Struct egui::containers::scroll_area::ScrollArea

pub struct ScrollArea {

    scroll_enabled: Vec2b,
    auto_shrink: Vec2b,
    max_size: Vec2,
    min_scrolled_size: Vec2,
    scroll_bar_visibility: ScrollBarVisibility,
    scroll_bar_rect: Option<Rect>,
    id_salt: Option<Id>,
    offset_x: Option<f32>,
    offset_y: Option<f32>,
    scrolling_enabled: bool,
    drag_to_scroll: bool,
    stick_to_end: Vec2b,
    animated: bool,
}

Add vertical and/or horizontal scrolling to a contained Ui.

By default, scroll bars only show up when needed, i.e. when the contents is larger than the container. This is controlled by Self::scroll_bar_visibility.

There are two flavors of scroll areas: solid and floating. Solid scroll bars use up space, reducing the amount of space available to the contents. Floating scroll bars float on top of the contents, covering it. You can change the scroll style by changing the crate::style::Spacing::scroll.

Coordinate system

• content: size of contents (generally large; that’s why we want scroll bars)
• outer: size of scroll area including scroll bar(s)
• inner: excluding scroll bar(s). The area we clip the contents to.

If the floating scroll bars settings is turned on then inner == outer.

Example

egui::ScrollArea::vertical().show(ui, |ui| {
    // Add a lot of widgets here.
});

You can scroll to an element using crate::Response::scroll_to_me, Ui::scroll_to_cursor and Ui::scroll_to_rect.

Fields

scroll_enabled: Vec2b

Do we have horizontal/vertical scrolling enabled?

auto_shrink: Vec2b

max_size: Vec2

min_scrolled_size: Vec2

scroll_bar_visibility: ScrollBarVisibility

scroll_bar_rect: Option<Rect>

id_salt: Option<Id>

offset_x: Option<f32>

offset_y: Option<f32>

scrolling_enabled: bool

If false, we ignore scroll events.

drag_to_scroll: bool

stick_to_end: Vec2b

If true for vertical or horizontal the scroll wheel will stick to the end position until user manually changes position. It will become true again once scroll handle makes contact with end.

animated: bool

If false, scroll_to_* functions will not be animated

Implementations

impl ScrollArea

pub fn horizontal() -> Self

Create a horizontal scroll area.

pub fn vertical() -> Self

Create a vertical scroll area.

pub fn both() -> Self

Create a bi-directional (horizontal and vertical) scroll area.

pub fn neither() -> Self

Create a scroll area where both direction of scrolling is disabled. It’s unclear why you would want to do this.

pub fn new(scroll_enabled: impl Into<Vec2b>) -> Self

Create a scroll area where you decide which axis has scrolling enabled. For instance, ScrollArea::new([true, false]) enables horizontal scrolling.

pub fn max_width(self, max_width: f32) -> Self

The maximum width of the outer frame of the scroll area.

Use f32::INFINITY if you want the scroll area to expand to fit the surrounding Ui (default).

See also Self::auto_shrink.

pub fn max_height(self, max_height: f32) -> Self

The maximum height of the outer frame of the scroll area.

Use f32::INFINITY if you want the scroll area to expand to fit the surrounding Ui (default).

See also Self::auto_shrink.

pub fn min_scrolled_width(self, min_scrolled_width: f32) -> Self

The minimum width of a horizontal scroll area which requires scroll bars.

The ScrollArea will only become smaller than this if the content is smaller than this (and so we don’t require scroll bars).

Default: 64.0.

pub fn min_scrolled_height(self, min_scrolled_height: f32) -> Self

The minimum height of a vertical scroll area which requires scroll bars.

The ScrollArea will only become smaller than this if the content is smaller than this (and so we don’t require scroll bars).

Default: 64.0.

pub fn scroll_bar_visibility( self, scroll_bar_visibility: ScrollBarVisibility, ) -> Self

Set the visibility of both horizontal and vertical scroll bars.

With ScrollBarVisibility::VisibleWhenNeeded (default), the scroll bar will be visible only when needed.

pub fn scroll_bar_rect(self, scroll_bar_rect: Rect) -> Self

Specify within which screen-space rectangle to show the scroll bars.

This can be used to move the scroll bars to a smaller region of the ScrollArea, for instance if you are painting a sticky header on top of it.

pub fn id_source(self, id_salt: impl Hash) -> Self

👎Deprecated: Renamed id_salt

A source for the unique Id, e.g. .id_source("second_scroll_area") or .id_source(loop_index).

pub fn id_salt(self, id_salt: impl Hash) -> Self

A source for the unique Id, e.g. .id_salt("second_scroll_area") or .id_salt(loop_index).

pub fn scroll_offset(self, offset: Vec2) -> Self

Set the horizontal and vertical scroll offset position.

Positive offset means scrolling down/right.

See also: Self::vertical_scroll_offset, Self::horizontal_scroll_offset, Ui::scroll_to_cursor and Response::scroll_to_me

pub fn vertical_scroll_offset(self, offset: f32) -> Self

Set the vertical scroll offset position.

Positive offset means scrolling down.

See also: Self::scroll_offset, Ui::scroll_to_cursor and Response::scroll_to_me

pub fn horizontal_scroll_offset(self, offset: f32) -> Self

Set the horizontal scroll offset position.

Positive offset means scrolling right.

See also: Self::scroll_offset, Ui::scroll_to_cursor and Response::scroll_to_me

pub fn hscroll(self, hscroll: bool) -> Self

Turn on/off scrolling on the horizontal axis.

pub fn vscroll(self, vscroll: bool) -> Self

Turn on/off scrolling on the vertical axis.

pub fn scroll(self, scroll_enabled: impl Into<Vec2b>) -> Self

Turn on/off scrolling on the horizontal/vertical axes.

You can pass in false, true, [false, true] etc.

pub fn scroll2(self, scroll_enabled: impl Into<Vec2b>) -> Self

👎Deprecated: Renamed to scroll

Turn on/off scrolling on the horizontal/vertical axes.

pub fn enable_scrolling(self, enable: bool) -> Self

Control the scrolling behavior.

• If true (default), the scroll area will respond to user scrolling.
• If false, the scroll area will not respond to user scrolling.

This can be used, for example, to optionally freeze scrolling while the user is typing text in a crate::TextEdit widget contained within the scroll area.

This controls both scrolling directions.

pub fn drag_to_scroll(self, drag_to_scroll: bool) -> Self

Can the user drag the scroll area to scroll?

This is useful for touch screens.

If true, the ScrollArea will sense drags.

Default: true.

pub fn auto_shrink(self, auto_shrink: impl Into<Vec2b>) -> Self

For each axis, should the containing area shrink if the content is small?

• If true, egui will add blank space outside the scroll area.
• If false, egui will add blank space inside the scroll area.

Default: true.

pub fn animated(self, animated: bool) -> Self

Should the scroll area animate scroll_to_* functions?

Default: true.

pub(crate) fn is_any_scroll_enabled(&self) -> bool

Is any scrolling enabled?

pub fn stick_to_right(self, stick: bool) -> Self

The scroll handle will stick to the rightmost position even while the content size changes dynamically. This can be useful to simulate text scrollers coming in from right hand side. The scroll handle remains stuck until user manually changes position. Once “unstuck” it will remain focused on whatever content viewport the user left it on. If the scroll handle is dragged all the way to the right it will again become stuck and remain there until manually pulled from the end position.

pub fn stick_to_bottom(self, stick: bool) -> Self

The scroll handle will stick to the bottom position even while the content size changes dynamically. This can be useful to simulate terminal UIs or log/info scrollers. The scroll handle remains stuck until user manually changes position. Once “unstuck” it will remain focused on whatever content viewport the user left it on. If the scroll handle is dragged to the bottom it will again become stuck and remain there until manually pulled from the end position.

impl ScrollArea

fn begin(self, ui: &mut Ui) -> Prepared

pub fn show<R>( self, ui: &mut Ui, add_contents: impl FnOnce(&mut Ui) -> R, ) -> ScrollAreaOutput<R>

Show the ScrollArea, and add the contents to the viewport.

If the inner area can be very long, consider using Self::show_rows instead.

pub fn show_rows<R>( self, ui: &mut Ui, row_height_sans_spacing: f32, total_rows: usize, add_contents: impl FnOnce(&mut Ui, Range<usize>) -> R, ) -> ScrollAreaOutput<R>

Efficiently show only the visible part of a large number of rows.

let text_style = egui::TextStyle::Body;
let row_height = ui.text_style_height(&text_style);
// let row_height = ui.spacing().interact_size.y; // if you are adding buttons instead of labels.
let total_rows = 10_000;
egui::ScrollArea::vertical().show_rows(ui, row_height, total_rows, |ui, row_range| {
    for row in row_range {
        let text = format!("Row {}/{}", row + 1, total_rows);
        ui.label(text);
    }
});

pub fn show_viewport<R>( self, ui: &mut Ui, add_contents: impl FnOnce(&mut Ui, Rect) -> R, ) -> ScrollAreaOutput<R>

This can be used to only paint the visible part of the contents.

add_contents is given the viewport rectangle, which is the relative view of the content. So if the passed rect has min = zero, then show the top left content (the user has not scrolled).

fn show_viewport_dyn<'c, R>( self, ui: &mut Ui, add_contents: Box<dyn FnOnce(&mut Ui, Rect) -> R + 'c>, ) -> ScrollAreaOutput<R>

Trait Implementations

impl Clone for ScrollArea

fn clone(&self) -> ScrollArea

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ScrollArea

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.