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-rw-r--r--native/src/widget/column.rs2
-rw-r--r--native/src/widget/row.rs2
-rw-r--r--native/src/widget/tooltip.rs2
-rw-r--r--pure/src/element.rs146
-rw-r--r--pure/src/helpers.rs50
-rw-r--r--pure/src/lib.rs119
-rw-r--r--pure/src/overlay.rs5
-rw-r--r--pure/src/widget.rs49
-rw-r--r--pure/src/widget/button.rs36
-rw-r--r--pure/src/widget/checkbox.rs1
-rw-r--r--pure/src/widget/column.rs13
-rw-r--r--pure/src/widget/image.rs1
-rw-r--r--pure/src/widget/pane_grid.rs2
-rw-r--r--pure/src/widget/pane_grid/content.rs4
-rw-r--r--pure/src/widget/pane_grid/title_bar.rs4
-rw-r--r--pure/src/widget/progress_bar.rs1
-rw-r--r--pure/src/widget/radio.rs1
-rw-r--r--pure/src/widget/row.rs13
-rw-r--r--pure/src/widget/rule.rs1
-rw-r--r--pure/src/widget/scrollable.rs1
-rw-r--r--pure/src/widget/svg.rs1
-rw-r--r--pure/src/widget/text_input.rs6
-rw-r--r--pure/src/widget/toggler.rs1
-rw-r--r--pure/src/widget/tooltip.rs2
-rw-r--r--pure/src/widget/tree.rs48
-rw-r--r--src/pure.rs78
26 files changed, 558 insertions, 31 deletions
diff --git a/native/src/widget/column.rs b/native/src/widget/column.rs
index f161d1f2..268218b1 100644
--- a/native/src/widget/column.rs
+++ b/native/src/widget/column.rs
@@ -48,7 +48,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
/// Sets the vertical spacing _between_ elements.
///
- /// Custom margins per element do not exist in Iced. You should use this
+ /// Custom margins per element do not exist in iced. You should use this
/// method instead! While less flexible, it helps you keep spacing between
/// elements consistent.
pub fn spacing(mut self, units: u16) -> Self {
diff --git a/native/src/widget/row.rs b/native/src/widget/row.rs
index e34befb2..7a7c70c6 100644
--- a/native/src/widget/row.rs
+++ b/native/src/widget/row.rs
@@ -48,7 +48,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
/// Sets the horizontal spacing _between_ elements.
///
- /// Custom margins per element do not exist in Iced. You should use this
+ /// Custom margins per element do not exist in iced. You should use this
/// method instead! While less flexible, it helps you keep spacing between
/// elements consistent.
pub fn spacing(mut self, units: u16) -> Self {
diff --git a/native/src/widget/tooltip.rs b/native/src/widget/tooltip.rs
index e178c8b2..c929395f 100644
--- a/native/src/widget/tooltip.rs
+++ b/native/src/widget/tooltip.rs
@@ -29,7 +29,7 @@ where
/// The default padding of a [`Tooltip`] drawn by this renderer.
const DEFAULT_PADDING: u16 = 5;
- /// Creates an empty [`Tooltip`].
+ /// Creates a new [`Tooltip`].
///
/// [`Tooltip`]: struct.Tooltip.html
pub fn new(
diff --git a/pure/src/element.rs b/pure/src/element.rs
index 08096103..704b3d0b 100644
--- a/pure/src/element.rs
+++ b/pure/src/element.rs
@@ -8,25 +8,171 @@ use iced_native::mouse;
use iced_native::renderer;
use iced_native::{Clipboard, Length, Point, Rectangle, Shell};
+/// A generic [`Widget`].
+///
+/// It is useful to build composable user interfaces that do not leak
+/// implementation details in their __view logic__.
+///
+/// If you have a [built-in widget], you should be able to use `Into<Element>`
+/// to turn it into an [`Element`].
+///
+/// [built-in widget]: crate::widget
pub struct Element<'a, Message, Renderer> {
widget: Box<dyn Widget<Message, Renderer> + 'a>,
}
impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
+ /// Creates a new [`Element`] containing the given [`Widget`].
pub fn new(widget: impl Widget<Message, Renderer> + 'a) -> Self {
Self {
widget: Box::new(widget),
}
}
+ /// Returns a reference to the [`Widget`] of the [`Element`],
pub fn as_widget(&self) -> &dyn Widget<Message, Renderer> {
self.widget.as_ref()
}
+ /// Returns a mutable reference to the [`Widget`] of the [`Element`],
pub fn as_widget_mut(&mut self) -> &mut dyn Widget<Message, Renderer> {
self.widget.as_mut()
}
+ /// Applies a transformation to the produced message of the [`Element`].
+ ///
+ /// This method is useful when you want to decouple different parts of your
+ /// UI and make them __composable__.
+ ///
+ /// # Example
+ /// Imagine we want to use [our counter](index.html#usage). But instead of
+ /// showing a single counter, we want to display many of them. We can reuse
+ /// the `Counter` type as it is!
+ ///
+ /// We use composition to model the __state__ of our new application:
+ ///
+ /// ```
+ /// # mod counter {
+ /// # pub struct Counter;
+ /// # }
+ /// use counter::Counter;
+ ///
+ /// struct ManyCounters {
+ /// counters: Vec<Counter>,
+ /// }
+ /// ```
+ ///
+ /// We can store the state of multiple counters now. However, the
+ /// __messages__ we implemented before describe the user interactions
+ /// of a __single__ counter. Right now, we need to also identify which
+ /// counter is receiving user interactions. Can we use composition again?
+ /// Yes.
+ ///
+ /// ```
+ /// # mod counter {
+ /// # #[derive(Debug, Clone, Copy)]
+ /// # pub enum Message {}
+ /// # }
+ /// #[derive(Debug, Clone, Copy)]
+ /// pub enum Message {
+ /// Counter(usize, counter::Message)
+ /// }
+ /// ```
+ ///
+ /// We compose the previous __messages__ with the index of the counter
+ /// producing them. Let's implement our __view logic__ now:
+ ///
+ /// ```
+ /// # mod counter {
+ /// # type Text = iced_pure::widget::Text<iced_native::renderer::Null>;
+ /// #
+ /// # #[derive(Debug, Clone, Copy)]
+ /// # pub enum Message {}
+ /// # pub struct Counter;
+ /// #
+ /// # impl Counter {
+ /// # pub fn view(&mut self) -> Text {
+ /// # Text::new("")
+ /// # }
+ /// # }
+ /// # }
+ /// #
+ /// # mod iced_wgpu {
+ /// # pub use iced_native::renderer::Null as Renderer;
+ /// # }
+ /// #
+ /// # use counter::Counter;
+ /// #
+ /// # struct ManyCounters {
+ /// # counters: Vec<Counter>,
+ /// # }
+ /// #
+ /// # #[derive(Debug, Clone, Copy)]
+ /// # pub enum Message {
+ /// # Counter(usize, counter::Message)
+ /// # }
+ /// use iced_pure::Element;
+ /// use iced_pure::widget::Row;
+ /// use iced_wgpu::Renderer;
+ ///
+ /// impl ManyCounters {
+ /// pub fn view(&mut self) -> Row<Message, Renderer> {
+ /// // We can quickly populate a `Row` by folding over our counters
+ /// self.counters.iter_mut().enumerate().fold(
+ /// Row::new().spacing(20),
+ /// |row, (index, counter)| {
+ /// // We display the counter
+ /// let element: Element<counter::Message, Renderer> =
+ /// counter.view().into();
+ ///
+ /// row.push(
+ /// // 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))
+ /// )
+ /// }
+ /// )
+ /// }
+ /// }
+ /// ```
+ ///
+ /// Finally, our __update logic__ is pretty straightforward: simple
+ /// delegation.
+ ///
+ /// ```
+ /// # mod counter {
+ /// # #[derive(Debug, Clone, Copy)]
+ /// # pub enum Message {}
+ /// # pub struct Counter;
+ /// #
+ /// # impl Counter {
+ /// # pub fn update(&mut self, _message: Message) {}
+ /// # }
+ /// # }
+ /// #
+ /// # use counter::Counter;
+ /// #
+ /// # struct ManyCounters {
+ /// # counters: Vec<Counter>,
+ /// # }
+ /// #
+ /// # #[derive(Debug, Clone, Copy)]
+ /// # pub enum Message {
+ /// # Counter(usize, counter::Message)
+ /// # }
+ /// impl ManyCounters {
+ /// pub fn update(&mut self, message: Message) {
+ /// match message {
+ /// Message::Counter(index, counter_msg) => {
+ /// if let Some(counter) = self.counters.get_mut(index) {
+ /// counter.update(counter_msg);
+ /// }
+ /// }
+ /// }
+ /// }
+ /// }
+ /// ```
pub fn map<B>(
self,
f: impl Fn(Message) -> B + 'a,
diff --git a/pure/src/helpers.rs b/pure/src/helpers.rs
index d6744262..2c4a37be 100644
--- a/pure/src/helpers.rs
+++ b/pure/src/helpers.rs
@@ -1,3 +1,4 @@
+//! Helper functions to create pure widgets.
use crate::widget;
use crate::Element;
@@ -5,6 +6,9 @@ use iced_native::Length;
use std::borrow::Cow;
use std::ops::RangeInclusive;
+/// Creates a new [`Container`] with the provided content.
+///
+/// [`Container`]: widget::Container
pub fn container<'a, Message, Renderer>(
content: impl Into<Element<'a, Message, Renderer>>,
) -> widget::Container<'a, Message, Renderer>
@@ -14,15 +18,24 @@ where
widget::Container::new(content)
}
+/// Creates a new [`Column`].
+///
+/// [`Column`]: widget::Column
pub fn column<'a, Message, Renderer>() -> widget::Column<'a, Message, Renderer>
{
widget::Column::new()
}
+/// Creates a new [`Row`].
+///
+/// [`Row`]: widget::Row
pub fn row<'a, Message, Renderer>() -> widget::Row<'a, Message, Renderer> {
widget::Row::new()
}
+/// Creates a new [`Scrollable`] with the provided content.
+///
+/// [`Scrollable`]: widget::Scrollable
pub fn scrollable<'a, Message, Renderer>(
content: impl Into<Element<'a, Message, Renderer>>,
) -> widget::Scrollable<'a, Message, Renderer>
@@ -32,12 +45,19 @@ where
widget::Scrollable::new(content)
}
+/// Creates a new [`Button`] with the provided content.
+///
+/// [`Button`]: widget::Button
pub fn button<'a, Message, Renderer>(
content: impl Into<Element<'a, Message, Renderer>>,
) -> widget::Button<'a, Message, Renderer> {
widget::Button::new(content)
}
+/// Creates a new [`Tooltip`] with the provided content, tooltip text, and [`tooltip::Position`].
+///
+/// [`Tooltip`]: widget::Tooltip
+/// [`tooltip::Position`]: widget::tooltip::Position
pub fn tooltip<'a, Message, Renderer>(
content: impl Into<Element<'a, Message, Renderer>>,
tooltip: impl ToString,
@@ -49,6 +69,9 @@ where
widget::Tooltip::new(content, tooltip, position)
}
+/// Creates a new [`Text`] widget with the provided content.
+///
+/// [`Text`]: widget::Text
pub fn text<Renderer>(text: impl Into<String>) -> widget::Text<Renderer>
where
Renderer: iced_native::text::Renderer,
@@ -56,6 +79,9 @@ where
widget::Text::new(text)
}
+/// Creates a new [`Checkbox`].
+///
+/// [`Checkbox`]: widget::Checkbox
pub fn checkbox<'a, Message, Renderer>(
label: impl Into<String>,
is_checked: bool,
@@ -67,6 +93,9 @@ where
widget::Checkbox::new(is_checked, label, f)
}
+/// Creates a new [`Radio`].
+///
+/// [`Radio`]: widget::Radio
pub fn radio<'a, Message, Renderer, V>(
label: impl Into<String>,
value: V,
@@ -81,6 +110,9 @@ where
widget::Radio::new(value, label, selected, on_click)
}
+/// Creates a new [`Toggler`].
+///
+/// [`Toggler`]: widget::Toggler
pub fn toggler<'a, Message, Renderer>(
label: impl Into<Option<String>>,
is_checked: bool,
@@ -92,6 +124,9 @@ where
widget::Toggler::new(is_checked, label, f)
}
+/// Creates a new [`TextInput`].
+///
+/// [`TextInput`]: widget::TextInput
pub fn text_input<'a, Message, Renderer>(
placeholder: &str,
value: &str,
@@ -104,6 +139,9 @@ where
widget::TextInput::new(placeholder, value, on_change)
}
+/// Creates a new [`Slider`].
+///
+/// [`Slider`]: widget::Slider
pub fn slider<'a, Message, T>(
range: std::ops::RangeInclusive<T>,
value: T,
@@ -116,6 +154,9 @@ where
widget::Slider::new(range, value, on_change)
}
+/// Creates a new [`PickList`].
+///
+/// [`PickList`]: widget::PickList
pub fn pick_list<'a, Message, Renderer, T>(
options: impl Into<Cow<'a, [T]>>,
selected: Option<T>,
@@ -129,14 +170,23 @@ where
widget::PickList::new(options, selected, on_selected)
}
+/// Creates a new [`Image`].
+///
+/// [`Image`]: widget::Image
pub fn image<Handle>(handle: impl Into<Handle>) -> widget::Image<Handle> {
widget::Image::new(handle.into())
}
+/// Creates a new horizontal [`Space`] with the given [`Length`].
+///
+/// [`Space`]: widget::Space
pub fn horizontal_space(width: Length) -> widget::Space {
widget::Space::with_width(width)
}
+/// Creates a new vertical [`Space`] with the given [`Length`].
+///
+/// [`Space`]: widget::Space
pub fn vertical_space(height: Length) -> widget::Space {
widget::Space::with_height(height)
}
diff --git a/pure/src/lib.rs b/pure/src/lib.rs
index f9f0ae2d..fc803222 100644
--- a/pure/src/lib.rs
+++ b/pure/src/lib.rs
@@ -1,3 +1,93 @@
+//! Stateless, pure widgets for iced.
+//!
+//! # The Elm Architecture, purity, and continuity
+//! As you may know, applications made with `iced` use [The Elm Architecture].
+//!
+//! In a nutshell, this architecture defines the initial state of the application, a way to `view` it, and a way to `update` it after a user interaction. The `update` logic is called after a meaningful user interaction, which in turn updates the state of the application. Then, the `view` logic is executed to redisplay the application.
+//!
+//! Since `view` logic is only run after an `update`, all of the mutations to the application state must only happen in the `update` logic. If the application state changes anywhere else, the `view` logic will not be rerun and, therefore, the previously generated `view` may stay outdated.
+//!
+//! However, the `Application` trait in `iced` defines `view` as:
+//!
+//! ```ignore
+//! pub trait Application {
+//! fn view(&mut self) -> Element<Self::Message>;
+//! }
+//! ```
+//!
+//! As a consequence, the application state can be mutated in `view` logic. The `view` logic in `iced` is __impure__.
+//!
+//! This impurity is necessary because `iced` puts the burden of widget __continuity__ on its users. In other words, it's up to you to provide `iced` with the internal state of each widget every time `view` is called.
+//!
+//! If we take a look at the classic `counter` example:
+//!
+//! ```ignore
+//! struct Counter {
+//! value: i32,
+//! increment_button: button::State,
+//! decrement_button: button::State,
+//! }
+//!
+//! // ...
+//!
+//! impl Counter {
+//! pub fn view(&mut self) -> Column<Message> {
+//! Column::new()
+//! .push(
+//! Button::new(&mut self.increment_button, Text::new("+"))
+//! .on_press(Message::IncrementPressed),
+//! )
+//! .push(Text::new(self.value.to_string()).size(50))
+//! .push(
+//! Button::new(&mut self.decrement_button, Text::new("-"))
+//! .on_press(Message::DecrementPressed),
+//! )
+//! }
+//! }
+//! ```
+//!
+//! We can see how we need to keep track of the `button::State` of each `Button` in our `Counter` state and provide a mutable reference to the widgets in our `view` logic. The widgets produced by `view` are __stateful__.
+//!
+//! While this approach forces users to keep track of widget state and causes impurity, I originally chose it because it allows `iced` to directly consume the widget tree produced by `view`. Since there is no internal state decoupled from `view` maintained by the runtime, `iced` does not need to compare (e.g. reconciliate) widget trees in order to ensure continuity.
+//!
+//! # Stateless widgets
+//! As the library matures, the need for some kind of persistent widget data (see #553) between `view` calls becomes more apparent (e.g. incremental rendering, animations, accessibility, etc.).
+//!
+//! If we are going to end up having persistent widget data anyways... There is no reason to have impure, stateful widgets anymore!
+//!
+//! And so I started exploring and ended up creating a new subcrate called `iced_pure`, which introduces a completely stateless implementation for every widget in `iced`.
+//!
+//! With the help of this crate, we can now write a pure `counter` example:
+//!
+//! ```ignore
+//! struct Counter {
+//! value: i32,
+//! }
+//!
+//! // ...
+//!
+//! impl Counter {
+//! fn view(&self) -> Column<Message> {
+//! Column::new()
+//! .push(Button::new("Increment").on_press(Message::IncrementPressed))
+//! .push(Text::new(self.value.to_string()).size(50))
+//! .push(Button::new("Decrement").on_press(Message::DecrementPressed))
+//! }
+//! }
+//! ```
+//!
+//! Notice how we no longer need to keep track of the `button::State`! The widgets in `iced_pure` do not take any mutable application state in `view`. They are __stateless__ widgets. As a consequence, we do not need mutable access to `self` in `view` anymore. `view` becomes __pure__.
+//!
+//! [The Elm Architecture]: https://guide.elm-lang.org/architecture/
+#![doc(
+ html_logo_url = "https://raw.githubusercontent.com/iced-rs/iced/9ab6923e943f784985e9ef9ca28b10278297225d/docs/logo.svg"
+)]
+#![deny(missing_docs)]
+//#![deny(missing_debug_implementations)]
+//#![deny(unused_results)]
+#![forbid(unsafe_code)]
+//#![forbid(rust_2018_idioms)]
+
pub mod helpers;
pub mod overlay;
pub mod widget;
@@ -16,6 +106,32 @@ use iced_native::mouse;
use iced_native::renderer;
use iced_native::{Clipboard, Length, Point, Rectangle, Shell};
+/// A bridge between impure and pure widgets.
+///
+/// If you already have an existing `iced` application, you do not need to switch completely to the new traits in order to benefit from the `pure` module. Instead, you can leverage the new `Pure` widget to include `pure` widgets in your impure `Application`.
+///
+/// For instance, let's say we want to use our pure `Counter` in an impure application:
+///
+/// ```ignore
+/// use iced_pure::{self, Pure};
+///
+/// struct Impure {
+/// state: pure::State,
+/// counter: Counter,
+/// }
+///
+/// impl Sandbox for Impure {
+/// // ...
+///
+/// pub fn view(&mut self) -> Element<Self::Message> {
+/// Pure::new(&mut self.state, self.counter.view()).into()
+/// }
+/// }
+/// ```
+///
+/// [`Pure`] acts as a bridge between pure and impure widgets. It is completely opt-in and can be used to slowly migrate your application to the new architecture.
+///
+/// The purification of your application may trigger a bunch of important refactors, since it's far easier to keep your data decoupled from the GUI state with stateless widgets. For this reason, I recommend starting small in the most nested views of your application and slowly expand the purity upwards.
pub struct Pure<'a, Message, Renderer> {
state: &'a mut State,
element: Element<'a, Message, Renderer>,
@@ -26,6 +142,7 @@ where
Message: 'a,
Renderer: iced_native::Renderer + 'a,
{
+ /// Creates a new [`Pure`] widget with the given [`State`] and impure [`Element`].
pub fn new(
state: &'a mut State,
content: impl Into<Element<'a, Message, Renderer>>,
@@ -37,6 +154,7 @@ where
}
}
+/// The internal state of a [`Pure`] widget.
pub struct State {
state_tree: widget::Tree,
}
@@ -48,6 +166,7 @@ impl Default for State {
}
impl State {
+ /// Creates a new [`State`] for a [`Pure`] widget.
pub fn new() -> Self {
Self {
state_tree: widget::Tree::empty(),
diff --git a/pure/src/overlay.rs b/pure/src/overlay.rs
index c87dfce8..fecaa2ac 100644
--- a/pure/src/overlay.rs
+++ b/pure/src/overlay.rs
@@ -1,9 +1,14 @@
+//! Display interactive elements on top of other widgets.
use crate::widget::Tree;
use iced_native::Layout;
pub use iced_native::overlay::*;
+/// Obtains the first overlay [`Element`] found in the given children.
+///
+/// This method will generally only be used by advanced users that are
+/// implementing the [`Widget`](crate::Widget) trait.
pub fn from_children<'a, Message, Renderer>(
children: &'a [crate::Element<'_, Message, Renderer>],
tree: &'a mut Tree,
diff --git a/pure/src/widget.rs b/pure/src/widget.rs
index adce17ea..cc04cc96 100644
--- a/pure/src/widget.rs
+++ b/pure/src/widget.rs
@@ -1,3 +1,4 @@
+//! Use the built-in widgets or create your own.
pub mod button;
pub mod checkbox;
pub mod container;
@@ -48,17 +49,28 @@ use iced_native::overlay;
use iced_native::renderer;
use iced_native::{Clipboard, Length, Point, Rectangle, Shell};
+/// A component that displays information and allows interaction.
+///
+/// If you want to build your own widgets, you will need to implement this
+/// trait.
pub trait Widget<Message, Renderer> {
+ /// Returns the width of the [`Widget`].
fn width(&self) -> Length;
+ /// Returns the height of the [`Widget`].
fn height(&self) -> Length;
+ /// Returns the [`layout::Node`] of the [`Widget`].
+ ///
+ /// This [`layout::Node`] is used by the runtime to compute the [`Layout`] of the
+ /// user interface.
fn layout(
&self,
renderer: &Renderer,
limits: &layout::Limits,
) -> layout::Node;
+ /// Draws the [`Widget`] using the associated `Renderer`.
fn draw(
&self,
state: &Tree,
@@ -69,31 +81,31 @@ pub trait Widget<Message, Renderer> {
viewport: &Rectangle,
);
+ /// Returns the [`Tag`] of the [`Widget`].
+ ///
+ /// [`Tag`]: tree::Tag
fn tag(&self) -> tree::Tag {
tree::Tag::stateless()
}
+ /// Returns the [`State`] of the [`Widget`].
+ ///
+ /// [`State`]: tree::State
fn state(&self) -> tree::State {
tree::State::None
}
+ /// Returns the state [`Tree`] of the children of the [`Widget`].
fn children(&self) -> Vec<Tree> {
Vec::new()
}
+ /// Reconciliates the [`Widget`] with the provided [`Tree`].
fn diff(&self, _tree: &mut Tree) {}
- fn mouse_interaction(
- &self,
- _state: &Tree,
- _layout: Layout<'_>,
- _cursor_position: Point,
- _viewport: &Rectangle,
- _renderer: &Renderer,
- ) -> mouse::Interaction {
- mouse::Interaction::Idle
- }
-
+ /// Processes a runtime [`Event`].
+ ///
+ /// By default, it does nothing.
fn on_event(
&mut self,
_state: &mut Tree,
@@ -107,6 +119,21 @@ pub trait Widget<Message, Renderer> {
event::Status::Ignored
}
+ /// Returns the current [`mouse::Interaction`] of the [`Widget`].
+ ///
+ /// By default, it returns [`mouse::Interaction::Idle`].
+ fn mouse_interaction(
+ &self,
+ _state: &Tree,
+ _layout: Layout<'_>,
+ _cursor_position: Point,
+ _viewport: &Rectangle,
+ _renderer: &Renderer,
+ ) -> mouse::Interaction {
+ mouse::Interaction::Idle
+ }
+
+ /// Returns the overlay of the [`Widget`], if there is any.
fn overlay<'a>(
&'a self,
_state: &'a mut Tree,
diff --git a/pure/src/widget/button.rs b/pure/src/widget/button.rs
index e083ea73..456c2509 100644
--- a/pure/src/widget/button.rs
+++ b/pure/src/widget/button.rs
@@ -1,3 +1,4 @@
+//! Allow your users to perform actions by pressing a button.
use crate::overlay;
use crate::widget::tree::{self, Tree};
use crate::{Element, Widget};
@@ -15,6 +16,40 @@ pub use iced_style::button::{Style, StyleSheet};
use button::State;
+/// A generic widget that produces a message when pressed.
+///
+/// ```
+/// # type Button<'a, Message> =
+/// # iced_pure::widget::Button<'a, Message, iced_native::renderer::Null>;
+/// #
+/// #[derive(Clone)]
+/// enum Message {
+/// ButtonPressed,
+/// }
+///
+/// let button = Button::new("Press me!").on_press(Message::ButtonPressed);
+/// ```
+///
+/// If a [`Button::on_press`] handler is not set, the resulting [`Button`] will
+/// be disabled:
+///
+/// ```
+/// # type Button<'a, Message> =
+/// # iced_pure::widget::Button<'a, Message, iced_native::renderer::Null>;
+/// #
+/// #[derive(Clone)]
+/// enum Message {
+/// ButtonPressed,
+/// }
+///
+/// fn disabled_button<'a>() -> Button<'a, Message> {
+/// Button::new("I'm disabled!")
+/// }
+///
+/// fn enabled_button<'a>() -> Button<'a, Message> {
+/// disabled_button().on_press(Message::ButtonPressed)
+/// }
+/// ```
pub struct Button<'a, Message, Renderer> {
content: Element<'a, Message, Renderer>,
on_press: Option<Message>,
@@ -25,6 +60,7 @@ pub struct Button<'a, Message, Renderer> {
}
impl<'a, Message, Renderer> Button<'a, Message, Renderer> {
+ /// Creates a new [`Button`] with the given content.
pub fn new(content: impl Into<Element<'a, Message, Renderer>>) -> Self {
Button {
content: content.into(),
diff --git a/pure/src/widget/checkbox.rs b/pure/src/widget/checkbox.rs
index 971980e3..98f55a56 100644
--- a/pure/src/widget/checkbox.rs
+++ b/pure/src/widget/checkbox.rs
@@ -1,3 +1,4 @@
+//! Show toggle controls using checkboxes.
use crate::widget::Tree;
use crate::{Element, Widget};
diff --git a/pure/src/widget/column.rs b/pure/src/widget/column.rs
index a4c0987b..7256f474 100644
--- a/pure/src/widget/column.rs
+++ b/pure/src/widget/column.rs
@@ -13,6 +13,7 @@ use iced_native::{
use std::u32;
+/// A container that distributes its contents vertically.
pub struct Column<'a, Message, Renderer> {
spacing: u16,
padding: Padding,
@@ -24,10 +25,12 @@ pub struct Column<'a, Message, Renderer> {
}
impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
+ /// Creates an empty [`Column`].
pub fn new() -> Self {
Self::with_children(Vec::new())
}
+ /// Creates a [`Column`] with the given elements.
pub fn with_children(
children: Vec<Element<'a, Message, Renderer>>,
) -> Self {
@@ -42,21 +45,29 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
}
}
+ /// Sets the vertical spacing _between_ elements.
+ ///
+ /// Custom margins per element do not exist in iced. You should use this
+ /// method instead! While less flexible, it helps you keep spacing between
+ /// elements consistent.
pub fn spacing(mut self, units: u16) -> Self {
self.spacing = units;
self
}
+ /// Sets the [`Padding`] of the [`Column`].
pub fn padding<P: Into<Padding>>(mut self, padding: P) -> Self {
self.padding = padding.into();
self
}
+ /// Sets the width of the [`Column`].
pub fn width(mut self, width: Length) -> Self {
self.width = width;
self
}
+ /// Sets the height of the [`Column`].
pub fn height(mut self, height: Length) -> Self {
self.height = height;
self
@@ -68,11 +79,13 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
self
}
+ /// Sets the horizontal alignment of the contents of the [`Column`] .
pub fn align_items(mut self, align: Alignment) -> Self {
self.align_items = align;
self
}
+ /// Adds an element to the [`Column`].
pub fn push(
mut self,
child: impl Into<Element<'a, Message, Renderer>>,
diff --git a/pure/src/widget/image.rs b/pure/src/widget/image.rs
index a5bca5a0..ef764ec2 100644
--- a/pure/src/widget/image.rs
+++ b/pure/src/widget/image.rs
@@ -1,3 +1,4 @@
+//! Display images in your user interface.
use crate::widget::{Tree, Widget};
use crate::Element;
diff --git a/pure/src/widget/pane_grid.rs b/pure/src/widget/pane_grid.rs
index b361664b..c532a6de 100644
--- a/pure/src/widget/pane_grid.rs
+++ b/pure/src/widget/pane_grid.rs
@@ -213,7 +213,7 @@ where
fn diff(&self, tree: &mut Tree) {
tree.diff_children_custom(
&self.elements,
- |(_, content), state| content.diff(state),
+ |state, (_, content)| content.diff(state),
|(_, content)| content.state(),
)
}
diff --git a/pure/src/widget/pane_grid/content.rs b/pure/src/widget/pane_grid/content.rs
index 6388b016..e66ac40b 100644
--- a/pure/src/widget/pane_grid/content.rs
+++ b/pure/src/widget/pane_grid/content.rs
@@ -57,7 +57,7 @@ impl<'a, Message, Renderer> Content<'a, Message, Renderer>
where
Renderer: iced_native::Renderer,
{
- pub fn state(&self) -> Tree {
+ pub(super) fn state(&self) -> Tree {
let children = if let Some(title_bar) = self.title_bar.as_ref() {
vec![Tree::new(&self.body), title_bar.state()]
} else {
@@ -70,7 +70,7 @@ where
}
}
- pub fn diff(&self, tree: &mut Tree) {
+ pub(super) fn diff(&self, tree: &mut Tree) {
if tree.children.len() == 2 {
if let Some(title_bar) = self.title_bar.as_ref() {
title_bar.diff(&mut tree.children[1]);
diff --git a/pure/src/widget/pane_grid/title_bar.rs b/pure/src/widget/pane_grid/title_bar.rs
index 567db913..4a7c8c17 100644
--- a/pure/src/widget/pane_grid/title_bar.rs
+++ b/pure/src/widget/pane_grid/title_bar.rs
@@ -81,7 +81,7 @@ impl<'a, Message, Renderer> TitleBar<'a, Message, Renderer>
where
Renderer: iced_native::Renderer,
{
- pub fn state(&self) -> Tree {
+ pub(super) fn state(&self) -> Tree {
let children = if let Some(controls) = self.controls.as_ref() {
vec![Tree::new(&self.content), Tree::new(controls)]
} else {
@@ -94,7 +94,7 @@ where
}
}
- pub fn diff(&self, tree: &mut Tree) {
+ pub(super) fn diff(&self, tree: &mut Tree) {
if tree.children.len() == 2 {
if let Some(controls) = self.controls.as_ref() {
tree.children[1].diff(controls);
diff --git a/pure/src/widget/progress_bar.rs b/pure/src/widget/progress_bar.rs
index 3f4ffd55..3016a81a 100644
--- a/pure/src/widget/progress_bar.rs
+++ b/pure/src/widget/progress_bar.rs
@@ -1,3 +1,4 @@
+//! Provide progress feedback to your users.
use crate::widget::Tree;
use crate::{Element, Widget};
diff --git a/pure/src/widget/radio.rs b/pure/src/widget/radio.rs
index c20f8f3e..7c98c937 100644
--- a/pure/src/widget/radio.rs
+++ b/pure/src/widget/radio.rs
@@ -1,3 +1,4 @@
+//! Create choices using radio buttons.
use crate::widget::Tree;
use crate::{Element, Widget};
diff --git a/pure/src/widget/row.rs b/pure/src/widget/row.rs
index 92812d27..0385b8bd 100644
--- a/pure/src/widget/row.rs
+++ b/pure/src/widget/row.rs
@@ -11,6 +11,7 @@ use iced_native::{
Alignment, Clipboard, Length, Padding, Point, Rectangle, Shell,
};
+/// A container that distributes its contents horizontally.
pub struct Row<'a, Message, Renderer> {
spacing: u16,
padding: Padding,
@@ -21,10 +22,12 @@ pub struct Row<'a, Message, Renderer> {
}
impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
+ /// Creates an empty [`Row`].
pub fn new() -> Self {
Self::with_children(Vec::new())
}
+ /// Creates a [`Row`] with the given elements.
pub fn with_children(
children: Vec<Element<'a, Message, Renderer>>,
) -> Self {
@@ -38,31 +41,41 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
}
}
+ /// Sets the horizontal spacing _between_ elements.
+ ///
+ /// Custom margins per element do not exist in iced. You should use this
+ /// method instead! While less flexible, it helps you keep spacing between
+ /// elements consistent.
pub fn spacing(mut self, units: u16) -> Self {
self.spacing = units;
self
}
+ /// Sets the [`Padding`] of the [`Row`].
pub fn padding<P: Into<Padding>>(mut self, padding: P) -> Self {
self.padding = padding.into();
self
}
+ /// Sets the width of the [`Row`].
pub fn width(mut self, width: Length) -> Self {
self.width = width;
self
}
+ /// Sets the height of the [`Row`].
pub fn height(mut self, height: Length) -> Self {
self.height = height;
self
}
+ /// Sets the vertical alignment of the contents of the [`Row`] .
pub fn align_items(mut self, align: Alignment) -> Self {
self.align_items = align;
self
}
+ /// Adds an [`Element`] to the [`Row`].
pub fn push(
mut self,
child: impl Into<Element<'a, Message, Renderer>>,
diff --git a/pure/src/widget/rule.rs b/pure/src/widget/rule.rs
index 40b1fc90..ab8537ae 100644
--- a/pure/src/widget/rule.rs
+++ b/pure/src/widget/rule.rs
@@ -1,3 +1,4 @@
+//! Display a horizontal or vertical rule for dividing content.
use crate::widget::Tree;
use crate::{Element, Widget};
diff --git a/pure/src/widget/scrollable.rs b/pure/src/widget/scrollable.rs
index 24263c95..70e951ef 100644
--- a/pure/src/widget/scrollable.rs
+++ b/pure/src/widget/scrollable.rs
@@ -1,3 +1,4 @@
+//! Navigate an endless amount of content with a scrollbar.
use crate::overlay;
use crate::widget::tree::{self, Tree};
use crate::{Element, Widget};
diff --git a/pure/src/widget/svg.rs b/pure/src/widget/svg.rs
index 2758c5b1..14180097 100644
--- a/pure/src/widget/svg.rs
+++ b/pure/src/widget/svg.rs
@@ -1,3 +1,4 @@
+//! Display vector graphics in your application.
use crate::widget::{Tree, Widget};
use crate::Element;
diff --git a/pure/src/widget/text_input.rs b/pure/src/widget/text_input.rs
index 11e93b44..57ad26d9 100644
--- a/pure/src/widget/text_input.rs
+++ b/pure/src/widget/text_input.rs
@@ -1,3 +1,4 @@
+//! Display fields that can be filled with text.
use crate::widget::tree::{self, Tree};
use crate::{Element, Widget};
@@ -15,10 +16,7 @@ pub use iced_style::text_input::{Style, StyleSheet};
///
/// # Example
/// ```
-/// # use iced_native::renderer::Null;
-/// # use iced_pure::widget::text_input;
-/// #
-/// # pub type TextInput<'a, Message> = iced_pure::widget::TextInput<'a, Message, Null>;
+/// # pub type TextInput<'a, Message> = iced_pure::widget::TextInput<'a, Message, iced_native::renderer::Null>;
/// #[derive(Debug, Clone)]
/// enum Message {
/// TextInputChanged(String),
diff --git a/pure/src/widget/toggler.rs b/pure/src/widget/toggler.rs
index 1b3367a4..b9c5ec02 100644
--- a/pure/src/widget/toggler.rs
+++ b/pure/src/widget/toggler.rs
@@ -1,3 +1,4 @@
+//! Show toggle controls using togglers.
use crate::widget::{Tree, Widget};
use crate::Element;
diff --git a/pure/src/widget/tooltip.rs b/pure/src/widget/tooltip.rs
index 75c4d856..3887732a 100644
--- a/pure/src/widget/tooltip.rs
+++ b/pure/src/widget/tooltip.rs
@@ -32,7 +32,7 @@ where
/// The default padding of a [`Tooltip`] drawn by this renderer.
const DEFAULT_PADDING: u16 = 5;
- /// Creates an empty [`Tooltip`].
+ /// Creates a new [`Tooltip`].
///
/// [`Tooltip`]: struct.Tooltip.html
pub fn new(
diff --git a/pure/src/widget/tree.rs b/pure/src/widget/tree.rs
index bd7c259c..d81dd02c 100644
--- a/pure/src/widget/tree.rs
+++ b/pure/src/widget/tree.rs
@@ -1,14 +1,24 @@
+//! Store internal widget state in a state tree to ensure continuity.
use crate::Element;
use std::any::{self, Any};
+/// A persistent state widget tree.
+///
+/// A [`Tree`] is normally associated with a specific widget in the widget tree.
pub struct Tree {
+ /// The tag of the [`Tree`].
pub tag: Tag,
+
+ /// The [`State`] of the [`Tree`].
pub state: State,
+
+ /// The children of the root widget of the [`Tree`].
pub children: Vec<Tree>,
}
impl Tree {
+ /// Creates an empty, stateless [`Tree`] with no children.
pub fn empty() -> Self {
Self {
tag: Tag::stateless(),
@@ -17,6 +27,7 @@ impl Tree {
}
}
+ /// Creates a new [`Tree`] for the provided [`Element`].
pub fn new<Message, Renderer>(
element: &Element<'_, Message, Renderer>,
) -> Self {
@@ -27,6 +38,14 @@ impl Tree {
}
}
+ /// Reconciliates the current tree with the provided [`Element`].
+ ///
+ /// If the tag of the [`Element`] matches the tag of the [`Tree`], then the
+ /// [`Element`] proceeds with the reconciliation (i.e. [`Widget::diff`] is called).
+ ///
+ /// Otherwise, the whole [`Tree`] is recreated.
+ ///
+ /// [`Widget::diff`]: crate::Widget::diff
pub fn diff<Message, Renderer>(
&mut self,
new: &Element<'_, Message, Renderer>,
@@ -38,21 +57,20 @@ impl Tree {
}
}
+ /// Reconciliates the children of the tree with the provided list of [`Element`].
pub fn diff_children<Message, Renderer>(
&mut self,
new_children: &[Element<'_, Message, Renderer>],
) {
- self.diff_children_custom(
- new_children,
- |new, child_state| child_state.diff(new),
- Self::new,
- )
+ self.diff_children_custom(new_children, Self::diff, Self::new)
}
+ /// Reconciliates the children of the tree with the provided list of [`Element`] using custom
+ /// logic both for diffing and creating new widget state.
pub fn diff_children_custom<T>(
&mut self,
new_children: &[T],
- diff: impl Fn(&T, &mut Tree),
+ diff: impl Fn(&mut Tree, &T),
new_state: impl Fn(&T) -> Self,
) {
if self.children.len() > new_children.len() {
@@ -62,7 +80,7 @@ impl Tree {
for (child_state, new) in
self.children.iter_mut().zip(new_children.iter())
{
- diff(new, child_state);
+ diff(child_state, new);
}
if self.children.len() < new_children.len() {
@@ -73,10 +91,12 @@ impl Tree {
}
}
+/// The identifier of some widget state.
#[derive(Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash)]
pub struct Tag(any::TypeId);
impl Tag {
+ /// Creates a [`Tag`] for a state of type `T`.
pub fn of<T>() -> Self
where
T: 'static,
@@ -84,17 +104,23 @@ impl Tag {
Self(any::TypeId::of::<T>())
}
+ /// Creates a [`Tag`] for a stateless widget.
pub fn stateless() -> Self {
Self::of::<()>()
}
}
+/// The internal [`State`] of a widget.
pub enum State {
+ /// No meaningful internal state.
None,
+
+ /// Some meaningful internal state.
Some(Box<dyn Any>),
}
impl State {
+ /// Creates a new [`State`].
pub fn new<T>(state: T) -> Self
where
T: 'static,
@@ -102,6 +128,10 @@ impl State {
State::Some(Box::new(state))
}
+ /// Downcasts the [`State`] to `T` and returns a reference to it.
+ ///
+ /// # Panics
+ /// This method will panic if the downcast fails or the [`State`] is [`State::None`].
pub fn downcast_ref<T>(&self) -> &T
where
T: 'static,
@@ -114,6 +144,10 @@ impl State {
}
}
+ /// Downcasts the [`State`] to `T` and returns a mutable reference to it.
+ ///
+ /// # Panics
+ /// This method will panic if the downcast fails or the [`State`] is [`State::None`].
pub fn downcast_mut<T>(&mut self) -> &mut T
where
T: 'static,
diff --git a/src/pure.rs b/src/pure.rs
index 5776de40..7785a104 100644
--- a/src/pure.rs
+++ b/src/pure.rs
@@ -14,6 +14,84 @@
//! offers an alternate [`Application`] trait with a completely pure `view`
//! method.
//!
+//! # The Elm Architecture, purity, and continuity
+//! As you may know, applications made with `iced` use [The Elm Architecture].
+//!
+//! In a nutshell, this architecture defines the initial state of the application, a way to `view` it, and a way to `update` it after a user interaction. The `update` logic is called after a meaningful user interaction, which in turn updates the state of the application. Then, the `view` logic is executed to redisplay the application.
+//!
+//! Since `view` logic is only run after an `update`, all of the mutations to the application state must only happen in the `update` logic. If the application state changes anywhere else, the `view` logic will not be rerun and, therefore, the previously generated `view` may stay outdated.
+//!
+//! However, the `Application` trait in `iced` defines `view` as:
+//!
+//! ```ignore
+//! pub trait Application {
+//! fn view(&mut self) -> Element<Self::Message>;
+//! }
+//! ```
+//!
+//! As a consequence, the application state can be mutated in `view` logic. The `view` logic in `iced` is __impure__.
+//!
+//! This impurity is necessary because `iced` puts the burden of widget __continuity__ on its users. In other words, it's up to you to provide `iced` with the internal state of each widget every time `view` is called.
+//!
+//! If we take a look at the classic `counter` example:
+//!
+//! ```ignore
+//! struct Counter {
+//! value: i32,
+//! increment_button: button::State,
+//! decrement_button: button::State,
+//! }
+//!
+//! // ...
+//!
+//! impl Counter {
+//! pub fn view(&mut self) -> Column<Message> {
+//! Column::new()
+//! .push(
+//! Button::new(&mut self.increment_button, Text::new("+"))
+//! .on_press(Message::IncrementPressed),
+//! )
+//! .push(Text::new(self.value.to_string()).size(50))
+//! .push(
+//! Button::new(&mut self.decrement_button, Text::new("-"))
+//! .on_press(Message::DecrementPressed),
+//! )
+//! }
+//! }
+//! ```
+//!
+//! We can see how we need to keep track of the `button::State` of each `Button` in our `Counter` state and provide a mutable reference to the widgets in our `view` logic. The widgets produced by `view` are __stateful__.
+//!
+//! While this approach forces users to keep track of widget state and causes impurity, I originally chose it because it allows `iced` to directly consume the widget tree produced by `view`. Since there is no internal state decoupled from `view` maintained by the runtime, `iced` does not need to compare (e.g. reconciliate) widget trees in order to ensure continuity.
+//!
+//! # Stateless widgets
+//! As the library matures, the need for some kind of persistent widget data (see #553) between `view` calls becomes more apparent (e.g. incremental rendering, animations, accessibility, etc.).
+//!
+//! If we are going to end up having persistent widget data anyways... There is no reason to have impure, stateful widgets anymore!
+//!
+//! With the help of this module, we can now write a pure `counter` example:
+//!
+//! ```ignore
+//! struct Counter {
+//! value: i32,
+//! }
+//!
+//! // ...
+//!
+//! impl Counter {
+//! fn view(&self) -> Column<Message> {
+//! Column::new()
+//! .push(Button::new("Increment").on_press(Message::IncrementPressed))
+//! .push(Text::new(self.value.to_string()).size(50))
+//! .push(Button::new("Decrement").on_press(Message::DecrementPressed))
+//! }
+//! }
+//! ```
+//!
+//! Notice how we no longer need to keep track of the `button::State`! The widgets in `iced_pure` do not take any mutable application state in `view`. They are __stateless__ widgets. As a consequence, we do not need mutable access to `self` in `view` anymore. `view` becomes __pure__.
+//!
+//! [The Elm Architecture]: https://guide.elm-lang.org/architecture/
+//!
//! [the original widgets]: crate::widget
//! [`button::State`]: crate::widget::button::State
//! [impure `Application`]: crate::Application
generated by cgit (git 2.34.1) at 2025-04-16 05:39:58 +0000