo.toml b/core/Cargo.toml
index 43865e4d..dac31828 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "iced_core"
-version = "0.8.0"
+version = "0.8.1"
 authors = ["Héctor Ramón Jiménez <hector0193@gmail.com>"]
 edition = "2021"
 description = "The essential concepts of Iced"
@@ -9,6 +9,8 @@ repository = "https://github.com/iced-rs/iced"
 
 [dependencies]
 bitflags = "1.2"
+thiserror = "1"
+twox-hash = { version = "1.5", default-features = false }
 
 [dependencies.palette]
 version = "0.6"
diff --git a/core/src/alignment.rs b/core/src/alignment.rs
index 73f41d3f..51b7fca9 100644
--- a/core/src/alignment.rs
+++ b/core/src/alignment.rs
@@ -11,9 +11,6 @@ pub enum Alignment {
 
     /// Align at the end of the axis.
     End,
-
-    /// Fill the entire axis.
-    Fill,
 }
 
 impl From<Horizontal> for Alignment {
diff --git a/core/src/clipboard.rs b/core/src/clipboard.rs
new file mode 100644
index 00000000..081b4004
--- /dev/null
+++ b/core/src/clipboard.rs
@@ -0,0 +1,23 @@
+//! Access the clipboard.
+
+/// A buffer for short-term storage and transfer within and between
+/// applications.
+pub trait Clipboard {
+    /// Reads the current content of the [`Clipboard`] as text.
+    fn read(&self) -> Option<String>;
+
+    /// Writes the given text contents to the [`Clipboard`].
+    fn write(&mut self, contents: String);
+}
+
+/// A null implementation of the [`Clipboard`] trait.
+#[derive(Debug, Clone, Copy)]
+pub struct Null;
+
+impl Clipboard for Null {
+    fn read(&self) -> Option<String> {
+        None
+    }
+
+    fn write(&mut self, _contents: String) {}
+}
diff --git a/native/src/element.rs b/core/src/element.rs
index 0a677d20..98c53737 100644
--- a/native/src/element.rs
+++ b/core/src/element.rs
@@ -90,41 +90,65 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     /// We compose the previous __messages__ with the index of the counter
     /// producing them. Let's implement our __view logic__ now:
     ///
-    /// ```
+    /// ```no_run
     /// # mod counter {
-    /// #     type Text<'a> = iced_native::widget::Text<'a, iced_native::renderer::Null>;
-    /// #
     /// #     #[derive(Debug, Clone, Copy)]
     /// #     pub enum Message {}
     /// #     pub struct Counter;
     /// #
     /// #     impl Counter {
-    /// #         pub fn view(&mut self) -> Text {
-    /// #             Text::new("")
+    /// #         pub fn view(
+    /// #             &self,
+    /// #         ) -> iced_core::Element<Message, iced_core::renderer::Null> {
+    /// #             unimplemented!()
     /// #         }
     /// #     }
     /// # }
     /// #
-    /// # mod iced_wgpu {
-    /// #     pub use iced_native::renderer::Null as Renderer;
-    /// # }
+    /// # mod iced {
+    /// #     pub use iced_core::renderer::Null as Renderer;
+    /// #     pub use iced_core::Element;
     /// #
-    /// # use counter::Counter;
+    /// #     pub mod widget {
+    /// #         pub struct Row<Message> {
+    /// #             _t: std::marker::PhantomData<Message>,
+    /// #         }
     /// #
-    /// # struct ManyCounters {
-    /// #     counters: Vec<Counter>,
-    /// # }
+    /// #         impl<Message> Row<Message> {
+    /// #             pub fn new() -> Self {
+    /// #                 unimplemented!()
+    /// #             }
     /// #
-    /// # #[derive(Debug, Clone, Copy)]
-    /// # pub enum Message {
-    /// #    Counter(usize, counter::Message)
+    /// #             pub fn spacing(mut self, _: u32) -> Self {
+    /// #                 unimplemented!()
+    /// #             }
+    /// #
+    /// #             pub fn push(
+    /// #                 mut self,
+    /// #                 _: iced_core::Element<Message, iced_core::renderer::Null>,
+    /// #             ) -> Self {
+    /// #                 unimplemented!()
+    /// #             }
+    /// #         }
+    /// #     }
     /// # }
-    /// use iced_native::Element;
-    /// use iced_native::widget::Row;
-    /// use iced_wgpu::Renderer;
+    /// #
+    /// use counter::Counter;
+    ///
+    /// use iced::widget::Row;
+    /// use iced::{Element, Renderer};
+    ///
+    /// struct ManyCounters {
+    ///     counters: Vec<Counter>,
+    /// }
+    ///
+    /// #[derive(Debug, Clone, Copy)]
+    /// pub enum Message {
+    ///     Counter(usize, counter::Message),
+    /// }
     ///
     /// impl ManyCounters {
-    ///     pub fn view(&mut self) -> Row<Message, Renderer> {
+    ///     pub fn view(&mut self) -> Row<Message> {
     ///         // We can quickly populate a `Row` by folding over our counters
     ///         self.counters.iter_mut().enumerate().fold(
     ///             Row::new().spacing(20),
@@ -137,9 +161,10 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     ///                     // Here we turn our `Element<counter::Message>` into
     ///                     // an `Element<Message>` by combining the `index` and the
     ///                     // message of the `element`.
-    ///                     element.map(move |message| Message::Counter(index, message))
+    ///                     element
+    ///                         .map(move |message| Message::Counter(index, message)),
     ///                 )
-    ///             }
+    ///             },
     ///         )
     ///     }
     /// }
diff --git a/native/src/event.rs b/core/src/event.rs
index bcfaf891..953cd73f 100644
--- a/native/src/event.rs
+++ b/core/src/event.rs
@@ -62,7 +62,7 @@ impl Status {
     /// `Captured` takes precedence over `Ignored`:
     ///
     /// ```
-    /// use iced_native::event::Status;
+    /// use iced_core::event::Status;
     ///
     /// assert_eq!(Status::Ignored.merge(Status::Ignored), Status::Ignored);
     /// assert_eq!(Status::Ignored.merge(Status::Captured), Status::Captured);
diff --git a/graphics/src/gradient.rs b/core/src/gradient.rs
index 61e919d6..61e919d6 100644
--- a/graphics/src/gradient.rs
+++ b/core/src/gradient.rs
diff --git a/graphics/src/gradient/linear.rs b/core/src/gradient/linear.rs
index c886db47..c886db47 100644
--- a/graphics/src/gradient/linear.rs
+++ b/core/src/gradient/linear.rs
diff --git a/native/src/hasher.rs b/core/src/hasher.rs
index fa52f16d..fa52f16d 100644
--- a/native/src/hasher.rs
+++ b/core/src/hasher.rs
diff --git a/native/src/image.rs b/core/src/image.rs
index 70fbade0..70fbade0 100644
--- a/native/src/image.rs
+++ b/core/src/image.rs
diff --git a/native/src/layout.rs b/core/src/layout.rs
index 04954fb9..04954fb9 100644
--- a/native/src/layout.rs
+++ b/core/src/layout.rs
diff --git a/native/src/layout/DRUID_LICENSE b/core/src/layout/DRUID_LICENSE
index d6456956..d6456956 100644
--- a/native/src/layout/DRUID_LICENSE
+++ b/core/src/layout/DRUID_LICENSE
diff --git a/native/src/layout/flex.rs b/core/src/layout/flex.rs
index 5d70c2fc..8b967849 100644
--- a/native/src/layout/flex.rs
+++ b/core/src/layout/flex.rs
@@ -81,32 +81,6 @@ where
     let mut nodes: Vec<Node> = Vec::with_capacity(items.len());
     nodes.resize(items.len(), Node::default());
 
-    if align_items == Alignment::Fill {
-        let mut fill_cross = axis.cross(limits.min());
-
-        items.iter().for_each(|child| {
-            let cross_fill_factor = match axis {
-                Axis::Horizontal => child.as_widget().height(),
-                Axis::Vertical => child.as_widget().width(),
-            }
-            .fill_factor();
-
-            if cross_fill_factor == 0 {
-                let (max_width, max_height) = axis.pack(available, max_cross);
-
-                let child_limits =
-                    Limits::new(Size::ZERO, Size::new(max_width, max_height));
-
-                let layout = child.as_widget().layout(renderer, &child_limits);
-                let size = layout.size();
-
-                fill_cross = fill_cross.max(axis.cross(size));
-            }
-        });
-
-        cross = fill_cross;
-    }
-
     for (i, child) in items.iter().enumerate() {
         let fill_factor = match axis {
             Axis::Horizontal => child.as_widget().width(),
@@ -115,31 +89,16 @@ where
         .fill_factor();
 
         if fill_factor == 0 {
-            let (min_width, min_height) = if align_items == Alignment::Fill {
-                axis.pack(0.0, cross)
-            } else {
-                axis.pack(0.0, 0.0)
-            };
+            let (max_width, max_height) = axis.pack(available, max_cross);
 
-            let (max_width, max_height) = if align_items == Alignment::Fill {
-                axis.pack(available, cross)
-            } else {
-                axis.pack(available, max_cross)
-            };
-
-            let child_limits = Limits::new(
-                Size::new(min_width, min_height),
-                Size::new(max_width, max_height),
-            );
+            let child_limits =
+                Limits::new(Size::ZERO, Size::new(max_width, max_height));
 
             let layout = child.as_widget().layout(renderer, &child_limits);
             let size = layout.size();
 
             available -= axis.main(size);
-
-            if align_items != Alignment::Fill {
-                cross = cross.max(axis.cross(size));
-            }
+            cross = cross.max(axis.cross(size));
 
             nodes[i] = layout;
         } else {
@@ -164,17 +123,10 @@ where
                 max_main
             };
 
-            let (min_width, min_height) = if align_items == Alignment::Fill {
-                axis.pack(min_main, cross)
-            } else {
-                axis.pack(min_main, axis.cross(limits.min()))
-            };
+            let (min_width, min_height) =
+                axis.pack(min_main, axis.cross(limits.min()));
 
-            let (max_width, max_height) = if align_items == Alignment::Fill {
-                axis.pack(max_main, cross)
-            } else {
-                axis.pack(max_main, max_cross)
-            };
+            let (max_width, max_height) = axis.pack(max_main, max_cross);
 
             let child_limits = Limits::new(
                 Size::new(min_width, min_height),
@@ -182,10 +134,7 @@ where
             );
 
             let layout = child.as_widget().layout(renderer, &child_limits);
-
-            if align_items != Alignment::Fill {
-                cross = cross.max(axis.cross(layout.size()));
-            }
+            cross = cross.max(axis.cross(layout.size()));
 
             nodes[i] = layout;
         }
diff --git a/native/src/layout/limits.rs b/core/src/layout/limits.rs
index 5d3c1556..5d3c1556 100644
--- a/native/src/layout/limits.rs
+++ b/core/src/layout/limits.rs
diff --git a/native/src/layout/node.rs b/core/src/layout/node.rs
index e0c7dcb2..2b44a7d5 100644
--- a/native/src/layout/node.rs
+++ b/core/src/layout/node.rs
@@ -56,9 +56,6 @@ impl Node {
             Alignment::End => {
                 self.bounds.x += space.width - self.bounds.width;
             }
-            Alignment::Fill => {
-                self.bounds.width = space.width;
-            }
         }
 
         match vertical_alignment {
@@ -69,9 +66,6 @@ impl Node {
             Alignment::End => {
                 self.bounds.y += space.height - self.bounds.height;
             }
-            Alignment::Fill => {
-                self.bounds.height = space.height;
-            }
         }
     }
 
diff --git a/core/src/lib.rs b/core/src/lib.rs
index d7314851..5bdcee6a 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -25,31 +25,57 @@
 #![forbid(unsafe_code, rust_2018_idioms)]
 #![allow(clippy::inherent_to_string, clippy::type_complexity)]
 pub mod alignment;
+pub mod clipboard;
+pub mod event;
 pub mod font;
+pub mod gradient;
+pub mod image;
 pub mod keyboard;
+pub mod layout;
 pub mod mouse;
+pub mod overlay;
+pub mod renderer;
+pub mod svg;
+pub mod text;
 pub mod time;
+pub mod touch;
+pub mod widget;
+pub mod window;
 
 mod background;
 mod color;
 mod content_fit;
+mod element;
+mod hasher;
 mod length;
 mod padding;
 mod pixels;
 mod point;
 mod rectangle;
+mod shell;
 mod size;
 mod vector;
 
 pub use alignment::Alignment;
 pub use background::Background;
+pub use clipboard::Clipboard;
 pub use color::Color;
 pub use content_fit::ContentFit;
+pub use element::Element;
+pub use event::Event;
 pub use font::Font;
+pub use gradient::Gradient;
+pub use hasher::Hasher;
+pub use layout::Layout;
 pub use length::Length;
+pub use overlay::Overlay;
 pub use padding::Padding;
 pub use pixels::Pixels;
 pub use point::Point;
 pub use rectangle::Rectangle;
+pub use renderer::Renderer;
+pub use shell::Shell;
 pub use size::Size;
+pub use text::Text;
 pub use vector::Vector;
+pub use widget::Widget;
diff --git a/core/src/mouse.rs b/core/src/mouse.rs
index 48214f65..0c405ce6 100644
--- a/core/src/mouse.rs
+++ b/core/src/mouse.rs
@@ -1,8 +1,11 @@
 //! Handle mouse events.
+pub mod click;
+
 mod button;
 mod event;
 mod interaction;
 
 pub use button::Button;
+pub use click::Click;
 pub use event::{Event, ScrollDelta};
 pub use interaction::Interaction;
diff --git a/native/src/mouse/click.rs b/core/src/mouse/click.rs
index 4a7d796c..4a7d796c 100644
--- a/native/src/mouse/click.rs
+++ b/core/src/mouse/click.rs
diff --git a/native/src/overlay.rs b/core/src/overlay.rs
index 6cada416..b9f3c735 100644
--- a/native/src/overlay.rs
+++ b/core/src/overlay.rs
@@ -2,11 +2,8 @@
 mod element;
 mod group;
 
-pub mod menu;
-
 pub use element::Element;
 pub use group::Group;
-pub use menu::Menu;
 
 use crate::event::{self, Event};
 use crate::layout;
diff --git a/native/src/overlay/element.rs b/core/src/overlay/element.rs
index 237d25d1..237d25d1 100644
--- a/native/src/overlay/element.rs
+++ b/core/src/overlay/element.rs
diff --git a/native/src/overlay/group.rs b/core/src/overlay/group.rs
index 1126f0cf..0c48df34 100644
--- a/native/src/overlay/group.rs
+++ b/core/src/overlay/group.rs
@@ -1,12 +1,10 @@
-use iced_core::{Point, Rectangle, Size};
-
 use crate::event;
 use crate::layout;
 use crate::mouse;
 use crate::overlay;
 use crate::renderer;
 use crate::widget;
-use crate::{Clipboard, Event, Layout, Overlay, Shell};
+use crate::{Clipboard, Event, Layout, Overlay, Point, Rectangle, Shell, Size};
 
 /// An [`Overlay`] container that displays multiple overlay [`overlay::Element`]
 /// children.
diff --git a/core/src/padding.rs b/core/src/padding.rs
index 752b2b86..0b1bba13 100644
--- a/core/src/padding.rs
+++ b/core/src/padding.rs
@@ -77,12 +77,14 @@ impl Padding {
     /// Fits the [`Padding`] between the provided `inner` and `outer` [`Size`].
     pub fn fit(self, inner: Size, outer: Size) -> Self {
         let available = (outer - inner).max(Size::ZERO);
+        let new_top = self.top.min(available.height);
+        let new_left = self.left.min(available.width);
 
         Padding {
-            top: self.top.min(available.height / 2.0),
-            right: self.right.min(available.width / 2.0),
-            bottom: self.bottom.min(available.height / 2.0),
-            left: self.left.min(available.width / 2.0),
+            top: new_top,
+            bottom: self.bottom.min(available.height - new_top),
+            left: new_left,
+            right: self.right.min(available.width - new_left),
         }
     }
 }
diff --git a/native/src/renderer.rs b/core/src/renderer.rs
index 2ac78982..d6247e39 100644
--- a/native/src/renderer.rs
+++ b/core/src/renderer.rs
@@ -1,6 +1,7 @@
 //! Write your own renderer.
 #[cfg(debug_assertions)]
 mod null;
+
 #[cfg(debug_assertions)]
 pub use null::Null;
 
diff --git a/native/src/renderer/null.rs b/core/src/renderer/null.rs
index 150ee786..d93338ae 100644
--- a/native/src/renderer/null.rs
+++ b/core/src/renderer/null.rs
@@ -1,6 +1,6 @@
 use crate::renderer::{self, Renderer};
 use crate::text::{self, Text};
-use crate::{Background, Font, Point, Rectangle, Size, Theme, Vector};
+use crate::{Background, Font, Point, Rectangle, Size, Vector};
 
 use std::borrow::Cow;
 
@@ -18,7 +18,7 @@ impl Null {
 }
 
 impl Renderer for Null {
-    type Theme = Theme;
+    type Theme = ();
 
     fn with_layer(&mut self, _bounds: Rectangle, _f: impl FnOnce(&mut Self)) {}
 
diff --git a/native/src/shell.rs b/core/src/shell.rs
index 74a5c616..74a5c616 100644
--- a/native/src/shell.rs
+++ b/core/src/shell.rs
diff --git a/core/src/size.rs b/core/src/size.rs
index fbe940ef..7ef2f602 100644
--- a/core/src/size.rs
+++ b/core/src/size.rs
@@ -1,7 +1,7 @@
 use crate::{Padding, Vector};
 
 /// An amount of space in 2 dimensions.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Size<T = f32> {
     /// The width.
     pub width: T,
diff --git a/native/src/svg.rs b/core/src/svg.rs
index 9b98877a..9b98877a 100644
--- a/native/src/svg.rs
+++ b/core/src/svg.rs
diff --git a/native/src/text.rs b/core/src/text.rs
index 4c72abc3..4c72abc3 100644
--- a/native/src/text.rs
+++ b/core/src/text.rs
diff --git a/native/src/touch.rs b/core/src/touch.rs
index 18120644..18120644 100644
--- a/native/src/touch.rs
+++ b/core/src/touch.rs
diff --git a/native/src/widget.rs b/core/src/widget.rs
index 2b3ca7be..70e2c2d9 100644
--- a/native/src/widget.rs
+++ b/core/src/widget.rs
@@ -1,98 +1,21 @@
-//! Use the built-in widgets or create your own.
-//!
-//! # Built-in widgets
-//! Every built-in drawable widget has its own module with a `Renderer` trait
-//! that must be implemented by a [renderer] before being able to use it as
-//! a [`Widget`].
-//!
-//! # Custom widgets
-//! If you want to implement a custom widget, you simply need to implement the
-//! [`Widget`] trait. You can use the API of the built-in widgets as a guide or
-//! source of inspiration.
-//!
-//! [renderer]: crate::renderer
-pub mod button;
-pub mod checkbox;
-pub mod column;
-pub mod container;
-pub mod helpers;
-pub mod image;
+//! Create custom widgets and operate on them.
 pub mod operation;
-pub mod pane_grid;
-pub mod pick_list;
-pub mod progress_bar;
-pub mod radio;
-pub mod row;
-pub mod rule;
-pub mod scrollable;
-pub mod slider;
-pub mod space;
-pub mod svg;
 pub mod text;
-pub mod text_input;
-pub mod toggler;
-pub mod tooltip;
 pub mod tree;
-pub mod vertical_slider;
 
-mod action;
 mod id;
 
-#[doc(no_inline)]
-pub use button::Button;
-#[doc(no_inline)]
-pub use checkbox::Checkbox;
-#[doc(no_inline)]
-pub use column::Column;
-#[doc(no_inline)]
-pub use container::Container;
-#[doc(no_inline)]
-pub use helpers::*;
-#[doc(no_inline)]
-pub use image::Image;
-#[doc(no_inline)]
-pub use pane_grid::PaneGrid;
-#[doc(no_inline)]
-pub use pick_list::PickList;
-#[doc(no_inline)]
-pub use progress_bar::ProgressBar;
-#[doc(no_inline)]
-pub use radio::Radio;
-#[doc(no_inline)]
-pub use row::Row;
-#[doc(no_inline)]
-pub use rule::Rule;
-#[doc(no_inline)]
-pub use scrollable::Scrollable;
-#[doc(no_inline)]
-pub use slider::Slider;
-#[doc(no_inline)]
-pub use space::Space;
-#[doc(no_inline)]
-pub use svg::Svg;
-#[doc(no_inline)]
-pub use text::Text;
-#[doc(no_inline)]
-pub use text_input::TextInput;
-#[doc(no_inline)]
-pub use toggler::Toggler;
-#[doc(no_inline)]
-pub use tooltip::Tooltip;
-#[doc(no_inline)]
-pub use tree::Tree;
-#[doc(no_inline)]
-pub use vertical_slider::VerticalSlider;
-
-pub use action::Action;
 pub use id::Id;
 pub use operation::Operation;
+pub use text::Text;
+pub use tree::Tree;
 
 use crate::event::{self, Event};
-use crate::layout;
+use crate::layout::{self, Layout};
 use crate::mouse;
 use crate::overlay;
 use crate::renderer;
-use crate::{Clipboard, Layout, Length, Point, Rectangle, Shell};
+use crate::{Clipboard, Length, Point, Rectangle, Shell};
 
 /// A component that displays information and allows interaction.
 ///
diff --git a/native/src/widget/id.rs b/core/src/widget/id.rs
index 4b8fedf1..ae739bb7 100644
--- a/native/src/widget/id.rs
+++ b/core/src/widget/id.rs
@@ -24,7 +24,7 @@ impl Id {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub enum Internal {
+enum Internal {
     Unique(usize),
     Custom(borrow::Cow<'static, str>),
 }
diff --git a/core/src/widget/operation.rs b/core/src/widget/operation.rs
new file mode 100644
index 00000000..ad188c36
--- /dev/null
+++ b/core/src/widget/operation.rs
@@ -0,0 +1,226 @@
+//! Query or update internal widget state.
+pub mod focusable;
+pub mod scrollable;
+pub mod text_input;
+
+pub use focusable::Focusable;
+pub use scrollable::Scrollable;
+pub use text_input::TextInput;
+
+use crate::widget::Id;
+
+use std::any::Any;
+use std::fmt;
+use std::rc::Rc;
+
+/// A piece of logic that can traverse the widget tree of an application in
+/// order to query or update some widget state.
+pub trait Operation<T> {
+    /// Operates on a widget that contains other widgets.
+    ///
+    /// The `operate_on_children` function can be called to return control to
+    /// the widget tree and keep traversing it.
+    fn container(
+        &mut self,
+        id: Option<&Id>,
+        operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+    );
+
+    /// Operates on a widget that can be focused.
+    fn focusable(&mut self, _state: &mut dyn Focusable, _id: Option<&Id>) {}
+
+    /// Operates on a widget that can be scrolled.
+    fn scrollable(&mut self, _state: &mut dyn Scrollable, _id: Option<&Id>) {}
+
+    /// Operates on a widget that has text input.
+    fn text_input(&mut self, _state: &mut dyn TextInput, _id: Option<&Id>) {}
+
+    /// Operates on a custom widget with some state.
+    fn custom(&mut self, _state: &mut dyn Any, _id: Option<&Id>) {}
+
+    /// Finishes the [`Operation`] and returns its [`Outcome`].
+    fn finish(&self) -> Outcome<T> {
+        Outcome::None
+    }
+}
+
+/// The result of an [`Operation`].
+pub enum Outcome<T> {
+    /// The [`Operation`] produced no result.
+    None,
+
+    /// The [`Operation`] produced some result.
+    Some(T),
+
+    /// The [`Operation`] needs to be followed by another [`Operation`].
+    Chain(Box<dyn Operation<T>>),
+}
+
+impl<T> fmt::Debug for Outcome<T>
+where
+    T: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::None => write!(f, "Outcome::None"),
+            Self::Some(output) => write!(f, "Outcome::Some({output:?})"),
+            Self::Chain(_) => write!(f, "Outcome::Chain(...)"),
+        }
+    }
+}
+
+/// Maps the output of an [`Operation`] using the given function.
+pub fn map<A, B>(
+    operation: Box<dyn Operation<A>>,
+    f: impl Fn(A) -> B + 'static,
+) -> impl Operation<B>
+where
+    A: 'static,
+    B: 'static,
+{
+    #[allow(missing_debug_implementations)]
+    struct Map<A, B> {
+        operation: Box<dyn Operation<A>>,
+        f: Rc<dyn Fn(A) -> B>,
+    }
+
+    impl<A, B> Operation<B> for Map<A, B>
+    where
+        A: 'static,
+        B: 'static,
+    {
+        fn container(
+            &mut self,
+            id: Option<&Id>,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<B>),
+        ) {
+            struct MapRef<'a, A> {
+                operation: &'a mut dyn Operation<A>,
+            }
+
+            impl<'a, A, B> Operation<B> for MapRef<'a, A> {
+                fn container(
+                    &mut self,
+                    id: Option<&Id>,
+                    operate_on_children: &mut dyn FnMut(&mut dyn Operation<B>),
+                ) {
+                    let Self { operation, .. } = self;
+
+                    operation.container(id, &mut |operation| {
+                        operate_on_children(&mut MapRef { operation });
+                    });
+                }
+
+                fn scrollable(
+                    &mut self,
+                    state: &mut dyn Scrollable,
+                    id: Option<&Id>,
+                ) {
+                    self.operation.scrollable(state, id);
+                }
+
+                fn focusable(
+                    &mut self,
+                    state: &mut dyn Focusable,
+                    id: Option<&Id>,
+                ) {
+                    self.operation.focusable(state, id);
+                }
+
+                fn text_input(
+                    &mut self,
+                    state: &mut dyn TextInput,
+                    id: Option<&Id>,
+                ) {
+                    self.operation.text_input(state, id);
+                }
+
+                fn custom(&mut self, state: &mut dyn Any, id: Option<&Id>) {
+                    self.operation.custom(state, id);
+                }
+            }
+
+            let Self { operation, .. } = self;
+
+            MapRef {
+                operation: operation.as_mut(),
+            }
+            .container(id, operate_on_children);
+        }
+
+        fn focusable(&mut self, state: &mut dyn Focusable, id: Option<&Id>) {
+            self.operation.focusable(state, id);
+        }
+
+        fn scrollable(&mut self, state: &mut dyn Scrollable, id: Option<&Id>) {
+            self.operation.scrollable(state, id);
+        }
+
+        fn text_input(&mut self, state: &mut dyn TextInput, id: Option<&Id>) {
+            self.operation.text_input(state, id);
+        }
+
+        fn custom(&mut self, state: &mut dyn Any, id: Option<&Id>) {
+            self.operation.custom(state, id);
+        }
+
+        fn finish(&self) -> Outcome<B> {
+            match self.operation.finish() {
+                Outcome::None => Outcome::None,
+                Outcome::Some(output) => Outcome::Some((self.f)(output)),
+                Outcome::Chain(next) => Outcome::Chain(Box::new(Map {
+                    operation: next,
+                    f: self.f.clone(),
+                })),
+            }
+        }
+    }
+
+    Map {
+        operation,
+        f: Rc::new(f),
+    }
+}
+
+/// Produces an [`Operation`] that applies the given [`Operation`] to the
+/// children of a container with the given [`Id`].
+pub fn scope<T: 'static>(
+    target: Id,
+    operation: impl Operation<T> + 'static,
+) -> impl Operation<T> {
+    struct ScopedOperation<Message> {
+        target: Id,
+        operation: Box<dyn Operation<Message>>,
+    }
+
+    impl<Message: 'static> Operation<Message> for ScopedOperation<Message> {
+        fn container(
+            &mut self,
+            id: Option<&Id>,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<Message>),
+        ) {
+            if id == Some(&self.target) {
+                operate_on_children(self.operation.as_mut());
+            } else {
+                operate_on_children(self);
+            }
+        }
+
+        fn finish(&self) -> Outcome<Message> {
+            match self.operation.finish() {
+                Outcome::Chain(next) => {
+                    Outcome::Chain(Box::new(ScopedOperation {
+                        target: self.target.clone(),
+                        operation: next,
+                    }))
+                }
+                outcome => outcome,
+            }
+        }
+    }
+
+    ScopedOperation {
+        target,
+        operation: Box::new(operation),
+    }
+}
diff --git a/native/src/widget/operation/focusable.rs b/core/src/widget/operation/focusable.rs
index 312e4894..312e4894 100644
--- a/native/src/widget/operation/focusable.rs
+++ b/core/src/widget/operation/focusable.rs
diff --git a/native/src/widget/operation/scrollable.rs b/core/src/widget/operation/scrollable.rs
index 3b20631f..3b20631f 100644
--- a/native/src/widget/operation/scrollable.rs
+++ b/core/src/widget/operation/scrollable.rs
diff --git a/native/src/widget/operation/text_input.rs b/core/src/widget/operation/text_input.rs
index 4c773e99..4c773e99 100644
--- a/native/src/widget/operation/text_input.rs
+++ b/core/src/widget/operation/text_input.rs
diff --git a/native/src/widget/text.rs b/core/src/widget/text.rs
index aede754a..485bb542 100644
--- a/native/src/widget/text.rs
+++ b/core/src/widget/text.rs
@@ -4,27 +4,13 @@ use crate::layout;
 use crate::renderer;
 use crate::text;
 use crate::widget::Tree;
-use crate::{Element, Layout, Length, Pixels, Point, Rectangle, Size, Widget};
+use crate::{
+    Color, Element, Layout, Length, Pixels, Point, Rectangle, Size, Widget,
+};
 
 use std::borrow::Cow;
 
-pub use iced_style::text::{Appearance, StyleSheet};
-
 /// A paragraph of text.
-///
-/// # Example
-///
-/// ```
-/// # use iced_native::Color;
-/// #
-/// # type Text<'a> = iced_native::widget::Text<'a, iced_native::renderer::Null>;
-/// #
-/// Text::new("I <3 iced!")
-///     .size(40)
-///     .style(Color::from([0.0, 0.0, 1.0]));
-/// ```
-///
-/// ![Text drawn by `iced_wgpu`](https://github.com/iced-rs/iced/blob/7760618fb112074bc40b148944521f312152012a/docs/images/text.png?raw=true)
 #[allow(missing_debug_implementations)]
 pub struct Text<'a, Renderer>
 where
@@ -211,7 +197,7 @@ pub fn draw<Renderer>(
         alignment::Vertical::Bottom => bounds.y + bounds.height,
     };
 
-    renderer.fill_text(crate::text::Text {
+    renderer.fill_text(crate::Text {
         content,
         size: size.unwrap_or_else(|| renderer.default_size()),
         bounds: Rectangle { x, y, ..bounds },
@@ -252,12 +238,40 @@ where
     }
 }
 
+impl<'a, Renderer> From<&'a str> for Text<'a, Renderer>
+where
+    Renderer: text::Renderer,
+    Renderer::Theme: StyleSheet,
+{
+    fn from(content: &'a str) -> Self {
+        Self::new(content)
+    }
+}
+
 impl<'a, Message, Renderer> From<&'a str> for Element<'a, Message, Renderer>
 where
     Renderer: text::Renderer + 'a,
     Renderer::Theme: StyleSheet,
 {
-    fn from(contents: &'a str) -> Self {
-        Text::new(contents).into()
+    fn from(content: &'a str) -> Self {
+        Text::from(content).into()
     }
 }
+
+/// The style sheet of some text.
+pub trait StyleSheet {
+    /// The supported style of the [`StyleSheet`].
+    type Style: Default + Copy;
+
+    /// Produces the [`Appearance`] of some text.
+    fn appearance(&self, style: Self::Style) -> Appearance;
+}
+
+/// The apperance of some text.
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Appearance {
+    /// The [`Color`] of the text.
+    ///
+    /// The default, `None`, means using the inherited color.
+    pub color: Option<Color>,
+}
diff --git a/native/src/widget/tree.rs b/core/src/widget/tree.rs
index 0af40c33..0af40c33 100644
--- a/native/src/widget/tree.rs
+++ b/core/src/widget/tree.rs
diff --git a/core/src/window.rs b/core/src/window.rs
new file mode 100644
index 00000000..d829a4b4
--- /dev/null
+++ b/core/src/window.rs
@@ -0,0 +1,10 @@
+//! Build window-based GUI applications.
+mod event;
+mod mode;
+mod redraw_request;
+mod user_attention;
+
+pub use event::Event;
+pub use mode::Mode;
+pub use redraw_request::RedrawRequest;
+pub use user_attention::UserAttention;
diff --git a/native/src/window/event.rs b/core/src/window/event.rs
index e2fb5e66..e2fb5e66 100644
--- a/native/src/window/event.rs
+++ b/core/src/window/event.rs
diff --git a/native/src/window/mode.rs b/core/src/window/mode.rs
index fdce8e23..fdce8e23 100644
--- a/native/src/window/mode.rs
+++ b/core/src/window/mode.rs
diff --git a/native/src/window/redraw_request.rs b/core/src/window/redraw_request.rs
index 3b4f0fd3..3b4f0fd3 100644
--- a/native/src/window/redraw_request.rs
+++ b/core/src/window/redraw_request.rs
diff --git a/native/src/window/user_attention.rs b/core/src/window/user_attention.rs
index b03dfeef..b03dfeef 100644
--- a/native/src/window/user_attention.rs
+++ b/core/src/window/user_attention.rs