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|
//! This example showcases an interactive `Canvas` for drawing Bézier curves.
use iced::{
button, Align, Button, Column, Element, Length, Sandbox, Settings, Text,
};
pub fn main() {
Example::run(Settings {
antialiasing: true,
..Settings::default()
});
}
#[derive(Default)]
struct Example {
bezier: bezier::State,
curves: Vec<bezier::Curve>,
button_state: button::State,
}
#[derive(Debug, Clone, Copy)]
enum Message {
AddCurve(bezier::Curve),
Clear,
}
impl Sandbox for Example {
type Message = Message;
fn new() -> Self {
Example::default()
}
fn title(&self) -> String {
String::from("Bezier tool - Iced")
}
fn update(&mut self, message: Message) {
match message {
Message::AddCurve(curve) => {
self.curves.push(curve);
self.bezier.request_redraw();
}
Message::Clear => {
self.bezier = bezier::State::default();
self.curves.clear();
}
}
}
fn view(&mut self) -> Element<Message> {
Column::new()
.padding(20)
.spacing(20)
.align_items(Align::Center)
.push(
Text::new("Bezier tool example")
.width(Length::Shrink)
.size(50),
)
.push(self.bezier.view(&self.curves).map(Message::AddCurve))
.push(
Button::new(&mut self.button_state, Text::new("Clear"))
.padding(8)
.on_press(Message::Clear),
)
.into()
}
}
mod bezier {
use iced::{
canvas::{
self, Canvas, Drawable, Event, Frame, Geometry, Path, Stroke,
},
mouse, ButtonState, Element, Length, Point, Size,
};
#[derive(Default)]
pub struct State {
pending: Option<Pending>,
cursor_position: Point,
cache: canvas::Cache,
}
impl State {
pub fn view<'a>(
&'a mut self,
curves: &'a [Curve],
) -> Element<'a, Curve> {
Canvas::new(Bezier {
state: self,
curves,
})
.width(Length::Fill)
.height(Length::Fill)
.into()
}
pub fn request_redraw(&mut self) {
self.cache.clear()
}
}
struct Bezier<'a> {
state: &'a mut State,
curves: &'a [Curve],
}
impl<'a> canvas::State<Curve> for Bezier<'a> {
fn update(&mut self, event: Event, _bounds: Size) -> Option<Curve> {
match event {
Event::Mouse(mouse_event) => match mouse_event {
mouse::Event::CursorMoved { x, y } => {
self.state.cursor_position = Point::new(x, y);
None
}
mouse::Event::Input {
button: mouse::Button::Left,
state: ButtonState::Pressed,
} => match self.state.pending {
None => {
self.state.pending = Some(Pending::One {
from: self.state.cursor_position,
});
None
}
Some(Pending::One { from }) => {
self.state.pending = Some(Pending::Two {
from,
to: self.state.cursor_position,
});
None
}
Some(Pending::Two { from, to }) => {
self.state.pending = None;
Some(Curve {
from,
to,
control: self.state.cursor_position,
})
}
},
_ => None,
},
}
}
fn draw(&self, bounds: Size) -> Vec<Geometry> {
let curves = self.state.cache.draw(bounds, &self.curves);
if let Some(pending) = &self.state.pending {
let pending_curve =
pending.draw(bounds, self.state.cursor_position);
vec![curves, pending_curve]
} else {
vec![curves]
}
}
}
#[derive(Debug, Clone, Copy)]
pub struct Curve {
from: Point,
to: Point,
control: Point,
}
impl Drawable for Curve {
fn draw(&self, frame: &mut Frame) {
let curve = Path::new(|p| {
p.move_to(self.from);
p.quadratic_curve_to(self.control, self.to);
});
frame.stroke(&curve, Stroke::default().with_width(2.0));
}
}
#[derive(Debug, Clone, Copy)]
enum Pending {
One { from: Point },
Two { from: Point, to: Point },
}
impl Pending {
fn draw(&self, bounds: Size, cursor_position: Point) -> Geometry {
let mut frame = Frame::new(bounds);
match *self {
Pending::One { from } => {
let line = Path::line(from, cursor_position);
frame.stroke(&line, Stroke::default().with_width(2.0));
}
Pending::Two { from, to } => {
let curve = Curve {
from,
to,
control: cursor_position,
};
curve.draw(&mut frame);
}
};
frame.into_geometry()
}
}
}
|
