Minor Scrollable Improvements

[AustinMReppert]

This PR provides minor improvements for the Scrollable widget.

• Align vertical and horizontal properties. Vertical properties are now optional and None by default.
• Prevent mouse wheel scrolling when vertical/horizontal properties are None.

[tarkah]

Prevent mouse wheel scrolling when vertical/horizontal properties are None.

Good catch on this!

[AustinMReppert]

What is the purpose of changing the mouse coordinates like this?

iced/widget/src/scrollable.rs

Line 467 in fcb1b45

Point::new(-1.0, -1.0)

This will cause strange behaviors when trying scroll with the mouse outside of the window bounds with nested scrollables.

use iced::widget::scrollable::{Properties, Viewport};
use iced::widget::{Container, Scrollable};
use iced::{
    executor, widget, Application, Background, Color, Command, Element, Length, Settings, Size,
    Theme,
};

pub fn main() -> iced::Result {
    HelloWorld::run(Settings::default())
}

#[derive(Debug, Clone, Copy)]
pub enum Message {
    Scrolled(Viewport),
}

struct HelloWorld {}

impl Application for HelloWorld {
    type Executor = executor::Default;
    type Message = Message;
    type Theme = Theme;
    type Flags = ();

    fn new(_flags: Self::Flags) -> (Self, Command<Self::Message>) {
        (HelloWorld {}, Command::none())
    }

    fn title(&self) -> String {
        String::from("Hello World!")
    }

    fn update(&mut self, _message: Message) -> Command<Self::Message> {
        Command::none()
    }

    fn view(&self) -> Element<Message> {
        Scrollable::new(
            Scrollable::new(
                Container::new("Foo")
                    .style(|theme: &iced::Theme| widget::container::Appearance {
                        text_color: None,
                        background: Some(Background::Color(Color::new(1.0, 0.2, 0.3, 1.0))),
                        border_radius: Default::default(),
                        border_width: 0.0,
                        border_color: Default::default(),
                    })
                    .width(Length::Fixed(5000.0))
                    .height(Length::Fixed(5000.0)),
            )
            .on_scroll(Message::Scrolled)
            .width(Length::Fill)
            .height(Length::Fill)
            .vertical_scroll(Properties::default())
            .horizontal_scroll(Properties::default()),
        )
        .into()
    }

    fn theme(&self) -> Theme {
        Theme::default()
    }
}

[bungoboingo]

Align vertical and horizontal properties. Vertical properties are now optional and None by default.

I also messed with making vertical scroll optional when I was adding horizontal support, but couldn't see the usefulness of a situation where a Scrollable couldn't scroll (e.g. both directions are None). Originally I made an enum that was like:

enum ScrollDirection {
    #[default]
    Vertical,
    Horizontal,
    Both,
}

which might be a better representation of how it's actually being used?

[hecrj]

@bungoboingo I agree. A scrollable that does not scroll does not make sense. Use another widget instead.

Also, we definitely do not want scrollable to disable scrolling on both axes by default, which is what this PR is currently doing.

[hecrj]

Awesome! Thanks 🙇

I have just renamed ScrollbarProperties to simply Direction and simplified some stuff here and there.

We can merge this! 🚢