Initial commit for a new software rendering backend for use in MCUs

This adds the skeleton, including a winit driven simulator window
and a dummy ItemRenderer implementation.

sixtyfps_runtime/rendering_backends/mcu/lib.rs

@@ -0,0 +1,102 @@
+/* LICENSE BEGIN
+    This file is part of the SixtyFPS Project -- https://sixtyfps.io
+    Copyright (c) 2021 Olivier Goffart <olivier.goffart@sixtyfps.io>
+    Copyright (c) 2021 Simon Hausmann <simon.hausmann@sixtyfps.io>
+
+    SPDX-License-Identifier: GPL-3.0-only
+    This file is also available under commercial licensing terms.
+    Please contact info@sixtyfps.io for more information.
+LICENSE END */
+/*!
+
+**NOTE**: This library is an **internal** crate for the [SixtyFPS project](https://sixtyfps.io).
+This crate should **not be used directly** by applications using SixtyFPS.
+You should use the `sixtyfps` crate instead.
+
+**WARNING**: This crate does not follow the semver convention for versioning and can
+only be used with `version = "=x.y.z"` in Cargo.toml.
+
+*/
+#![doc(html_logo_url = "https://sixtyfps.io/resources/logo.drawio.svg")]
+
+use sixtyfps_corelib::{
+    graphics::{Image, Size},
+    window::Window,
+    ImageInner,
+};
+use std::rc::Rc;
+
+#[cfg(feature = "simulator")]
+mod simulator;
+
+#[cfg(feature = "simulator")]
+use simulator::*;
+
+mod renderer;
+
+pub struct Backend;
+
+impl sixtyfps_corelib::backend::Backend for Backend {
+    fn create_window(&'static self) -> Rc<Window> {
+        sixtyfps_corelib::window::Window::new(|window| SimulatorWindow::new(window))
+    }
+
+    fn run_event_loop(&'static self, behavior: sixtyfps_corelib::backend::EventLoopQuitBehavior) {
+        simulator::event_loop::run(behavior);
+    }
+
+    fn quit_event_loop(&'static self) {
+        crate::event_loop::with_window_target(|event_loop| {
+            event_loop.event_loop_proxy().send_event(simulator::event_loop::CustomEvent::Exit).ok();
+        })
+    }
+
+    fn register_font_from_memory(
+        &'static self,
+        _data: &'static [u8],
+    ) -> Result<(), Box<dyn std::error::Error>> {
+        unimplemented!()
+    }
+
+    fn register_font_from_path(
+        &'static self,
+        _path: &std::path::Path,
+    ) -> Result<(), Box<dyn std::error::Error>> {
+        unimplemented!()
+    }
+
+    fn set_clipboard_text(&'static self, _text: String) {
+        unimplemented!()
+    }
+
+    fn clipboard_text(&'static self) -> Option<String> {
+        unimplemented!()
+    }
+
+    fn post_event(&'static self, event: Box<dyn FnOnce() + Send>) {
+        let e = crate::event_loop::CustomEvent::UserEvent(event);
+        crate::event_loop::GLOBAL_PROXY.get_or_init(Default::default).lock().unwrap().send_event(e);
+    }
+
+    fn image_size(&'static self, image: &Image) -> Size {
+        let inner: &ImageInner = image.into();
+        match inner {
+            ImageInner::None => Default::default(),
+            ImageInner::AbsoluteFilePath(_) => todo!(),
+            ImageInner::EmbeddedData { .. } => todo!(),
+            ImageInner::EmbeddedImage(buffer) => {
+                [buffer.width() as f32, buffer.height() as f32].into()
+            }
+        }
+    }
+}
+
+pub type NativeWidgets = ();
+pub type NativeGlobals = ();
+pub mod native_widgets {}
+pub const HAS_NATIVE_STYLE: bool = false;
+pub const IS_AVAILABLE: bool = true;
+
+pub fn init() {
+    sixtyfps_corelib::backend::instance_or_init(|| Box::new(Backend));
+}