fix(ui): Support free-scroll and auto-scroll for the installer logs (#1736) (#1836)

lib/ui/views/installer/installer_view.dart

@@ -75,14 +75,20 @@ class InstallerView extends StatelessWidget {
                 ),
               ),
             ),
-            body: CustomScrollView(
+            body: NotificationListener<ScrollNotification>(
+              onNotification: model.handleAutoScrollNotification,
+              child: Stack(
+                children: [
+                  CustomScrollView(
+                    key: model.logCustomScrollKey,
                     controller: model.scrollController,
                     slivers: <Widget>[
                       CustomSliverAppBar(
                         title: Text(
                           model.headerLogs,
                           style: GoogleFonts.inter(
-                      color: Theme.of(context).textTheme.titleLarge!.color,
+                            color:
+                                Theme.of(context).textTheme.titleLarge!.color,
                           ),
                           maxLines: 1,
                           overflow: TextOverflow.ellipsis,
@@ -90,7 +96,9 @@ class InstallerView extends StatelessWidget {
                         onBackButtonPressed: () => Navigator.maybePop(context),
                         bottom: PreferredSize(
                           preferredSize: const Size(double.infinity, 1.0),
-                    child: GradientProgressIndicator(progress: model.progress),
+                          child: GradientProgressIndicator(
+                            progress: model.progress,
+                          ),
                         ),
                       ),
                       SliverPadding(
@@ -113,6 +121,19 @@ class InstallerView extends StatelessWidget {
                       ),
                     ],
                   ),
+                  Visibility(
+                    visible: model.showAutoScrollButton,
+                    child: Align(
+                      alignment: const Alignment(0.9, 0.97),
+                      child: FloatingActionButton(
+                        onPressed: model.scrollToBottom,
+                        child: const Icon(Icons.arrow_downward_rounded),
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+            ),
           ),
         ),
       ),

lib/ui/views/installer/installer_viewmodel.dart

@@ -30,6 +30,7 @@ class InstallerViewModel extends BaseViewModel {
   static const _installerChannel = MethodChannel(
     'app.revanced.manager.flutter/installer',
   );
+  final Key logCustomScrollKey = UniqueKey();
   final ScrollController scrollController = ScrollController();
   final ScreenshotCallback screenshotCallback = ScreenshotCallback();
   double? progress = 0.0;
@@ -44,6 +45,57 @@ class InstallerViewModel extends BaseViewModel {
   bool cancel = false;
   bool showPopupScreenshotWarning = true;
 
+  bool showAutoScrollButton = false;
+  bool _isAutoScrollEnabled = true;
+  bool _isAutoScrolling = false;
+
+  double get getCurrentScrollPercentage {
+    final maxScrollExtent = scrollController.position.maxScrollExtent;
+    final currentPosition = scrollController.position.pixels;
+
+    return currentPosition / maxScrollExtent;
+  }
+
+  bool handleAutoScrollNotification(ScrollNotification event) {
+    if (_isAutoScrollEnabled && event is ScrollStartNotification) {
+      _isAutoScrollEnabled = _isAutoScrolling;
+      showAutoScrollButton = false;
+      notifyListeners();
+
+      return true;
+    }
+
+    if (event is ScrollEndNotification) {
+      const anchorThreshold = 0.987;
+
+      _isAutoScrollEnabled =
+          _isAutoScrolling || getCurrentScrollPercentage >= anchorThreshold;
+
+      showAutoScrollButton = !_isAutoScrollEnabled && !_isAutoScrolling;
+      notifyListeners();
+
+      return true;
+    }
+
+    return false;
+  }
+
+  void scrollToBottom() {
+    _isAutoScrolling = true;
+
+    WidgetsBinding.instance.addPostFrameCallback((_) async {
+      final maxScrollExtent = scrollController.position.maxScrollExtent;
+
+      await scrollController.animateTo(
+        maxScrollExtent,
+        duration: const Duration(milliseconds: 100),
+        curve: Curves.fastOutSlowIn,
+      );
+
+      _isAutoScrolling = false;
+    });
+  }
+
   Future<void> initialize(BuildContext context) async {
     isRooted = await _rootAPI.isRooted();
     if (await Permission.ignoreBatteryOptimizations.isGranted) {
@@ -123,13 +175,9 @@ class InstallerViewModel extends BaseViewModel {
       if (logs[logs.length - 1] == '\n') {
         logs = logs.substring(0, logs.length - 1);
       }
-      Future.delayed(const Duration(milliseconds: 100)).then((value) {
+      if (_isAutoScrollEnabled) {
-        scrollController.animateTo(
+        scrollToBottom();
-          scrollController.position.maxScrollExtent,
+      }
-          duration: const Duration(milliseconds: 100),
-          curve: Curves.fastOutSlowIn,
-        );
-      });
     }
     notifyListeners();
   }