feat: add theme feature on Linux (#468)

.changes/impl-theme-linux.md

@@ -0,0 +1,5 @@
+---
+"tao": patch
+---
+
+Add theme feature on Linux.

examples/theme.rs

@@ -1,7 +1,6 @@
 // Copyright 2019-2021 Tauri Programme within The Commons Conservancy
 // SPDX-License-Identifier: Apache-2.0
 
-#[cfg(any(target_os = "windows", target_os = "macos"))]
 #[allow(clippy::single_match)]
 fn main() {
   use tao::{
@@ -10,11 +9,6 @@ fn main() {
     window::WindowBuilder,
   };
 
-  #[cfg(any(target_os = "macos"))]
-  use tao::platform::macos::{WindowBuilderExtMacOS, WindowExtMacOS};
-  #[cfg(target_os = "windows")]
-  use tao::platform::windows::{WindowBuilderExtWindows, WindowExtWindows};
-
   env_logger::init();
   let event_loop = EventLoop::new();
 
@@ -45,16 +39,3 @@ fn main() {
     }
   });
 }
-
-#[cfg(any(
-  target_os = "ios",
-  target_os = "android",
-  target_os = "linux",
-  target_os = "dragonfly",
-  target_os = "freebsd",
-  target_os = "netbsd",
-  target_os = "openbsd"
-))]
-fn main() {
-  println!("This platform doesn't support theme.");
-}

src/event.rs

@@ -469,7 +469,9 @@ pub enum WindowEvent<'a> {
   /// Applications might wish to react to this to change the theme of the content of the window
   /// when the system changes the window theme.
   ///
-  /// At the moment this is only supported on Windows.
+  /// ## Platform-specific
+  ///
+  /// - **Linux / Android / iOS:** Unsupported
   ThemeChanged(Theme),
 
   /// The window decorations has been clicked.

src/platform/macos.rs

@@ -11,7 +11,7 @@ use crate::{
   menu::CustomMenuItem,
   monitor::MonitorHandle,
   platform_impl::{get_aux_state_mut, Parent},
-  window::{Icon, Theme, Window, WindowBuilder},
+  window::{Icon, Window, WindowBuilder},
 };
 
 #[cfg(feature = "tray")]
@@ -54,9 +54,6 @@ pub trait WindowExtMacOS {
 
   /// Sets whether or not the window has shadow.
   fn set_has_shadow(&self, has_shadow: bool);
-
-  /// Returns the current window theme.
-  fn theme(&self) -> Theme;
 }
 
 impl WindowExtMacOS for Window {
@@ -89,11 +86,6 @@ impl WindowExtMacOS for Window {
   fn set_has_shadow(&self, has_shadow: bool) {
     self.window.set_has_shadow(has_shadow)
   }
-
-  #[inline]
-  fn theme(&self) -> Theme {
-    self.window.theme()
-  }
 }
 
 /// Corresponds to `NSApplicationActivationPolicy`.
@@ -346,8 +338,6 @@ pub trait WindowBuilderExtMacOS {
   fn with_resize_increments(self, increments: LogicalSize<f64>) -> WindowBuilder;
   fn with_disallow_hidpi(self, disallow_hidpi: bool) -> WindowBuilder;
   fn with_has_shadow(self, has_shadow: bool) -> WindowBuilder;
-  /// Forces a theme or uses the system settings if `None` was provided.
-  fn with_theme(self, theme: Option<Theme>) -> WindowBuilder;
 }
 
 impl WindowBuilderExtMacOS for WindowBuilder {
@@ -413,12 +403,6 @@ impl WindowBuilderExtMacOS for WindowBuilder {
     self.platform_specific.has_shadow = has_shadow;
     self
   }
-
-  #[inline]
-  fn with_theme(mut self, theme: Option<Theme>) -> WindowBuilder {
-    self.platform_specific.preferred_theme = theme;
-    self
-  }
 }
 
 pub trait EventLoopExtMacOS {

src/platform/windows.rs

@@ -207,9 +207,6 @@ pub trait WindowBuilderExtWindows {
   /// See <https://docs.microsoft.com/en-us/windows/win32/api/objbase/nf-objbase-coinitialize#remarks> for more information.
   fn with_drag_and_drop(self, flag: bool) -> WindowBuilder;
 
-  /// Forces a theme or uses the system settings if `None` was provided.
-  fn with_theme(self, theme: Option<Theme>) -> WindowBuilder;
-
   /// Whether to create the window icon with the taskbar icon or not.
   fn with_skip_taskbar(self, skip: bool) -> WindowBuilder;
 }
@@ -251,12 +248,6 @@ impl WindowBuilderExtWindows for WindowBuilder {
     self
   }
 
-  #[inline]
-  fn with_theme(mut self, theme: Option<Theme>) -> WindowBuilder {
-    self.platform_specific.preferred_theme = theme;
-    self
-  }
-
   #[inline]
   fn with_skip_taskbar(mut self, skip: bool) -> WindowBuilder {
     self.platform_specific.skip_taskbar = skip;

src/platform_impl/android/mod.rs

@@ -10,7 +10,8 @@ use crate::{
   icon::Icon,
   keyboard::{Key, KeyCode, KeyLocation, NativeKeyCode},
   menu::{CustomMenuItem, MenuId, MenuItem, MenuType},
-  monitor, window,
+  monitor,
+  window::{self, Theme},
 };
 use ndk::{
   configuration::Configuration,
@@ -689,6 +690,10 @@ impl Window {
   pub fn content_rect(&self) -> Rect {
     ndk_glue::content_rect()
   }
+
+  pub fn theme(&self) -> Theme {
+    Theme::Light
+  }
 }
 
 #[derive(Default, Clone, Debug)]

src/platform_impl/ios/window.rs

@@ -25,7 +25,9 @@ use crate::{
     },
     monitor, view, EventLoopWindowTarget, Menu, MonitorHandle,
   },
-  window::{CursorIcon, Fullscreen, UserAttentionType, WindowAttributes, WindowId as RootWindowId},
+  window::{
+    CursorIcon, Fullscreen, Theme, UserAttentionType, WindowAttributes, WindowId as RootWindowId,
+  },
 };
 
 pub struct Inner {
@@ -351,6 +353,10 @@ impl Inner {
     handle.ui_view_controller = self.view_controller as _;
     RawWindowHandle::UiKit(handle)
   }
+
+  pub fn theme(&self) -> Theme {
+    Theme::Light
+  }
 }
 
 pub struct Window {

src/platform_impl/linux/window.rs

@@ -9,7 +9,7 @@ use std::{
 };
 
 use gdk::{WindowEdge, WindowState};
-use gtk::{prelude::*, AccelGroup, Orientation};
+use gtk::{prelude::*, traits::SettingsExt, AccelGroup, Orientation, Settings};
 use raw_window_handle::{RawWindowHandle, XlibHandle};
 
 use crate::{
@@ -18,7 +18,9 @@ use crate::{
   icon::Icon,
   menu::{MenuId, MenuItem},
   monitor::MonitorHandle as RootMonitorHandle,
-  window::{CursorIcon, Fullscreen, UserAttentionType, WindowAttributes, BORDERLESS_RESIZE_INSET},
+  window::{
+    CursorIcon, Fullscreen, Theme, UserAttentionType, WindowAttributes, BORDERLESS_RESIZE_INSET,
+  },
 };
 
 use super::{
@@ -192,6 +194,26 @@ impl Window {
       window.set_icon(Some(&icon.inner.into()));
     }
 
+    let settings = Settings::default();
+
+    if let Some(settings) = settings {
+      if let Some(preferred_theme) = attributes.preferred_theme {
+        match preferred_theme {
+          Theme::Dark => settings.set_gtk_application_prefer_dark_theme(true),
+          Theme::Light => {
+            let theme_name = settings.gtk_theme_name().map(|t| t.as_str().to_owned());
+            if let Some(theme) = theme_name {
+              // Remove dark variant.
+              match (theme.strip_suffix("-dark"), theme.strip_suffix("-Dark")) {
+                (theme, None) | (None, theme) => settings.set_gtk_theme_name(theme),
+                _ => {}
+              }
+            }
+          }
+        }
+      }
+    }
+
     if attributes.visible {
       window.show_all();
     } else {
@@ -647,6 +669,20 @@ impl Window {
       log::warn!("Fail to send skip taskbar request: {}", e);
     }
   }
+
+  pub fn theme(&self) -> Theme {
+    if let Some(settings) = Settings::default() {
+      let theme_name = settings.gtk_theme_name().map(|s| s.as_str().to_owned());
+      if let Some(theme) = theme_name {
+        // Currently GTK doesn't provide feature for detect theme, so we need to check theme manually.
+        // ref: https://github.com/WebKit/WebKit/blob/e44ffaa0d999a9807f76f1805943eea204cfdfbc/Source/WebKit/UIProcess/API/gtk/PageClientImpl.cpp#L587
+        if theme.ends_with("-dark") || theme.ends_with("-Dark") {
+          return Theme::Dark;
+        }
+      }
+    }
+    return Theme::Light;
+  }
 }
 
 // We need GtkWindow to initialize WebView, so we have to keep it in the field.

src/platform_impl/macos/window.rs

@@ -87,7 +87,6 @@ pub struct PlatformSpecificWindowBuilderAttributes {
   pub resize_increments: Option<LogicalSize<f64>>,
   pub disallow_hidpi: bool,
   pub has_shadow: bool,
-  pub preferred_theme: Option<Theme>,
 }
 
 impl Default for PlatformSpecificWindowBuilderAttributes {
@@ -104,7 +103,6 @@ impl Default for PlatformSpecificWindowBuilderAttributes {
       resize_increments: None,
       disallow_hidpi: false,
       has_shadow: true,
-      preferred_theme: None,
     }
   }
 }
@@ -484,6 +482,8 @@ impl UnownedWindow {
       .inner_size
       .map(|size| size.to_physical(scale_factor));
 
+    let cloned_preferred_theme = win_attribs.preferred_theme.clone();
+
     let window = Arc::new(UnownedWindow {
       ns_view,
       ns_window,
@@ -494,11 +494,11 @@ impl UnownedWindow {
       inner_rect,
     });
 
-    match pl_attribs.preferred_theme {
+    match cloned_preferred_theme {
       Some(theme) => {
         set_ns_theme(theme);
         let mut state = window.shared_state.lock().unwrap();
-        state.current_theme = theme;
+        state.current_theme = theme.clone();
       }
       None => {
         let mut state = window.shared_state.lock().unwrap();
@@ -1208,6 +1208,12 @@ impl UnownedWindow {
     handle.ns_view = *self.ns_view as *mut _;
     RawWindowHandle::AppKit(handle)
   }
+
+  #[inline]
+  pub fn theme(&self) -> Theme {
+    let state = self.shared_state.lock().unwrap();
+    state.current_theme
+  }
 }
 
 impl WindowExtMacOS for UnownedWindow {
@@ -1323,12 +1329,6 @@ impl WindowExtMacOS for UnownedWindow {
         .setHasShadow_(if has_shadow { YES } else { NO })
     }
   }
-
-  #[inline]
-  fn theme(&self) -> Theme {
-    let state = self.shared_state.lock().unwrap();
-    state.current_theme
-  }
 }
 
 impl Drop for UnownedWindow {

src/platform_impl/windows/window.rs

@@ -916,7 +916,7 @@ unsafe fn init<T: 'static>(
   // If the system theme is dark, we need to set the window theme now
   // before we update the window flags (and possibly show the
   // window for the first time).
-  let current_theme = try_theme(real_window.0, pl_attribs.preferred_theme);
+  let current_theme = try_theme(real_window.0, attributes.preferred_theme);
 
   let window_state = {
     let window_state = WindowState::new(

src/window.rs

@@ -197,6 +197,8 @@ pub struct WindowAttributes {
   ///
   /// The default is `None`.
   pub window_menu: Option<platform_impl::Menu>,
+
+  pub preferred_theme: Option<Theme>,
 }
 
 impl Default for WindowAttributes {
@@ -217,6 +219,7 @@ impl Default for WindowAttributes {
       always_on_top: false,
       window_icon: None,
       window_menu: None,
+      preferred_theme: None,
     }
   }
 }
@@ -378,6 +381,13 @@ impl WindowBuilder {
     self
   }
 
+  /// Forces a theme or uses the system settings if `None` was provided.
+  #[inline]
+  pub fn with_theme(mut self, theme: Option<Theme>) -> WindowBuilder {
+    self.window.preferred_theme = theme;
+    self
+  }
+
   /// Builds the window.
   ///
   /// Possible causes of error include denied permission, incompatible system, and lack of memory.
@@ -832,6 +842,16 @@ impl Window {
   pub fn is_menu_visible(&self) -> bool {
     self.window.is_menu_visible()
   }
+
+  /// Returns the current window theme.
+  ///
+  /// ## Platform-specific
+  ///
+  /// - **iOS / Android:** Unsupported.
+  #[inline]
+  pub fn theme(&self) -> Theme {
+    self.window.theme()
+  }
 }
 
 /// Cursor functions.