fix to ink rotation to preserve rotation center between rotations.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/client/views/InkingStroke.tsx b/src/client/views/InkingStroke.tsx
index d312331d0..b039579ce 100644
--- a/src/client/views/InkingStroke.tsx
+++ b/src/client/views/InkingStroke.tsx
@@ -21,6 +21,7 @@ import { InkStrokeProperties } from "./InkStrokeProperties";
 import { InkTangentHandles } from "./InkTangentHandles";
 import { FieldView, FieldViewProps } from "./nodes/FieldView";
 import Color = require("color");
+import { Transform } from "../util/Transform";
 
 type InkDocument = makeInterface<[typeof documentSchema]>;
 const InkDocument = makeInterface(documentSchema);
@@ -56,6 +57,22 @@ export class InkingStroke extends ViewBoxBaseComponent<FieldViewProps, InkDocume
         this._selDisposer?.();
     }
 
+    getCenter = (xf: Transform) => {
+        const { inkData, inkScaleX, inkScaleY, inkStrokeWidth, inkTop, inkLeft } = this.inkScaledData();
+        const angle = -NumCast(this.layoutDoc.rotation);
+        const newPoints = inkData.map(pt => {
+            const newX = Math.cos(angle) * pt.X - Math.sin(angle) * pt.Y * inkScaleY / inkScaleX;
+            const newY = Math.sin(angle) * pt.X * inkScaleX / inkScaleY + Math.cos(angle) * pt.Y;
+            return { X: newX, Y: newY };
+        });
+        const crx = (Math.max(...newPoints.map(np => np.X)) + Math.min(...newPoints.map(np => np.X))) / 2;
+        const cry = (Math.max(...newPoints.map(np => np.Y)) + Math.min(...newPoints.map(np => np.Y))) / 2;
+        const cx = Math.cos(-angle) * crx - Math.sin(-angle) * cry * inkScaleY / inkScaleX;
+        const cy = Math.sin(-angle) * crx * inkScaleX / inkScaleY + Math.cos(-angle) * cry;
+        const tc = xf.transformPoint((cx - inkLeft - inkStrokeWidth / 2) * inkScaleX + inkStrokeWidth / 2, (cy - inkTop - inkStrokeWidth / 2) * inkScaleY + inkStrokeWidth / 2);
+        return { X: tc[0], Y: tc[1] };
+    }
+
     analyzeStrokes() {
         const data: InkData = Cast(this.dataDoc[this.fieldKey], InkField)?.inkData ?? [];
         CognitiveServices.Inking.Appliers.ConcatenateHandwriting(this.dataDoc, ["inkAnalysis", "handwriting"], [data]);