Add Path tool support for Ctrl-dragging to pull out zero-length handles with angle locking (#2620)

* implement check-drag and angle-lock

* track bool

* flip-smooth-sharp

* fixed bugs

* fixed flip-smooth jump bug and random angle locking bug

* ctrl-alt 90 case

* aligned flip-smooth sharp and fixed arbitrary handle-length when flipped

* code-review change

* 0.5 instead of 0.8

---------

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

Author: 0SlowPoke0

editor/src/consts.rs

@@ -102,6 +102,7 @@ pub const HIDE_HANDLE_DISTANCE: f64 = 3.;
 pub const HANDLE_ROTATE_SNAP_ANGLE: f64 = 15.;
 pub const SEGMENT_INSERTION_DISTANCE: f64 = 7.5;
 pub const SEGMENT_OVERLAY_SIZE: f64 = 10.;
+pub const HANDLE_LENGTH_FACTOR: f64 = 0.5;
 
 // PEN TOOL
 pub const CREATE_CURVE_THRESHOLD: f64 = 5.;

editor/src/messages/input_mapper/input_mappings.rs

@@ -212,7 +212,7 @@ pub fn input_mappings() -> Mapping {
 		entry!(KeyDown(Delete); modifiers=[Shift], action_dispatch=PathToolMessage::BreakPath),
 		entry!(KeyDown(Backspace); modifiers=[Shift], action_dispatch=PathToolMessage::BreakPath),
 		entry!(KeyDownNoRepeat(Tab); action_dispatch=PathToolMessage::SwapSelectedHandles),
-		entry!(KeyDown(MouseLeft); action_dispatch=PathToolMessage::MouseDown { extend_selection: Shift, lasso_select: Control, handle_drag_from_anchor: Alt }),
+		entry!(KeyDown(MouseLeft); action_dispatch=PathToolMessage::MouseDown { extend_selection: Shift, lasso_select: Control, handle_drag_from_anchor: Alt, drag_restore_handle: Control }),
 		entry!(KeyDown(MouseRight); action_dispatch=PathToolMessage::RightClick),
 		entry!(KeyDown(Escape); action_dispatch=PathToolMessage::Escape),
 		entry!(KeyDown(KeyG); action_dispatch=PathToolMessage::GRS { key: KeyG }),

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

@@ -1,5 +1,7 @@
 use super::graph_modification_utils::{self, merge_layers};
 use super::snapping::{SnapCache, SnapCandidatePoint, SnapData, SnapManager, SnappedPoint};
+use super::utility_functions::calculate_segment_angle;
+use crate::consts::HANDLE_LENGTH_FACTOR;
 use crate::messages::portfolio::document::utility_types::document_metadata::{DocumentMetadata, LayerNodeIdentifier};
 use crate::messages::portfolio::document::utility_types::misc::{PathSnapSource, SnapSource};
 use crate::messages::portfolio::document::utility_types::network_interface::NodeNetworkInterface;
@@ -728,23 +730,33 @@ impl ShapeState {
 			return;
 		};
 		let handles = vector_data.all_connected(point_id).take(2).collect::<Vec<_>>();
+		let non_zero_handles = handles.iter().filter(|handle| handle.length(vector_data) > 1e-6).count();
+		let handle_segments = handles.iter().map(|handles| handles.segment).collect::<Vec<_>>();
 
 		// Grab the next and previous manipulator groups by simply looking at the next / previous index
 		let points = handles.iter().map(|handle| vector_data.other_point(handle.segment, point_id));
 		let anchor_positions = points
 			.map(|point| point.and_then(|point| ManipulatorPointId::Anchor(point).get_position(vector_data)))
 			.collect::<Vec<_>>();
 
-		// Use the position relative to the anchor
-		let mut directions = anchor_positions
-			.iter()
-			.map(|position| position.map(|position| (position - anchor_position)).and_then(DVec2::try_normalize));
+		let mut segment_angle = 0.;
+		let mut segment_count = 0.;
+
+		for segment in &handle_segments {
+			let Some(angle) = calculate_segment_angle(point_id, *segment, vector_data, false) else {
+				continue;
+			};
+			segment_angle += angle;
+			segment_count += 1.;
+		}
 
-		// The direction of the handles is either the perpendicular vector to the sum of the anchors' positions or just the anchor's position (if only one)
-		let mut handle_direction = match (directions.next().flatten(), directions.next().flatten()) {
-			(Some(previous), Some(next)) => (previous - next).try_normalize().unwrap_or(next.perp()),
-			(Some(val), None) | (None, Some(val)) => val,
-			(None, None) => return,
+		// For a non-endpoint anchor, handles are perpendicular to the average tangent of adjacent segments.(Refer:https://github.com/GraphiteEditor/Graphite/pull/2620#issuecomment-2881501494)
+		let mut handle_direction = if segment_count > 1. {
+			segment_angle = segment_angle / segment_count;
+			segment_angle += std::f64::consts::FRAC_PI_2;
+			DVec2::new(segment_angle.cos(), segment_angle.sin())
+		} else {
+			DVec2::new(segment_angle.cos(), segment_angle.sin())
 		};
 
 		// Set the manipulator to have colinear handles
@@ -762,20 +774,41 @@ impl ShapeState {
 			handle_direction *= -1.;
 		}
 
-		// Push both in and out handles into the correct position
-		for ((handle, sign), other_anchor) in handles.iter().zip([1., -1.]).zip(&anchor_positions) {
-			// To find the length of the new tangent we just take the distance to the anchor and divide by 3 (pretty arbitrary)
-			let Some(length) = other_anchor.map(|position| (position - anchor_position).length() / 3.) else {
-				continue;
+		if non_zero_handles != 0 {
+			let [a, b] = handles.as_slice() else { return };
+			let (non_zero_handle, zero_handle) = if a.length(vector_data) > 1e-6 { (a, b) } else { (b, a) };
+			let Some(direction) = non_zero_handle
+				.to_manipulator_point()
+				.get_position(&vector_data)
+				.and_then(|position| (position - anchor_position).try_normalize())
+			else {
+				return;
 			};
-			let new_position = handle_direction * length * sign;
-			let modification_type = handle.set_relative_position(new_position);
+			let new_position = -direction * non_zero_handle.length(vector_data);
+			let modification_type = zero_handle.set_relative_position(new_position);
 			responses.add(GraphOperationMessage::Vector { layer, modification_type });
+		} else {
+			// Push both in and out handles into the correct position
+			for ((handle, sign), other_anchor) in handles.iter().zip([1., -1.]).zip(&anchor_positions) {
+				let Some(anchor_vector) = other_anchor.map(|position| (position - anchor_position)) else {
+					continue;
+				};
+
+				let Some(unit_vector) = anchor_vector.try_normalize() else {
+					continue;
+				};
 
-			// Create the opposite handle if it doesn't exist (if it is not a cubic segment)
-			if handle.opposite().to_manipulator_point().get_position(vector_data).is_none() {
-				let modification_type = handle.opposite().set_relative_position(DVec2::ZERO);
+				let projection = anchor_vector.length() * HANDLE_LENGTH_FACTOR * handle_direction.dot(unit_vector).abs();
+
+				let new_position = handle_direction * projection * sign;
+				let modification_type = handle.set_relative_position(new_position);
 				responses.add(GraphOperationMessage::Vector { layer, modification_type });
+
+				// Create the opposite handle if it doesn't exist (if it is not a cubic segment)
+				if handle.opposite().to_manipulator_point().get_position(vector_data).is_none() {
+					let modification_type = handle.opposite().set_relative_position(DVec2::ZERO);
+					responses.add(GraphOperationMessage::Vector { layer, modification_type });
+				}
 			}
 		}
 	}
@@ -1503,13 +1536,13 @@ impl ShapeState {
 
 			let (id, anchor) = result?;
 			let handles = vector_data.all_connected(id);
-			let mut positions = handles
+			let positions = handles
 				.filter_map(|handle| handle.to_manipulator_point().get_position(&vector_data))
-				.filter(|&handle| !anchor.abs_diff_eq(handle, 1e-5));
+				.filter(|&handle| anchor.abs_diff_eq(handle, 1e-5))
+				.count();
 
 			// Check by comparing the handle positions to the anchor if this manipulator group is a point
-			let already_sharp = positions.next().is_none();
-			if already_sharp {
+			if positions != 0 {
 				self.convert_manipulator_handles_to_colinear(&vector_data, id, responses, layer);
 			} else {
 				for handle in vector_data.all_connected(id) {

editor/src/messages/tool/tool_messages/path_tool.rs

@@ -67,6 +67,7 @@ pub enum PathToolMessage {
 		extend_selection: Key,
 		lasso_select: Key,
 		handle_drag_from_anchor: Key,
+		drag_restore_handle: Key,
 	},
 	NudgeSelectedPoints {
 		delta_x: f64,
@@ -362,7 +363,6 @@ struct PathToolData {
 	saved_points_before_handle_drag: Vec<ManipulatorPointId>,
 	handle_drag_toggle: bool,
 	dragging_state: DraggingState,
-	current_selected_handle_id: Option<ManipulatorPointId>,
 	angle: f64,
 	opposite_handle_position: Option<DVec2>,
 	last_clicked_point_was_selected: bool,
@@ -438,6 +438,7 @@ impl PathToolData {
 		extend_selection: bool,
 		lasso_select: bool,
 		handle_drag_from_anchor: bool,
+		drag_zero_handle: bool,
 	) -> PathToolFsmState {
 		self.double_click_handled = false;
 		self.opposing_handle_lengths = None;
@@ -500,6 +501,24 @@ impl PathToolData {
 					}
 				}
 
+				if let Some((Some(point), Some(vector_data))) = shape_editor
+					.find_nearest_point_indices(&document.network_interface, input.mouse.position, SELECTION_THRESHOLD)
+					.and_then(|(layer, point)| Some((point.as_anchor(), document.network_interface.compute_modified_vector(layer))))
+				{
+					let handles = vector_data
+						.all_connected(point)
+						.filter(|handle| handle.length(&vector_data) < 1e-6)
+						.map(|handle| handle.to_manipulator_point())
+						.collect::<Vec<_>>();
+					let endpoint = vector_data.extendable_points(false).any(|anchor| point == anchor);
+
+					if drag_zero_handle && (handles.len() == 1 && !endpoint) {
+						shape_editor.deselect_all_points();
+						shape_editor.select_points_by_manipulator_id(&handles);
+						shape_editor.convert_selected_manipulators_to_colinear_handles(responses, document);
+					}
+				}
+
 				self.start_dragging_point(selected_points, input, document, shape_editor);
 				responses.add(OverlaysMessage::Draw);
 			}
@@ -689,6 +708,7 @@ impl PathToolData {
 		handle_id: ManipulatorPointId,
 		lock_angle: bool,
 		snap_angle: bool,
+		tangent_to_neighboring_tangents: bool,
 	) -> f64 {
 		let current_angle = -handle_vector.angle_to(DVec2::X);
 
@@ -699,17 +719,22 @@ impl PathToolData {
 			.and_then(|(layer, _)| document.network_interface.compute_modified_vector(*layer))
 		{
 			if relative_vector.length() < 25. && lock_angle && !self.angle_locked {
-				if let Some(angle) = calculate_lock_angle(self, shape_editor, responses, document, &vector_data, handle_id) {
+				if let Some(angle) = calculate_lock_angle(self, shape_editor, responses, document, &vector_data, handle_id, tangent_to_neighboring_tangents) {
 					self.angle = angle;
+					self.angle_locked = true;
 					return angle;
 				}
 			}
 		}
 
-		// When the angle is locked we use the old angle
-
-		if self.current_selected_handle_id == Some(handle_id) && lock_angle {
+		if lock_angle && !self.angle_locked {
 			self.angle_locked = true;
+			self.angle = -relative_vector.angle_to(DVec2::X);
+			return -relative_vector.angle_to(DVec2::X);
+		}
+
+		// When the angle is locked we use the old angle
+		if self.angle_locked {
 			return self.angle;
 		}
 
@@ -720,8 +745,6 @@ impl PathToolData {
 			handle_angle = (handle_angle / snap_resolution).round() * snap_resolution;
 		}
 
-		// Cache the angle and handle id for lock angle
-		self.current_selected_handle_id = Some(handle_id);
 		self.angle = handle_angle;
 
 		handle_angle
@@ -747,6 +770,7 @@ impl PathToolData {
 					origin: anchor_position,
 					direction: handle_direction.normalize_or_zero(),
 				};
+
 				self.snap_manager.constrained_snap(&snap_data, &snap_point, snap_constraint, Default::default())
 			}
 			false => self.snap_manager.free_snap(&snap_data, &snap_point, Default::default()),
@@ -850,7 +874,17 @@ impl PathToolData {
 		let snapped_delta = if let Some((handle_pos, anchor_pos, handle_id)) = self.try_get_selected_handle_and_anchor(shape_editor, document) {
 			let cursor_pos = handle_pos + raw_delta;
 
-			let handle_angle = self.calculate_handle_angle(shape_editor, document, responses, handle_pos - anchor_pos, cursor_pos - anchor_pos, handle_id, lock_angle, snap_angle);
+			let handle_angle = self.calculate_handle_angle(
+				shape_editor,
+				document,
+				responses,
+				handle_pos - anchor_pos,
+				cursor_pos - anchor_pos,
+				handle_id,
+				lock_angle,
+				snap_angle,
+				equidistant,
+			);
 
 			let constrained_direction = DVec2::new(handle_angle.cos(), handle_angle.sin());
 			let projected_length = (cursor_pos - anchor_pos).dot(constrained_direction);
@@ -1109,17 +1143,18 @@ impl Fsm for PathToolFsmState {
 					extend_selection,
 					lasso_select,
 					handle_drag_from_anchor,
-					..
+					drag_restore_handle,
 				},
 			) => {
 				let extend_selection = input.keyboard.get(extend_selection as usize);
 				let lasso_select = input.keyboard.get(lasso_select as usize);
 				let handle_drag_from_anchor = input.keyboard.get(handle_drag_from_anchor as usize);
+				let drag_zero_handle = input.keyboard.get(drag_restore_handle as usize);
 
 				tool_data.selection_mode = None;
 				tool_data.lasso_polygon.clear();
 
-				tool_data.mouse_down(shape_editor, document, input, responses, extend_selection, lasso_select, handle_drag_from_anchor)
+				tool_data.mouse_down(shape_editor, document, input, responses, extend_selection, lasso_select, handle_drag_from_anchor, drag_zero_handle)
 			}
 			(
 				PathToolFsmState::Drawing { selection_shape },
@@ -1375,6 +1410,7 @@ impl Fsm for PathToolFsmState {
 					tool_data.saved_points_before_handle_drag.clear();
 					tool_data.handle_drag_toggle = false;
 				}
+				tool_data.angle_locked = false;
 				responses.add(DocumentMessage::AbortTransaction);
 				tool_data.snap_manager.cleanup(responses);
 				PathToolFsmState::Ready
@@ -1443,6 +1479,7 @@ impl Fsm for PathToolFsmState {
 
 				tool_data.alt_dragging_from_anchor = false;
 				tool_data.alt_clicked_on_anchor = false;
+				tool_data.angle_locked = false;
 
 				if tool_data.select_anchor_toggled {
 					shape_editor.deselect_all_points();
@@ -1775,6 +1812,7 @@ fn calculate_lock_angle(
 	document: &DocumentMessageHandler,
 	vector_data: &VectorData,
 	handle_id: ManipulatorPointId,
+	tangent_to_neighboring_tangents: bool,
 ) -> Option<f64> {
 	let anchor = handle_id.get_anchor(vector_data)?;
 	let anchor_position = vector_data.point_domain.position_from_id(anchor);
@@ -1808,7 +1846,14 @@ fn calculate_lock_angle(
 			let angle_2 = calculate_segment_angle(anchor, segment, vector_data, false);
 
 			match (angle_1, angle_2) {
-				(Some(angle_1), Some(angle_2)) => Some((angle_1 + angle_2) / 2.0),
+				(Some(angle_1), Some(angle_2)) => {
+					let angle = Some((angle_1 + angle_2) / 2.);
+					if tangent_to_neighboring_tangents {
+						angle.map(|angle| angle + std::f64::consts::FRAC_PI_2)
+					} else {
+						angle
+					}
+				}
 				(Some(angle_1), None) => Some(angle_1),
 				(None, Some(angle_2)) => Some(angle_2),
 				(None, None) => None,