Added LowPassFilter and support for smooth scatter rotation and zoom.

lib/scatter.js

@@ -1,11 +1,11 @@
 /* eslint-disable no-unused-vars */
 /* eslint-disable no-console */
 /* globals TweenLite debugCanvas */
-import { Points, Polygon, Angle, Elements } from './utils.js'
+import { Points, Polygon, Angle, Elements, LowPassFilter } from './utils.js'
 import Events from './events.js'
 import { InteractionMapper } from './interaction.js'
 import { Capabilities } from './capabilities.js'
-import PopupMenu from './popupmenu.js'
+
 /**
  * A base class for scatter specific events.
  *
@@ -270,7 +270,8 @@ export class AbstractScatter extends Throwable {
         scaleAutoClose = false,
         scaleCloseThreshold = 0.10,
         scaleCloseBuffer = 0.05,
-        maxRotation = Angle.degree2radian(5)
+        maxRotation = Angle.degree2radian(5),
+        useLowPassFilter = true
     } = {}) {
         if (rotationDegrees != null && rotation != null) {
             throw new Error('Use rotationDegrees or rotation but not both')
@@ -314,7 +315,12 @@ export class AbstractScatter extends Throwable {
         this.resizable = resizable
         this.mouseZoomFactor = mouseZoomFactor
         this.autoBringToFront = autoBringToFront
-
+        this.useLowPassFilter = useLowPassFilter
+        if (useLowPassFilter) {
+            this.rotateLPF = new LowPassFilter()
+            this.zoomLPF = new LowPassFilter()
+            this.zoomLPF.setup([1, 1, 1, 1, 1, 1, 1, 1, 1, 1])
+        }
         this.dragging = false
         this.onTransform = onTransform != null ? [onTransform] : null
         this.onClose = onClose != null ? [onClose] : null
@@ -338,6 +344,11 @@ export class AbstractScatter extends Throwable {
         this.bringToFront()
         this.killAnimation()
         this.observeVelocity()
+        if (this.useLowPassFilter) {
+            this.rotateLPF.clear()
+            this.zoomLPF.clear()
+            this.zoomLPF.setup([1, 1, 1, 1, 1, 1, 1, 1, 1, 1])
+        }
         return true
     }
 
@@ -351,14 +362,19 @@ export class AbstractScatter extends Throwable {
         let delta = interaction.delta()
         if (delta != null) {
             this.addVelocity(delta)
-            let alpha = delta.rotate
+            let rotate = delta.rotate
+            let zoom = delta.zoom
             if (this.maxRotation != null) {
-                if (Math.abs(alpha) > this.maxRotation) {
-                    alpha = 0
+                if (Math.abs(rotate) > this.maxRotation) {
+                    rotate = 0
                 }
             }
-            this.transform(delta, delta.zoom, alpha, delta.about)
-            if (delta.zoom != 1) this.interactionAnchor = delta.about
+            if (this.useLowPassFilter) {
+                rotate = this.rotateLPF.next(rotate)
+                zoom = this.zoomLPF.next(zoom)
+            }
+            this.transform(delta, zoom, rotate, delta.about)
+            if (zoom != 1) this.interactionAnchor = delta.about
         }
     }