Artefacts at the end of moving canvas::Path::lines

[carlhammann]

Is your issue REALLY a bug?

• My issue is indeed a bug!
• I am not crazy! I will not fill out this form just to ask a question or request a feature. Pinky promise.

Is there an existing issue for this?

• I have searched the existing issues.

Is this issue related to iced?

• My hardware is compatible and my graphics drivers are up-to-date.

What happened?

Hello, and thanks for the great library! I encountered this while investigating #2281 (which is closed, but still seems to abide; see my comment there), but this is a separate issue.

Sometimes, the endpoints of a Path::line drawn with frame.stroke will "sweep out" some artefacts, as visible in the following recording:

recording.mp4

Also, note, in the second half of the video, that these artefacts "flicker" on redraw (which is triggered by the mouse moving).

The code:

main.rs

use iced::{
    widget::{
        canvas,
        canvas::{Frame, Geometry, Path, Program, Stroke},
        column, slider,
    },
    Element, Point, Rectangle, Renderer, Theme,
};

pub fn main() -> iced::Result {
    iced::run("", update, view)
}

fn update(state: &mut State, message: Message) {
    match message {
        Message::SetX(x) => state.x = x,
    }
}

fn view(state: &State) -> Element<Message> {
    column![
        canvas(state).height(120.0).width(200.0),
        slider(0.0..=200.0, state.x, Message::SetX)
    ]
    .into()
}

#[derive(Clone, Debug)]
enum Message {
    SetX(f32),
}

struct State {
    x: f32,
    y: f32,
}

impl Default for State {
    fn default() -> Self {
        State { x: 100.0, y: 100.0 }
    }
}

impl Program<Message> for State {
    type State = ();

    fn draw(
        &self,
        _state: &(),
        renderer: &Renderer,
        _theme: &Theme,
        bounds: Rectangle,
        _cursor: iced::mouse::Cursor,
    ) -> Vec<Geometry> {
        let mut frame = Frame::new(renderer, bounds.size());

        let origin = Point::new(0.0, 0.0);
        frame.stroke(
            &Path::line(origin, Point::new(self.x, self.y)),
            Stroke::default().with_width(8.0),
        );

        vec![frame.into_geometry()]
    }
}

What is the expected behavior?

I expect to see only a moving line.

Version

crates.io release

Operating System

Linux

Do you have any log output?

No response