Stateless widgets

Cargo.toml

@@ -14,24 +14,20 @@ resolver = "2"
 
 [features]
 default = ["wgpu"]
-# Enables the `iced_wgpu` renderer
-wgpu = ["iced_wgpu"]
 # Enables the `Image` widget
 image = ["iced_wgpu/image"]
 # Enables the `Svg` widget
 svg = ["iced_wgpu/svg"]
 # Enables the `Canvas` widget
-canvas = ["iced_wgpu/canvas"]
+canvas = ["iced_graphics/canvas"]
 # Enables the `QRCode` widget
-qr_code = ["iced_wgpu/qr_code"]
+qr_code = ["iced_graphics/qr_code"]
+# Enables the `iced_wgpu` renderer
+wgpu = ["iced_wgpu"]
 # Enables using system fonts
 default_system_font = ["iced_wgpu/default_system_font"]
 # Enables the `iced_glow` renderer. Overrides `iced_wgpu`
 glow = ["iced_glow", "iced_glutin"]
-# Enables the `Canvas` widget for `iced_glow`
-glow_canvas = ["iced_glow/canvas"]
-# Enables the `QRCode` widget for `iced_glow`
-glow_qr_code = ["iced_glow/qr_code"]
 # Enables using system fonts for `iced_glow`
 glow_default_system_font = ["iced_glow/default_system_font"]
 # Enables a debug view in native platforms (press F12)
@@ -44,6 +40,8 @@ async-std = ["iced_futures/async-std"]
 smol = ["iced_futures/smol"]
 # Enables advanced color conversion via `palette`
 palette = ["iced_core/palette"]
+# Enables pure, virtual widgets in the `pure` module
+pure = ["iced_pure", "iced_graphics/pure"]
 
 [badges]
 maintenance = { status = "actively-developed" }
@@ -57,6 +55,7 @@ members = [
     "glutin",
     "lazy",
     "native",
+    "pure",
     "style",
     "wgpu",
     "winit",
@@ -87,15 +86,25 @@ members = [
     "examples/tooltip",
     "examples/tour",
     "examples/url_handler",
+    "examples/pure/component",
+    "examples/pure/counter",
+    "examples/pure/game_of_life",
+    "examples/pure/pane_grid",
+    "examples/pure/pick_list",
+    "examples/pure/todos",
+    "examples/pure/tour",
     "examples/websocket",
 ]
 
 [dependencies]
 iced_core = { version = "0.4", path = "core" }
 iced_futures = { version = "0.3", path = "futures" }
+iced_native = { version = "0.4", path = "native" }
+iced_graphics = { version = "0.2", path = "graphics" }
 iced_winit = { version = "0.3", path = "winit" }
 iced_glutin = { version = "0.2", path = "glutin", optional = true }
 iced_glow = { version = "0.2", path = "glow", optional = true }
+iced_pure = { version = "0.1", path = "pure", optional = true }
 thiserror = "1.0"
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]

examples/clock/src/main.rs

@@ -76,7 +76,7 @@ impl Application for Clock {
     }
 }
 
-impl canvas::Program<Message> for Clock {
+impl<Message> canvas::Program<Message> for Clock {
     fn draw(&self, bounds: Rectangle, _cursor: Cursor) -> Vec<Geometry> {
         let clock = self.clock.draw(bounds.size(), |frame| {
             let center = frame.center();

examples/color_palette/src/main.rs

@@ -235,7 +235,7 @@ impl Theme {
     }
 }
 
-impl canvas::Program<Message> for Theme {
+impl<Message> canvas::Program<Message> for Theme {
     fn draw(&self, bounds: Rectangle, _cursor: Cursor) -> Vec<Geometry> {
         let theme = self.canvas_cache.draw(bounds.size(), |frame| {
             self.draw(frame);

examples/pure/component/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "pure_component"
+version = "0.1.0"
+authors = ["Héctor Ramón Jiménez <hector0193@gmail.com>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../../..", features = ["debug", "pure"] }
+iced_native = { path = "../../../native" }
+iced_lazy = { path = "../../../lazy", features = ["pure"] }
+iced_pure = { path = "../../../pure" }

examples/pure/component/src/main.rs

@@ -0,0 +1,166 @@
+use iced::pure::container;
+use iced::pure::{Element, Sandbox};
+use iced::{Length, Settings};
+
+use numeric_input::numeric_input;
+
+pub fn main() -> iced::Result {
+    Component::run(Settings::default())
+}
+
+#[derive(Default)]
+struct Component {
+    value: Option<u32>,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Message {
+    NumericInputChanged(Option<u32>),
+}
+
+impl Sandbox for Component {
+    type Message = Message;
+
+    fn new() -> Self {
+        Self::default()
+    }
+
+    fn title(&self) -> String {
+        String::from("Component - Iced")
+    }
+
+    fn update(&mut self, message: Message) {
+        match message {
+            Message::NumericInputChanged(value) => {
+                self.value = value;
+            }
+        }
+    }
+
+    fn view(&self) -> Element<Message> {
+        container(numeric_input(self.value, Message::NumericInputChanged))
+            .padding(20)
+            .height(Length::Fill)
+            .center_y()
+            .into()
+    }
+}
+
+mod numeric_input {
+    use iced::pure::{button, row, text, text_input};
+    use iced_lazy::pure::{self, Component};
+    use iced_native::alignment::{self, Alignment};
+    use iced_native::text;
+    use iced_native::Length;
+    use iced_pure::Element;
+
+    pub struct NumericInput<Message> {
+        value: Option<u32>,
+        on_change: Box<dyn Fn(Option<u32>) -> Message>,
+    }
+
+    pub fn numeric_input<Message>(
+        value: Option<u32>,
+        on_change: impl Fn(Option<u32>) -> Message + 'static,
+    ) -> NumericInput<Message> {
+        NumericInput::new(value, on_change)
+    }
+
+    #[derive(Debug, Clone)]
+    pub enum Event {
+        InputChanged(String),
+        IncrementPressed,
+        DecrementPressed,
+    }
+
+    impl<Message> NumericInput<Message> {
+        pub fn new(
+            value: Option<u32>,
+            on_change: impl Fn(Option<u32>) -> Message + 'static,
+        ) -> Self {
+            Self {
+                value,
+                on_change: Box::new(on_change),
+            }
+        }
+    }
+
+    impl<Message, Renderer> Component<Message, Renderer> for NumericInput<Message>
+    where
+        Renderer: text::Renderer + 'static,
+    {
+        type State = ();
+        type Event = Event;
+
+        fn update(
+            &mut self,
+            _state: &mut Self::State,
+            event: Event,
+        ) -> Option<Message> {
+            match event {
+                Event::IncrementPressed => Some((self.on_change)(Some(
+                    self.value.unwrap_or_default().saturating_add(1),
+                ))),
+                Event::DecrementPressed => Some((self.on_change)(Some(
+                    self.value.unwrap_or_default().saturating_sub(1),
+                ))),
+                Event::InputChanged(value) => {
+                    if value.is_empty() {
+                        Some((self.on_change)(None))
+                    } else {
+                        value
+                            .parse()
+                            .ok()
+                            .map(Some)
+                            .map(self.on_change.as_ref())
+                    }
+                }
+            }
+        }
+
+        fn view(&self, _state: &Self::State) -> Element<Event, Renderer> {
+            let button = |label, on_press| {
+                button(
+                    text(label)
+                        .width(Length::Fill)
+                        .height(Length::Fill)
+                        .horizontal_alignment(alignment::Horizontal::Center)
+                        .vertical_alignment(alignment::Vertical::Center),
+                )
+                .width(Length::Units(50))
+                .on_press(on_press)
+            };
+
+            row()
+                .push(button("-", Event::DecrementPressed))
+                .push(
+                    text_input(
+                        "Type a number",
+                        self.value
+                            .as_ref()
+                            .map(u32::to_string)
+                            .as_ref()
+                            .map(String::as_str)
+                            .unwrap_or(""),
+                        Event::InputChanged,
+                    )
+                    .padding(10),
+                )
+                .push(button("+", Event::IncrementPressed))
+                .align_items(Alignment::Fill)
+                .spacing(10)
+                .into()
+        }
+    }
+
+    impl<'a, Message, Renderer> From<NumericInput<Message>>
+        for Element<'a, Message, Renderer>
+    where
+        Message: 'a,
+        Renderer: 'static + text::Renderer,
+    {
+        fn from(numeric_input: NumericInput<Message>) -> Self {
+            pure::component(numeric_input)
+        }
+    }
+}

examples/pure/counter/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "pure_counter"
+version = "0.1.0"
+authors = ["Héctor Ramón Jiménez <hector0193@gmail.com>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../../..", features = ["pure"] }

examples/pure/counter/src/main.rs

@@ -0,0 +1,49 @@
+use iced::pure::{button, column, text, Element, Sandbox};
+use iced::{Alignment, Settings};
+
+pub fn main() -> iced::Result {
+    Counter::run(Settings::default())
+}
+
+struct Counter {
+    value: i32,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Message {
+    IncrementPressed,
+    DecrementPressed,
+}
+
+impl Sandbox for Counter {
+    type Message = Message;
+
+    fn new() -> Self {
+        Self { value: 0 }
+    }
+
+    fn title(&self) -> String {
+        String::from("Counter - Iced")
+    }
+
+    fn update(&mut self, message: Message) {
+        match message {
+            Message::IncrementPressed => {
+                self.value += 1;
+            }
+            Message::DecrementPressed => {
+                self.value -= 1;
+            }
+        }
+    }
+
+    fn view(&self) -> Element<Message> {
+        column()
+            .padding(20)
+            .align_items(Alignment::Center)
+            .push(button("Increment").on_press(Message::IncrementPressed))
+            .push(text(self.value.to_string()).size(50))
+            .push(button("Decrement").on_press(Message::DecrementPressed))
+            .into()
+    }
+}

examples/pure/game_of_life/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "pure_game_of_life"
+version = "0.1.0"
+authors = ["Héctor Ramón Jiménez <hector0193@gmail.com>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../../..", features = ["pure", "canvas", "tokio", "debug"] }
+tokio = { version = "1.0", features = ["sync"] }
+itertools = "0.9"
+rustc-hash = "1.1"
+env_logger = "0.9"

examples/pure/game_of_life/README.md

@@ -0,0 +1,22 @@
+## Game of Life
+
+An interactive version of the [Game of Life], invented by [John Horton Conway].
+
+It runs a simulation in a background thread while allowing interaction with a `Canvas` that displays an infinite grid with zooming, panning, and drawing support.
+
+The __[`main`]__ file contains the relevant code of the example.
+
+<div align="center">
+  <a href="https://gfycat.com/WhichPaltryChick">
+    <img src="https://thumbs.gfycat.com/WhichPaltryChick-size_restricted.gif">
+  </a>
+</div>
+
+You can run it with `cargo run`:
+```
+cargo run --package game_of_life
+```
+
+[`main`]: src/main.rs
+[Game of Life]: https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life
+[John Horton Conway]: https://en.wikipedia.org/wiki/John_Horton_Conway