[Location History] Display "loading..." + improve performance + fix lag

Space_Mapper/lib/models/list_view.dart

@@ -22,6 +22,12 @@ class CustomLocationsManager {
     return ret;
   }
 
+  static void removeAllCustomLocations() {
+    print("Removing " + customLocations.length.toString() + " customLocations");
+    customLocations.clear();
+    print("All customLocations removed");
+  }
+
   /// Makes timestamp readable by a human
   static String formatTimestamp(String timestamp) {
     //2021-10-25T21:25:08.210Z <- This is the original format
@@ -80,8 +86,8 @@ class CustomLocation {
       /// We need this checker to ensure that the user doesn't send the delete request twice, causing an exception
       _toDelete = true;
       await bg.BackgroundGeolocation.destroyLocation(this.getUUID());
-      CustomLocationsManager.customLocations
-          .removeWhere((element) => element.getUUID() == this.getUUID());
+      //CustomLocationsManager.customLocations
+      //    .removeWhere((element) => element.getUUID() == this.getUUID());
     }
   }
 

Space_Mapper/lib/ui/list_view.dart

@@ -18,10 +18,11 @@ Future<Placemark?> getLocationData(double lat, double long) async {
   }
 }
 
-void createCustomLocation(var recordedLocation, Placemark? placemark) {
+CustomLocation createCustomLocation(
+    var recordedLocation, Placemark? placemark) {
   CustomLocation location = new CustomLocation();
   //Add location to list
-  CustomLocationsManager.customLocations.add(location);
+  //CustomLocationsManager.customLocations.add(location);
 
   //Save data from flutter_background_geolocation library
   location.setUUID(recordedLocation['uuid']);
@@ -46,6 +47,8 @@ void createCustomLocation(var recordedLocation, Placemark? placemark) {
     location.setStreet(street!);
     location.setISOCountry(ISO!);
   }
+
+  return location;
 }
 
 class STOListView extends StatefulWidget {
@@ -56,46 +59,45 @@ class STOListView extends StatefulWidget {
 }
 
 class _STOListViewState extends State<STOListView> {
-  late List<CustomLocation> customLocations =
-      CustomLocationsManager.fetchAll(sortByNewest: true);
+  final int maxElements = 25; // Maximum amount of elements displayed on screen
+
+  Future<List<CustomLocation>> recalculateLocations() async {
+    List<CustomLocation> customLocations = [];
 
-  Future<void> recalculateLocations() async {
+    // Make the current list to be empty. We want to fill it according to our custom parameters
+    //CustomLocationsManager.removeAllCustomLocations();
+
+    // Get a list of locations from the flutter_background_geolocation plugin database
     List recordedLocations = await bg.BackgroundGeolocation.locations;
 
-    /// We check if there are new location entries that we haven't saved in our list
-    if (recordedLocations.length != customLocations.length) {
-      for (int i = recordedLocations.length - 1; i >= 0; --i) {
-        for (int j = customLocations.length - 1; j >= 0; --j) {
-          if (recordedLocations[i]['uuid'] ==
-              CustomLocationsManager.customLocations[j].getUUID()) continue;
-        }
-        //Match not found, we add the location
-        createCustomLocation(
-            recordedLocations[i],
-            await getLocationData(recordedLocations[i]['coords']['latitude'],
-                recordedLocations[i]['coords']['longitude']));
-
-        //We update the state to display the new locations
-        if (this
-            .mounted) // We check if this screen is active. If we do 'setState' while it's not active, it'll crash (throw exception)
-        {
-          setState(() {
-            customLocations =
-                CustomLocationsManager.fetchAll(sortByNewest: true);
-            print("Loading positions: " +
-                customLocations.length.toString() +
-                " out of " +
-                recordedLocations.length.toString());
-          });
-        }
+    // n is the minimum value of either the specified maximum amount of elements (maxElements), or the current size of recordedLocations
+    int n;
+    if (maxElements <= recordedLocations.length)
+      n = maxElements;
+    else
+      n = recordedLocations.length;
+
+    // Fill the custom locations list, to display beautiful tiles instead of json data
+    for (int i = 0; i < n; ++i) {
+      // Check if there's already a location with the same UUID
+      for (int j = customLocations.length - 1; j >= 0; --j) {
+        if (recordedLocations[i]['uuid'] == customLocations[j].getUUID())
+          continue; //CustomLocationsManager.customLocations[j].getUUID()) continue;
       }
+      // Match not found, we add the location
+      CustomLocation newLocation = createCustomLocation(
+          recordedLocations[i],
+          await getLocationData(recordedLocations[i]['coords']['latitude'],
+              recordedLocations[i]['coords']['longitude']));
+      customLocations.add(newLocation);
     }
+    return customLocations;
   }
 
   @override
   void initState() {
     super.initState();
-    recalculateLocations();
+    //recalculateLocations();
   }
 
   @override
@@ -104,34 +106,23 @@ class _STOListViewState extends State<STOListView> {
         appBar: AppBar(
             title: Text(
                 AppLocalizations.of(context)!.translate("locations_history"))),
-        body: ListView.builder(
-          itemCount: customLocations.length,
-          itemBuilder: (context, index) {
-            CustomLocation thisLocation = customLocations[index];
-            return Dismissible(
-              child: _tile(thisLocation, context),
-              background: Container(
-                child: Container(
-                  margin: EdgeInsets.only(right: 10.0),
-                  alignment: Alignment.centerRight,
-                  child: new LayoutBuilder(builder: (context, constraint) {
-                    return new Icon(Icons.delete_forever,
-                        size: constraint.biggest.height * 0.5);
-                  }),
-                ),
-                color: Colors.red,
-              ),
-              key: ValueKey<CustomLocation>(customLocations[index]),
-              confirmDismiss: (DismissDirection direction) async {
-                await thisLocation.deleteThisLocation();
-                setState(() {
-                  customLocations =
-                      CustomLocationsManager.fetchAll(sortByNewest: true);
-                  thisLocation = customLocations[index];
+        body: FutureBuilder<List<CustomLocation>>(
+          future: recalculateLocations(),
+          builder: (context, snapshot) {
+            if (!snapshot.hasData) {
+              return Center(
+                child: CircularProgressIndicator(),
+              );
+            }
+            if (snapshot.hasError) {
+              return Container();
+            }
+            return ListView.builder(
+                itemCount: snapshot.data!.length,
+                itemBuilder: (context, index) {
+                  CustomLocation thisLocation = snapshot.data![index];
+                  return _tile(thisLocation, context);
                 });
-                return true;
-              },
-            );
           },
         ));
   }