Replace stateful widgets with new iced_pure API

graphics/src/widget/canvas/cache.rs

@@ -1,7 +1,5 @@
-use crate::{
-    canvas::{Frame, Geometry},
-    Primitive,
-};
+use crate::widget::canvas::{Frame, Geometry};
+use crate::Primitive;
 
 use iced_native::Size;
 use std::{cell::RefCell, sync::Arc};

graphics/src/widget/canvas/frame.rs

@@ -2,11 +2,10 @@ use std::borrow::Cow;
 
 use iced_native::{Point, Rectangle, Size, Vector};
 
-use crate::{
-    canvas::path,
-    canvas::{Fill, Geometry, Path, Stroke, Text},
-    triangle, Primitive,
-};
+use crate::triangle;
+use crate::widget::canvas::path;
+use crate::widget::canvas::{Fill, Geometry, Path, Stroke, Text};
+use crate::Primitive;
 
 use lyon::tessellation;
 

graphics/src/widget/canvas/path.rs

@@ -7,7 +7,7 @@ mod builder;
 pub use arc::Arc;
 pub use builder::Builder;
 
-use crate::canvas::LineDash;
+use crate::widget::canvas::LineDash;
 
 use iced_native::{Point, Size};
 use lyon::algorithms::walk::{walk_along_path, RepeatedPattern, WalkerEvent};

graphics/src/widget/canvas/path/builder.rs

@@ -1,4 +1,4 @@
-use crate::canvas::path::{arc, Arc, Path};
+use crate::widget::canvas::path::{arc, Arc, Path};
 
 use iced_native::{Point, Size};
 use lyon::path::builder::SvgPathBuilder;

graphics/src/widget/canvas/program.rs

@@ -1,8 +1,7 @@
-use crate::canvas::event::{self, Event};
-use crate::canvas::{Cursor, Geometry};
-
-use iced_native::mouse;
-use iced_native::Rectangle;
+use crate::widget::canvas::event::{self, Event};
+use crate::widget::canvas::mouse;
+use crate::widget::canvas::{Cursor, Geometry};
+use crate::Rectangle;
 
 /// The state and logic of a [`Canvas`].
 ///
@@ -11,7 +10,10 @@ use iced_native::Rectangle;
 ///
 /// [`Canvas`]: crate::widget::Canvas
 pub trait Program<Message, Theme = iced_native::Theme> {
-    /// Updates the state of the [`Program`].
+    /// The internal state mutated by the [`Program`].
+    type State: Default + 'static;
+
+    /// Updates the [`State`](Self::State) of the [`Program`].
     ///
     /// When a [`Program`] is used in a [`Canvas`], the runtime will call this
     /// method for each [`Event`].
@@ -23,7 +25,8 @@ pub trait Program<Message, Theme = iced_native::Theme> {
     ///
     /// [`Canvas`]: crate::widget::Canvas
     fn update(
-        &mut self,
+        &self,
+        _state: &mut Self::State,
         _event: Event,
         _bounds: Rectangle,
         _cursor: Cursor,
@@ -40,6 +43,7 @@ pub trait Program<Message, Theme = iced_native::Theme> {
     /// [`Cache`]: crate::widget::canvas::Cache
     fn draw(
         &self,
+        state: &Self::State,
         theme: &Theme,
         bounds: Rectangle,
         cursor: Cursor,
@@ -53,6 +57,7 @@ pub trait Program<Message, Theme = iced_native::Theme> {
     /// [`Canvas`]: crate::widget::Canvas
     fn mouse_interaction(
         &self,
+        _state: &Self::State,
         _bounds: Rectangle,
         _cursor: Cursor,
     ) -> mouse::Interaction {
@@ -60,33 +65,38 @@ pub trait Program<Message, Theme = iced_native::Theme> {
     }
 }
 
-impl<T, Message, Theme> Program<Message, Theme> for &mut T
+impl<Message, Theme, T> Program<Message, Theme> for &T
 where
     T: Program<Message, Theme>,
 {
+    type State = T::State;
+
     fn update(
-        &mut self,
+        &self,
+        state: &mut Self::State,
         event: Event,
         bounds: Rectangle,
         cursor: Cursor,
     ) -> (event::Status, Option<Message>) {
-        T::update(self, event, bounds, cursor)
+        T::update(self, state, event, bounds, cursor)
     }
 
     fn draw(
         &self,
+        state: &Self::State,
         theme: &Theme,
         bounds: Rectangle,
         cursor: Cursor,
     ) -> Vec<Geometry> {
-        T::draw(self, theme, bounds, cursor)
+        T::draw(self, state, theme, bounds, cursor)
     }
 
     fn mouse_interaction(
         &self,
+        state: &Self::State,
         bounds: Rectangle,
         cursor: Cursor,
     ) -> mouse::Interaction {
-        T::mouse_interaction(self, bounds, cursor)
+        T::mouse_interaction(self, state, bounds, cursor)
     }
 }