Support custom renderers in iced_test through renderer::Headless trait

core/src/lib.rs

@@ -40,6 +40,7 @@ mod pixels;
 mod point;
 mod rectangle;
 mod rotation;
+mod settings;
 mod shadow;
 mod shell;
 mod size;
@@ -67,6 +68,7 @@ pub use point::Point;
 pub use rectangle::Rectangle;
 pub use renderer::Renderer;
 pub use rotation::Rotation;
+pub use settings::Settings;
 pub use shadow::Shadow;
 pub use shell::Shell;
 pub use size::Size;

core/src/renderer.rs

@@ -3,7 +3,8 @@
 mod null;
 
 use crate::{
-    Background, Border, Color, Rectangle, Shadow, Size, Transformation, Vector,
+    Background, Border, Color, Font, Pixels, Rectangle, Shadow, Size,
+    Transformation, Vector,
 };
 
 /// A component that can be used by widgets to draw themselves on a screen.
@@ -100,3 +101,19 @@ impl Default for Style {
         }
     }
 }
+
+/// A headless renderer is a renderer that can render offscreen without
+/// a window nor a compositor.
+pub trait Headless {
+    /// Creates a new [`Headless`] renderer;
+    fn new(default_font: Font, default_text_size: Pixels) -> Self;
+
+    /// Draws offscreen into a screenshot, returning a collection of
+    /// bytes representing the rendered pixels in RGBA order.
+    fn screenshot(
+        &mut self,
+        size: Size<u32>,
+        scale_factor: f32,
+        background_color: Color,
+    ) -> Vec<u8>;
+}

core/src/settings.rs

@@ -48,12 +48,3 @@ impl Default for Settings {
         }
     }
 }
-
-impl From<Settings> for iced_winit::Settings {
-    fn from(settings: Settings) -> iced_winit::Settings {
-        iced_winit::Settings {
-            id: settings.id,
-            fonts: settings.fonts,
-        }
-    }
-}

examples/todos/snapshots/creates_a_new_task.sha256

@@ -1 +1 @@
-b41c73d214894bf5f94f787e5f265cff6500822b2d4a29a4ac0c847a71db7123
+a7c2ac4b57f84416812e2134e48fe34db55a757d9176beedf5854a2f69532e32

examples/todos/src/main.rs

@@ -590,16 +590,25 @@ impl SavedState {
 mod tests {
     use super::*;
 
-    use iced_test::{interface, load_font, selector, Error};
+    use iced::Settings;
+    use iced_test::{selector, Error, Simulator};
+
+    fn simulator(todos: &Todos) -> Simulator<Message> {
+        Simulator::with_settings(
+            Settings {
+                fonts: vec![Todos::ICON_FONT.into()],
+                ..Settings::default()
+            },
+            todos.view(),
+        )
+    }
 
     #[test]
     fn it_creates_a_new_task() -> Result<(), Error> {
-        load_font(Todos::ICON_FONT)?;
-
         let (mut todos, _command) = Todos::new();
         let _command = todos.update(Message::Loaded(Err(LoadError::File)));
 
-        let mut ui = interface(todos.view());
+        let mut ui = simulator(&todos);
         let _input = ui.click("new-task")?;
 
         ui.typewrite("Create the universe");
@@ -609,7 +618,7 @@ mod tests {
             let _command = todos.update(message);
         }
 
-        let mut ui = interface(todos.view());
+        let mut ui = simulator(&todos);
         let _ = ui.find(selector::text("Create the universe"))?;
 
         let snapshot = ui.snapshot()?;

graphics/src/text.rs

@@ -146,7 +146,8 @@ impl Text {
 
 /// The regular variant of the [Fira Sans] font.
 ///
-/// It is loaded as part of the default fonts in Wasm builds.
+/// It is loaded as part of the default fonts when the `fira-sans`
+/// feature is enabled.
 ///
 /// [Fira Sans]: https://mozilla.github.io/Fira/
 #[cfg(feature = "fira-sans")]

renderer/src/lib.rs

@@ -23,6 +23,9 @@ pub type Compositor = renderer::Compositor;
 
 #[cfg(all(feature = "wgpu", feature = "tiny-skia"))]
 mod renderer {
+    use crate::core::renderer;
+    use crate::core::{Color, Font, Pixels, Size};
+
     pub type Renderer = crate::fallback::Renderer<
         iced_wgpu::Renderer,
         iced_tiny_skia::Renderer,
@@ -32,6 +35,31 @@ mod renderer {
         iced_wgpu::window::Compositor,
         iced_tiny_skia::window::Compositor,
     >;
+
+    impl renderer::Headless for Renderer {
+        fn new(default_font: Font, default_text_size: Pixels) -> Self {
+            Self::Secondary(iced_tiny_skia::Renderer::new(
+                default_font,
+                default_text_size,
+            ))
+        }
+
+        fn screenshot(
+            &mut self,
+            size: Size<u32>,
+            scale_factor: f32,
+            background_color: Color,
+        ) -> Vec<u8> {
+            match self {
+                crate::fallback::Renderer::Primary(_) => unreachable!(
+                    "iced_wgpu does not support headless mode yet!"
+                ),
+                crate::fallback::Renderer::Secondary(renderer) => {
+                    renderer.screenshot(size, scale_factor, background_color)
+                }
+            }
+        }
+    }
 }
 
 #[cfg(all(feature = "wgpu", not(feature = "tiny-skia")))]

src/lib.rs

@@ -491,7 +491,6 @@ mod program;
 
 pub mod application;
 pub mod daemon;
-pub mod settings;
 pub mod time;
 pub mod window;
 
@@ -506,8 +505,8 @@ pub use crate::core::padding;
 pub use crate::core::theme;
 pub use crate::core::{
     Alignment, Background, Border, Color, ContentFit, Degrees, Gradient,
-    Length, Padding, Pixels, Point, Radians, Rectangle, Rotation, Shadow, Size,
-    Theme, Transformation, Vector,
+    Length, Padding, Pixels, Point, Radians, Rectangle, Rotation, Settings,
+    Shadow, Size, Theme, Transformation, Vector,
 };
 pub use crate::runtime::exit;
 pub use iced_futures::Subscription;
@@ -626,7 +625,6 @@ pub use executor::Executor;
 pub use font::Font;
 pub use program::Program;
 pub use renderer::Renderer;
-pub use settings::Settings;
 pub use task::Task;
 
 #[doc(inline)]

test/Cargo.toml

@@ -15,10 +15,9 @@ workspace = true
 
 [dependencies]
 iced_runtime.workspace = true
-iced_tiny_skia.workspace = true
 
 iced_renderer.workspace = true
-iced_renderer.features = ["tiny-skia", "fira-sans"]
+iced_renderer.features = ["fira-sans"]
 
 png.workspace = true
 sha2.workspace = true

test/src/lib.rs

@@ -7,7 +7,6 @@ pub use selector::Selector;
 use iced_renderer as renderer;
 use iced_runtime as runtime;
 use iced_runtime::core;
-use iced_tiny_skia as tiny_skia;
 
 use crate::core::clipboard;
 use crate::core::keyboard;
@@ -16,8 +15,7 @@ use crate::core::theme;
 use crate::core::time;
 use crate::core::widget;
 use crate::core::window;
-use crate::core::{Element, Event, Font, Pixels, Rectangle, Size, SmolStr};
-use crate::renderer::Renderer;
+use crate::core::{Element, Event, Font, Rectangle, Settings, Size, SmolStr};
 use crate::runtime::user_interface;
 use crate::runtime::UserInterface;
 
@@ -27,32 +25,17 @@ use std::io;
 use std::path::Path;
 use std::sync::Arc;
 
-pub fn interface<'a, Message, Theme>(
+pub fn simulator<'a, Message, Theme, Renderer>(
     element: impl Into<Element<'a, Message, Theme, Renderer>>,
-) -> Interface<'a, Message, Theme, Renderer> {
-    let size = Size::new(512.0, 512.0);
-
-    let mut renderer = Renderer::Secondary(tiny_skia::Renderer::new(
-        Font::with_name("Fira Sans"),
-        Pixels(16.0),
-    ));
-
-    let raw = UserInterface::build(
-        element,
-        size,
-        user_interface::Cache::default(),
-        &mut renderer,
-    );
-
-    Interface {
-        raw,
-        renderer,
-        size,
-        messages: Vec::new(),
-    }
+) -> Simulator<'a, Message, Theme, Renderer>
+where
+    Theme: Default + theme::Base,
+    Renderer: core::Renderer + core::renderer::Headless,
+{
+    Simulator::new(element)
 }
 
-pub fn load_font(font: impl Into<Cow<'static, [u8]>>) -> Result<(), Error> {
+fn load_font(font: impl Into<Cow<'static, [u8]>>) -> Result<(), Error> {
     renderer::graphics::text::font_system()
         .write()
         .expect("Write to font system")
@@ -61,21 +44,78 @@ pub fn load_font(font: impl Into<Cow<'static, [u8]>>) -> Result<(), Error> {
     Ok(())
 }
 
-pub struct Interface<'a, Message, Theme, Renderer> {
+pub struct Simulator<
+    'a,
+    Message,
+    Theme = core::Theme,
+    Renderer = renderer::Renderer,
+> {
     raw: UserInterface<'a, Message, Theme, Renderer>,
     renderer: Renderer,
-    size: Size,
+    window_size: Size,
     messages: Vec<Message>,
 }
 
 pub struct Target {
-    bounds: Rectangle,
+    pub bounds: Rectangle,
 }
 
-impl<Message, Theme> Interface<'_, Message, Theme, Renderer>
+impl<'a, Message, Theme, Renderer> Simulator<'a, Message, Theme, Renderer>
 where
     Theme: Default + theme::Base,
+    Renderer: core::Renderer + core::renderer::Headless,
 {
+    pub fn new(
+        element: impl Into<Element<'a, Message, Theme, Renderer>>,
+    ) -> Self {
+        Self::with_settings(Settings::default(), element)
+    }
+
+    pub fn with_settings(
+        settings: Settings,
+        element: impl Into<Element<'a, Message, Theme, Renderer>>,
+    ) -> Self {
+        Self::with_settings_and_size(
+            settings,
+            window::Settings::default().size,
+            element,
+        )
+    }
+
+    pub fn with_settings_and_size(
+        settings: Settings,
+        window_size: impl Into<Size>,
+        element: impl Into<Element<'a, Message, Theme, Renderer>>,
+    ) -> Self {
+        let window_size = window_size.into();
+
+        let default_font = match settings.default_font {
+            Font::DEFAULT => Font::with_name("Fira Sans"),
+            _ => settings.default_font,
+        };
+
+        for font in settings.fonts {
+            load_font(font).expect("Font must be valid");
+        }
+
+        let mut renderer =
+            Renderer::new(default_font, settings.default_text_size);
+
+        let raw = UserInterface::build(
+            element,
+            window_size,
+            user_interface::Cache::default(),
+            &mut renderer,
+        );
+
+        Simulator {
+            raw,
+            renderer,
+            window_size,
+            messages: Vec::new(),
+        }
+    }
+
     pub fn find(
         &mut self,
         selector: impl Into<Selector>,
@@ -301,34 +341,26 @@ where
             mouse::Cursor::Unavailable,
         );
 
-        if let Renderer::Secondary(renderer) = &mut self.renderer {
         let scale_factor = 2.0;
 
-            let viewport = renderer::graphics::Viewport::with_physical_size(
-                Size::new(
-                    (self.size.width * scale_factor).round() as u32,
-                    (self.size.height * scale_factor).round() as u32,
-                ),
-                f64::from(scale_factor),
+        let physical_size = Size::new(
+            (self.window_size.width * scale_factor).round() as u32,
+            (self.window_size.height * scale_factor).round() as u32,
         );
 
-            let rgba = tiny_skia::window::compositor::screenshot::<&str>(
-                renderer,
-                &viewport,
+        let rgba = self.renderer.screenshot(
+            physical_size,
+            scale_factor,
             base.background_color,
-                &[],
         );
 
         Ok(Snapshot {
             screenshot: window::Screenshot::new(
                 rgba,
-                    viewport.physical_size(),
-                    viewport.scale_factor(),
+                physical_size,
+                f64::from(scale_factor),
             ),
         })
-        } else {
-            unreachable!()
-        }
     }
 
     pub fn into_messages(self) -> impl IntoIterator<Item = Message> {

tiny_skia/src/lib.rs

@@ -29,7 +29,7 @@ pub use geometry::Geometry;
 
 use crate::core::renderer;
 use crate::core::{
-    Background, Color, Font, Pixels, Point, Rectangle, Transformation,
+    Background, Color, Font, Pixels, Point, Rectangle, Size, Transformation,
 };
 use crate::engine::Engine;
 use crate::graphics::compositor;
@@ -405,3 +405,26 @@ impl core::svg::Renderer for Renderer {
 impl compositor::Default for Renderer {
     type Compositor = window::Compositor;
 }
+
+impl renderer::Headless for Renderer {
+    fn new(default_font: Font, default_text_size: Pixels) -> Self {
+        Self::new(default_font, default_text_size)
+    }
+
+    fn screenshot(
+        &mut self,
+        size: Size<u32>,
+        scale_factor: f32,
+        background_color: Color,
+    ) -> Vec<u8> {
+        let viewport =
+            Viewport::with_physical_size(size, f64::from(scale_factor));
+
+        window::compositor::screenshot::<&str>(
+            self,
+            &viewport,
+            background_color,
+            &[],
+        )
+    }
+}

winit/src/settings.rs

@@ -1,4 +1,6 @@
 //! Configure your application.
+use crate::core;
+
 use std::borrow::Cow;
 
 /// The settings of an application.
@@ -13,3 +15,12 @@ pub struct Settings {
     /// The fonts to load on boot.
     pub fonts: Vec<Cow<'static, [u8]>>,
 }
+
+impl From<core::Settings> for Settings {
+    fn from(settings: core::Settings) -> Self {
+        Self {
+            id: settings.id,
+            fonts: settings.fonts,
+        }
+    }
+}