Split servoshell into Desktop and common part (#32457)

* servoshell: Move desktop files

Move files related to winit into a desktop module.
This is a preparation to merge the android and ohos apps into
servoshell.

* servoshell: Format imports

* servoshell: Move panic hook into separate file

* servoshell: Move desktop main

* Consider ohos as not desktop

* servoshell: Adjust dependencies for shared code

* servoshell: Remove native-bluetooth from default features

There currently is no good way to have target specific default features.

* Rename desktop_main.rs to cli.rs

* Remove todo

ports/servoshell/desktop/egui_glue.rs

@@ -0,0 +1,143 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! A modified version of EguiGlow [from egui_glow 0.22.0][0] that retains its shapes,
+//! allowing [`EguiGlow::paint`] to be called multiple times.
+//!
+//! [0]: https://github.com/emilk/egui/blob/0.22.0/crates/egui_glow/src/winit.rs
+
+// Copyright (c) 2018-2021 Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
+//
+// Permission is hereby granted, free of charge, to any
+// person obtaining a copy of this software and associated
+// documentation files (the "Software"), to deal in the
+// Software without restriction, including without
+// limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software
+// is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice
+// shall be included in all copies or substantial portions
+// of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+use egui::{ViewportId, ViewportOutput};
+use egui_glow::ShaderVersion;
+pub use egui_winit;
+use egui_winit::winit;
+pub use egui_winit::EventResponse;
+
+/// Use [`egui`] from a [`glow`] app based on [`winit`].
+pub struct EguiGlow {
+    pub egui_ctx: egui::Context,
+    pub egui_winit: egui_winit::State,
+    pub painter: egui_glow::Painter,
+
+    shapes: Vec<egui::epaint::ClippedShape>,
+    textures_delta: egui::TexturesDelta,
+}
+
+impl EguiGlow {
+    /// For automatic shader version detection set `shader_version` to `None`.
+    pub fn new<E>(
+        event_loop: &winit::event_loop::EventLoopWindowTarget<E>,
+        gl: std::sync::Arc<glow::Context>,
+        shader_version: Option<ShaderVersion>,
+    ) -> Self {
+        let painter = egui_glow::Painter::new(gl, "", shader_version)
+            .map_err(|err| {
+                log::error!("error occurred in initializing painter:\n{err}");
+            })
+            .unwrap();
+
+        let egui_ctx = egui::Context::default();
+        Self {
+            egui_winit: egui_winit::State::new(
+                egui_ctx.clone(),
+                ViewportId::ROOT,
+                event_loop,
+                None,
+                None,
+            ),
+            egui_ctx,
+            painter,
+            shapes: Default::default(),
+            textures_delta: Default::default(),
+        }
+    }
+
+    pub fn on_window_event(
+        &mut self,
+        window: &winit::window::Window,
+        event: &winit::event::WindowEvent,
+    ) -> EventResponse {
+        self.egui_winit.on_window_event(window, event)
+    }
+
+    /// Returns the `Duration` of the timeout after which egui should be repainted even if there's no new events.
+    ///
+    /// Call [`Self::paint`] later to paint.
+    pub fn run(
+        &mut self,
+        window: &winit::window::Window,
+        run_ui: impl FnMut(&egui::Context),
+    ) -> std::time::Duration {
+        let raw_input = self.egui_winit.take_egui_input(window);
+        let egui::FullOutput {
+            platform_output,
+            viewport_output,
+            textures_delta,
+            shapes,
+            pixels_per_point: _pixels_per_point,
+        } = self.egui_ctx.run(raw_input, run_ui);
+
+        self.egui_winit
+            .handle_platform_output(window, platform_output);
+
+        self.shapes = shapes;
+        self.textures_delta.append(textures_delta);
+        match viewport_output.get(&ViewportId::ROOT) {
+            Some(&ViewportOutput { repaint_delay, .. }) => repaint_delay,
+            None => std::time::Duration::ZERO,
+        }
+    }
+
+    /// Paint the results of the last call to [`Self::run`].
+    pub fn paint(&mut self, window: &winit::window::Window) {
+        /////// let shapes = std::mem::take(&mut self.shapes);
+        let shapes = &self.shapes;
+        let mut textures_delta = std::mem::take(&mut self.textures_delta);
+
+        for (id, image_delta) in textures_delta.set {
+            self.painter.set_texture(id, &image_delta);
+        }
+
+        let pixels_per_point = self.egui_ctx.pixels_per_point();
+        /////// let clipped_primitives = self.egui_ctx.tessellate(shapes);
+        let clipped_primitives = self.egui_ctx.tessellate(shapes.clone(), pixels_per_point);
+        let dimensions: [u32; 2] = window.inner_size().into();
+        self.painter
+            .paint_primitives(dimensions, pixels_per_point, &clipped_primitives);
+
+        for id in textures_delta.free.drain(..) {
+            self.painter.free_texture(id);
+        }
+    }
+
+    /// Call to release the allocated graphics resources.
+    pub fn destroy(&mut self) {
+        self.painter.destroy();
+    }
+}