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/input/input_mapper.rs

@@ -18,6 +18,7 @@ const SHIFT_NUDGE_AMOUNT: f64 = 10.;
 pub enum InputMapperMessage {
 	PointerMove,
 	MouseScroll,
+	#[child]
 	KeyUp(Key),
 	#[child]
 	KeyDown(Key),
@@ -43,6 +44,7 @@ impl KeyMappingEntries {
 		}
 		None
 	}
+
 	fn push(&mut self, entry: MappingEntry) {
 		self.0.push(entry)
 	}
@@ -187,7 +189,8 @@ impl Default for Mapping {
 			entry! {action=PenMessage::Confirm, key_down=KeyEscape},
 			entry! {action=PenMessage::Confirm, key_down=KeyEnter},
 			// Fill
-			entry! {action=FillMessage::MouseDown, key_down=Lmb},
+			entry! {action=FillMessage::LeftMouseDown, key_down=Lmb},
+			entry! {action=FillMessage::RightMouseDown, key_down=Rmb},
 			// Tool Actions
 			entry! {action=ToolMessage::ActivateTool(ToolType::Select), key_down=KeyV},
 			entry! {action=ToolMessage::ActivateTool(ToolType::Eyedropper), key_down=KeyI},

editor/src/input/keyboard.rs

@@ -16,6 +16,7 @@ pub type KeyStates = BitVector<KEY_MASK_STORAGE_LENGTH>;
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
 pub enum Key {
 	UnknownKey,
+
 	// MouseKeys
 	Lmb,
 	Rmb,
@@ -87,6 +88,20 @@ pub enum Key {
 	NumKeys,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+pub enum MouseMotion {
+	None,
+	Lmb,
+	Rmb,
+	Mmb,
+	ScrollUp,
+	ScrollDown,
+	Drag,
+	LmbDrag,
+	RmbDrag,
+	MmbDrag,
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct BitVector<const LENGTH: usize>([StorageType; LENGTH]);