Working multitouch example

2 files changed, 161 insertions, 0 deletions

diff --git a/examples/multitouch/Cargo.toml b/examples/multitouch/Cargo.toml
new file mode 100644
index 00000000..ecd4760c
--- /dev/null
+++ b/examples/multitouch/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "multitouch"
+version = "0.1.0"
+authors = ["Artur Sapek <artur@kraken.com>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../..", features = ["canvas", "tokio", "debug"] }
+tokio = { version = "1.0", features = ["sync"] }
+env_logger = "0.9"
diff --git a/examples/multitouch/src/main.rs b/examples/multitouch/src/main.rs
new file mode 100644
index 00000000..f1d2f216
--- /dev/null
+++ b/examples/multitouch/src/main.rs
@@ -0,0 +1,150 @@
+//! 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, Path, 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.clone());
+                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<'a> 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| {
+            for finger in &self.fingers {
+                dbg!(&finger);
+
+                let circle = Path::new(|p| p.circle(*finger.1, 50.0));
+
+                frame.stroke(
+                    &circle,
+                    Stroke {
+                        color: Color::BLACK,
+                        width: 3.0,
+                        ..Stroke::default()
+                    },
+                );
+            }
+        });
+
+        vec![fingerweb]
+    }
+}