Merge pull request #2351 from iced-rs/custom-renderer-injection

Type-Driven Renderer Fallback

6 files changed, 77 insertions, 33 deletions

diff --git a/core/src/element.rs b/core/src/element.rs
index 989eaa3b..7d918a2e 100644
--- a/core/src/element.rs
+++ b/core/src/element.rs
@@ -95,7 +95,7 @@ impl<'a, Message, Theme, Renderer> Element<'a, Message, Theme, Renderer> {
     ///
     /// ```no_run
     /// # mod iced {
-    /// #     pub type Element<'a, Message> = iced_core::Element<'a, Message, iced_core::Theme, iced_core::renderer::Null>;
+    /// #     pub type Element<'a, Message> = iced_core::Element<'a, Message, iced_core::Theme, ()>;
     /// #
     /// #     pub mod widget {
     /// #         pub fn row<'a, Message>(iter: impl IntoIterator<Item = super::Element<'a, Message>>) -> super::Element<'a, Message> {
@@ -109,7 +109,7 @@ impl<'a, Message, Theme, Renderer> Element<'a, Message, Theme, Renderer> {
     /// #     pub enum Message {}
     /// #     pub struct Counter;
     /// #
-    /// #     pub type Element<'a, Message> = iced_core::Element<'a, Message, iced_core::Theme, iced_core::renderer::Null>;
+    /// #     pub type Element<'a, Message> = iced_core::Element<'a, Message, iced_core::Theme, ()>;
     /// #
     /// #     impl Counter {
     /// #         pub fn view(&self) -> Element<Message> {
diff --git a/core/src/image.rs b/core/src/image.rs
index e5fdcd83..32b95f03 100644
--- a/core/src/image.rs
+++ b/core/src/image.rs
@@ -186,11 +186,11 @@ pub trait Renderer: crate::Renderer {
     type Handle: Clone + Hash;
 
     /// Returns the dimensions of an image for the given [`Handle`].
-    fn dimensions(&self, handle: &Self::Handle) -> Size<u32>;
+    fn measure_image(&self, handle: &Self::Handle) -> Size<u32>;
 
     /// Draws an image with the given [`Handle`] and inside the provided
     /// `bounds`.
-    fn draw(
+    fn draw_image(
         &mut self,
         handle: Self::Handle,
         filter_method: FilterMethod,
diff --git a/core/src/renderer.rs b/core/src/renderer.rs
index 1139b41c..6712314e 100644
--- a/core/src/renderer.rs
+++ b/core/src/renderer.rs
@@ -2,26 +2,47 @@
 #[cfg(debug_assertions)]
 mod null;
 
-#[cfg(debug_assertions)]
-pub use null::Null;
-
 use crate::{
     Background, Border, Color, Rectangle, Shadow, Size, Transformation, Vector,
 };
 
 /// A component that can be used by widgets to draw themselves on a screen.
-pub trait Renderer: Sized {
+pub trait Renderer {
+    /// Starts recording a new layer.
+    fn start_layer(&mut self);
+
+    /// Ends recording a new layer.
+    ///
+    /// The new layer will clip its contents to the provided `bounds`.
+    fn end_layer(&mut self, bounds: Rectangle);
+
     /// Draws the primitives recorded in the given closure in a new layer.
     ///
     /// The layer will clip its contents to the provided `bounds`.
-    fn with_layer(&mut self, bounds: Rectangle, f: impl FnOnce(&mut Self));
+    fn with_layer(&mut self, bounds: Rectangle, f: impl FnOnce(&mut Self)) {
+        self.start_layer();
+        f(self);
+        self.end_layer(bounds);
+    }
+
+    /// Starts recording with a new [`Transformation`].
+    fn start_transformation(&mut self);
+
+    /// Ends recording a new layer.
+    ///
+    /// The new layer will clip its contents to the provided `bounds`.
+    fn end_transformation(&mut self, transformation: Transformation);
 
     /// Applies a [`Transformation`] to the primitives recorded in the given closure.
     fn with_transformation(
         &mut self,
         transformation: Transformation,
         f: impl FnOnce(&mut Self),
-    );
+    ) {
+        self.start_transformation();
+        f(self);
+        self.end_transformation(transformation);
+    }
 
     /// Applies a translation to the primitives recorded in the given closure.
     fn with_translation(
diff --git a/core/src/renderer/null.rs b/core/src/renderer/null.rs
index 83688ff7..c26ce1a5 100644
--- a/core/src/renderer/null.rs
+++ b/core/src/renderer/null.rs
@@ -1,5 +1,7 @@
 use crate::alignment;
+use crate::image;
 use crate::renderer::{self, Renderer};
+use crate::svg;
 use crate::text::{self, Text};
 use crate::{
     Background, Color, Font, Pixels, Point, Rectangle, Size, Transformation,
@@ -7,28 +9,14 @@ use crate::{
 
 use std::borrow::Cow;
 
-/// A renderer that does nothing.
-///
-/// It can be useful if you are writing tests!
-#[derive(Debug, Clone, Copy, Default)]
-pub struct Null;
+impl Renderer for () {
+    fn start_layer(&mut self) {}
 
-impl Null {
-    /// Creates a new [`Null`] renderer.
-    pub fn new() -> Null {
-        Null
-    }
-}
+    fn end_layer(&mut self, _bounds: Rectangle) {}
 
-impl Renderer for Null {
-    fn with_layer(&mut self, _bounds: Rectangle, _f: impl FnOnce(&mut Self)) {}
+    fn start_transformation(&mut self) {}
 
-    fn with_transformation(
-        &mut self,
-        _transformation: Transformation,
-        _f: impl FnOnce(&mut Self),
-    ) {
-    }
+    fn end_transformation(&mut self, _transformation: Transformation) {}
 
     fn clear(&mut self) {}
 
@@ -40,7 +28,7 @@ impl Renderer for Null {
     }
 }
 
-impl text::Renderer for Null {
+impl text::Renderer for () {
     type Font = Font;
     type Paragraph = ();
     type Editor = ();
@@ -174,3 +162,33 @@ impl text::Editor for () {
     ) {
     }
 }
+
+impl image::Renderer for () {
+    type Handle = ();
+
+    fn measure_image(&self, _handle: &Self::Handle) -> Size<u32> {
+        Size::default()
+    }
+
+    fn draw_image(
+        &mut self,
+        _handle: Self::Handle,
+        _filter_method: image::FilterMethod,
+        _bounds: Rectangle,
+    ) {
+    }
+}
+
+impl svg::Renderer for () {
+    fn measure_svg(&self, _handle: &svg::Handle) -> Size<u32> {
+        Size::default()
+    }
+
+    fn draw_svg(
+        &mut self,
+        _handle: svg::Handle,
+        _color: Option<Color>,
+        _bounds: Rectangle,
+    ) {
+    }
+}
diff --git a/core/src/size.rs b/core/src/size.rs
index 267fc90e..55db759d 100644
--- a/core/src/size.rs
+++ b/core/src/size.rs
@@ -1,7 +1,7 @@
 use crate::Vector;
 
 /// An amount of space in 2 dimensions.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
 pub struct Size<T = f32> {
     /// The width.
     pub width: T,
diff --git a/core/src/svg.rs b/core/src/svg.rs
index d63e3c95..ab207cca 100644
--- a/core/src/svg.rs
+++ b/core/src/svg.rs
@@ -91,8 +91,13 @@ impl std::fmt::Debug for Data {
 /// [renderer]: crate::renderer
 pub trait Renderer: crate::Renderer {
     /// Returns the default dimensions of an SVG for the given [`Handle`].
-    fn dimensions(&self, handle: &Handle) -> Size<u32>;
+    fn measure_svg(&self, handle: &Handle) -> Size<u32>;
 
     /// Draws an SVG with the given [`Handle`], an optional [`Color`] filter, and inside the provided `bounds`.
-    fn draw(&mut self, handle: Handle, color: Option<Color>, bounds: Rectangle);
+    fn draw_svg(
+        &mut self,
+        handle: Handle,
+        color: Option<Color>,
+        bounds: Rectangle,
+    );
 }