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

OpenGL renderer and backend-agnostic graphics subcrate

9 files changed, 506 insertions, 64 deletions

diff --git a/native/Cargo.toml b/native/Cargo.toml
index 7e9c2a5a..75b4a56b 100644
--- a/native/Cargo.toml
+++ b/native/Cargo.toml
@@ -7,9 +7,11 @@ description = "A renderer-agnostic library for native GUIs"
 license = "MIT"
 repository = "https://github.com/hecrj/iced"
 
+[features]
+debug = []
+
 [dependencies]
 twox-hash = "1.5"
-raw-window-handle = "0.3"
 unicode-segmentation = "1.6"
 
 [dependencies.iced_core]
diff --git a/native/src/debug/basic.rs b/native/src/debug/basic.rs
new file mode 100644
index 00000000..5338d0d9
--- /dev/null
+++ b/native/src/debug/basic.rs
@@ -0,0 +1,216 @@
+#![allow(missing_docs)]
+use std::{collections::VecDeque, time};
+
+/// A bunch of time measurements for debugging purposes.
+#[derive(Debug)]
+pub struct Debug {
+    is_enabled: bool,
+
+    startup_start: time::Instant,
+    startup_duration: time::Duration,
+
+    update_start: time::Instant,
+    update_durations: TimeBuffer,
+
+    view_start: time::Instant,
+    view_durations: TimeBuffer,
+
+    layout_start: time::Instant,
+    layout_durations: TimeBuffer,
+
+    event_start: time::Instant,
+    event_durations: TimeBuffer,
+
+    draw_start: time::Instant,
+    draw_durations: TimeBuffer,
+
+    render_start: time::Instant,
+    render_durations: TimeBuffer,
+
+    message_count: usize,
+    last_messages: VecDeque<String>,
+}
+
+impl Debug {
+    /// Creates a new [`Debug`].
+    ///
+    /// [`Debug`]: struct.Debug.html
+    pub fn new() -> Self {
+        let now = time::Instant::now();
+
+        Self {
+            is_enabled: false,
+            startup_start: now,
+            startup_duration: time::Duration::from_secs(0),
+
+            update_start: now,
+            update_durations: TimeBuffer::new(200),
+
+            view_start: now,
+            view_durations: TimeBuffer::new(200),
+
+            layout_start: now,
+            layout_durations: TimeBuffer::new(200),
+
+            event_start: now,
+            event_durations: TimeBuffer::new(200),
+
+            draw_start: now,
+            draw_durations: TimeBuffer::new(200),
+
+            render_start: now,
+            render_durations: TimeBuffer::new(50),
+
+            message_count: 0,
+            last_messages: VecDeque::new(),
+        }
+    }
+
+    pub fn toggle(&mut self) {
+        self.is_enabled = !self.is_enabled;
+    }
+
+    pub fn startup_started(&mut self) {
+        self.startup_start = time::Instant::now();
+    }
+
+    pub fn startup_finished(&mut self) {
+        self.startup_duration = time::Instant::now() - self.startup_start;
+    }
+
+    pub fn update_started(&mut self) {
+        self.update_start = time::Instant::now();
+    }
+
+    pub fn update_finished(&mut self) {
+        self.update_durations
+            .push(time::Instant::now() - self.update_start);
+    }
+
+    pub fn view_started(&mut self) {
+        self.view_start = time::Instant::now();
+    }
+
+    pub fn view_finished(&mut self) {
+        self.view_durations
+            .push(time::Instant::now() - self.view_start);
+    }
+
+    pub fn layout_started(&mut self) {
+        self.layout_start = time::Instant::now();
+    }
+
+    pub fn layout_finished(&mut self) {
+        self.layout_durations
+            .push(time::Instant::now() - self.layout_start);
+    }
+
+    pub fn event_processing_started(&mut self) {
+        self.event_start = time::Instant::now();
+    }
+
+    pub fn event_processing_finished(&mut self) {
+        self.event_durations
+            .push(time::Instant::now() - self.event_start);
+    }
+
+    pub fn draw_started(&mut self) {
+        self.draw_start = time::Instant::now();
+    }
+
+    pub fn draw_finished(&mut self) {
+        self.draw_durations
+            .push(time::Instant::now() - self.draw_start);
+    }
+
+    pub fn render_started(&mut self) {
+        self.render_start = time::Instant::now();
+    }
+
+    pub fn render_finished(&mut self) {
+        self.render_durations
+            .push(time::Instant::now() - self.render_start);
+    }
+
+    pub fn log_message<Message: std::fmt::Debug>(&mut self, message: &Message) {
+        self.last_messages.push_back(format!("{:?}", message));
+
+        if self.last_messages.len() > 10 {
+            let _ = self.last_messages.pop_front();
+        }
+
+        self.message_count += 1;
+    }
+
+    pub fn overlay(&self) -> Vec<String> {
+        if !self.is_enabled {
+            return Vec::new();
+        }
+
+        let mut lines = Vec::new();
+
+        fn key_value<T: std::fmt::Debug>(key: &str, value: T) -> String {
+            format!("{} {:?}", key, value)
+        }
+
+        lines.push(format!(
+            "{} {} - {}",
+            env!("CARGO_PKG_NAME"),
+            env!("CARGO_PKG_VERSION"),
+            env!("CARGO_PKG_REPOSITORY"),
+        ));
+        lines.push(key_value("Startup:", self.startup_duration));
+        lines.push(key_value("Update:", self.update_durations.average()));
+        lines.push(key_value("View:", self.view_durations.average()));
+        lines.push(key_value("Layout:", self.layout_durations.average()));
+        lines.push(key_value(
+            "Event processing:",
+            self.event_durations.average(),
+        ));
+        lines.push(key_value(
+            "Primitive generation:",
+            self.draw_durations.average(),
+        ));
+        lines.push(key_value("Render:", self.render_durations.average()));
+        lines.push(key_value("Message count:", self.message_count));
+        lines.push(String::from("Last messages:"));
+        lines.extend(
+            self.last_messages.iter().map(|msg| format!("    {}", msg)),
+        );
+
+        lines
+    }
+}
+
+#[derive(Debug)]
+struct TimeBuffer {
+    head: usize,
+    size: usize,
+    contents: Vec<time::Duration>,
+}
+
+impl TimeBuffer {
+    fn new(capacity: usize) -> TimeBuffer {
+        TimeBuffer {
+            head: 0,
+            size: 0,
+            contents: vec![time::Duration::from_secs(0); capacity],
+        }
+    }
+
+    fn push(&mut self, duration: time::Duration) {
+        self.head = (self.head + 1) % self.contents.len();
+        self.contents[self.head] = duration;
+        self.size = (self.size + 1).min(self.contents.len());
+    }
+
+    fn average(&self) -> time::Duration {
+        let sum: time::Duration = if self.size == self.contents.len() {
+            self.contents[..].iter().sum()
+        } else {
+            self.contents[..self.size].iter().sum()
+        };
+
+        sum / self.size.max(1) as u32
+    }
+}
diff --git a/native/src/debug/null.rs b/native/src/debug/null.rs
new file mode 100644
index 00000000..60e6122d
--- /dev/null
+++ b/native/src/debug/null.rs
@@ -0,0 +1,47 @@
+#![allow(missing_docs)]
+#[derive(Debug)]
+pub struct Debug;
+
+impl Debug {
+    pub fn new() -> Self {
+        Self
+    }
+
+    pub fn startup_started(&mut self) {}
+
+    pub fn startup_finished(&mut self) {}
+
+    pub fn update_started(&mut self) {}
+
+    pub fn update_finished(&mut self) {}
+
+    pub fn view_started(&mut self) {}
+
+    pub fn view_finished(&mut self) {}
+
+    pub fn layout_started(&mut self) {}
+
+    pub fn layout_finished(&mut self) {}
+
+    pub fn event_processing_started(&mut self) {}
+
+    pub fn event_processing_finished(&mut self) {}
+
+    pub fn draw_started(&mut self) {}
+
+    pub fn draw_finished(&mut self) {}
+
+    pub fn render_started(&mut self) {}
+
+    pub fn render_finished(&mut self) {}
+
+    pub fn log_message<Message: std::fmt::Debug>(
+        &mut self,
+        _message: &Message,
+    ) {
+    }
+
+    pub fn overlay(&self) -> Vec<String> {
+        Vec::new()
+    }
+}
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;
diff --git a/native/src/window/backend.rs b/native/src/window/backend.rs
deleted file mode 100644
index 892d4bb9..00000000
--- a/native/src/window/backend.rs
+++ /dev/null
@@ -1,55 +0,0 @@
-use crate::mouse;
-
-use raw_window_handle::HasRawWindowHandle;
-
-/// A graphics backend that can render to windows.
-pub trait Backend: Sized {
-    /// The settings of the backend.
-    type Settings: Default;
-
-    /// The iced renderer of the backend.
-    type Renderer: crate::Renderer;
-
-    /// The surface of the backend.
-    type Surface;
-
-    /// The swap chain of the backend.
-    type SwapChain;
-
-    /// Creates a new [`Backend`] and an associated iced renderer.
-    ///
-    /// [`Backend`]: trait.Backend.html
-    fn new(settings: Self::Settings) -> (Self, Self::Renderer);
-
-    /// Crates a new [`Surface`] for the given window.
-    ///
-    /// [`Surface`]: #associatedtype.Surface
-    fn create_surface<W: HasRawWindowHandle>(
-        &mut self,
-        window: &W,
-    ) -> Self::Surface;
-
-    /// Crates a new [`SwapChain`] for the given [`Surface`].
-    ///
-    /// [`SwapChain`]: #associatedtype.SwapChain
-    /// [`Surface`]: #associatedtype.Surface
-    fn create_swap_chain(
-        &mut self,
-        surface: &Self::Surface,
-        width: u32,
-        height: u32,
-    ) -> Self::SwapChain;
-
-    /// Draws the output primitives to the next frame of the given [`SwapChain`].
-    ///
-    /// [`SwapChain`]: #associatedtype.SwapChain
-    /// [`Surface`]: #associatedtype.Surface
-    fn draw<T: AsRef<str>>(
-        &mut self,
-        renderer: &mut Self::Renderer,
-        swap_chain: &mut Self::SwapChain,
-        output: &<Self::Renderer as crate::Renderer>::Output,
-        scale_factor: f64,
-        overlay: &[T],
-    ) -> mouse::Interaction;
-}