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//! Backend-agnostic interface for writing apps using [`egui`].
//!
//! `epi` provides interfaces for window management and serialization.
//! An app written for `epi` can then be plugged into [`eframe`](https://docs.rs/eframe),
//! the egui framework crate.
//!
//! Start by looking at the [`App`] trait, and implement [`App::update`].
// Forbid warnings in release builds:
#![cfg_attr(not(debug_assertions), deny(warnings))]
#![forbid(unsafe_code)]
#![warn(
clippy::all,
clippy::await_holding_lock,
clippy::char_lit_as_u8,
clippy::checked_conversions,
clippy::dbg_macro,
clippy::debug_assert_with_mut_call,
clippy::disallowed_method,
clippy::doc_markdown,
clippy::empty_enum,
clippy::enum_glob_use,
clippy::exit,
clippy::expl_impl_clone_on_copy,
clippy::explicit_deref_methods,
clippy::explicit_into_iter_loop,
clippy::fallible_impl_from,
clippy::filter_map_next,
clippy::flat_map_option,
clippy::float_cmp_const,
clippy::fn_params_excessive_bools,
clippy::from_iter_instead_of_collect,
clippy::if_let_mutex,
clippy::implicit_clone,
clippy::imprecise_flops,
clippy::inefficient_to_string,
clippy::invalid_upcast_comparisons,
clippy::large_digit_groups,
clippy::large_stack_arrays,
clippy::large_types_passed_by_value,
clippy::let_unit_value,
clippy::linkedlist,
clippy::lossy_float_literal,
clippy::macro_use_imports,
clippy::manual_ok_or,
clippy::map_err_ignore,
clippy::map_flatten,
clippy::map_unwrap_or,
clippy::match_on_vec_items,
clippy::match_same_arms,
clippy::match_wild_err_arm,
clippy::match_wildcard_for_single_variants,
clippy::mem_forget,
clippy::mismatched_target_os,
clippy::missing_errors_doc,
clippy::missing_safety_doc,
clippy::mut_mut,
clippy::mutex_integer,
clippy::needless_borrow,
clippy::needless_continue,
clippy::needless_for_each,
clippy::needless_pass_by_value,
clippy::option_option,
clippy::path_buf_push_overwrite,
clippy::ptr_as_ptr,
clippy::ref_option_ref,
clippy::rest_pat_in_fully_bound_structs,
clippy::same_functions_in_if_condition,
clippy::semicolon_if_nothing_returned,
clippy::single_match_else,
clippy::string_add_assign,
clippy::string_add,
clippy::string_lit_as_bytes,
clippy::string_to_string,
clippy::todo,
clippy::trait_duplication_in_bounds,
clippy::unimplemented,
clippy::unnested_or_patterns,
clippy::unused_self,
clippy::useless_transmute,
clippy::verbose_file_reads,
clippy::zero_sized_map_values,
future_incompatible,
missing_crate_level_docs,
nonstandard_style,
rust_2018_idioms
)]
#![allow(clippy::float_cmp)]
#![allow(clippy::manual_range_contains)]
#![warn(missing_docs)] // Let's keep `epi` well-documented.
/// File storage which can be used by native backends.
#[cfg(feature = "file_storage")]
pub mod file_storage;
pub use egui; // Re-export for user convenience
// ----------------------------------------------------------------------------
/// Implement this trait to write apps that can be compiled both natively using the [`egui_glium`](https://github.com/emilk/egui/tree/master/egui_glium) crate,
/// and deployed as a web site using the [`egui_web`](https://github.com/emilk/egui/tree/master/egui_web) crate.
pub trait App {
/// Called each time the UI needs repainting, which may be many times per second.
///
/// Put your widgets into a [`egui::SidePanel`], [`egui::TopBottomPanel`], [`egui::CentralPanel`], [`egui::Window`] or [`egui::Area`].
///
/// To force a repaint, call either [`egui::Context::request_repaint`] or use [`Frame::repaint_signal`].
fn update(&mut self, ctx: &egui::CtxRef, frame: &mut Frame<'_>);
/// Called once before the first frame.
///
/// Allows you to do setup code, e.g to call [`egui::Context::set_fonts`],
/// [`egui::Context::set_visuals`] etc.
///
/// Also allows you to restore state, if there is a storage (required the "persistence" feature).
fn setup(
&mut self,
_ctx: &egui::CtxRef,
_frame: &mut Frame<'_>,
_storage: Option<&dyn Storage>,
) {
}
/// If `true` a warm-up call to [`Self::update`] will be issued where
/// `ctx.memory().everything_is_visible()` will be set to `true`.
///
/// This will help pre-caching all text, preventing stutter when
/// opening a window containing new glyphs.
///
/// In this warm-up call, all painted shapes will be ignored.
fn warm_up_enabled(&self) -> bool {
false
}
/// Called on shutdown, and perhaps at regular intervals. Allows you to save state.
///
/// Only called when the "persistence" feature is enabled.
///
/// On web the states is stored to "Local Storage".
/// On native the path is picked using [`directories_next::ProjectDirs::data_dir`](https://docs.rs/directories-next/2.0.0/directories_next/struct.ProjectDirs.html#method.data_dir) which is:
/// * Linux: `/home/UserName/.local/share/APPNAME`
/// * macOS: `/Users/UserName/Library/Application Support/APPNAME`
/// * Windows: `C:\Users\UserName\AppData\Roaming\APPNAME`
///
/// where `APPNAME` is what is returned by [`Self::name()`].
fn save(&mut self, _storage: &mut dyn Storage) {}
/// Called once on shutdown (before or after [`Self::save`])
fn on_exit(&mut self) {}
// ---------
// Settings:
/// The name of your App, used for the title bar of native windows
/// and the save location of persistence (see [`Self::save`]).
fn name(&self) -> &str;
/// Time between automatic calls to [`Self::save`]
fn auto_save_interval(&self) -> std::time::Duration {
std::time::Duration::from_secs(30)
}
/// The size limit of the web app canvas.
fn max_size_points(&self) -> egui::Vec2 {
// Some browsers get slow with huge WebGL canvases, so we limit the size:
egui::Vec2::new(1024.0, 2048.0)
}
/// Background color for the app, e.g. what is sent to `gl.clearColor`.
/// This is the background of your windows if you don't set a central panel.
fn clear_color(&self) -> egui::Rgba {
// NOTE: a bright gray makes the shadows of the windows look weird.
// We use a bit of transparency so that if the user switches on the
// `transparent()` option they get immediate results.
egui::Color32::from_rgba_unmultiplied(12, 12, 12, 180).into()
}
/// Controls wether or not the native window position and size will be
/// persisted (only if the "persistence" feature is enabled).
fn persist_native_window(&self) -> bool {
true
}
/// Controls wether or not the egui memory (window positions etc) will be
/// persisted (only if the "persistence" feature is enabled).
fn persist_egui_memory(&self) -> bool {
true
}
}
/// Options controlling the behavior of a native window
#[derive(Clone)]
pub struct NativeOptions {
/// Sets whether or not the window will always be on top of other windows.
pub always_on_top: bool,
/// Show window in maximized mode
pub maximized: bool,
/// On desktop: add window decorations (i.e. a frame around your app)?
/// If false it will be difficult to move and resize the app.
pub decorated: bool,
/// On Windows: enable drag and drop support.
/// Default is `false` to avoid issues with crates such as [`cpal`](https://github.com/RustAudio/cpal) which
/// will hang when combined with drag-and-drop.
/// See <https://github.com/rust-windowing/winit/issues/1255>.
pub drag_and_drop_support: bool,
/// The application icon, e.g. in the Windows task bar etc.
pub icon_data: Option<IconData>,
/// The initial size of the native window in points (logical pixels).
pub initial_window_size: Option<egui::Vec2>,
/// Should the app window be resizable?
pub resizable: bool,
/// On desktop: make the window transparent.
/// You control the transparency with [`App::clear_color()`].
/// You should avoid having a [`egui::CentralPanel`], or make sure its frame is also transparent.
pub transparent: bool,
}
impl Default for NativeOptions {
fn default() -> Self {
Self {
always_on_top: false,
maximized: false,
decorated: true,
drag_and_drop_support: false,
icon_data: None,
initial_window_size: None,
resizable: true,
transparent: false,
}
}
}
/// Image data for the icon.
#[derive(Clone)]
pub struct IconData {
/// RGBA pixels.
pub rgba: Vec<u8>,
/// Image width. This should be a multiple of 4.
pub width: u32,
/// Image height. This should be a multiple of 4.
pub height: u32,
}
/// Represents the surroundings of your app.
///
/// It provides methods to inspect the surroundings (are we on the web?),
/// allocate textures, and change settings (e.g. window size).
pub struct Frame<'a>(backend::FrameBuilder<'a>);
impl<'a> Frame<'a> {
/// True if you are in a web environment.
pub fn is_web(&self) -> bool {
self.info().web_info.is_some()
}
/// Information about the integration.
pub fn info(&self) -> &IntegrationInfo {
&self.0.info
}
/// A way to allocate textures.
pub fn tex_allocator(&mut self) -> &mut dyn TextureAllocator {
self.0.tex_allocator
}
/// Signal the app to stop/exit/quit the app (only works for native apps, not web apps).
/// The framework will not quit immediately, but at the end of the this frame.
pub fn quit(&mut self) {
self.0.output.quit = true;
}
/// Set the desired inner size of the window (in egui points).
pub fn set_window_size(&mut self, size: egui::Vec2) {
self.0.output.window_size = Some(size);
}
/// Set the desired title of the window.
pub fn set_window_title(&mut self, title: &str) {
self.0.output.window_title = Some(title.to_owned());
}
/// Set whether to show window decorations (i.e. a frame around you app).
/// If false it will be difficult to move and resize the app.
pub fn set_decorations(&mut self, decorated: bool) {
self.0.output.decorated = Some(decorated);
}
/// When called, the native window will follow the
/// movement of the cursor while the primary mouse button is down.
///
/// Does not work on the web, and works badly on Mac.
pub fn drag_window(&mut self) {
self.0.output.drag_window = true;
}
/// If you need to request a repaint from another thread, clone this and send it to that other thread.
pub fn repaint_signal(&self) -> std::sync::Arc<dyn RepaintSignal> {
self.0.repaint_signal.clone()
}
}
/// Information about the web environment (if applicable).
#[derive(Clone, Debug)]
pub struct WebInfo {
/// e.g. "#fragment" part of "www.example.com/index.html#fragment".
/// Note that the leading `#` is included in the string.
/// Also known as "hash-link" or "anchor".
pub web_location_hash: String,
}
/// Information about the integration passed to the use app each frame.
#[derive(Clone, Debug)]
pub struct IntegrationInfo {
/// The name of the integration, e.g. `egui_web`, `egui_glium`, `egui_glow`
pub name: &'static str,
/// If the app is running in a Web context, this returns information about the environment.
pub web_info: Option<WebInfo>,
/// Does the system prefer dark mode (over light mode)?
/// `None` means "don't know".
pub prefer_dark_mode: Option<bool>,
/// Seconds of cpu usage (in seconds) of UI code on the previous frame.
/// `None` if this is the first frame.
pub cpu_usage: Option<f32>,
/// The OS native pixels-per-point
pub native_pixels_per_point: Option<f32>,
}
/// How to allocate textures (images) to use in [`egui`].
pub trait TextureAllocator {
/// Allocate a new user texture.
///
/// There is no way to change a texture.
/// Instead allocate a new texture and free the previous one with [`Self::free`].
fn alloc_srgba_premultiplied(
&mut self,
size: (usize, usize),
srgba_pixels: &[egui::Color32],
) -> egui::TextureId;
/// Free the given texture.
fn free(&mut self, id: egui::TextureId);
}
/// Abstraction for platform dependent texture reference
pub trait NativeTexture {
/// The native texture type.
type Texture;
/// Bind native texture to egui texture
fn register_native_texture(&mut self, native: Self::Texture) -> egui::TextureId;
/// Change id's actual pointing texture
/// only for user texture
fn replace_native_texture(&mut self, id: egui::TextureId, replacing: Self::Texture);
}
/// How to signal the [`egui`] integration that a repaint is required.
pub trait RepaintSignal: Send + Sync {
/// This signals the [`egui`] integration that a repaint is required.
/// This is meant to be called when a background process finishes in an async context and/or background thread.
fn request_repaint(&self);
}
// ----------------------------------------------------------------------------
/// A place where you can store custom data in a way that persists when you restart the app.
///
/// On the web this is backed by [local storage](https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage).
/// On desktop this is backed by the file system.
pub trait Storage {
/// Get the value for the given key.
fn get_string(&self, key: &str) -> Option<String>;
/// Set the value for the given key.
fn set_string(&mut self, key: &str, value: String);
/// write-to-disk or similar
fn flush(&mut self);
}
/// Stores nothing.
#[derive(Clone, Default)]
pub struct DummyStorage {}
impl Storage for DummyStorage {
fn get_string(&self, _key: &str) -> Option<String> {
None
}
fn set_string(&mut self, _key: &str, _value: String) {}
fn flush(&mut self) {}
}
/// Get and deserialize the [RON](https://github.com/ron-rs/ron) stored at the given key.
#[cfg(feature = "ron")]
pub fn get_value<T: serde::de::DeserializeOwned>(storage: &dyn Storage, key: &str) -> Option<T> {
storage
.get_string(key)
.and_then(|value| ron::from_str(&value).ok())
}
/// Serialize the given value as [RON](https://github.com/ron-rs/ron) and store with the given key.
#[cfg(feature = "ron")]
pub fn set_value<T: serde::Serialize>(storage: &mut dyn Storage, key: &str, value: &T) {
storage.set_string(
key,
ron::ser::to_string_pretty(value, Default::default()).unwrap(),
);
}
/// [`Storage`] key used for app
pub const APP_KEY: &str = "app";
// ----------------------------------------------------------------------------
/// You only need to look here if you are writing a backend for `epi`.
pub mod backend {
use super::*;
/// The data required by [`Frame`] each frame.
pub struct FrameBuilder<'a> {
/// Information about the integration.
pub info: IntegrationInfo,
/// A way to allocate textures (on integrations that support it).
pub tex_allocator: &'a mut dyn TextureAllocator,
/// Where the app can issue commands back to the integration.
pub output: &'a mut AppOutput,
/// If you need to request a repaint from another thread, clone this and send it to that other thread.
pub repaint_signal: std::sync::Arc<dyn RepaintSignal>,
}
impl<'a> FrameBuilder<'a> {
/// Wrap us in a [`Frame`] to send to [`App::update`].
pub fn build(self) -> Frame<'a> {
Frame(self)
}
}
/// Action that can be taken by the user app.
#[derive(Clone, Debug, Default, PartialEq)]
pub struct AppOutput {
/// Set to `true` to stop the app.
/// This does nothing for web apps.
pub quit: bool,
/// Set to some size to resize the outer window (e.g. glium window) to this size.
pub window_size: Option<egui::Vec2>,
/// Set to some string to rename the outer window (e.g. glium window) to this title.
pub window_title: Option<String>,
/// Set to some bool to change window decorations
pub decorated: Option<bool>,
/// Set to true to drap window
pub drag_window: bool,
}
}