Use custom Application::style to enable transparency

Author: hecrj

examples/gradient/src/main.rs

@@ -1,4 +1,5 @@
-use iced::theme::Palette;
+use iced::application;
+use iced::theme::{self, Theme};
 use iced::widget::{
     checkbox, column, container, horizontal_space, row, slider, text,
 };
@@ -22,15 +23,15 @@ struct Gradient {
     start: Color,
     end: Color,
     angle: Radians,
-    transparent_window: bool,
+    transparent: bool,
 }
 
 #[derive(Debug, Clone, Copy)]
 enum Message {
     StartChanged(Color),
     EndChanged(Color),
     AngleChanged(Radians),
-    SetTransparent(bool),
+    TransparentToggled(bool),
 }
 
 impl Sandbox for Gradient {
@@ -41,7 +42,7 @@ impl Sandbox for Gradient {
             start: Color::WHITE,
             end: Color::new(0.0, 0.0, 1.0, 1.0),
             angle: Radians(0.0),
-            transparent_window: false,
+            transparent: false,
         }
     }
 
@@ -54,8 +55,8 @@ impl Sandbox for Gradient {
             Message::StartChanged(color) => self.start = color,
             Message::EndChanged(color) => self.end = color,
             Message::AngleChanged(angle) => self.angle = angle,
-            Message::SetTransparent(transparent) => {
-                self.transparent_window = transparent;
+            Message::TransparentToggled(transparent) => {
+                self.transparent = transparent;
             }
         }
     }
@@ -65,7 +66,7 @@ impl Sandbox for Gradient {
             start,
             end,
             angle,
-            transparent_window,
+            transparent,
         } = *self;
 
         let gradient_box = container(horizontal_space(Length::Fill))
@@ -93,8 +94,8 @@ impl Sandbox for Gradient {
         .align_items(Alignment::Center);
 
         let transparency_toggle = iced::widget::Container::new(
-            checkbox("Transparent window", transparent_window)
-                .on_toggle(Message::SetTransparent),
+            checkbox("Transparent window", transparent)
+                .on_toggle(Message::TransparentToggled),
         )
         .padding(8);
 
@@ -108,17 +109,16 @@ impl Sandbox for Gradient {
         .into()
     }
 
-    fn theme(&self) -> iced::Theme {
-        if self.transparent_window {
-            iced::Theme::custom(
-                String::new(),
-                Palette {
-                    background: Color::TRANSPARENT,
-                    ..iced::Theme::default().palette()
-                },
-            )
+    fn style(&self) -> theme::Application {
+        if self.transparent {
+            theme::Application::custom(|theme: &Theme| {
+                application::Appearance {
+                    background_color: Color::TRANSPARENT,
+                    text_color: theme.palette().text,
+                }
+            })
         } else {
-            iced::Theme::default()
+            theme::Application::Default
         }
     }
 }

style/src/theme.rs

@@ -172,6 +172,15 @@ pub enum Application {
     Custom(Box<dyn application::StyleSheet<Style = Theme>>),
 }
 
+impl Application {
+    /// Creates a custom [`Application`] style.
+    pub fn custom(
+        custom: impl application::StyleSheet<Style = Theme> + 'static,
+    ) -> Self {
+        Self::Custom(Box::new(custom))
+    }
+}
+
 impl application::StyleSheet for Theme {
     type Style = Application;
 
@@ -196,14 +205,6 @@ impl<T: Fn(&Theme) -> application::Appearance> application::StyleSheet for T {
     }
 }
 
-impl<T: Fn(&Theme) -> application::Appearance + 'static> From<T>
-    for Application
-{
-    fn from(f: T) -> Self {
-        Self::Custom(Box::new(f))
-    }
-}
-
 /// The style of a button.
 #[derive(Default)]
 pub enum Button {