refactor(nav): queue based transitions

src/navigation/swipe-back.ts

@@ -0,0 +1,54 @@
+import { assign } from '../util/util';
+import { GestureController, GesturePriority } from '../gestures/gesture-controller';
+import { NavControllerBase } from './nav-controller-base';
+import { SlideData } from '../gestures/slide-gesture';
+import { SlideEdgeGesture } from '../gestures/slide-edge-gesture';
+
+
+export class SwipeBackGesture extends SlideEdgeGesture {
+
+  constructor(
+    element: HTMLElement,
+    options: any,
+    private _nav: NavControllerBase,
+    gestureCtlr: GestureController
+  ) {
+    super(element, assign({
+      direction: 'x',
+      maxEdgeStart: 75,
+      gesture: gestureCtlr.create('goback-swipe', {
+        priority: GesturePriority.GoBackSwipe,
+      })
+    }, options));
+  }
+
+  canStart(ev: any): boolean {
+    // the gesture swipe angle must be mainly horizontal and the
+    // gesture distance would be relatively short for a swipe back
+    // and swipe back must be possible on this nav controller
+    return (
+      this._nav.canSwipeBack() &&
+      super.canStart(ev)
+    );
+  }
+
+
+  onSlideBeforeStart(slideData: SlideData, ev: any) {
+    console.debug('swipeBack, onSlideBeforeStart', ev.type);
+    this._nav.swipeBackStart();
+  }
+
+  onSlide(slide: SlideData) {
+    let stepValue = (slide.distance / slide.max);
+    console.debug('swipeBack, onSlide, distance', slide.distance, 'max', slide.max, 'stepValue', stepValue);
+    this._nav.swipeBackProgress(stepValue);
+  }
+
+  onSlideEnd(slide: SlideData, ev: any) {
+    let shouldComplete = (Math.abs(slide.velocity) > 0.2 || Math.abs(slide.delta) > Math.abs(slide.max) * 0.5);
+    let currentStepValue = (slide.distance / slide.max);
+
+    console.debug('swipeBack, onSlideEnd, shouldComplete', shouldComplete, 'currentStepValue', currentStepValue);
+    this._nav.swipeBackEnd(shouldComplete, currentStepValue);
+  }
+}