From 48dad1cc89c50ce7ac0185ad4500e9825810c898 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tau=20G=C3=A4rtli?= <git@tau.garden>
Date: Sun, 30 Jun 2024 22:53:09 +0200
Subject: [PATCH] Populate `system_theme`

---
 crates/eframe/src/native/glow_integration.rs |  3 +++
 crates/eframe/src/native/wgpu_integration.rs |  2 ++
 crates/eframe/src/web/app_runner.rs          |  1 +
 crates/eframe/src/web/events.rs              |  1 +
 crates/egui-winit/src/lib.rs                 | 21 ++++++++++++++++++--
 5 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/crates/eframe/src/native/glow_integration.rs b/crates/eframe/src/native/glow_integration.rs
index f6cb909a40db..27d978239c52 100644
--- a/crates/eframe/src/native/glow_integration.rs
+++ b/crates/eframe/src/native/glow_integration.rs
@@ -222,6 +222,9 @@ impl GlowWinitApp {
         for viewport in glutin.viewports.values_mut() {
             if let Some(egui_winit) = viewport.egui_winit.as_mut() {
                 egui_winit.set_max_texture_side(max_texture_side);
+                if let Some(window) = viewport.window.as_deref() {
+                    egui_winit.init_system_theme(window);
+                }
             }
         }
 
diff --git a/crates/eframe/src/native/wgpu_integration.rs b/crates/eframe/src/native/wgpu_integration.rs
index 285320d5d4a7..685b444322a0 100644
--- a/crates/eframe/src/native/wgpu_integration.rs
+++ b/crates/eframe/src/native/wgpu_integration.rs
@@ -254,6 +254,8 @@ impl WgpuWinitApp {
             let event_loop_proxy = self.repaint_proxy.lock().clone();
             integration.init_accesskit(&mut egui_winit, &window, event_loop_proxy);
         }
+        egui_winit.init_system_theme(&window);
+
         let theme = system_theme.unwrap_or(self.native_options.default_theme);
         egui_ctx.set_visuals(Visuals::theme(theme));
 
diff --git a/crates/eframe/src/web/app_runner.rs b/crates/eframe/src/web/app_runner.rs
index b253abc271a1..6a9722d60f50 100644
--- a/crates/eframe/src/web/app_runner.rs
+++ b/crates/eframe/src/web/app_runner.rs
@@ -132,6 +132,7 @@ impl AppRunner {
             .entry(egui::ViewportId::ROOT)
             .or_default()
             .native_pixels_per_point = Some(super::native_pixels_per_point());
+        runner.input.raw.system_theme = super::system_theme();
 
         Ok(runner)
     }
diff --git a/crates/eframe/src/web/events.rs b/crates/eframe/src/web/events.rs
index 48c2249b22e5..7395482c521d 100644
--- a/crates/eframe/src/web/events.rs
+++ b/crates/eframe/src/web/events.rs
@@ -370,6 +370,7 @@ pub(crate) fn install_color_scheme_change_event(runner_ref: &WebRunner) -> Resul
                 let theme = theme_from_dark_mode(event.matches());
                 runner.frame.info.system_theme = Some(theme);
                 runner.egui_ctx().set_visuals(Visuals::theme(theme));
+                runner.input.raw.system_theme = Some(theme);
                 runner.needs_repaint.repaint_asap();
             },
         )?;
diff --git a/crates/egui-winit/src/lib.rs b/crates/egui-winit/src/lib.rs
index 4854cd2fd68c..2c36b7463bc1 100644
--- a/crates/egui-winit/src/lib.rs
+++ b/crates/egui-winit/src/lib.rs
@@ -14,7 +14,7 @@ pub use accesskit_winit;
 pub use egui;
 #[cfg(feature = "accesskit")]
 use egui::accesskit;
-use egui::{Pos2, Rect, Vec2, ViewportBuilder, ViewportCommand, ViewportId, ViewportInfo};
+use egui::{Pos2, Rect, Theme, Vec2, ViewportBuilder, ViewportCommand, ViewportId, ViewportInfo};
 pub use winit;
 
 pub mod clipboard;
@@ -172,6 +172,10 @@ impl State {
         ));
     }
 
+    pub fn init_system_theme(&mut self, window: &Window) {
+        self.egui_input.system_theme = window.theme().map(to_egui_theme);
+    }
+
     /// Call this once a graphics context has been created to update the maximum texture dimensions
     /// that egui will use.
     pub fn set_max_texture_side(&mut self, max_texture_side: usize) {
@@ -405,6 +409,13 @@ impl State {
                     consumed: false,
                 }
             }
+            WindowEvent::ThemeChanged(winit_theme) => {
+                self.egui_input.system_theme = Some(to_egui_theme(*winit_theme));
+                EventResponse {
+                    repaint: true,
+                    consumed: false,
+                }
+            }
             WindowEvent::HoveredFile(path) => {
                 self.egui_input.hovered_files.push(egui::HoveredFile {
                     path: Some(path.clone()),
@@ -464,7 +475,6 @@ impl State {
             | WindowEvent::Occluded(_)
             | WindowEvent::Resized(_)
             | WindowEvent::Moved(_)
-            | WindowEvent::ThemeChanged(_)
             | WindowEvent::TouchpadPressure { .. }
             | WindowEvent::CloseRequested => EventResponse {
                 repaint: true,
@@ -891,6 +901,13 @@ impl State {
     }
 }
 
+fn to_egui_theme(theme: winit::window::Theme) -> Theme {
+    match theme {
+        winit::window::Theme::Dark => Theme::Dark,
+        winit::window::Theme::Light => Theme::Light,
+    }
+}
+
 pub fn inner_rect_in_points(window: &Window, pixels_per_point: f32) -> Option<Rect> {
     let inner_pos_px = window.inner_position().ok()?;
     let inner_pos_px = egui::pos2(inner_pos_px.x as f32, inner_pos_px.y as f32);