remove selectionPageCenter (#1766)

This PR removes `Editor.selectionPageCenter` and moves its
implementation inline where used (in two places).

### Change Type

- [x] `major` — Breaking change

### Release Notes

- [dev] Removes `Editor.selectionPageCenter`

packages/editor/api-report.md

@@ -913,7 +913,6 @@ export class Editor extends EventEmitter<TLEventMap> {
     get selectedShapes(): TLShape[];
     get selectionBounds(): Box2d | undefined;
     get selectionPageBounds(): Box2d | null;
-    get selectionPageCenter(): null | Vec2d;
     get selectionRotation(): number;
     selectNone(): this;
     sendBackward(shapes: TLShape[]): this;

packages/editor/src/lib/editor/Editor.ts

@@ -1657,18 +1657,6 @@ export class Editor extends EventEmitter<TLEventMap> {
 		return box
 	}
 
-	/**
-	 * The center of the selection bounding box.
-	 *
-	 * @readonly
-	 * @public
-	 */
-	@computed get selectionPageCenter() {
-		const { selectionBounds, selectionRotation } = this
-		if (!selectionBounds) return null
-		return Vec2d.RotWith(selectionBounds.center, selectionBounds.point, selectionRotation)
-	}
-
 	// Focus Layer Id
 
 	/**

packages/editor/src/lib/utils/rotation.ts

@@ -9,7 +9,7 @@ import { Vec2d } from '../primitives/Vec2d'
 export function getRotationSnapshot({ editor }: { editor: Editor }): TLRotationSnapshot | null {
 	const {
 		selectionRotation,
-		selectionPageCenter,
+		selectionBounds,
 		inputs: { originPagePoint },
 		selectedShapes,
 	} = editor
@@ -19,10 +19,14 @@ export function getRotationSnapshot({ editor }: { editor: Editor }): TLRotationS
 	// will produce the wrong results
 
 	// Return null if there are no selected shapes
-	if (!selectionPageCenter) {
+	if (!selectionBounds) {
 		return null
 	}
 
+	const selectionPageCenter = selectionBounds.center
+		.clone()
+		.rotWith(selectionBounds.point, selectionRotation)
+
 	return {
 		selectionPageCenter: selectionPageCenter,
 		initialCursorAngle: selectionPageCenter.angle(originPagePoint),

packages/tldraw/src/lib/tools/SelectTool/children/Rotating.ts

@@ -139,13 +139,19 @@ export class Rotating extends StateNode {
 
 	_getRotationFromPointerPosition({ snapToNearestDegree }: { snapToNearestDegree: boolean }) {
 		const {
-			selectionPageCenter,
+			selectionBounds,
+			selectionRotation,
 			inputs: { shiftKey, currentPagePoint },
 		} = this.editor
 		const { initialCursorAngle, initialSelectionRotation } = this.snapshot
 
+		if (!selectionBounds) return initialSelectionRotation
+
+		const selectionPageCenter = selectionBounds.center
+			.clone()
+			.rotWith(selectionBounds.point, selectionRotation)
+
 		// The delta is the difference between the current angle and the initial angle
-		if (!selectionPageCenter) return initialSelectionRotation
 		const preSnapRotationDelta = selectionPageCenter.angle(currentPagePoint) - initialCursorAngle
 		let newSelectionRotation = initialSelectionRotation + preSnapRotationDelta
 

packages/tldraw/src/test/TestEditor.ts

@@ -493,6 +493,18 @@ export class TestEditor extends Editor {
 		return this
 	}
 
+	/**
+	 * The center of the selection bounding box.
+	 *
+	 * @readonly
+	 * @public
+	 */
+	get selectionPageCenter() {
+		const { selectionBounds, selectionRotation } = this
+		if (!selectionBounds) return null
+		return Vec2d.RotWith(selectionBounds.center, selectionBounds.point, selectionRotation)
+	}
+
 	translateSelection(dx: number, dy: number, options?: Partial<TLPointerEventInfo>) {
 		if (this.selectedShapeIds.length === 0) {
 			throw new Error('No selection')

packages/tldraw/src/test/commands/rotateShapes.test.ts

@@ -77,6 +77,6 @@ describe('editor.rotateShapes', () => {
 			.expectShapeToMatch({ id: ids.box2, rotation: Math.PI })
 
 		// Are the centers the same?
-		expect(selectionPageCenter).toMatchObject(editor.selectionPageCenter!)
+		expect(selectionPageCenter).toCloselyMatchObject(editor.selectionPageCenter!)
 	})
 })