Restructure the entire editor codebase to consistently match the message hierarchy

Closes #744

editor/src/messages/portfolio/document/overlays/mod.rs

@@ -0,0 +1,7 @@
+mod overlays_message;
+mod overlays_message_handler;
+
+#[doc(inline)]
+pub use overlays_message::{OverlaysMessage, OverlaysMessageDiscriminant};
+#[doc(inline)]
+pub use overlays_message_handler::OverlaysMessageHandler;

editor/src/messages/portfolio/document/overlays/overlays_message.rs

@@ -0,0 +1,24 @@
+use crate::messages::prelude::*;
+
+use graphene::Operation as DocumentOperation;
+
+use serde::{Deserialize, Serialize};
+
+#[remain::sorted]
+#[impl_message(Message, DocumentMessage, Overlays)]
+#[derive(PartialEq, Clone, Debug, Serialize, Deserialize)]
+pub enum OverlaysMessage {
+	// Sub-messages
+	#[remain::unsorted]
+	DispatchOperation(Box<DocumentOperation>),
+
+	// Messages
+	ClearAllOverlays,
+	Rerender,
+}
+
+impl From<DocumentOperation> for OverlaysMessage {
+	fn from(operation: DocumentOperation) -> OverlaysMessage {
+		Self::DispatchOperation(Box::new(operation))
+	}
+}

editor/src/messages/portfolio/document/overlays/overlays_message_handler.rs

@@ -0,0 +1,51 @@
+use crate::messages::prelude::*;
+
+use graphene::document::Document as GrapheneDocument;
+use graphene::layers::style::{RenderData, ViewMode};
+use graphene::layers::text_layer::FontCache;
+
+#[derive(Debug, Clone, Default)]
+pub struct OverlaysMessageHandler {
+	pub overlays_graphene_document: GrapheneDocument,
+}
+
+impl MessageHandler<OverlaysMessage, (bool, &FontCache, &InputPreprocessorMessageHandler)> for OverlaysMessageHandler {
+	#[remain::check]
+	fn process_message(&mut self, message: OverlaysMessage, (overlays_visible, font_cache, ipp): (bool, &FontCache, &InputPreprocessorMessageHandler), responses: &mut VecDeque<Message>) {
+		use OverlaysMessage::*;
+
+		#[remain::sorted]
+		match message {
+			// Sub-messages
+			#[remain::unsorted]
+			DispatchOperation(operation) => match self.overlays_graphene_document.handle_operation(*operation, font_cache) {
+				Ok(_) => responses.push_back(OverlaysMessage::Rerender.into()),
+				Err(e) => log::error!("OverlaysError: {:?}", e),
+			},
+
+			// Messages
+			ClearAllOverlays => todo!(),
+			Rerender =>
+			// Render overlays
+			{
+				responses.push_back(
+					FrontendMessage::UpdateDocumentOverlays {
+						svg: if overlays_visible {
+							let render_data = RenderData::new(ViewMode::Normal, font_cache, Some(ipp.document_bounds()), false);
+							self.overlays_graphene_document.render_root(render_data)
+						} else {
+							String::from("")
+						},
+					}
+					.into(),
+				)
+			}
+		}
+	}
+
+	fn actions(&self) -> ActionList {
+		actions!(OverlaysMessageDiscriminant;
+			ClearAllOverlays,
+		)
+	}
+}