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

lib/ui/views/installer/installer_view.dart

@@ -75,43 +75,64 @@ class InstallerView extends StatelessWidget {
                 ),
               ),
             ),
-            body: CustomScrollView(
+            body: NotificationListener<ScrollNotification>(
-              controller: model.scrollController,
+              onNotification: model.handleAutoScrollNotification,
-              slivers: <Widget>[
+              child: Stack(
-                CustomSliverAppBar(
+                children: [
-                  title: Text(
+                  CustomScrollView(
-                    model.headerLogs,
+                    key: model.logCustomScrollKey,
-                    style: GoogleFonts.inter(
+                    controller: model.scrollController,
-                      color: Theme.of(context).textTheme.titleLarge!.color,
+                    slivers: <Widget>[
-                    ),
+                      CustomSliverAppBar(
-                    maxLines: 1,
+                        title: Text(
-                    overflow: TextOverflow.ellipsis,
+                          model.headerLogs,
-                  ),
+                          style: GoogleFonts.inter(
-                  onBackButtonPressed: () => Navigator.maybePop(context),
+                            color:
-                  bottom: PreferredSize(
+                                Theme.of(context).textTheme.titleLarge!.color,
-                    preferredSize: const Size(double.infinity, 1.0),
+                          ),
-                    child: GradientProgressIndicator(progress: model.progress),
+                          maxLines: 1,
-                  ),
+                          overflow: TextOverflow.ellipsis,
-                ),
+                        ),
-                SliverPadding(
+                        onBackButtonPressed: () => Navigator.maybePop(context),
-                  padding: const EdgeInsets.all(20.0),
+                        bottom: PreferredSize(
-                  sliver: SliverList(
+                          preferredSize: const Size(double.infinity, 1.0),
-                    delegate: SliverChildListDelegate.fixed(
+                          child: GradientProgressIndicator(
-                      <Widget>[
+                            progress: model.progress,
-                        CustomCard(
-                          child: Text(
-                            model.logs,
-                            style: GoogleFonts.jetBrainsMono(
-                              fontSize: 13,
-                              height: 1.5,
-                            ),
                           ),
                         ),
-                      ],
+                      ),
+                      SliverPadding(
+                        padding: const EdgeInsets.all(20.0),
+                        sliver: SliverList(
+                          delegate: SliverChildListDelegate.fixed(
+                            <Widget>[
+                              CustomCard(
+                                child: Text(
+                                  model.logs,
+                                  style: GoogleFonts.jetBrainsMono(
+                                    fontSize: 13,
+                                    height: 1.5,
+                                  ),
+                                ),
+                              ),
+                            ],
+                          ),
+                        ),
+                      ),
+                    ],
+                  ),
+                  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();
   }