From 98e9d75022b75cdf8df1d1b95d2dc8c097b426a6 Mon Sep 17 00:00:00 2001
From: Nico Burns <nico@nicoburns.com>
Date: Thu, 28 Nov 2024 19:44:32 +1300
Subject: [PATCH] Implement theme override for readme app

---
 apps/readme/src/readme_application.rs      | 30 ++++++++++++++++------
 packages/blitz-shell/src/stylo_to_winit.rs |  7 +++++
 packages/blitz-shell/src/window.rs         | 22 ++++++++++++++--
 3 files changed, 49 insertions(+), 10 deletions(-)

diff --git a/apps/readme/src/readme_application.rs b/apps/readme/src/readme_application.rs
index 436cb5ce..282e3784 100644
--- a/apps/readme/src/readme_application.rs
+++ b/apps/readme/src/readme_application.rs
@@ -2,13 +2,13 @@ use std::sync::Arc;
 
 use blitz_dom::net::Resource;
 use blitz_html::HtmlDocument;
-use blitz_shell::{BlitzApplication, BlitzEvent, WindowConfig};
+use blitz_shell::{BlitzApplication, BlitzEvent, View, WindowConfig};
 use blitz_traits::net::NetProvider;
 use winit::application::ApplicationHandler;
 use winit::event::{StartCause, WindowEvent};
 use winit::event_loop::{ActiveEventLoop, EventLoopProxy};
 use winit::keyboard::{KeyCode, PhysicalKey};
-use winit::window::WindowId;
+use winit::window::{Theme, WindowId};
 
 use crate::fetch;
 use crate::markdown::{markdown_to_html, BLITZ_MD_STYLES, GITHUB_MD_STYLES};
@@ -42,6 +42,10 @@ impl ReadmeApplication {
         self.inner.add_window(window_config);
     }
 
+    fn window_mut(&mut self) -> &mut View<HtmlDocument> {
+        self.inner.windows.values_mut().next().unwrap()
+    }
+
     fn reload_document(&mut self) {
         let (base_url, contents, is_md, _) = self.handle.block_on(fetch(&self.raw_url));
 
@@ -60,8 +64,16 @@ impl ReadmeApplication {
             self.net_provider.clone(),
             None,
         );
-        let window = self.inner.windows.values_mut().next().unwrap();
-        window.replace_document(doc);
+        self.window_mut().replace_document(doc);
+    }
+
+    fn toggle_theme(&mut self) {
+        let window = self.window_mut();
+        let new_theme = match window.current_theme() {
+            Theme::Light => Theme::Dark,
+            Theme::Dark => Theme::Light,
+        };
+        window.set_theme_override(Some(new_theme));
     }
 }
 
@@ -85,10 +97,12 @@ impl ApplicationHandler<BlitzEvent> for ReadmeApplication {
         event: WindowEvent,
     ) {
         if let WindowEvent::KeyboardInput { event, .. } = &event {
-            if event.state.is_pressed()
-                && matches!(event.physical_key, PhysicalKey::Code(KeyCode::KeyR))
-            {
-                self.reload_document();
+            if !event.state.is_pressed() {
+                match event.physical_key {
+                    PhysicalKey::Code(KeyCode::KeyR) => self.reload_document(),
+                    PhysicalKey::Code(KeyCode::KeyT) => self.toggle_theme(),
+                    _ => {}
+                }
             }
         }
 
diff --git a/packages/blitz-shell/src/stylo_to_winit.rs b/packages/blitz-shell/src/stylo_to_winit.rs
index 049e265d..9e3db664 100644
--- a/packages/blitz-shell/src/stylo_to_winit.rs
+++ b/packages/blitz-shell/src/stylo_to_winit.rs
@@ -54,3 +54,10 @@ pub(crate) fn theme_to_color_scheme(theme: Theme) -> ColorScheme {
         Theme::Dark => ColorScheme::Dark,
     }
 }
+
+pub(crate) fn color_scheme_to_theme(scheme: ColorScheme) -> Theme {
+    match scheme {
+        ColorScheme::Light => Theme::Light,
+        ColorScheme::Dark => Theme::Dark,
+    }
+}
diff --git a/packages/blitz-shell/src/window.rs b/packages/blitz-shell/src/window.rs
index 7ff8da05..696fd33b 100644
--- a/packages/blitz-shell/src/window.rs
+++ b/packages/blitz-shell/src/window.rs
@@ -1,6 +1,6 @@
 use crate::accessibility::AccessibilityState;
 use crate::event::{create_waker, BlitzEvent};
-use crate::stylo_to_winit::{self, theme_to_color_scheme};
+use crate::stylo_to_winit::{self, color_scheme_to_theme, theme_to_color_scheme};
 use blitz_dom::events::{EventData, RendererEvent};
 use blitz_dom::{DocumentLike, Viewport};
 use blitz_renderer_vello::Renderer;
@@ -52,6 +52,7 @@ pub struct View<Doc: DocumentLike> {
     /// The state of the keyboard modifiers (ctrl, shift, etc). Winit/Tao don't track these for us so we
     /// need to store them in order to have access to them when processing keypress events
     pub devtools: Devtools,
+    theme_override: Option<Theme>,
     keyboard_modifiers: Modifiers,
     mouse_pos: (f32, f32),
     dom_mouse_pos: (f32, f32),
@@ -94,6 +95,7 @@ impl<Doc: DocumentLike> View<Doc> {
             doc: config.doc,
             viewport,
             devtools: Default::default(),
+            theme_override: None,
             mouse_pos: Default::default(),
             dom_mouse_pos: Default::default(),
 
@@ -113,6 +115,22 @@ impl<Doc: DocumentLike> View<Doc> {
         self.poll();
         self.request_redraw();
     }
+
+    pub fn theme_override(&self) -> Option<Theme> {
+        self.theme_override
+    }
+
+    pub fn current_theme(&self) -> Theme {
+        color_scheme_to_theme(self.viewport.color_scheme)
+    }
+
+    pub fn set_theme_override(&mut self, theme: Option<Theme>) {
+        self.theme_override = theme;
+        let theme = theme.or(self.window.theme()).unwrap_or(Theme::Light);
+        self.viewport.color_scheme = theme_to_color_scheme(theme);
+        self.kick_viewport();
+        self.request_redraw();
+    }
 }
 
 impl<Doc: DocumentLike> View<Doc> {
@@ -285,7 +303,7 @@ impl<Doc: DocumentLike> View<Doc> {
 
             // Theme events
             WindowEvent::ThemeChanged(theme) => {
-                self.viewport.color_scheme = theme_to_color_scheme(theme);
+                self.viewport.color_scheme = theme_to_color_scheme(self.theme_override.unwrap_or(theme));
                 self.kick_viewport();
             }