From 97616e80199c74faa07fe008d93323f8bbe53a70 Mon Sep 17 00:00:00 2001
From: James Lindsay <78500760+0HyperCube@users.noreply.github.com>
Date: Mon, 8 Jul 2024 01:23:44 +0100
Subject: [PATCH] Fix Pen and Freehand tool path extension (#1809)

Improve path tool extend
---
 .../tool/common_functionality/utility_functions.rs        | 2 +-
 editor/src/messages/tool/tool_messages/freehand_tool.rs   | 8 +++++---
 editor/src/messages/tool/tool_messages/pen_tool.rs        | 8 +++++---
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/editor/src/messages/tool/common_functionality/utility_functions.rs b/editor/src/messages/tool/common_functionality/utility_functions.rs
index 51c1dd8e..dbec0b3d 100644
--- a/editor/src/messages/tool/common_functionality/utility_functions.rs
+++ b/editor/src/messages/tool/common_functionality/utility_functions.rs
@@ -5,7 +5,7 @@ use graphene_std::vector::PointId;
 
 use glam::DVec2;
 
-/// Determines if a path should be extended. Returns the path and if it is extending from the start, if applicable.
+/// Determines if a path should be extended. Goal in viewport space. Returns the path and if it is extending from the start, if applicable.
 pub fn should_extend(document: &DocumentMessageHandler, goal: DVec2, tolerance: f64) -> Option<(LayerNodeIdentifier, PointId, DVec2)> {
 	let mut best = None;
 	let mut best_distance_squared = tolerance * tolerance;
diff --git a/editor/src/messages/tool/tool_messages/freehand_tool.rs b/editor/src/messages/tool/tool_messages/freehand_tool.rs
index c0d72818..b3e44e4e 100644
--- a/editor/src/messages/tool/tool_messages/freehand_tool.rs
+++ b/editor/src/messages/tool/tool_messages/freehand_tool.rs
@@ -175,7 +175,6 @@ impl ToolTransition for FreehandTool {
 
 #[derive(Clone, Debug, Default)]
 struct FreehandToolData {
-	extend_from_start: bool,
 	end_point: Option<(DVec2, PointId)>,
 	dragged: bool,
 	weight: f64,
@@ -208,12 +207,13 @@ impl Fsm for FreehandToolFsmState {
 				responses.add(DocumentMessage::StartTransaction);
 
 				tool_data.dragged = false;
-				tool_data.extend_from_start = false;
+				tool_data.end_point = None;
 				tool_data.weight = tool_options.line_weight;
 
 				// Extend an endpoint of the selected path
-				if let Some((layer, _, position)) = should_extend(document, input.mouse.position, crate::consts::SNAP_POINT_TOLERANCE) {
+				if let Some((layer, point, position)) = should_extend(document, input.mouse.position, crate::consts::SNAP_POINT_TOLERANCE) {
 					tool_data.layer = Some(layer);
+					tool_data.end_point = Some((position, point));
 
 					extend_path_with_next_segment(tool_data, position, responses);
 
@@ -260,6 +260,7 @@ impl Fsm for FreehandToolFsmState {
 					responses.add(DocumentMessage::DocumentHistoryBackward);
 				}
 
+				tool_data.end_point = None;
 				tool_data.layer = None;
 
 				FreehandToolFsmState::Ready
@@ -267,6 +268,7 @@ impl Fsm for FreehandToolFsmState {
 			(FreehandToolFsmState::Drawing, FreehandToolMessage::Abort) => {
 				responses.add(DocumentMessage::AbortTransaction);
 				tool_data.layer = None;
+				tool_data.end_point = None;
 
 				FreehandToolFsmState::Ready
 			}
diff --git a/editor/src/messages/tool/tool_messages/pen_tool.rs b/editor/src/messages/tool/tool_messages/pen_tool.rs
index 9c17ac7d..315ec4a2 100644
--- a/editor/src/messages/tool/tool_messages/pen_tool.rs
+++ b/editor/src/messages/tool/tool_messages/pen_tool.rs
@@ -508,8 +508,12 @@ impl Fsm for PenToolFsmState {
 			(PenToolFsmState::Ready, PenToolMessage::DragStart) => {
 				responses.add(DocumentMessage::StartTransaction);
 
+				let point = SnapCandidatePoint::handle(document.metadata.document_to_viewport.inverse().transform_point2(input.mouse.position));
+				let snapped = tool_data.snap_manager.free_snap(&SnapData::new(document, input), &point, None, false);
+				let viewport = document.metadata.document_to_viewport.transform_point2(snapped.snapped_point_document);
+
 				// Perform extension of an existing path
-				if let Some((layer, point, position)) = should_extend(document, input.mouse.position, crate::consts::SNAP_POINT_TOLERANCE) {
+				if let Some((layer, point, position)) = should_extend(document, viewport, crate::consts::SNAP_POINT_TOLERANCE) {
 					tool_data.add_point(LastPoint {
 						id: point,
 						pos: position,
@@ -535,8 +539,6 @@ impl Fsm for PenToolFsmState {
 					// Generate first point
 					let id = PointId::generate();
 					let transform = document.metadata().transform_to_document(parent);
-					let point = SnapCandidatePoint::handle(document.metadata.document_to_viewport.inverse().transform_point2(input.mouse.position));
-					let snapped = tool_data.snap_manager.free_snap(&SnapData::new(document, input), &point, None, false);
 					let pos = transform.inverse().transform_point2(snapped.snapped_point_document);
 					let modification_type = VectorModificationType::InsertPoint { id, position: pos };
 					responses.add(GraphOperationMessage::Vector { layer, modification_type });