From e91ee811cb74b9f0c0e32280e01a82e0f9655298 Mon Sep 17 00:00:00 2001
From: Alex Butler <alexheretic@gmail.com>
Date: Wed, 24 Aug 2022 21:43:36 +0100
Subject: [PATCH] Use sctk-adwaita 0.5.1 auto theme selection

Co-authored-by: Kirill Chibisov <contact@kchibisov.com>
---
 CHANGELOG.md                                  |  1 +
 src/platform/unix.rs                          |  4 ++
 src/platform_impl/linux/wayland/window/mod.rs | 37 ++++++++++++++-----
 3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 696a41cb..60ab4234 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ And please only add new entries to the top of this list, right below the `# Unre
 - **Breaking:** On macOS, add support for two-finger touchpad magnification and rotation gestures with new events `WindowEvent::TouchpadMagnify` and `WindowEvent::TouchpadRotate`.
 - On Wayland, `wayland-csd-adwaita` now uses `ab_glyph` instead of `crossfont` to render the title for decorations.
 - On Wayland, a new `wayland-csd-adwaita-crossfont` feature was added to use `crossfont` instead of `ab_glyph` for decorations.
+- On Wayland, if not otherwise specified use upstream automatic CSD theme selection.
 
 # 0.27.2 (2022-8-12)
 
diff --git a/src/platform/unix.rs b/src/platform/unix.rs
index 1d33e846..99e82619 100644
--- a/src/platform/unix.rs
+++ b/src/platform/unix.rs
@@ -212,6 +212,8 @@ pub trait WindowExtUnix {
     ///
     /// You can also use `WINIT_WAYLAND_CSD_THEME` env variable to set the theme.
     /// Possible values for env variable are: "dark" and light"
+    ///
+    /// When unspecified a theme is automatically selected.
     #[cfg(feature = "wayland")]
     fn wayland_set_csd_theme(&self, config: Theme);
 
@@ -349,6 +351,8 @@ pub trait WindowBuilderExtUnix {
     ///
     /// You can also use `WINIT_WAYLAND_CSD_THEME` env variable to set the theme.
     /// Possible values for env variable are: "dark" and light"
+    ///
+    /// When unspecified a theme is automatically selected.
     #[cfg(feature = "wayland")]
     fn with_wayland_csd_theme(self, theme: Theme) -> Self;
 
diff --git a/src/platform_impl/linux/wayland/window/mod.rs b/src/platform_impl/linux/wayland/window/mod.rs
index 43b13f61..db63781d 100644
--- a/src/platform_impl/linux/wayland/window/mod.rs
+++ b/src/platform_impl/linux/wayland/window/mod.rs
@@ -170,17 +170,14 @@ impl Window {
             )
             .map_err(|_| os_error!(OsError::WaylandMisc("failed to create window.")))?;
 
-        // Set CSD frame config
+        // Set CSD frame config from theme if specified,
+        // otherwise use upstream automatic selection.
         #[cfg(feature = "sctk-adwaita")]
-        {
-            let theme = platform_attributes.csd_theme.unwrap_or_else(|| {
-                let env = std::env::var(WAYLAND_CSD_THEME_ENV_VAR).unwrap_or_default();
-                match env.to_lowercase().as_str() {
-                    "dark" => Theme::Dark,
-                    _ => Theme::Light,
-                }
-            });
-
+        if let Some(theme) = platform_attributes.csd_theme.or_else(|| {
+            std::env::var(WAYLAND_CSD_THEME_ENV_VAR)
+                .ok()
+                .and_then(|s| s.as_str().try_into().ok())
+        }) {
             window.set_frame_config(theme.into());
         }
 
@@ -636,3 +633,23 @@ impl From<Theme> for sctk_adwaita::FrameConfig {
         }
     }
 }
+
+impl TryFrom<&str> for Theme {
+    type Error = ();
+
+    /// ```
+    /// use winit::window::Theme;
+    ///
+    /// assert_eq!("dark".try_into(), Ok(Theme::Dark));
+    /// assert_eq!("lIghT".try_into(), Ok(Theme::Light));
+    /// ```
+    fn try_from(theme: &str) -> Result<Self, Self::Error> {
+        if theme.eq_ignore_ascii_case("dark") {
+            Ok(Self::Dark)
+        } else if theme.eq_ignore_ascii_case("light") {
+            Ok(Self::Light)
+        } else {
+            Err(())
+        }
+    }
+}