Merge pull request #354 from hecrj/feature/glow-renderer

OpenGL renderer and backend-agnostic graphics subcrate

8 files changed, 254 insertions, 16 deletions

diff --git a/native/src/window/backend.rs b/graphics/src/window/compositor.rs
index 892d4bb9..d5920c95 100644
--- a/native/src/window/backend.rs
+++ b/graphics/src/window/compositor.rs
@@ -1,14 +1,14 @@
-use crate::mouse;
-
+use crate::Viewport;
+use iced_native::mouse;
 use raw_window_handle::HasRawWindowHandle;
 
-/// A graphics backend that can render to windows.
-pub trait Backend: Sized {
+/// A graphics compositor that can draw to windows.
+pub trait Compositor: Sized {
     /// The settings of the backend.
     type Settings: Default;
 
     /// The iced renderer of the backend.
-    type Renderer: crate::Renderer;
+    type Renderer: iced_native::Renderer;
 
     /// The surface of the backend.
     type Surface;
@@ -16,7 +16,7 @@ pub trait Backend: Sized {
     /// The swap chain of the backend.
     type SwapChain;
 
-    /// Creates a new [`Backend`] and an associated iced renderer.
+    /// Creates a new [`Backend`].
     ///
     /// [`Backend`]: trait.Backend.html
     fn new(settings: Self::Settings) -> (Self, Self::Renderer);
@@ -48,8 +48,8 @@ pub trait Backend: Sized {
         &mut self,
         renderer: &mut Self::Renderer,
         swap_chain: &mut Self::SwapChain,
-        output: &<Self::Renderer as crate::Renderer>::Output,
-        scale_factor: f64,
+        viewport: &Viewport,
+        output: &<Self::Renderer as iced_native::Renderer>::Output,
         overlay: &[T],
     ) -> mouse::Interaction;
 }
diff --git a/winit/src/debug/basic.rs b/native/src/debug/basic.rs
index d46edba6..5338d0d9 100644
--- a/winit/src/debug/basic.rs
+++ b/native/src/debug/basic.rs
@@ -1,5 +1,7 @@
+#![allow(missing_docs)]
 use std::{collections::VecDeque, time};
 
+/// A bunch of time measurements for debugging purposes.
 #[derive(Debug)]
 pub struct Debug {
     is_enabled: bool,
@@ -30,6 +32,9 @@ pub struct Debug {
 }
 
 impl Debug {
+    /// Creates a new [`Debug`].
+    ///
+    /// [`Debug`]: struct.Debug.html
     pub fn new() -> Self {
         let now = time::Instant::now();
 
diff --git a/winit/src/debug/null.rs b/native/src/debug/null.rs
index 2a9430cd..60e6122d 100644
--- a/winit/src/debug/null.rs
+++ b/native/src/debug/null.rs
@@ -1,3 +1,4 @@
+#![allow(missing_docs)]
 #[derive(Debug)]
 pub struct Debug;
 
diff --git a/native/src/lib.rs b/native/src/lib.rs
index 9882803f..b67ff2a1 100644
--- a/native/src/lib.rs
+++ b/native/src/lib.rs
@@ -9,14 +9,11 @@
 //! - Event handling for all the built-in widgets
 //! - A renderer-agnostic API
 //!
-//! To achieve this, it introduces a bunch of reusable interfaces:
+//! To achieve this, it introduces a couple of reusable interfaces:
 //!
 //! - A [`Widget`] trait, which is used to implement new widgets: from layout
 //!   requirements to event and drawing logic.
 //! - A bunch of `Renderer` traits, meant to keep the crate renderer-agnostic.
-//! - A [`window::Backend`] trait, leveraging [`raw-window-handle`], which can be
-//!   implemented by graphical renderers that target _windows_. Window-based
-//!   shells (like [`iced_winit`]) can use this trait to stay renderer-agnostic.
 //!
 //! # Usage
 //! The strategy to use this crate depends on your particular use case. If you
@@ -31,7 +28,6 @@
 //! [`druid`]: https://github.com/xi-editor/druid
 //! [`raw-window-handle`]: https://github.com/rust-windowing/raw-window-handle
 //! [`Widget`]: widget/trait.Widget.html
-//! [`window::Backend`]: window/trait.Backend.html
 //! [`UserInterface`]: struct.UserInterface.html
 //! [renderer]: renderer/index.html
 #![deny(missing_docs)]
@@ -42,6 +38,7 @@
 pub mod keyboard;
 pub mod layout;
 pub mod mouse;
+pub mod program;
 pub mod renderer;
 pub mod subscription;
 pub mod widget;
@@ -54,6 +51,15 @@ mod hasher;
 mod runtime;
 mod user_interface;
 
+// We disable debug capabilities on release builds unless the `debug` feature
+// is explicitly enabled.
+#[cfg(feature = "debug")]
+#[path = "debug/basic.rs"]
+mod debug;
+#[cfg(not(feature = "debug"))]
+#[path = "debug/null.rs"]
+mod debug;
+
 pub use iced_core::{
     Align, Background, Color, Font, HorizontalAlignment, Length, Point,
     Rectangle, Size, Vector, VerticalAlignment,
@@ -64,10 +70,12 @@ pub use iced_futures::{executor, futures, Command};
 pub use executor::Executor;
 
 pub use clipboard::Clipboard;
+pub use debug::Debug;
 pub use element::Element;
 pub use event::Event;
 pub use hasher::Hasher;
 pub use layout::Layout;
+pub use program::Program;
 pub use renderer::Renderer;
 pub use runtime::Runtime;
 pub use subscription::Subscription;
diff --git a/native/src/program.rs b/native/src/program.rs
new file mode 100644
index 00000000..14afcd84
--- /dev/null
+++ b/native/src/program.rs
@@ -0,0 +1,39 @@
+//! Build interactive programs using The Elm Architecture.
+use crate::{Command, Element, Renderer};
+
+mod state;
+
+pub use state::State;
+
+/// The core of a user interface application following The Elm Architecture.
+pub trait Program: Sized {
+    /// The graphics backend to use to draw the [`Program`].
+    ///
+    /// [`Program`]: trait.Program.html
+    type Renderer: Renderer;
+
+    /// The type of __messages__ your [`Program`] will produce.
+    ///
+    /// [`Program`]: trait.Program.html
+    type Message: std::fmt::Debug + Send;
+
+    /// Handles a __message__ and updates the state of the [`Program`].
+    ///
+    /// This is where you define your __update logic__. All the __messages__,
+    /// produced by either user interactions or commands, will be handled by
+    /// this method.
+    ///
+    /// Any [`Command`] returned will be executed immediately in the
+    /// background by shells.
+    ///
+    /// [`Program`]: trait.Application.html
+    /// [`Command`]: struct.Command.html
+    fn update(&mut self, message: Self::Message) -> Command<Self::Message>;
+
+    /// Returns the widgets to display in the [`Program`].
+    ///
+    /// These widgets can produce __messages__ based on user interaction.
+    ///
+    /// [`Program`]: trait.Program.html
+    fn view(&mut self) -> Element<'_, Self::Message, Self::Renderer>;
+}
diff --git a/native/src/program/state.rs b/native/src/program/state.rs
new file mode 100644
index 00000000..8716d8b9
--- /dev/null
+++ b/native/src/program/state.rs
@@ -0,0 +1,185 @@
+use crate::{
+    Cache, Clipboard, Command, Debug, Event, Program, Renderer, Size,
+    UserInterface,
+};
+
+/// The execution state of a [`Program`]. It leverages caching, event
+/// processing, and rendering primitive storage.
+///
+/// [`Program`]: trait.Program.html
+#[allow(missing_debug_implementations)]
+pub struct State<P>
+where
+    P: Program + 'static,
+{
+    program: P,
+    cache: Option<Cache>,
+    primitive: <P::Renderer as Renderer>::Output,
+    queued_events: Vec<Event>,
+    queued_messages: Vec<P::Message>,
+}
+
+impl<P> State<P>
+where
+    P: Program + 'static,
+{
+    /// Creates a new [`State`] with the provided [`Program`], initializing its
+    /// primitive with the given logical bounds and renderer.
+    ///
+    /// [`State`]: struct.State.html
+    /// [`Program`]: trait.Program.html
+    pub fn new(
+        mut program: P,
+        bounds: Size,
+        renderer: &mut P::Renderer,
+        debug: &mut Debug,
+    ) -> Self {
+        let user_interface = build_user_interface(
+            &mut program,
+            Cache::default(),
+            renderer,
+            bounds,
+            debug,
+        );
+
+        debug.draw_started();
+        let primitive = user_interface.draw(renderer);
+        debug.draw_finished();
+
+        let cache = Some(user_interface.into_cache());
+
+        State {
+            program,
+            cache,
+            primitive,
+            queued_events: Vec::new(),
+            queued_messages: Vec::new(),
+        }
+    }
+
+    /// Returns a reference to the [`Program`] of the [`State`].
+    ///
+    /// [`Program`]: trait.Program.html
+    /// [`State`]: struct.State.html
+    pub fn program(&self) -> &P {
+        &self.program
+    }
+
+    /// Returns a reference to the current rendering primitive of the [`State`].
+    ///
+    /// [`State`]: struct.State.html
+    pub fn primitive(&self) -> &<P::Renderer as Renderer>::Output {
+        &self.primitive
+    }
+
+    /// Queues an event in the [`State`] for processing during an [`update`].
+    ///
+    /// [`State`]: struct.State.html
+    /// [`update`]: #method.update
+    pub fn queue_event(&mut self, event: Event) {
+        self.queued_events.push(event);
+    }
+
+    /// Queues a message in the [`State`] for processing during an [`update`].
+    ///
+    /// [`State`]: struct.State.html
+    /// [`update`]: #method.update
+    pub fn queue_message(&mut self, message: P::Message) {
+        self.queued_messages.push(message);
+    }
+
+    /// Processes all the queued events and messages, rebuilding and redrawing
+    /// the widgets of the linked [`Program`] if necessary.
+    ///
+    /// Returns the [`Command`] obtained from [`Program`] after updating it,
+    /// only if an update was necessary.
+    ///
+    /// [`Program`]: trait.Program.html
+    pub fn update(
+        &mut self,
+        clipboard: Option<&dyn Clipboard>,
+        bounds: Size,
+        renderer: &mut P::Renderer,
+        debug: &mut Debug,
+    ) -> Option<Command<P::Message>> {
+        if self.queued_events.is_empty() && self.queued_messages.is_empty() {
+            return None;
+        }
+
+        let mut user_interface = build_user_interface(
+            &mut self.program,
+            self.cache.take().unwrap(),
+            renderer,
+            bounds,
+            debug,
+        );
+
+        debug.event_processing_started();
+        let mut messages = user_interface.update(
+            self.queued_events.drain(..),
+            clipboard,
+            renderer,
+        );
+        messages.extend(self.queued_messages.drain(..));
+        debug.event_processing_finished();
+
+        if messages.is_empty() {
+            debug.draw_started();
+            self.primitive = user_interface.draw(renderer);
+            debug.draw_finished();
+
+            self.cache = Some(user_interface.into_cache());
+
+            None
+        } else {
+            // When there are messages, we are forced to rebuild twice
+            // for now :^)
+            let temp_cache = user_interface.into_cache();
+
+            let commands =
+                Command::batch(messages.into_iter().map(|message| {
+                    debug.log_message(&message);
+
+                    debug.update_started();
+                    let command = self.program.update(message);
+                    debug.update_finished();
+
+                    command
+                }));
+
+            let user_interface = build_user_interface(
+                &mut self.program,
+                temp_cache,
+                renderer,
+                bounds,
+                debug,
+            );
+
+            debug.draw_started();
+            self.primitive = user_interface.draw(renderer);
+            debug.draw_finished();
+
+            self.cache = Some(user_interface.into_cache());
+
+            Some(commands)
+        }
+    }
+}
+
+fn build_user_interface<'a, P: Program>(
+    program: &'a mut P,
+    cache: Cache,
+    renderer: &mut P::Renderer,
+    size: Size,
+    debug: &mut Debug,
+) -> UserInterface<'a, P::Message, P::Renderer> {
+    debug.view_started();
+    let view = program.view();
+    debug.view_finished();
+
+    debug.layout_started();
+    let user_interface = UserInterface::build(view, size, cache, renderer);
+    debug.layout_finished();
+
+    user_interface
+}
diff --git a/native/src/user_interface.rs b/native/src/user_interface.rs
index 48cd6111..e963b601 100644
--- a/native/src/user_interface.rs
+++ b/native/src/user_interface.rs
@@ -102,7 +102,9 @@ where
             hasher.finish()
         };
 
-        let layout = if hash == cache.hash && bounds == cache.bounds {
+        let layout_is_cached = hash == cache.hash && bounds == cache.bounds;
+
+        let layout = if layout_is_cached {
             cache.layout
         } else {
             renderer.layout(&root, &layout::Limits::new(Size::ZERO, bounds))
diff --git a/native/src/window.rs b/native/src/window.rs
index 4dcae62f..220bb3be 100644
--- a/native/src/window.rs
+++ b/native/src/window.rs
@@ -1,6 +1,4 @@
 //! Build window-based GUI applications.
-mod backend;
 mod event;
 
-pub use backend::Backend;
 pub use event::Event;