Desktop: Isolate CEF-rendered UI into separate crate and process (#4321)

* Extract CEF rendered UI into a separate process and crate

* Review

* Review

* Review

* Review

* Remove necessary workarounds

* Block on frame copy ack

* Crop and resample frames correctly

* Skip blank frames

* Fix deps

* Fix fmt

* Fix clippy warning

* Review

* Fix todo

desktop/ui/src/view.rs

@@ -0,0 +1,69 @@
+use std::sync::mpsc::Receiver;
+
+#[derive(Clone, Copy)]
+pub(crate) struct ViewInfo {
+	width: u32,
+	height: u32,
+	scale: f64,
+}
+
+impl ViewInfo {
+	pub(crate) fn new() -> Self {
+		Self { width: 1, height: 1, scale: 1. }
+	}
+
+	pub(crate) fn apply_update(&mut self, update: ViewInfoUpdate) {
+		match update {
+			ViewInfoUpdate::Size { width, height } if width > 0 && height > 0 => {
+				self.width = width;
+				self.height = height;
+			}
+			ViewInfoUpdate::Scale(scale) if scale > 0. => {
+				self.scale = scale;
+			}
+			_ => {}
+		}
+	}
+
+	pub(crate) fn zoom(&self) -> f64 {
+		self.scale.ln() / 1.2_f64.ln()
+	}
+
+	pub(crate) fn width(&self) -> u32 {
+		self.width
+	}
+
+	pub(crate) fn height(&self) -> u32 {
+		self.height
+	}
+}
+
+impl Default for ViewInfo {
+	fn default() -> Self {
+		Self::new()
+	}
+}
+
+#[derive(serde::Serialize, serde::Deserialize)]
+pub(crate) enum ViewInfoUpdate {
+	Size { width: u32, height: u32 },
+	Scale(f64),
+}
+
+pub(super) struct ViewInfoReceiver {
+	view_info: ViewInfo,
+	receiver: Receiver<ViewInfoUpdate>,
+}
+
+impl ViewInfoReceiver {
+	pub(super) fn new(receiver: Receiver<ViewInfoUpdate>) -> Self {
+		Self { view_info: ViewInfo::new(), receiver }
+	}
+
+	pub(super) fn current(&mut self) -> ViewInfo {
+		for update in self.receiver.try_iter() {
+			self.view_info.apply_update(update);
+		}
+		self.view_info
+	}
+}