Implement input hints based on the active tool state (#388)

* Hook up user input hints to display in the frontend status bar

Closes #171

* MVP hint system based on tool FSM

* Fix hints for Fill and Eyedropper tools

* Add icons for keyboard shortcuts

* Fix hints for Pen Tool

* Cleanup

editor/src/tool/tools/fill.rs

@@ -1,34 +1,117 @@
 use crate::consts::SELECTION_TOLERANCE;
+use crate::document::DocumentMessageHandler;
+use crate::input::{keyboard::MouseMotion, InputPreprocessor};
 use crate::message_prelude::*;
+use crate::misc::{HintData, HintGroup, HintInfo};
 use crate::tool::ToolActionHandlerData;
+use crate::tool::{DocumentToolData, Fsm, ToolMessage};
 use glam::DVec2;
 use graphene::{Operation, Quad};
 use serde::{Deserialize, Serialize};
 
 #[derive(Default)]
-pub struct Fill;
+pub struct Fill {
+	fsm_state: FillToolFsmState,
+	data: FillToolData,
+}
 
 #[impl_message(Message, ToolMessage, Fill)]
 #[derive(PartialEq, Clone, Debug, Hash, Serialize, Deserialize)]
 pub enum FillMessage {
-	MouseDown,
+	LeftMouseDown,
+	RightMouseDown,
+	Abort,
 }
 
 impl<'a> MessageHandler<ToolMessage, ToolActionHandlerData<'a>> for Fill {
-	fn process_action(&mut self, _action: ToolMessage, data: ToolActionHandlerData<'a>, responses: &mut VecDeque<Message>) {
-		let mouse_pos = data.2.mouse.position;
-		let tolerance = DVec2::splat(SELECTION_TOLERANCE);
-		let quad = Quad::from_box([mouse_pos - tolerance, mouse_pos + tolerance]);
+	fn process_action(&mut self, action: ToolMessage, data: ToolActionHandlerData<'a>, responses: &mut VecDeque<Message>) {
+		if action == ToolMessage::UpdateHints {
+			self.fsm_state.update_hints(responses);
+			return;
+		}
 
-		if let Some(path) = data.0.graphene_document.intersects_quad_root(quad).last() {
-			responses.push_back(
-				Operation::SetLayerFill {
-					path: path.to_vec(),
-					color: data.1.primary_color,
-				}
-				.into(),
-			);
+		let new_state = self.fsm_state.transition(action, data.0, data.1, &mut self.data, data.2, responses);
+
+		if self.fsm_state != new_state {
+			self.fsm_state = new_state;
+			self.fsm_state.update_hints(responses);
 		}
 	}
-	advertise_actions!(FillMessageDiscriminant; MouseDown);
+
+	advertise_actions!(FillMessageDiscriminant; LeftMouseDown, RightMouseDown);
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum FillToolFsmState {
+	Ready,
+}
+
+impl Default for FillToolFsmState {
+	fn default() -> Self {
+		FillToolFsmState::Ready
+	}
+}
+
+#[derive(Clone, Debug, Default)]
+struct FillToolData {}
+
+impl Fsm for FillToolFsmState {
+	type ToolData = FillToolData;
+
+	fn transition(
+		self,
+		event: ToolMessage,
+		document: &DocumentMessageHandler,
+		tool_data: &DocumentToolData,
+		data: &mut Self::ToolData,
+		input: &InputPreprocessor,
+		responses: &mut VecDeque<Message>,
+	) -> Self {
+		use FillMessage::*;
+		use FillToolFsmState::*;
+		if let ToolMessage::Fill(event) = event {
+			match (self, event) {
+				(Ready, lmb_or_rmb) if lmb_or_rmb == LeftMouseDown || lmb_or_rmb == RightMouseDown => {
+					let mouse_pos = input.mouse.position;
+					let tolerance = DVec2::splat(SELECTION_TOLERANCE);
+					let quad = Quad::from_box([mouse_pos - tolerance, mouse_pos + tolerance]);
+
+					if let Some(path) = document.graphene_document.intersects_quad_root(quad).last() {
+						let color = match lmb_or_rmb {
+							LeftMouseDown => tool_data.primary_color,
+							RightMouseDown => tool_data.secondary_color,
+							Abort => unreachable!(),
+						};
+						responses.push_back(Operation::SetLayerFill { path: path.to_vec(), color }.into());
+					}
+
+					Ready
+				}
+				_ => self,
+			}
+		} else {
+			self
+		}
+	}
+
+	fn update_hints(&self, responses: &mut VecDeque<Message>) {
+		let hint_data = match self {
+			FillToolFsmState::Ready => HintData(vec![HintGroup(vec![
+				HintInfo {
+					key_groups: vec![],
+					mouse: Some(MouseMotion::Lmb),
+					label: String::from("Fill with Primary"),
+					plus: false,
+				},
+				HintInfo {
+					key_groups: vec![],
+					mouse: Some(MouseMotion::Rmb),
+					label: String::from("Fill with Secondary"),
+					plus: false,
+				},
+			])]),
+		};
+
+		responses.push_back(FrontendMessage::UpdateInputHints { hint_data }.into());
+	}
 }