Trait Scrollable 

pub trait Scrollable: Widget {
    // Required methods
    fn content_size(&self) -> Size;
    fn max_scroll_offset(&self) -> Offset;
    fn scroll_offset(&self) -> Offset;
    fn set_scroll_offset(
        &mut self,
        cx: &mut EventCx<'_>,
        offset: Offset,
    ) -> Offset;
}

Additional functionality on scrollable widgets

This trait should be implemented by widgets supporting scrolling, enabling a parent to control scrolling.

If the widget scrolls itself it should set a scroll action via EventCx::set_scroll.

Required Methods

fn content_size(&self) -> Size

Get the content size (the inner size of the scrolled pane)

This is used to determine the amount of scrolling required, hence it is acceptable to return 0 on non-scrolled dimensions.

Note: this is called before Layout::set_rect, thus must may need to perform independent calculation of the content size.

fn max_scroll_offset(&self) -> Offset

Get the maximum scroll offset

Note: the minimum scroll offset is always zero.

Note: this is called immediately after Layout::set_rect, thus should be updated there (as well as by Events::update if appropriate).

fn scroll_offset(&self) -> Offset

Get the current scroll offset

Contents of the scroll region are translated by this offset (to convert coordinates from the outer region to the scroll region, add this offset).

The offset is restricted between Offset::ZERO and Self::max_scroll_offset.

fn set_scroll_offset(&mut self, cx: &mut EventCx<'_>, offset: Offset) -> Offset

Set the scroll offset

This may be used for programmatic scrolling, e.g. by a wrapping widget with scroll controls. Note that calling this method directly on the scrolling widget will not update any controls in a wrapping widget.

The offset is clamped to the available scroll range and applied. The resulting offset is returned.

Implementors

impl<A, W> Scrollable for MapAny<A, W>

where W: Scrollable + Widget<Data = ()>,