Lazy Loading feature added

lib/ui/views/projects/featured_projects_view.dart

@@ -1,7 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:get/get.dart';
 import 'package:mobile_app/ui/components/cv_header.dart';
-import 'package:mobile_app/ui/components/cv_primary_button.dart';
 import 'package:mobile_app/ui/views/base_view.dart';
 import 'package:mobile_app/ui/views/projects/components/featured_project_card.dart';
 import 'package:mobile_app/ui/views/projects/project_details_view.dart';
@@ -21,13 +20,35 @@ class FeaturedProjectsView extends StatefulWidget {
 }
 
 class _FeaturedProjectsViewState extends State<FeaturedProjectsView> {
+  final _scrollController = ScrollController();
+  bool addedListener =
+      false; //Flag to know if a listener is already added to the controller or not.
+
+  dynamic _scrollListener(FeaturedProjectsViewModel model) {
+    var maxScroll = _scrollController.position.maxScrollExtent;
+    var currentScroll = _scrollController.position.pixels;
+    var delta =
+        200; // Loads more data if "delta" pixels left to reach maxScrollExtent
+    if (maxScroll - currentScroll <= delta) {
+      if (!model.isLoadingMoreCircuits &&
+          model?.previousFeaturedProjectsBatch?.links?.next != null) {
+        model.fetchFeaturedProjects();
+      }
+    }
+    addedListener = true;
+  }
+
   @override
   Widget build(BuildContext context) {
     return BaseView<FeaturedProjectsViewModel>(
       onModelReady: (model) => widget.embed
           ? model.fetchFeaturedProjects(size: 3)
           : model.fetchFeaturedProjects(),
       builder: (context, model, child) {
+        if (!addedListener) {
+          _scrollController.addListener(() => _scrollListener(model));
+        }
+
         final _items = <Widget>[];
 
         if (model.isSuccess(model.FETCH_FEATURED_PROJECTS)) {
@@ -43,16 +64,6 @@ class _FeaturedProjectsViewState extends State<FeaturedProjectsView> {
           });
         }
 
-        if (!widget.embed &&
-            model?.previousFeaturedProjectsBatch?.links?.next != null) {
-          _items.add(
-            CVPrimaryButton(
-              title: 'Load More',
-              onPressed: () => model.fetchFeaturedProjects(),
-            ),
-          );
-        }
-
         if (widget.embed) {
           return Column(
             children: _items,
@@ -67,12 +78,15 @@ class _FeaturedProjectsViewState extends State<FeaturedProjectsView> {
                 'These circuits have been hand-picked by our authors for their awesomeness.',
           ),
         );
-
+        if (model.isLoadingMoreCircuits) {
+          _items.add(CircularProgressIndicator());
+        }
         return Scaffold(
           appBar: widget.showAppBar
               ? AppBar(title: Text('Featured Circuits'))
               : null,
           body: SingleChildScrollView(
+            controller: _scrollController,
             padding: const EdgeInsets.all(16),
             child: Column(
               children: _items,

lib/viewmodels/projects/featured_projects_viewmodel.dart

@@ -24,10 +24,20 @@ class FeaturedProjectsViewModel extends BaseModel {
     notifyListeners();
   }
 
+  bool _isLoadingMoreCircuits = false;
+
+  bool get isLoadingMoreCircuits => _isLoadingMoreCircuits;
+
+  set isLoadingMoreCircuits(bool loading) {
+    _isLoadingMoreCircuits = loading;
+    notifyListeners();
+  }
+
   Future fetchFeaturedProjects({int size = 5}) async {
     try {
       if (previousFeaturedProjectsBatch?.links?.next != null) {
         // fetch next batch of projects..
+        isLoadingMoreCircuits = true;
         String _nextPageLink = previousFeaturedProjectsBatch.links.next;
 
         var _nextPageNumber =
@@ -38,6 +48,7 @@ class FeaturedProjectsViewModel extends BaseModel {
           page: _nextPageNumber,
           size: size,
         );
+        isLoadingMoreCircuits = false;
       } else {
         // Set State as busy only very first time..
         setStateFor(FETCH_FEATURED_PROJECTS, ViewState.Busy);
@@ -49,6 +60,7 @@ class FeaturedProjectsViewModel extends BaseModel {
       featuredProjects.addAll(previousFeaturedProjectsBatch.data);
       setStateFor(FETCH_FEATURED_PROJECTS, ViewState.Success);
     } on Failure catch (f) {
+      isLoadingMoreCircuits = false;
       setStateFor(FETCH_FEATURED_PROJECTS, ViewState.Error);
       setErrorMessageFor(FETCH_FEATURED_PROJECTS, f.message);
     }