Add Path tool support for the Tab key swapping to dragging the opposite handle (#2058)

* feat: tab alternates between handles

* fix: handle hints, remove anchor to handle switch
Added specific handle hints,
Can no longer switch to handle if just anchor is selected
typo fix

* fix: no longer deselect on esc/rclick

* feat: hides cursor when switching
A pointerlock implementation would be ideal in the future to keep the screen from panning,

* fix: tidy up dynamic tool hints
switch colinear to V

* fix: can no longer hide cursor if anchor selected
remove debug statement

* fix: clippy

* Solve some issues and remap V to C to toggle colinear

* Cleanup + change equidistant key from Shift to Alt

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

editor/src/messages/tool/common_functionality/shape_editor.rs

@@ -4,6 +4,7 @@ use crate::messages::portfolio::document::utility_types::document_metadata::{Doc
 use crate::messages::portfolio::document::utility_types::misc::{GeometrySnapSource, SnapSource};
 use crate::messages::portfolio::document::utility_types::network_interface::NodeNetworkInterface;
 use crate::messages::prelude::*;
+use crate::messages::tool::tool_messages::path_tool::PointSelectState;
 
 use bezier_rs::{Bezier, BezierHandles, TValue};
 use graphene_core::transform::Transform;
@@ -12,8 +13,9 @@ use graphene_core::vector::{ManipulatorPointId, PointId, VectorData, VectorModif
 use glam::DVec2;
 use graphene_std::vector::{HandleId, SegmentId};
 
-#[derive(Debug, PartialEq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone, Default)]
 pub enum ManipulatorAngle {
+	#[default]
 	Colinear,
 	Free,
 	Mixed,
@@ -161,9 +163,9 @@ impl ClosestSegment {
 		midpoint
 	}
 
-	pub fn adjusted_insert_and_select(&self, shape_editor: &mut ShapeState, responses: &mut VecDeque<Message>, add_to_selection: bool) {
+	pub fn adjusted_insert_and_select(&self, shape_editor: &mut ShapeState, responses: &mut VecDeque<Message>, extend_selection: bool) {
 		let id = self.adjusted_insert(responses);
-		shape_editor.select_anchor_point_by_id(self.layer, id, add_to_selection)
+		shape_editor.select_anchor_point_by_id(self.layer, id, extend_selection)
 	}
 }
 
@@ -221,7 +223,7 @@ impl ShapeState {
 
 	/// Select/deselect the first point within the selection threshold.
 	/// Returns a tuple of the points if found and the offset, or `None` otherwise.
-	pub fn change_point_selection(&mut self, network_interface: &NodeNetworkInterface, mouse_position: DVec2, select_threshold: f64, add_to_selection: bool) -> Option<Option<SelectedPointsInfo>> {
+	pub fn change_point_selection(&mut self, network_interface: &NodeNetworkInterface, mouse_position: DVec2, select_threshold: f64, extend_selection: bool) -> Option<Option<SelectedPointsInfo>> {
 		if self.selected_shape_state.is_empty() {
 			return None;
 		}
@@ -234,14 +236,14 @@ impl ShapeState {
 			let already_selected = selected_shape_state.is_selected(manipulator_point_id);
 
 			// Should we select or deselect the point?
-			let new_selected = if already_selected { !add_to_selection } else { true };
+			let new_selected = if already_selected { !extend_selection } else { true };
 
 			// Offset to snap the selected point to the cursor
 			let offset = mouse_position - network_interface.document_metadata().transform_to_viewport(layer).transform_point2(point_position);
 
 			// This is selecting the manipulator only for now, next to generalize to points
 			if new_selected {
-				let retain_existing_selection = add_to_selection || already_selected;
+				let retain_existing_selection = extend_selection || already_selected;
 				if !retain_existing_selection {
 					self.deselect_all_points();
 				}
@@ -267,8 +269,8 @@ impl ShapeState {
 		None
 	}
 
-	pub fn select_anchor_point_by_id(&mut self, layer: LayerNodeIdentifier, id: PointId, add_to_selection: bool) {
-		if !add_to_selection {
+	pub fn select_anchor_point_by_id(&mut self, layer: LayerNodeIdentifier, id: PointId, extend_selection: bool) {
+		if !extend_selection {
 			self.deselect_all_points();
 		}
 		let point = ManipulatorPointId::Anchor(id);
@@ -1060,6 +1062,71 @@ impl ShapeState {
 			_ => self.sorted_selected_layers(network_interface.document_metadata()).find_map(closest_seg),
 		}
 	}
+	pub fn get_dragging_state(&self, network_interface: &NodeNetworkInterface) -> PointSelectState {
+		for &layer in self.selected_shape_state.keys() {
+			let Some(vector_data) = network_interface.compute_modified_vector(layer) else { continue };
+
+			for point in self.selected_points() {
+				if point.as_anchor().is_some() {
+					return PointSelectState::Anchor;
+				}
+				if point.get_handle_pair(&vector_data).is_some() {
+					return PointSelectState::HandleWithPair;
+				}
+			}
+		}
+		PointSelectState::HandleNoPair
+	}
+
+	/// Returns true if at least one handle with pair is selected
+	pub fn handle_with_pair_selected(&mut self, network_interface: &NodeNetworkInterface) -> bool {
+		for &layer in self.selected_shape_state.keys() {
+			let Some(vector_data) = network_interface.compute_modified_vector(layer) else { continue };
+
+			for point in self.selected_points() {
+				if point.as_anchor().is_some() {
+					return false;
+				}
+				if point.get_handle_pair(&vector_data).is_some() {
+					return true;
+				}
+			}
+		}
+
+		false
+	}
+
+	/// Alternate selected handles to mirrors
+	pub fn alternate_selected_handles(&mut self, network_interface: &NodeNetworkInterface) {
+		let mut handles_to_update = Vec::new();
+
+		for &layer in self.selected_shape_state.keys() {
+			let Some(vector_data) = network_interface.compute_modified_vector(layer) else { continue };
+
+			for point in self.selected_points() {
+				if point.as_anchor().is_some() {
+					continue;
+				}
+				if let Some(handles) = point.get_handle_pair(&vector_data) {
+					// handle[0] is selected, handle[1] is opposite / mirror handle
+					handles_to_update.push((layer, handles[0].to_manipulator_point(), handles[1].to_manipulator_point()));
+				}
+			}
+		}
+
+		for (layer, handle_to_deselect, handle_to_select) in handles_to_update {
+			if let Some(state) = self.selected_shape_state.get_mut(&layer) {
+				let points = &state.selected_points;
+				let both_selected = points.contains(&handle_to_deselect) && points.contains(&handle_to_select);
+				if both_selected {
+					continue;
+				}
+
+				state.deselect_point(handle_to_deselect);
+				state.select_point(handle_to_select);
+			}
+		}
+	}
 
 	/// Selects handles and anchor connected to current handle
 	pub fn select_handles_and_anchor_connected_to_current_handle(&mut self, network_interface: &NodeNetworkInterface) {