1 files changed, 199 insertions, 0 deletions
diff --git a/examples/multitouch/src/main.rs b/examples/multitouch/src/main.rs
new file mode 100644
index 00000000..0345ceb7
--- /dev/null
+++ b/examples/multitouch/src/main.rs
@@ -0,0 +1,199 @@
+//! This example shows how to use touch events in `Canvas` to draw
+//! a circle around each fingertip. This only works on touch-enabled
+//! computers like Microsoft Surface.
+use iced::widget::canvas::event;
+use iced::widget::canvas::{self, Canvas, Cursor, Geometry, Stroke};
+use iced::{
+    executor, touch, window, Application, Color, Command, Element, Length,
+    Point, Rectangle, Settings, Subscription, Theme,
+};
+
+use std::collections::HashMap;
+
+pub fn main() -> iced::Result {
+    env_logger::builder().format_timestamp(None).init();
+
+    Multitouch::run(Settings {
+        antialiasing: true,
+        window: window::Settings {
+            position: window::Position::Centered,
+            ..window::Settings::default()
+        },
+        ..Settings::default()
+    })
+}
+
+struct Multitouch {
+    state: State,
+}
+
+#[derive(Debug)]
+struct State {
+    cache: canvas::Cache,
+    fingers: HashMap<touch::Finger, Point>,
+}
+
+impl State {
+    fn new() -> Self {
+        Self {
+            cache: canvas::Cache::new(),
+            fingers: HashMap::new(),
+        }
+    }
+}
+
+#[derive(Debug)]
+enum Message {
+    FingerPressed { id: touch::Finger, position: Point },
+    FingerLifted { id: touch::Finger },
+}
+
+impl Application for Multitouch {
+    type Executor = executor::Default;
+    type Message = Message;
+    type Theme = Theme;
+    type Flags = ();
+
+    fn new(_flags: ()) -> (Self, Command<Message>) {
+        (
+            Multitouch {
+                state: State::new(),
+            },
+            Command::none(),
+        )
+    }
+
+    fn title(&self) -> String {
+        String::from("Multitouch - Iced")
+    }
+
+    fn update(&mut self, message: Message) -> Command<Message> {
+        match message {
+            Message::FingerPressed { id, position } => {
+                self.state.fingers.insert(id, position);
+                self.state.cache.clear();
+            }
+            Message::FingerLifted { id } => {
+                self.state.fingers.remove(&id);
+                self.state.cache.clear();
+            }
+        }
+
+        Command::none()
+    }
+
+    fn subscription(&self) -> Subscription<Message> {
+        Subscription::none()
+    }
+
+    fn view(&self) -> Element<Message> {
+        Canvas::new(&self.state)
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .into()
+    }
+}
+
+impl canvas::Program<Message> for State {
+    type State = ();
+
+    fn update(
+        &self,
+        _state: &mut Self::State,
+        event: event::Event,
+        _bounds: Rectangle,
+        _cursor: Cursor,
+    ) -> (event::Status, Option<Message>) {
+        match event {
+            event::Event::Touch(touch_event) => match touch_event {
+                touch::Event::FingerPressed { id, position }
+                | touch::Event::FingerMoved { id, position } => (
+                    event::Status::Captured,
+                    Some(Message::FingerPressed { id, position }),
+                ),
+                touch::Event::FingerLifted { id, .. }
+                | touch::Event::FingerLost { id, .. } => (
+                    event::Status::Captured,
+                    Some(Message::FingerLifted { id }),
+                ),
+            },
+            _ => (event::Status::Ignored, None),
+        }
+    }
+
+    fn draw(
+        &self,
+        _state: &Self::State,
+        _theme: &Theme,
+        bounds: Rectangle,
+        _cursor: Cursor,
+    ) -> Vec<Geometry> {
+        let fingerweb = self.cache.draw(bounds.size(), |frame| {
+            if self.fingers.len() < 2 {
+                return;
+            }
+
+            // Collect tuples of (id, point);
+            let mut zones: Vec<(u64, Point)> =
+                self.fingers.iter().map(|(id, pt)| (id.0, *pt)).collect();
+
+            // Sort by ID
+            zones.sort_by(|a, b| a.0.partial_cmp(&b.0).unwrap());
+
+            // Generate sorted list of points
+            let vpoints: Vec<(f64, f64)> = zones
+                .iter()
+                .map(|(_, p)| (f64::from(p.x), f64::from(p.y)))
+                .collect();
+
+            let diagram: voronator::VoronoiDiagram<
+                voronator::delaunator::Point,
+            > = voronator::VoronoiDiagram::from_tuple(
+                &(0.0, 0.0),
+                &(700.0, 700.0),
+                &vpoints,
+            )
+            .expect("Generate Voronoi diagram");
+
+            for (cell, zone) in diagram.cells().iter().zip(zones) {
+                let mut builder = canvas::path::Builder::new();
+
+                for (index, p) in cell.points().iter().enumerate() {
+                    let p = Point::new(p.x as f32, p.y as f32);
+
+                    match index {
+                        0 => builder.move_to(p),
+                        _ => builder.line_to(p),
+                    }
+                }
+
+                let path = builder.build();
+
+                let color_r = (10 % zone.0) as f32 / 20.0;
+                let color_g = (10 % (zone.0 + 8)) as f32 / 20.0;
+                let color_b = (10 % (zone.0 + 3)) as f32 / 20.0;
+
+                frame.fill(
+                    &path,
+                    Color {
+                        r: color_r,
+                        g: color_g,
+                        b: color_b,
+                        a: 1.0,
+                    },
+                );
+
+                frame.stroke(
+                    &path,
+                    Stroke {
+                        color: Color::BLACK,
+                        width: 3.0,
+                        ..Stroke::default()
+                    },
+                );
+            }
+        });
+
+        vec![fingerweb]
+    }
+}