Perf: minor drawing speedup (#3464)

Tiny changes as I walk through freehand code. These would only really
make a difference on pages with many freehand shapes.

### Change Type

- [x] `sdk` — Changes the tldraw SDK
- [x] `improvement` — Improving existing features

### Release Notes

- Improve performance of draw shapes.

packages/tldraw/src/lib/shapes/draw/toolStates/Drawing.ts

@@ -97,7 +97,7 @@ export class Drawing extends StateNode {
 				this.mergeNextPoint = false
 			}
 
-			this.updateShapes()
+			this.updateDrawingShape()
 		}
 	}
 
@@ -115,7 +115,7 @@ export class Drawing extends StateNode {
 				}
 			}
 		}
-		this.updateShapes()
+		this.updateDrawingShape()
 	}
 
 	override onKeyUp: TLEventHandlers['onKeyUp'] = (info) => {
@@ -137,7 +137,7 @@ export class Drawing extends StateNode {
 			}
 		}
 
-		this.updateShapes()
+		this.updateDrawingShape()
 	}
 
 	override onExit? = () => {
@@ -281,7 +281,7 @@ export class Drawing extends StateNode {
 		this.initialShape = this.editor.getShape<DrawableShape>(id)
 	}
 
-	private updateShapes() {
+	private updateDrawingShape() {
 		const { initialShape } = this
 		const { inputs } = this.editor
 

packages/tldraw/src/lib/shapes/shared/freehand/svgInk.ts

@@ -1,12 +1,4 @@
-import {
-	Vec,
-	VecLike,
-	assert,
-	average,
-	precise,
-	shortAngleDist,
-	toDomPrecision,
-} from '@tldraw/editor'
+import { Vec, VecLike, assert, average, precise, toDomPrecision } from '@tldraw/editor'
 import { getStrokeOutlineTracks } from './getStrokeOutlinePoints'
 import { getStrokePoints } from './getStrokePoints'
 import { setStrokePointRadii } from './setStrokePointRadii'
@@ -36,17 +28,20 @@ function partitionAtElbows(points: StrokePoint[]): StrokePoint[][] {
 
 	const result: StrokePoint[][] = []
 	let currentPartition: StrokePoint[] = [points[0]]
-	for (let i = 1; i < points.length - 1; i++) {
-		const prevPoint = points[i - 1]
-		const thisPoint = points[i]
-		const nextPoint = points[i + 1]
-		const prevAngle = Vec.Angle(prevPoint.point, thisPoint.point)
-		const nextAngle = Vec.Angle(thisPoint.point, nextPoint.point)
-		// acuteness is a normalized representation of how acute the angle is.
-		// 1 is an infinitely thin wedge
-		// 0 is a straight line
-		const acuteness = Math.abs(shortAngleDist(prevAngle, nextAngle)) / Math.PI
-		if (acuteness > 0.8) {
+	let prevV = Vec.Sub(points[1].point, points[0].point).uni()
+	let nextV: Vec
+	let dpr: number
+	let prevPoint: StrokePoint, thisPoint: StrokePoint, nextPoint: StrokePoint
+	for (let i = 1, n = points.length; i < n - 1; i++) {
+		prevPoint = points[i - 1]
+		thisPoint = points[i]
+		nextPoint = points[i + 1]
+
+		nextV = Vec.Sub(nextPoint.point, thisPoint.point).uni()
+		dpr = Vec.Dpr(prevV, nextV)
+		prevV = nextV
+
+		if (dpr < -0.8) {
 			// always treat such acute angles as elbows
 			// and use the extended .input point as the elbow point for swooshiness in fast zaggy lines
 			const elbowPoint = {
@@ -59,19 +54,20 @@ function partitionAtElbows(points: StrokePoint[]): StrokePoint[][] {
 			continue
 		}
 		currentPartition.push(thisPoint)
-		if (acuteness < 0.25) {
-			// this is not an elbow, bail out
+
+		if (dpr > 0.7) {
+			// Not an elbow
 			continue
 		}
+
 		// so now we have a reasonably acute angle but it might not be an elbow if it's far
-		// away from it's neighbors
-		const avgRadius = (prevPoint.radius + thisPoint.radius + nextPoint.radius) / 3
-		const incomingNormalizedDist = Vec.Dist(prevPoint.point, thisPoint.point) / avgRadius
-		const outgoingNormalizedDist = Vec.Dist(thisPoint.point, nextPoint.point) / avgRadius
-		// angular dist is a normalized representation of how far away the point is from it's neighbors
+		// away from it's neighbors, angular dist is a normalized representation of how far away the point is from it's neighbors
 		// (normalized by the radius)
-		const angularDist = incomingNormalizedDist + outgoingNormalizedDist
-		if (angularDist < 1.5) {
+		if (
+			(Vec.Dist2(prevPoint.point, thisPoint.point) + Vec.Dist2(thisPoint.point, nextPoint.point)) /
+				((prevPoint.radius + thisPoint.radius + nextPoint.radius) / 3) ** 2 <
+			1.5
+		) {
 			// if this point is kinda close to its neighbors and it has a reasonably
 			// acute angle, it's probably a hard elbow
 			currentPartition.push(thisPoint)
@@ -89,11 +85,13 @@ function partitionAtElbows(points: StrokePoint[]): StrokePoint[][] {
 function cleanUpPartition(partition: StrokePoint[]) {
 	// clean up start of partition (remove points that are too close to the start)
 	const startPoint = partition[0]
+	let nextPoint: StrokePoint
 	while (partition.length > 2) {
-		const nextPoint = partition[1]
-		const dist = Vec.Dist(startPoint.point, nextPoint.point)
-		const avgRadius = (startPoint.radius + nextPoint.radius) / 2
-		if (dist < avgRadius * 0.5) {
+		nextPoint = partition[1]
+		if (
+			Vec.Dist2(startPoint.point, nextPoint.point) <
+			(((startPoint.radius + nextPoint.radius) / 2) * 0.5) ** 2
+		) {
 			partition.splice(1, 1)
 		} else {
 			break
@@ -101,11 +99,13 @@ function cleanUpPartition(partition: StrokePoint[]) {
 	}
 	// clean up end of partition in the same fashion
 	const endPoint = partition[partition.length - 1]
+	let prevPoint: StrokePoint
 	while (partition.length > 2) {
-		const prevPoint = partition[partition.length - 2]
-		const dist = Vec.Dist(endPoint.point, prevPoint.point)
-		const avgRadius = (endPoint.radius + prevPoint.radius) / 2
-		if (dist < avgRadius * 0.5) {
+		prevPoint = partition[partition.length - 2]
+		if (
+			Vec.Dist2(endPoint.point, prevPoint.point) <
+			(((endPoint.radius + prevPoint.radius) / 2) * 0.5) ** 2
+		) {
 			partition.splice(partition.length - 2, 1)
 		} else {
 			break
@@ -115,13 +115,14 @@ function cleanUpPartition(partition: StrokePoint[]) {
 	if (partition.length > 1) {
 		partition[0] = {
 			...partition[0],
-			vector: Vec.FromAngle(Vec.Angle(partition[1].point, partition[0].point)),
+			vector: Vec.Sub(partition[0].point, partition[1].point).uni(),
 		}
 		partition[partition.length - 1] = {
 			...partition[partition.length - 1],
-			vector: Vec.FromAngle(
-				Vec.Angle(partition[partition.length - 1].point, partition[partition.length - 2].point)
-			),
+			vector: Vec.Sub(
+				partition[partition.length - 2].point,
+				partition[partition.length - 1].point
+			).uni(),
 		}
 	}
 	return partition

packages/tldraw/src/test/drawing.test.ts

@@ -1,5 +1,6 @@
 import { TLDrawShape, TLHighlightShape, last } from '@tldraw/editor'
 import { TestEditor } from './TestEditor'
+import { TEST_DRAW_SHAPE_SCREEN_POINTS } from './drawing.data'
 
 jest.useFakeTimers()
 
@@ -260,3 +261,22 @@ for (const toolType of ['draw', 'highlight'] as const) {
 		})
 	})
 }
+
+it('Draws a bunch', () => {
+	editor.setCurrentTool('draw').setCamera({ x: 0, y: 0, z: 1 })
+
+	const [first, ...rest] = TEST_DRAW_SHAPE_SCREEN_POINTS
+	editor.pointerMove(first.x, first.y).pointerDown()
+
+	for (const point of rest) {
+		editor.pointerMove(point.x, point.y)
+	}
+
+	editor.pointerUp()
+	editor.selectAll()
+
+	const shape = { ...editor.getLastCreatedShape() }
+	// @ts-expect-error
+	delete shape.id
+	expect(shape).toMatchSnapshot('draw shape')
+})

packages/utils/src/lib/perf.ts

@@ -34,15 +34,17 @@ export function measureAverageDuration(
 		const start = performance.now()
 		const result = originalMethod.apply(this, args)
 		const end = performance.now()
-		const value = averages.get(descriptor.value)!
 		const length = end - start
-		const total = value.total + length
-		const count = value.count + 1
-		averages.set(descriptor.value, { total, count })
-		// eslint-disable-next-line no-console
-		console.log(
-			`${propertyKey} took ${(end - start).toFixed(2)}ms | average ${(total / count).toFixed(2)}ms`
-		)
+		if (length !== 0) {
+			const value = averages.get(descriptor.value)!
+			const total = value.total + length
+			const count = value.count + 1
+			averages.set(descriptor.value, { total, count })
+			// eslint-disable-next-line no-console
+			console.log(
+				`${propertyKey} took ${(end - start).toFixed(2)}ms | average ${(total / count).toFixed(2)}ms`
+			)
+		}
 		return result
 	}
 	averages.set(descriptor.value, { total: 0, count: 0 })