Unify shader::Program API with canvas::Program

widget/src/shader.rs

@@ -1,23 +1,22 @@
 //! A custom shader widget for wgpu applications.
-mod event;
 mod program;
 
-pub use event::Event;
 pub use program::Program;
 
-use crate::core;
+use crate::core::event;
 use crate::core::layout::{self, Layout};
 use crate::core::mouse;
 use crate::core::renderer;
 use crate::core::widget::tree::{self, Tree};
 use crate::core::widget::{self, Widget};
 use crate::core::window;
-use crate::core::{Clipboard, Element, Length, Rectangle, Shell, Size};
+use crate::core::{Clipboard, Element, Event, Length, Rectangle, Shell, Size};
 use crate::renderer::wgpu::primitive;
 
 use std::marker::PhantomData;
 
 pub use crate::graphics::Viewport;
+pub use crate::Action;
 pub use primitive::{Primitive, Storage};
 
 /// A widget which can render custom shaders with Iced's `wgpu` backend.
@@ -100,28 +99,30 @@ where
     ) {
         let bounds = layout.bounds();
 
-        let custom_shader_event = match event {
-            core::Event::Mouse(mouse_event) => Some(Event::Mouse(mouse_event)),
-            core::Event::Keyboard(keyboard_event) => {
-                Some(Event::Keyboard(keyboard_event))
+        let state = tree.state.downcast_mut::<P::State>();
+
+        if let Some(action) = self.program.update(state, event, bounds, cursor)
+        {
+            let (message, redraw_request, event_status) = action.into_inner();
+
+            if let Some(message) = message {
+                shell.publish(message);
             }
-            core::Event::Touch(touch_event) => Some(Event::Touch(touch_event)),
-            core::Event::Window(window::Event::RedrawRequested(instant)) => {
-                Some(Event::RedrawRequested(instant))
+
+            if let Some(redraw_request) = redraw_request {
+                match redraw_request {
+                    window::RedrawRequest::NextFrame => {
+                        shell.request_redraw();
+                    }
+                    window::RedrawRequest::At(at) => {
+                        shell.request_redraw_at(at);
+                    }
+                }
+            }
+
+            if event_status == event::Status::Captured {
+                shell.capture_event();
             }
-            core::Event::Window(_) => None,
-        };
-
-        if let Some(custom_shader_event) = custom_shader_event {
-            let state = tree.state.downcast_mut::<P::State>();
-
-            self.program.update(
-                state,
-                custom_shader_event,
-                bounds,
-                cursor,
-                shell,
-            );
         }
     }
 
@@ -186,9 +187,8 @@ where
         event: Event,
         bounds: Rectangle,
         cursor: mouse::Cursor,
-        shell: &mut Shell<'_, Message>,
-    ) {
-        T::update(self, state, event, bounds, cursor, shell);
+    ) -> Option<Action<Message>> {
+        T::update(self, state, event, bounds, cursor)
     }
 
     fn draw(

widget/src/shader/program.rs

@@ -1,7 +1,7 @@
 use crate::core::mouse;
-use crate::core::{Rectangle, Shell};
+use crate::core::Rectangle;
 use crate::renderer::wgpu::Primitive;
-use crate::shader;
+use crate::shader::{self, Action};
 
 /// The state and logic of a [`Shader`] widget.
 ///
@@ -17,10 +17,10 @@ pub trait Program<Message> {
     type Primitive: Primitive + 'static;
 
     /// Update the internal [`State`] of the [`Program`]. This can be used to reflect state changes
-    /// based on mouse & other events. You can use the [`Shell`] to publish messages, request a
-    /// redraw for the window, etc.
+    /// based on mouse & other events. You can return an [`Action`] to publish a message, request a
+    /// redraw, or capture the event.
     ///
-    /// By default, this method does and returns nothing.
+    /// By default, this method returns `None`.
     ///
     /// [`State`]: Self::State
     fn update(
@@ -29,8 +29,8 @@ pub trait Program<Message> {
         _event: shader::Event,
         _bounds: Rectangle,
         _cursor: mouse::Cursor,
-        _shell: &mut Shell<'_, Message>,
-    ) {
+    ) -> Option<Action<Message>> {
+        None
     }
 
     /// Draws the [`Primitive`].