Add `game_of_life` example

RIP John Conway

6 files changed, 569 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 9c52ea8f..d394d516 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -43,6 +43,7 @@ members = [
     "examples/custom_widget",
     "examples/download_progress",
     "examples/events",
+    "examples/game_of_life",
     "examples/geometry",
     "examples/integration",
     "examples/pane_grid",
diff --git a/examples/game_of_life/Cargo.toml b/examples/game_of_life/Cargo.toml
new file mode 100644
index 00000000..8855b3e8
--- /dev/null
+++ b/examples/game_of_life/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "game_of_life"
+version = "0.1.0"
+authors = ["Héctor Ramón Jiménez <hector0193@gmail.com>"]
+edition = "2018"
+publish = false
+
+[dependencies]
+iced = { path = "../..", features = ["async-std", "canvas", "debug"] }
+iced_native = { path = "../../native" }
+async-std = { version = "1.0", features = ["unstable"] }
+itertools = "0.9"
diff --git a/examples/game_of_life/README.md b/examples/game_of_life/README.md
new file mode 100644
index 00000000..ebbb12cc
--- /dev/null
+++ b/examples/game_of_life/README.md
@@ -0,0 +1,18 @@
+## Bézier tool
+
+A Paint-like tool for drawing Bézier curves using the `Canvas` widget.
+
+The __[`main`]__ file contains all the code of the example.
+
+<div align="center">
+  <a href="https://gfycat.com/soulfulinfiniteantbear">
+    <img src="https://thumbs.gfycat.com/SoulfulInfiniteAntbear-small.gif">
+  </a>
+</div>
+
+You can run it with `cargo run`:
+```
+cargo run --package bezier_tool
+```
+
+[`main`]: src/main.rs
diff --git a/examples/game_of_life/src/main.rs b/examples/game_of_life/src/main.rs
new file mode 100644
index 00000000..3e6848df
--- /dev/null
+++ b/examples/game_of_life/src/main.rs
@@ -0,0 +1,408 @@
+//! This example showcases an interactive version of the Game of Life, invented
+//! by John Conway. It leverages a `Canvas` together with other widgets.
+mod style;
+mod time;
+
+use grid::Grid;
+use iced::{
+    button::{self, Button},
+    executor,
+    slider::{self, Slider},
+    Align, Application, Column, Command, Container, Element, Length, Row,
+    Settings, Subscription, Text,
+};
+use std::time::{Duration, Instant};
+
+pub fn main() {
+    GameOfLife::run(Settings {
+        antialiasing: true,
+        ..Settings::default()
+    })
+}
+
+#[derive(Default)]
+struct GameOfLife {
+    grid: Grid,
+    is_playing: bool,
+    speed: u64,
+    next_speed: Option<u64>,
+    toggle_button: button::State,
+    next_button: button::State,
+    clear_button: button::State,
+    speed_slider: slider::State,
+}
+
+#[derive(Debug, Clone)]
+enum Message {
+    Grid(grid::Message),
+    Tick(Instant),
+    Toggle,
+    Next,
+    Clear,
+    SpeedChanged(f32),
+}
+
+impl Application for GameOfLife {
+    type Message = Message;
+    type Executor = executor::Default;
+    type Flags = ();
+
+    fn new(_flags: ()) -> (Self, Command<Message>) {
+        (
+            Self {
+                speed: 1,
+                ..Self::default()
+            },
+            Command::none(),
+        )
+    }
+
+    fn title(&self) -> String {
+        String::from("Game of Life - Iced")
+    }
+
+    fn update(&mut self, message: Message) -> Command<Message> {
+        match message {
+            Message::Grid(message) => {
+                self.grid.update(message);
+            }
+            Message::Tick(_) | Message::Next => {
+                self.grid.tick();
+
+                if let Some(speed) = self.next_speed.take() {
+                    self.speed = speed;
+                }
+            }
+            Message::Toggle => {
+                self.is_playing = !self.is_playing;
+            }
+            Message::Clear => {
+                self.grid = Grid::default();
+            }
+            Message::SpeedChanged(speed) => {
+                if self.is_playing {
+                    self.next_speed = Some(speed.round() as u64);
+                } else {
+                    self.speed = speed.round() as u64;
+                }
+            }
+        }
+
+        Command::none()
+    }
+
+    fn subscription(&self) -> Subscription<Message> {
+        if self.is_playing {
+            time::every(Duration::from_millis(1000 / self.speed))
+                .map(Message::Tick)
+        } else {
+            Subscription::none()
+        }
+    }
+
+    fn view(&mut self) -> Element<Message> {
+        let playback_controls = Row::new()
+            .spacing(10)
+            .push(
+                Button::new(
+                    &mut self.toggle_button,
+                    Text::new(if self.is_playing { "Pause" } else { "Play" }),
+                )
+                .on_press(Message::Toggle)
+                .style(style::Button),
+            )
+            .push(
+                Button::new(&mut self.next_button, Text::new("Next"))
+                    .on_press(Message::Next)
+                    .style(style::Button),
+            )
+            .push(
+                Button::new(&mut self.clear_button, Text::new("Clear"))
+                    .on_press(Message::Clear)
+                    .style(style::Button),
+            );
+
+        let selected_speed = self.next_speed.unwrap_or(self.speed);
+        let speed_controls = Row::new()
+            .spacing(10)
+            .push(
+                Slider::new(
+                    &mut self.speed_slider,
+                    1.0..=20.0,
+                    selected_speed as f32,
+                    Message::SpeedChanged,
+                )
+                .width(Length::Units(200))
+                .style(style::Slider),
+            )
+            .push(Text::new(format!("x{}", selected_speed)).size(16))
+            .align_items(Align::Center);
+
+        let controls = Row::new()
+            .spacing(20)
+            .push(playback_controls)
+            .push(speed_controls);
+
+        let content = Column::new()
+            .spacing(10)
+            .padding(10)
+            .align_items(Align::Center)
+            .push(self.grid.view().map(Message::Grid))
+            .push(controls);
+
+        Container::new(content)
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .style(style::Container)
+            .into()
+    }
+}
+
+mod grid {
+    use iced::{
+        canvas::{self, Canvas, Cursor, Event, Frame, Geometry, Path},
+        mouse, ButtonState, Color, Element, Length, MouseCursor, Point,
+        Rectangle, Size, Vector,
+    };
+
+    const SIZE: usize = 32;
+
+    #[derive(Default)]
+    pub struct Grid {
+        cells: [[Cell; SIZE]; SIZE],
+        mouse_pressed: bool,
+        cache: canvas::Cache,
+    }
+
+    impl Grid {
+        pub fn tick(&mut self) {
+            let mut populated_neighbors: [[usize; SIZE]; SIZE] =
+                [[0; SIZE]; SIZE];
+
+            for (i, row) in self.cells.iter().enumerate() {
+                for (j, _) in row.iter().enumerate() {
+                    populated_neighbors[i][j] = self.populated_neighbors(i, j);
+                }
+            }
+
+            for (i, row) in populated_neighbors.iter().enumerate() {
+                for (j, amount) in row.iter().enumerate() {
+                    let is_populated = self.cells[i][j] == Cell::Populated;
+
+                    self.cells[i][j] = match amount {
+                        2 if is_populated => Cell::Populated,
+                        3 => Cell::Populated,
+                        _ => Cell::Unpopulated,
+                    };
+                }
+            }
+
+            self.cache.clear()
+        }
+
+        pub fn update(&mut self, message: Message) {
+            match message {
+                Message::Populate { i, j } => {
+                    self.cells[i][j] = Cell::Populated;
+                    self.cache.clear()
+                }
+            }
+        }
+
+        pub fn view<'a>(&'a mut self) -> Element<'a, Message> {
+            Canvas::new(self)
+                .width(Length::Fill)
+                .height(Length::Fill)
+                .into()
+        }
+
+        fn populated_neighbors(&self, row: usize, column: usize) -> usize {
+            use itertools::Itertools;
+
+            let rows = row.saturating_sub(1)..=row + 1;
+            let columns = column.saturating_sub(1)..=column + 1;
+
+            let is_inside_bounds = |i: usize, j: usize| i < SIZE && j < SIZE;
+            let is_neighbor = |i: usize, j: usize| i != row || j != column;
+
+            let is_populated =
+                |i: usize, j: usize| self.cells[i][j] == Cell::Populated;
+
+            rows.cartesian_product(columns)
+                .filter(|&(i, j)| {
+                    is_inside_bounds(i, j)
+                        && is_neighbor(i, j)
+                        && is_populated(i, j)
+                })
+                .count()
+        }
+
+        fn region(&self, size: Size) -> Rectangle {
+            let side = size.width.min(size.height);
+
+            Rectangle {
+                x: (size.width - side) / 2.0,
+                y: (size.height - side) / 2.0,
+                width: side,
+                height: side,
+            }
+        }
+
+        fn cell_at(
+            &self,
+            region: Rectangle,
+            position: Point,
+        ) -> Option<(usize, usize)> {
+            if region.contains(position) {
+                let cell_size = region.width / SIZE as f32;
+
+                let i = ((position.y - region.y) / cell_size).ceil() as usize;
+                let j = ((position.x - region.x) / cell_size).ceil() as usize;
+
+                Some((i.saturating_sub(1), j.saturating_sub(1)))
+            } else {
+                None
+            }
+        }
+    }
+
+    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    enum Cell {
+        Unpopulated,
+        Populated,
+    }
+
+    impl Default for Cell {
+        fn default() -> Cell {
+            Cell::Unpopulated
+        }
+    }
+
+    #[derive(Debug, Clone, Copy)]
+    pub enum Message {
+        Populate { i: usize, j: usize },
+    }
+
+    impl<'a> canvas::Program<Message> for Grid {
+        fn update(
+            &mut self,
+            event: Event,
+            bounds: Rectangle,
+            cursor: Cursor,
+        ) -> Option<Message> {
+            if let Event::Mouse(mouse::Event::Input {
+                button: mouse::Button::Left,
+                state,
+            }) = event
+            {
+                self.mouse_pressed = state == ButtonState::Pressed;
+            }
+
+            let cursor_position = cursor.internal_position(&bounds)?;
+
+            let region = self.region(bounds.size());
+            let (i, j) = self.cell_at(region, cursor_position)?;
+
+            let populate = if self.cells[i][j] != Cell::Populated {
+                Some(Message::Populate { i, j })
+            } else {
+                None
+            };
+
+            match event {
+                Event::Mouse(mouse::Event::Input {
+                    button: mouse::Button::Left,
+                    ..
+                }) if self.mouse_pressed => populate,
+                Event::Mouse(mouse::Event::CursorMoved { .. })
+                    if self.mouse_pressed =>
+                {
+                    populate
+                }
+                _ => None,
+            }
+        }
+
+        fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Vec<Geometry> {
+            let region = self.region(bounds.size());
+            let cell_size = Size::new(1.0, 1.0);
+
+            let life = self.cache.draw(bounds.size(), |frame| {
+                let background =
+                    Path::rectangle(region.position(), region.size());
+                frame.fill(
+                    &background,
+                    Color::from_rgb(
+                        0x40 as f32 / 255.0,
+                        0x44 as f32 / 255.0,
+                        0x4B as f32 / 255.0,
+                    ),
+                );
+
+                frame.with_save(|frame| {
+                    frame.translate(Vector::new(region.x, region.y));
+                    frame.scale(region.width / SIZE as f32);
+
+                    let cells = Path::new(|p| {
+                        for (i, row) in self.cells.iter().enumerate() {
+                            for (j, cell) in row.iter().enumerate() {
+                                if *cell == Cell::Populated {
+                                    p.rectangle(
+                                        Point::new(j as f32, i as f32),
+                                        cell_size,
+                                    );
+                                }
+                            }
+                        }
+                    });
+                    frame.fill(&cells, Color::WHITE);
+                });
+            });
+
+            let hovered_cell = {
+                let mut frame = Frame::new(bounds.size());
+
+                frame.translate(Vector::new(region.x, region.y));
+                frame.scale(region.width / SIZE as f32);
+
+                if let Some(cursor_position) = cursor.internal_position(&bounds)
+                {
+                    if let Some((i, j)) = self.cell_at(region, cursor_position)
+                    {
+                        let interaction = Path::rectangle(
+                            Point::new(j as f32, i as f32),
+                            cell_size,
+                        );
+
+                        frame.fill(
+                            &interaction,
+                            Color {
+                                a: 0.5,
+                                ..Color::BLACK
+                            },
+                        );
+                    }
+                }
+
+                frame.into_geometry()
+            };
+
+            vec![life, hovered_cell]
+        }
+
+        fn mouse_cursor(
+            &self,
+            bounds: Rectangle,
+            cursor: Cursor,
+        ) -> MouseCursor {
+            let region = self.region(bounds.size());
+
+            match cursor.internal_position(&bounds) {
+                Some(position) if region.contains(position) => {
+                    MouseCursor::Crosshair
+                }
+                _ => MouseCursor::default(),
+            }
+        }
+    }
+}
diff --git a/examples/game_of_life/src/style.rs b/examples/game_of_life/src/style.rs
new file mode 100644
index 00000000..0becb5be
--- /dev/null
+++ b/examples/game_of_life/src/style.rs
@@ -0,0 +1,96 @@
+use iced::{button, container, slider, Background, Color};
+
+const ACTIVE: Color = Color::from_rgb(
+    0x72 as f32 / 255.0,
+    0x89 as f32 / 255.0,
+    0xDA as f32 / 255.0,
+);
+
+const HOVERED: Color = Color::from_rgb(
+    0x67 as f32 / 255.0,
+    0x7B as f32 / 255.0,
+    0xC4 as f32 / 255.0,
+);
+
+pub struct Container;
+
+impl container::StyleSheet for Container {
+    fn style(&self) -> container::Style {
+        container::Style {
+            background: Some(Background::Color(Color::from_rgb8(
+                0x36, 0x39, 0x3F,
+            ))),
+            text_color: Some(Color::WHITE),
+            ..container::Style::default()
+        }
+    }
+}
+
+pub struct Button;
+
+impl button::StyleSheet for Button {
+    fn active(&self) -> button::Style {
+        button::Style {
+            background: Some(Background::Color(ACTIVE)),
+            border_radius: 3,
+            text_color: Color::WHITE,
+            ..button::Style::default()
+        }
+    }
+
+    fn hovered(&self) -> button::Style {
+        button::Style {
+            background: Some(Background::Color(HOVERED)),
+            text_color: Color::WHITE,
+            ..self.active()
+        }
+    }
+
+    fn pressed(&self) -> button::Style {
+        button::Style {
+            border_width: 1,
+            border_color: Color::WHITE,
+            ..self.hovered()
+        }
+    }
+}
+
+pub struct Slider;
+
+impl slider::StyleSheet for Slider {
+    fn active(&self) -> slider::Style {
+        slider::Style {
+            rail_colors: (ACTIVE, Color { a: 0.1, ..ACTIVE }),
+            handle: slider::Handle {
+                shape: slider::HandleShape::Circle { radius: 9 },
+                color: ACTIVE,
+                border_width: 0,
+                border_color: Color::TRANSPARENT,
+            },
+        }
+    }
+
+    fn hovered(&self) -> slider::Style {
+        let active = self.active();
+
+        slider::Style {
+            handle: slider::Handle {
+                color: HOVERED,
+                ..active.handle
+            },
+            ..active
+        }
+    }
+
+    fn dragging(&self) -> slider::Style {
+        let active = self.active();
+
+        slider::Style {
+            handle: slider::Handle {
+                color: Color::from_rgb(0.85, 0.85, 0.85),
+                ..active.handle
+            },
+            ..active
+        }
+    }
+}
diff --git a/examples/game_of_life/src/time.rs b/examples/game_of_life/src/time.rs
new file mode 100644
index 00000000..7b475ecd
--- /dev/null
+++ b/examples/game_of_life/src/time.rs
@@ -0,0 +1,34 @@
+use iced::futures;
+
+pub fn every(
+    duration: std::time::Duration,
+) -> iced::Subscription<std::time::Instant> {
+    iced::Subscription::from_recipe(Every(duration))
+}
+
+struct Every(std::time::Duration);
+
+impl<H, I> iced_native::subscription::Recipe<H, I> for Every
+where
+    H: std::hash::Hasher,
+{
+    type Output = std::time::Instant;
+
+    fn hash(&self, state: &mut H) {
+        use std::hash::Hash;
+
+        std::any::TypeId::of::<Self>().hash(state);
+        self.0.hash(state);
+    }
+
+    fn stream(
+        self: Box<Self>,
+        _input: futures::stream::BoxStream<'static, I>,
+    ) -> futures::stream::BoxStream<'static, Self::Output> {
+        use futures::stream::StreamExt;
+
+        async_std::stream::interval(self.0)
+            .map(|_| std::time::Instant::now())
+            .boxed()
+    }
+}