egui_animate

Egui Animate

Custom animations and transitions.

Features

• Out/in egui::Ui element or variable transitioning.
• Out animations for hiding egui::Ui elements or variables.
• In animations for presenting egui::Ui elements or variables.
• Individual durations for out/in animation segments.
• Direct access to a scoped &mut egui::Ui for custom animations.

Functionality

egui_animate offers simple, customizable animations based on state variables. Define transitioning or individual out/in animations for entire ui interfaces, and/or individual variables. Animations can be customized by providing your own fn(&mut egui::Ui, f32) definitions that mutate a scoped egui::Ui. See the example project for common animations/transitions.

Animations

Animations define function(s) that mutate the egui::Ui given the normalized progression of the animation (segment) between 0.0 and 1.0 (named normal in examples). Calling [animate] will scope all egui::Ui mutations within. Animations are triggered by mutations of the value passed to the animate function. Any variable implementing Default, PartialEq and Clone is supported.

In the example below, an egui::Label is displayed by linearly mutating opacity from 0.0 to 1.0 over a duration of 0.5 seconds. Animation begins when show_ui is set to true.

// Animation definition
const FADE_IN: Animation = Animation::new_in(0.5, |ui, normal| ui.set_opacity(normal));

// Ui state.
let mut show_ui = false;

if ui.button("Click to show").clicked() {
    show_ui = true;
}

animate(
    ui,                // The `egui::Ui`.
    "anim",            // A *unique* name assigned to the animation layer.
    show_ui,           // The variable that will trigger animation on change.
    FADE_IN,           // The animation (for the current frame).
    |ui, show_ui| {    // The scoped `egui::Ui` that all mutations are applied to.
        if show_ui {
            // Show our label.
            ui.label("I am in scope");
        } else {
            // Show nothing.
        }
    },
);

The following animation transitions between interfaces, dynamically setting the animation on input.

// Left and right slide animations. See the example project for definitions.
// const SLIDE_FADE_LEFT: Animation = ..;
// const SLIDE_FADE_RIGHT: Animation = ..;

#[derive(Default, Clone, Copy, PartialEq)]
enum MyMenu {
    #[default]
    MainMenu,
    Options,
}

// Store the menu state and the animation to dynamically change it on input.
let mut menu_state = MyMenu::MainMenu;
let mut menu_anim_state = SLIDE_FADE_LEFT;

animate(
    ui,
    "menu_anim",
    menu_state,
    menu_anim_state,
    |ui, menu| match menu {
        // Display the `MainMenu` interface.
        MyMenu::MainMenu => {
            if ui.button("Options").clicked() {
                // Slide left on click.
                menu_anim_state = SLIDE_FADE_LEFT;
                menu_state = MyMenu::Options;
            }
        }
        // Display the `Options` interface.
        MyMenu::Options => {
            ui.button("Option 1");
            ui.button("Option 2");
            if ui.button("Back").clicked() {
                // Slide right on click.
                menu_anim_state = SLIDE_FADE_RIGHT;
                menu_state = MyMenu::MainMenu;
            }
        }
    },
);

Animation Run State

The animation [RunState] provides insight into the current animation segment and normal. Calling run_state will retrieve the state outside of the animations scoped context. In the example below, RunState is used to disable an egui::Button for the duration of an animation.

let button = egui::Button::new("Increment u32");

// Get the `RunState` of "my_anim".
if run_state(ui, "my_anim", MY_ANIM).is_running() {
    // Render a disabled button during animation.
    ui.add_enabled(false, button);
} else {
    // Render an enabled button when not animating.
    if ui.add(button).clicked() {
        my_state += 1;
    }
}
// Animate "my_anim".
animate(
    ui,
    "my_anim",
    my_state,
    MY_ANIM,
    |ui, show_ui| {
        // ...
    },
);

Examples

showcase | Various example animations. menu | A minimal dynamic "Main Menu" example. variable | Dynamic increment/decrement animations.

cargo run --example [EXAMPLE]

License: MIT OR Apache-2.0