egui-winit: Automatically detect and apply dark or light mode

Closes #1001

Uses the `dark-light` crate: https://crates.io/crates/dark-light

eframe/CHANGELOG.md

@@ -8,6 +8,7 @@ NOTE: [`egui_web`](../egui_web/CHANGELOG.md), [`egui-winit`](../egui-winit/CHANG
 * Removed `Frame::alloc_texture`. Use `egui::Context::load_texture` instead ([#1110](https://github.com/emilk/egui/pull/1110)).
 * The default native backend is now `egui_glow` (instead of `egui_glium`) ([#1020](https://github.com/emilk/egui/pull/1020)).
 * The default web painter is now `egui_glow` (instead of WebGL) ([#1020](https://github.com/emilk/egui/pull/1020)).
+* Automatically detect and apply dark or light mode from system ([#1045](https://github.com/emilk/egui/pull/1045)).
 * Fix horizontal scrolling direction on Linux.
 * Added `App::on_exit_event` ([#1038](https://github.com/emilk/egui/pull/1038))
 * Shift-scroll will now result in horizontal scrolling on all platforms ([#1136](https://github.com/emilk/egui/pull/1136)).

egui-winit/CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to the `egui-winit` integration will be noted in this file.
 
 ## Unreleased
 * Fixed horizontal scrolling direction on Linux.
+* Automatically detect and apply dark or light mode from system ([#1045](https://github.com/emilk/egui/pull/1045)).
 * Replaced `std::time::Instant` with `instant::Instant` for WebAssembly compatability ([#1023](https://github.com/emilk/egui/pull/1023))
 * Shift-scroll will now result in horizontal scrolling on all platforms ([#1136](https://github.com/emilk/egui/pull/1136)).
 * Require knowledge about max texture side (e.g. `GL_MAX_TEXTURE_SIZE`)) ([#1154](https://github.com/emilk/egui/pull/1154)).

egui-winit/Cargo.toml

@@ -30,14 +30,15 @@ winit = "0.26.1"
 epi = { version = "0.16.0", path = "../epi", optional = true }
 
 copypasta = { version = "0.7", optional = true }
+dark-light = { version = "0.1.1", optional = true } # detect dark mode system preference
 serde = { version = "1.0", optional = true, features = ["derive"] }
 webbrowser = { version = "0.5", optional = true }
 
 # feature screen_reader
 tts = { version = "0.19", optional = true }
 
 [features]
-default = ["clipboard", "links"]
+default = ["clipboard", "dark-light", "links"]
 
 # enable cut/copy/paste to OS clipboard.
 # if disabled a clipboard will be simulated so you can still copy/paste within the egui app.

egui-winit/src/epi.rs

@@ -223,18 +223,26 @@ impl EpiIntegration {
 
  *egui_ctx.memory() = persistence.load_memory().unwrap_or_default();
 
+ let prefer_dark_mode = prefer_dark_mode();
+
  let frame = epi::Frame::new(epi::backend::FrameData {
  info: epi::IntegrationInfo {
  name: integration_name,
  web_info: None,
- prefer_dark_mode: None, // TODO: figure out system default
+ prefer_dark_mode,
  cpu_usage: None,
  native_pixels_per_point: Some(crate::native_pixels_per_point(window)),
  },
  output: Default::default(),
  repaint_signal,
  });
 
+ if prefer_dark_mode == Some(true) {
+ egui_ctx.set_visuals(egui::Visuals::dark());
+ } else {
+ egui_ctx.set_visuals(egui::Visuals::light());
+ }
+
  let mut slf = Self {
  frame,
  persistence,
@@ -340,3 +348,16 @@ impl EpiIntegration {
  .save(&mut *self.app, &self.egui_ctx, window);
  }
 }
+
+#[cfg(feature = "dark-light")]
+fn prefer_dark_mode() -> Option<bool> {
+ match dark_light::detect() {
+ dark_light::Mode::Dark => Some(true),
+ dark_light::Mode::Light => Some(false),
+ }
+}
+
+#[cfg(not(feature = "dark-light"))]
+fn prefer_dark_mode() -> Option<bool> {
+ None
+}

egui_glium/CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to the `egui_glium` integration will be noted in this file.
 ## Unreleased
 * `EguiGlium::run` no longer returns the shapes to paint, but stores them internally until you call `EguiGlium::paint` ([#1110](https://github.com/emilk/egui/pull/1110)).
 * Optimize the painter and texture uploading ([#1110](https://github.com/emilk/egui/pull/1110)).
+* Automatically detect and apply dark or light mode from system ([#1045](https://github.com/emilk/egui/pull/1045)).
 
 
 ## 0.16.0 - 2021-12-29

egui_glow/CHANGELOG.md

@@ -7,7 +7,9 @@ All notable changes to the `egui_glow` integration will be noted in this file.
 * Added `set_texture_filter` method to `Painter` ([#1041](https://github.com/emilk/egui/pull/1041)).
 * Fix failure to run in Chrome ([#1092](https://github.com/emilk/egui/pull/1092)).
 * `EguiGlow::new` now takes `&winit::Window` because there are no reason to use `&glutin::WindowedContext` ([#1151](https://github.com/emilk/egui/pull/1151)).
-* `EguiGlow::paint` now takes `&winit::Window` because there are no reason to use `&glutin::WindowedContext` ([#1151](https://github.com/emilk/egui/pull/1151)). 
+* `EguiGlow::paint` now takes `&winit::Window` because there are no reason to use `&glutin::WindowedContext` ([#1151](https://github.com/emilk/egui/pull/1151)).
+* Automatically detect and apply dark or light mode from system ([#1045](https://github.com/emilk/egui/pull/1045)).
+
 
 ## 0.16.0 - 2021-12-29
 * Made winit/glutin an optional dependency ([#868](https://github.com/emilk/egui/pull/868)).

egui_glow/Cargo.toml

@@ -35,7 +35,7 @@ memoffset = "0.6"
 tracing = "0.1"
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-egui-winit = { version = "0.16.0", path = "../egui-winit", default-features = false, features = ["epi"], optional = true }
+egui-winit = { version = "0.16.0", path = "../egui-winit", default-features = false, features = ["dark-light", "epi"], optional = true }
 glutin = { version = "0.28.0", optional = true }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]