onRenderHandlers for early min/maxIndex set

Author: dhilt

src/modules/viewport.js

@@ -86,7 +86,7 @@ export default function Viewport(elementRoutines, buffer, element, viewportContr
         buffer.eof = false;
         buffer.remove(buffer.length - overage, buffer.length);
         buffer.next -= overage;
-        viewport.adjustPadding();
+        viewport.adjustPaddings();
       }
     },
 
@@ -121,7 +121,7 @@ export default function Viewport(elementRoutines, buffer, element, viewportContr
       }
     },
 
-    adjustPadding() {
+    adjustPaddings() {
       if (!buffer.length) {
         return;
       }
@@ -145,15 +145,20 @@ export default function Viewport(elementRoutines, buffer, element, viewportContr
       bottomPadding.height(bottomPaddingHeight + bottomPaddingHeightAdd);
     },
 
-    adjustScrollTopAfterMinIndexSet(topPaddingHeightOld) {
+    onAfterMinIndexSet(topPaddingHeightOld) {
       // additional scrollTop adjustment in case of datasource.minIndex external set
       if (buffer.minIndexUser !== null && buffer.minIndex > buffer.minIndexUser) {
         let diff = topPadding.height() - topPaddingHeightOld;
         viewport.scrollTop(viewport.scrollTop() + diff);
+        diff -= viewport.scrollTop();
+        if(diff > 0) {
+          bottomPadding.height(bottomPadding.height() + diff);
+          viewport.scrollTop(viewport.scrollTop() + diff);
+        }
       }
     },
 
-    adjustScrollTopAfterPrepend(updates) {
+    onAfterPrepend(updates) {
       if (!updates.prepended.length)
         return;
       const height = buffer.effectiveHeight(updates.prepended);

src/ui-scroll.js

@@ -96,48 +96,65 @@ angular.module('ui.scroll', [])
           }
         }
 
-        function defineProperty(datasource, propName, propUserName) {
+        let onRenderHandlers = [];
+        function onRenderHandlersRunner() {
+          if(onRenderHandlers.length) {
+            angular.forEach(onRenderHandlers, (handler) => handler());
+            onRenderHandlers = [];
+          }
+        }
+        function preDefineIndexProperty(datasource, propName) {
+          let getter;
+          // need to postpone min/maxIndexUser processing if the view is empty
+          if(datasource.hasOwnProperty(propName) && !buffer.length) {
+            getter = datasource[propName];
+            delete datasource[propName];
+            onRenderHandlers.push(() => datasource[propName] = getter);
+          }
+        }
+
+        function defineIndexProperty(datasource, propName, propUserName) {
           let descriptor = Object.getOwnPropertyDescriptor(datasource, propName);
           if (descriptor && (descriptor.set || descriptor.get)) {
             return;
           }
           let getter;
+          preDefineIndexProperty(datasource, propName);
           Object.defineProperty(datasource, propName, {
             set: (value) => {
               getter = value;
               buffer[propUserName] = value;
-              if (!pending.length) {
-                let topPaddingHeightOld = viewport.topDataPos();
-                viewport.adjustPadding();
-                if (propName === 'minIndex') {
-                  viewport.adjustScrollTopAfterMinIndexSet(topPaddingHeightOld);
-                }
+              viewport.adjustPaddings();
+              if (propName === 'minIndex') {
+                viewport.onAfterMinIndexSet(viewport.topDataPos());
               }
             },
             get: () => getter
           });
         }
 
-        defineProperty(datasource, 'minIndex', 'minIndexUser');
-        defineProperty(datasource, 'maxIndex', 'maxIndexUser');
-
-        const fetchNext = (datasource.get.length !== 2) ? (success) => datasource.get(buffer.next, bufferSize, success)
-          : (success) => {
-          datasource.get({
-            index: buffer.next,
-            append: buffer.length ? buffer[buffer.length - 1].item : void 0,
-            count: bufferSize
-          }, success);
-        };
-
-        const fetchPrevious = (datasource.get.length !== 2) ? (success) => datasource.get(buffer.first - bufferSize, bufferSize, success)
-          : (success) => {
-          datasource.get({
-            index: buffer.first - bufferSize,
-            prepend: buffer.length ? buffer[0].item : void 0,
-            count: bufferSize
-          }, success);
-        };
+        defineIndexProperty(datasource, 'minIndex', 'minIndexUser');
+        defineIndexProperty(datasource, 'maxIndex', 'maxIndexUser');
+
+        const fetchNext = (datasource.get.length !== 2) ?
+          (success) => datasource.get(buffer.next, bufferSize, success) :
+          (success) => {
+            datasource.get({
+              index: buffer.next,
+              append: buffer.length ? buffer[buffer.length - 1].item : void 0,
+              count: bufferSize
+            }, success);
+          };
+
+        const fetchPrevious = (datasource.get.length !== 2) ?
+          (success) => datasource.get(buffer.first - bufferSize, bufferSize, success) :
+          (success) => {
+            datasource.get({
+              index: buffer.first - bufferSize,
+              prepend: buffer.length ? buffer[0].item : void 0,
+              count: bufferSize
+            }, success);
+          };
 
         /**
          * Build padding elements
@@ -292,11 +309,11 @@ angular.module('ui.scroll', [])
           // schedule another adjustBuffer after animation completion
           if (updates.animated.length) {
             $q.all(updates.animated).then(() => {
-              viewport.adjustPadding();
+              viewport.adjustPaddings();
               adjustBuffer(rid);
             });
           } else {
-            viewport.adjustPadding();
+            viewport.adjustPaddings();
           }
         }
 
@@ -357,13 +374,14 @@ angular.module('ui.scroll', [])
           updates.inserted.forEach(w => w.element.removeClass('ng-hide'));
           updates.prepended.forEach(w => w.element.removeClass('ng-hide'));
 
-          viewport.adjustScrollTopAfterPrepend(updates);
+          viewport.onAfterPrepend(updates);
 
           if (isInvalid(rid)) {
             return;
           }
 
           updatePaddings(rid, updates);
+          onRenderHandlersRunner();
           enqueueFetch(rid, updates);
           pending.shift();