Merge pull request #238 from angular-ui/inertia-fix

Inertia fix

Author: dhilt

Diff for: README.md

@@ -477,6 +477,10 @@ Pull Rerquest should include source code (./scr) changes, may include tests (./t
 
 ## Change log
 
+### v1.8.0
+ * Reconsidered scroll event handling
+ * Fixed inertia scrolling issues
+
 ### v1.7.6
  * Added immutableTop option for applyUpdates and prepend Adapter methods.
 

Diff for: bower.json

@@ -1,7 +1,7 @@
 {
   "name": "angular-ui-scroll",
   "description": "AngularJS infinite scrolling module",
-  "version": "1.7.6",
+  "version": "1.8.0",
   "main": "./dist/ui-scroll.js",
   "homepage": "https://github.com/angular-ui/ui-scroll.git",
   "license": "MIT",

Diff for: dist/ui-scroll-grid.js

@@ -1,7 +1,7 @@
 {
   "name": "angular-ui-scroll",
   "description": "AngularJS infinite scrolling module",
-  "version": "1.7.6",
+  "version": "1.8.0",
   "src": "./src/",
   "public": "./dist/",
   "main": "./dist/ui-scroll.js",

Diff for: dist/ui-scroll-grid.js.map

@@ -178,17 +178,20 @@ export default function Viewport(elementRoutines, buffer, element, viewportContr
     },
 
     onAfterPrepend(updates) {
-      if (!updates.prepended.length)
+      if (!updates.prepended.length) {
         return;
+      }
       const height = buffer.effectiveHeight(updates.prepended);
       const paddingHeight = topPadding.height() - height;
       if (paddingHeight >= 0) {
         topPadding.height(paddingHeight);
+        return;
       }
-      else {
-        topPadding.height(0);
-        viewport.scrollTop(viewport.scrollTop() - paddingHeight);
-      }
+      const position = viewport.scrollTop();
+      const newPosition = position - paddingHeight;
+      viewport.synthetic = { previous: position, next: newPosition };
+      topPadding.height(0);
+      viewport.scrollTop(newPosition);
     },
 
     resetTopPadding() {

Diff for: dist/ui-scroll-grid.min.js

@@ -73,10 +73,16 @@ angular.module('ui.scroll', [])
           return parseNumber(result, defaultValue, isFloat);
         }
 
+        function parseBooleanAttr(value, defaultValue) {
+          const result = $parse(value)($scope);
+          return typeof result === 'boolean' ? result : defaultValue;
+        }
+
         const BUFFER_MIN = 3;
         const BUFFER_DEFAULT = 10;
         const PADDING_MIN = 0.3;
         const PADDING_DEFAULT = 0.5;
+        const HANDLE_INERTIA_DEFAULT = true;
         const START_INDEX_DEFAULT = 1;
         const MAX_VIEWPORT_DELAY = 500;
         const VIEWPORT_POLLING_INTERVAL = 50;
@@ -87,6 +93,7 @@ angular.module('ui.scroll', [])
         const viewportController = controllers[0];
         const bufferSize = Math.max(BUFFER_MIN, parseNumericAttr($attr.bufferSize, BUFFER_DEFAULT));
         const padding = Math.max(PADDING_MIN, parseNumericAttr($attr.padding, PADDING_DEFAULT, true));
+        const handleInertia = parseBooleanAttr($attr.handleInertia, HANDLE_INERTIA_DEFAULT);
         let startIndex = parseNumericAttr($attr.startIndex, START_INDEX_DEFAULT);
         let ridActual = 0; // current data revision id
         let pending = [];
@@ -485,7 +492,32 @@ angular.module('ui.scroll', [])
           }
         }
 
+        function fixInertia() {
+          if (!viewport.synthetic) {
+            return;
+          }
+          const oldPosition = viewport.synthetic.previous;
+          const newPosition = viewport.synthetic.next;
+          if (viewport.scrollTop() !== newPosition) {
+            requestAnimationFrame(() => {
+              const position = viewport.scrollTop();
+              const diff = oldPosition - position;
+              if (diff > 0) { // inertia over synthetic
+                viewport.scrollTop(newPosition - diff);
+              } else {
+                viewport.scrollTop(newPosition);
+              }
+              viewport.synthetic = null;
+            });
+            return true;
+          }
+          viewport.synthetic = null;
+        }
+
         function resizeAndScrollHandler() {
+          if (handleInertia && fixInertia()) {
+            return;
+          }
           if (!$rootScope.$$phase && !adapter.isLoading && !adapter.disabled) {
 
             enqueueFetch(ridActual);