PointerTracker refactor. (#2931)

## Description

Fixing #2929 required adding additional information to `TrackerElement`. If we were to leave current structure of `PointerTracker`, we would have to add few more methods. After refactoring, there are only 2 that were not present before:

- `getLastViewRelativeCoords`
- `getViewRelativeCoordsSum`

I'd like to make similar changes to our handlers in the future (i.e. use `coords` object instead of `lastX` and `lastY` variables).

## Test plan

Tested on example app.

Author: m-bert

src/web/detectors/RotationGestureDetector.ts

@@ -39,16 +39,14 @@ export default class RotationGestureDetector
 
     const [firstPointerID, secondPointerID] = this.keyPointers;
 
-    const firstPointerX: number = tracker.getLastX(firstPointerID);
-    const firstPointerY: number = tracker.getLastY(firstPointerID);
-    const secondPointerX: number = tracker.getLastX(secondPointerID);
-    const secondPointerY: number = tracker.getLastY(secondPointerID);
+    const firstPointerCoords = tracker.getLastAbsoluteCoords(firstPointerID);
+    const secondPointerCoords = tracker.getLastAbsoluteCoords(secondPointerID);
 
-    const vectorX: number = secondPointerX - firstPointerX;
-    const vectorY: number = secondPointerY - firstPointerY;
+    const vectorX: number = secondPointerCoords.x - firstPointerCoords.x;
+    const vectorY: number = secondPointerCoords.y - firstPointerCoords.y;
 
-    this.anchorX = (firstPointerX + secondPointerX) / 2;
-    this.anchorY = (firstPointerY + secondPointerY) / 2;
+    this.anchorX = (firstPointerCoords.x + secondPointerCoords.x) / 2;
+    this.anchorY = (firstPointerCoords.y + secondPointerCoords.y) / 2;
 
     //Angle diff should be positive when rotating in clockwise direction
     const angle: number = -Math.atan2(vectorY, vectorX);

src/web/detectors/ScaleGestureDetector.ts

@@ -76,11 +76,10 @@ export default class ScaleGestureDetector implements ScaleGestureListener {
 
     const div: number = pointerUp ? numOfPointers - 1 : numOfPointers;
 
-    const sumX = tracker.getSumX(ignoredPointer);
-    const sumY = tracker.getSumY(ignoredPointer);
+    const coordsSum = tracker.getAbsoluteCoordsSum();
 
-    const focusX = sumX / div;
-    const focusY = sumY / div;
+    const focusX = coordsSum.x / div;
+    const focusY = coordsSum.y / div;
 
     //Determine average deviation from focal point
 
@@ -92,8 +91,8 @@ export default class ScaleGestureDetector implements ScaleGestureListener {
         return;
       }
 
-      devSumX += Math.abs(value.lastX - focusX);
-      devSumY += Math.abs(value.lastY - focusY);
+      devSumX += Math.abs(value.abosoluteCoords.x - focusX);
+      devSumY += Math.abs(value.abosoluteCoords.y - focusY);
     });
 
     const devX: number = devSumX / div;

src/web/handlers/GestureHandler.ts

@@ -405,10 +405,9 @@ export default abstract class GestureHandler implements IGestureHandler {
       nativeEvent: {
         numberOfPointers: this.tracker.getTrackedPointersCount(),
         state: newState,
-        pointerInside: this.delegate.isPointerInBounds({
-          x: this.tracker.getLastAvgX(),
-          y: this.tracker.getLastAvgY(),
-        }),
+        pointerInside: this.delegate.isPointerInBounds(
+          this.tracker.getAbsoluteCoordsAverage()
+        ),
         ...this.transformNativeEvent(),
         handlerTag: this.handlerTag,
         target: this.viewRef,
@@ -442,10 +441,10 @@ export default abstract class GestureHandler implements IGestureHandler {
 
       all.push({
         id: id,
-        x: element.lastX - rect.pageX,
-        y: element.lastY - rect.pageY,
-        absoluteX: element.lastX,
-        absoluteY: element.lastY,
+        x: element.abosoluteCoords.x - rect.pageX,
+        y: element.abosoluteCoords.y - rect.pageY,
+        absoluteX: element.abosoluteCoords.x,
+        absoluteY: element.abosoluteCoords.y,
       });
     });
 
@@ -465,10 +464,10 @@ export default abstract class GestureHandler implements IGestureHandler {
 
         changed.push({
           id: id,
-          x: element.lastX - rect.pageX,
-          y: element.lastY - rect.pageY,
-          absoluteX: element.lastX,
-          absoluteY: element.lastY,
+          x: element.abosoluteCoords.x - rect.pageX,
+          y: element.abosoluteCoords.y - rect.pageY,
+          absoluteX: element.abosoluteCoords.x,
+          absoluteY: element.abosoluteCoords.y,
         });
       });
     }
@@ -534,18 +533,18 @@ export default abstract class GestureHandler implements IGestureHandler {
 
       all.push({
         id: id,
-        x: element.lastX - rect.pageX,
-        y: element.lastY - rect.pageY,
-        absoluteX: element.lastX,
-        absoluteY: element.lastY,
+        x: element.abosoluteCoords.x - rect.pageX,
+        y: element.abosoluteCoords.y - rect.pageY,
+        absoluteX: element.abosoluteCoords.x,
+        absoluteY: element.abosoluteCoords.y,
       });
 
       changed.push({
         id: id,
-        x: element.lastX - rect.pageX,
-        y: element.lastY - rect.pageY,
-        absoluteX: element.lastX,
-        absoluteY: element.lastY,
+        x: element.abosoluteCoords.x - rect.pageX,
+        y: element.abosoluteCoords.y - rect.pageY,
+        absoluteX: element.abosoluteCoords.x,
+        absoluteY: element.abosoluteCoords.y,
       });
     });
 
@@ -570,12 +569,13 @@ export default abstract class GestureHandler implements IGestureHandler {
   protected transformNativeEvent(): Record<string, unknown> {
     // those properties are shared by most handlers and if not this method will be overriden
     const rect = this.delegate.measureView();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
 
     return {
-      x: this.tracker.getLastAvgX() - rect.pageX,
-      y: this.tracker.getLastAvgY() - rect.pageY,
-      absoluteX: this.tracker.getLastAvgX(),
-      absoluteY: this.tracker.getLastAvgY(),
+      x: lastCoords.x - rect.pageX,
+      y: lastCoords.y - rect.pageY,
+      absoluteX: lastCoords.x,
+      absoluteY: lastCoords.y,
     };
   }
 
@@ -720,8 +720,9 @@ export default abstract class GestureHandler implements IGestureHandler {
     }
 
     const rect = this.delegate.measureView();
-    const offsetX: number = this.tracker.getLastX() - rect.pageX;
-    const offsetY: number = this.tracker.getLastY() - rect.pageY;
+    const { x, y } = this.tracker.getLastAbsoluteCoords();
+    const offsetX: number = x - rect.pageX;
+    const offsetY: number = y - rect.pageY;
 
     if (
       offsetX >= left &&

src/web/handlers/NativeViewGestureHandler.ts

@@ -64,8 +64,9 @@ export default class NativeViewGestureHandler extends GestureHandler {
   }
 
   private newPointerAction(): void {
-    this.startX = this.tracker.getLastAvgX();
-    this.startY = this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.startX = lastCoords.x;
+    this.startY = lastCoords.y;
 
     if (this.currentState !== State.UNDETERMINED) {
       return;
@@ -80,8 +81,9 @@ export default class NativeViewGestureHandler extends GestureHandler {
   protected onPointerMove(event: AdaptedEvent): void {
     this.tracker.track(event);
 
-    const dx = this.startX - this.tracker.getLastAvgX();
-    const dy = this.startY - this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    const dx = this.startX - lastCoords.x;
+    const dy = this.startY - lastCoords.y;
     const distSq = dx * dx + dy * dy;
 
     if (distSq >= this.minDistSq) {

src/web/handlers/PanGestureHandler.ts

@@ -219,8 +219,9 @@ export default class PanGestureHandler extends GestureHandler {
     this.tracker.addToTracker(event);
     super.onPointerDown(event);
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
 
     this.startX = this.lastX;
     this.startY = this.lastY;
@@ -239,8 +240,9 @@ export default class PanGestureHandler extends GestureHandler {
     this.offsetX += this.lastX - this.startX;
     this.offsetY += this.lastY - this.startY;
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
 
     this.startX = this.lastX;
     this.startY = this.lastY;
@@ -259,8 +261,9 @@ export default class PanGestureHandler extends GestureHandler {
   protected onPointerUp(event: AdaptedEvent): void {
     super.onPointerUp(event);
     if (this.currentState === State.ACTIVE) {
-      this.lastX = this.tracker.getLastAvgX();
-      this.lastY = this.tracker.getLastAvgY();
+      const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+      this.lastX = lastCoords.x;
+      this.lastY = lastCoords.y;
     }
 
     this.tracker.removeFromTracker(event.pointerId);
@@ -280,8 +283,9 @@ export default class PanGestureHandler extends GestureHandler {
     this.offsetX += this.lastX - this.startX;
     this.offsetY += this.lastY - this.startY;
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
 
     this.startX = this.lastX;
     this.startY = this.lastY;
@@ -299,10 +303,13 @@ export default class PanGestureHandler extends GestureHandler {
   protected onPointerMove(event: AdaptedEvent): void {
     this.tracker.track(event);
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
-    this.velocityX = this.tracker.getVelocityX(event.pointerId);
-    this.velocityY = this.tracker.getVelocityY(event.pointerId);
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
+
+    const velocity = this.tracker.getVelocity(event.pointerId);
+    this.velocityX = velocity.x;
+    this.velocityY = velocity.y;
 
     this.checkBegan();
 
@@ -316,10 +323,13 @@ export default class PanGestureHandler extends GestureHandler {
 
     this.tracker.track(event);
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
-    this.velocityX = this.tracker.getVelocityX(event.pointerId);
-    this.velocityY = this.tracker.getVelocityY(event.pointerId);
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
+
+    const velocity = this.tracker.getVelocity(event.pointerId);
+    this.velocityX = velocity.x;
+    this.velocityY = velocity.y;
 
     this.checkBegan();
 
@@ -453,8 +463,9 @@ export default class PanGestureHandler extends GestureHandler {
         }, this.activateAfterLongPress);
       }
     } else {
-      this.velocityX = this.tracker.getVelocityX(event.pointerId);
-      this.velocityY = this.tracker.getVelocityY(event.pointerId);
+      const velocity = this.tracker.getVelocity(event.pointerId);
+      this.velocityX = velocity.x;
+      this.velocityY = velocity.y;
     }
   }
 

src/web/handlers/TapGestureHandler.ts

@@ -133,19 +133,22 @@ export default class TapGestureHandler extends GestureHandler {
     this.offsetX += this.lastX - this.startX;
     this.offsetY += this.lastY - this.startY;
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
 
-    this.startX = this.tracker.getLastAvgX();
-    this.startY = this.tracker.getLastAvgY();
+    this.startX = lastCoords.x;
+    this.startY = lastCoords.y;
 
     this.updateState(event);
   }
 
   protected onPointerUp(event: AdaptedEvent): void {
     super.onPointerUp(event);
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
+
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
 
     this.tracker.removeFromTracker(event.pointerId);
 
@@ -159,8 +162,9 @@ export default class TapGestureHandler extends GestureHandler {
     this.offsetX += this.lastX - this.startX;
     this.offsetY += this.lastY = this.startY;
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
 
     this.startX = this.lastX;
     this.startY = this.lastY;
@@ -172,8 +176,9 @@ export default class TapGestureHandler extends GestureHandler {
     this.trySettingPosition(event);
     this.tracker.track(event);
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
 
     this.updateState(event);
 
@@ -184,8 +189,9 @@ export default class TapGestureHandler extends GestureHandler {
     this.trySettingPosition(event);
     this.tracker.track(event);
 
-    this.lastX = this.tracker.getLastAvgX();
-    this.lastY = this.tracker.getLastAvgY();
+    const lastCoords = this.tracker.getAbsoluteCoordsAverage();
+    this.lastX = lastCoords.x;
+    this.lastY = lastCoords.y;
 
     this.updateState(event);
 

src/web/tools/GestureHandlerOrchestrator.ts

@@ -335,13 +335,7 @@ export default class GestureHandlerOrchestrator {
     // TODO: Find better way to handle that issue, for example by activation order and handler cancelling
 
     const isPointerWithinBothBounds = (pointer: number) => {
-      const handlerX: number = handler.getTracker().getLastX(pointer);
-      const handlerY: number = handler.getTracker().getLastY(pointer);
-
-      const point = {
-        x: handlerX,
-        y: handlerY,
-      };
+      const point = handler.getTracker().getLastAbsoluteCoords(pointer);
 
       return (
         handler.getDelegate().isPointerInBounds(point) &&