Struct egui::Memory

pub struct Memory {
    pub options: Options,
    pub data: IdTypeMap,
    pub caches: CacheStorage,
    /* private fields */
}

The data that egui persists between frames.

This includes window positions and sizes, how far the user has scrolled in a ScrollArea etc.

If you want this to persist when closing your app you should serialize Memory and store it. For this you need to enable the persistence.

If you want to store data for your widgets, you should look at Memory::data

Fields

options: Options

Global egui options.

data: IdTypeMap

This map stores some superficial state for all widgets with custom Ids.

This includes storing if a crate::CollapsingHeader is open, how far scrolled a crate::ScrollArea is, where the cursor in a crate::TextEdit is, etc.

This is NOT meant to store any important data. Store that in your own structures!

Each read clones the data, so keep your values cheap to clone. If you want to store a lot of data you should wrap it in Arc<Mutex<…>> so it is cheap to clone.

This will be saved between different program runs if you use the persistence feature.

To store a state common for all your widgets (a singleton), use Id::NULL as the key.

caches: CacheStorage

Can be used to cache computations from one frame to another.

This is for saving CPU when you have something that may take 1-100ms to compute. Things that are very slow (>100ms) should instead be done async (i.e. in another thread) so as not to lock the UI thread.

use egui::util::cache::{ComputerMut, FrameCache};

#[derive(Default)]
struct CharCounter {}
impl ComputerMut<&str, usize> for CharCounter {
    fn compute(&mut self, s: &str) -> usize {
        s.chars().count() // you probably want to cache something more expensive than this
    }
}
type CharCountCache<'a> = FrameCache<usize, CharCounter>;

ctx.memory_mut(|mem| {
    let cache = mem.caches.cache::<CharCountCache<'_>>();
    assert_eq!(cache.get("hello"), 5);
});

Implementations

impl Memory

pub fn areas(&self) -> &Areas

Access memory of the Areas, such as Windows.

pub fn areas_mut(&mut self) -> &mut Areas

Access memory of the Areas, such as Windows.

pub fn layer_id_at( &self, pos: Pos2, resize_interact_radius_side: f32 ) -> Option<LayerId>

Top-most layer at the given position.

pub fn layer_ids(&self) -> impl ExactSizeIterator<Item = LayerId> + '_

An iterator over all layers. Back-to-front. Top is last.

pub fn has_focus(&self, id: Id) -> bool

Does this widget have keyboard focus?

This function does not consider whether the UI as a whole (e.g. window) has the keyboard focus. That makes this function suitable for deciding widget state that should not be disrupted if the user moves away from the window and back.

pub fn focus(&self) -> Option<Id>

Which widget has keyboard focus?

pub fn set_focus_lock_filter(&mut self, id: Id, event_filter: EventFilter)

Set an event filter for a widget.

This allows you to control whether the widget will loose focus when the user presses tab, arrow keys, or escape.

You must first give focus to the widget before calling this.

pub fn request_focus(&mut self, id: Id)

Give keyboard focus to a specific widget. See also crate::Response::request_focus.

pub fn surrender_focus(&mut self, id: Id)

Surrender keyboard focus for a specific widget. See also crate::Response::surrender_focus.

pub fn interested_in_focus(&mut self, id: Id)

Register this widget as being interested in getting keyboard focus. This will allow the user to select it with tab and shift-tab. This is normally done automatically when handling interactions, but it is sometimes useful to pre-register interest in focus, e.g. before deciding which type of underlying widget to use, as in the crate::DragValue widget, so a widget can be focused and rendered correctly in a single frame.

pub fn stop_text_input(&mut self)

Stop editing of active TextEdit (if any).

pub fn is_anything_being_dragged(&self) -> bool

Is any widget being dragged?

pub fn is_being_dragged(&self, id: Id) -> bool

Is this specific widget being dragged?

Usually it is better to use crate::Response::dragged.

A widget that sense both clicks and drags is only marked as “dragged” when the mouse has moved a bit, but is_being_dragged will return true immediately.

pub fn dragged_id(&self) -> Option<Id>

Get the id of the widget being dragged, if any.

Note that this is set as soon as the mouse is pressed, so the widget may not yet be marked as “dragged”, as that can only happen after the mouse has moved a bit (at least if the widget is interesated in both clicks and drags).

pub fn set_dragged_id(&mut self, id: Id)

Set which widget is being dragged.

pub fn stop_dragging(&mut self)

Stop dragging any widget.

pub fn dragging_something_else(&self, not_this: Id) -> bool

Is something else being dragged?

Returns true if we are dragging something, but not the given widget.

pub fn reset_areas(&mut self)

Forget window positions, sizes etc. Can be used to auto-layout windows.

pub fn area_rect(&self, id: impl Into<Id>) -> Option<Rect>

Obtain the previous rectangle of an area.

impl Memory

Popups

Popups are things like combo-boxes, color pickers, menus etc. Only one can be be open at a time.

pub fn is_popup_open(&self, popup_id: Id) -> bool

Is the given popup open?

pub fn any_popup_open(&self) -> bool

Is any popup open?

pub fn open_popup(&mut self, popup_id: Id)

Open the given popup, and close all other.

pub fn close_popup(&mut self)

Close the open popup, if any.

pub fn toggle_popup(&mut self, popup_id: Id)

Toggle the given popup between closed and open.

Note: at most one popup can be open at one time.

pub fn everything_is_visible(&self) -> bool

If true, all windows, menus, tooltips etc are to be visible at once.

This is useful for testing, benchmarking, pre-caching, etc.

Experimental feature!

pub fn set_everything_is_visible(&mut self, value: bool)

If true, all windows, menus, tooltips etc are to be visible at once.

This is useful for testing, benchmarking, pre-caching, etc.

Experimental feature!

Trait Implementations

impl Clone for Memory

fn clone(&self) -> Memory

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Memory

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

Formats the value using the given formatter.

impl Default for Memory

fn default() -> Self

Returns the “default value” for a type.