TF-4084 Fix cannot read or scroll emails when opening them in Twake Mail on Android chrome mobile browser

core/lib/presentation/views/html_viewer/html_content_viewer_on_web_widget.dart

@@ -8,6 +8,7 @@ import 'package:core/utils/app_logger.dart';
 import 'package:core/utils/html/html_interaction.dart';
 import 'package:core/utils/html/html_template.dart';
 import 'package:core/utils/html/html_utils.dart';
+import 'package:core/utils/platform_info.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:universal_html/html.dart' as html;
 
@@ -87,6 +88,7 @@ class _HtmlContentViewerOnWebState extends State<HtmlContentViewerOnWeb>
   static const String iframeOnLoadMessage = 'iframeHasBeenLoaded';
   static const String onClickHyperLinkName = 'onClickHyperLink';
   static const String onScrollChangedEvent = 'onScrollChanged';
+  static const String onScrollEndEvent = 'onScrollEnd';
 
   @override
   void initState() {
@@ -106,9 +108,12 @@ class _HtmlContentViewerOnWebState extends State<HtmlContentViewerOnWeb>
       if (viewId != _createdViewId) return;
 
       final type = data['type'];
-      if (_isScrollChangedEventTriggered(type)) {
+      if (_isScrollingIsAvailable && _isScrollChangedEventTriggered(type)) {
         _handleIframeOnScrollChangedListener(data, widget.scrollController!);
         return;
+      } else if (_isScrollingIsAvailable && _isScrollEndEventTriggered(type)) {
+        _handleIframeOnScrollEndListener(data, widget.scrollController!);
+        return;
       }
 
       if (data['message'] == iframeOnLoadMessage) {
@@ -130,10 +135,17 @@ class _HtmlContentViewerOnWebState extends State<HtmlContentViewerOnWeb>
     }
   }
 
-  bool _isScrollChangedEventTriggered(String? type) {
+  bool get _isScrollingIsAvailable {
     return widget.scrollController != null &&
-        widget.scrollController?.hasClients == true &&
+        widget.scrollController?.hasClients == true;
-        type?.contains('toDart: $onScrollChangedEvent') == true;
+  }
+
+  bool _isScrollChangedEventTriggered(String? type) {
+    return type?.contains('toDart: $onScrollChangedEvent') == true;
+  }
+
+  bool _isScrollEndEventTriggered(String? type) {
+    return type?.contains('toDart: $onScrollEndEvent') == true;
   }
 
   void _handleIframeOnScrollChangedListener(
@@ -141,17 +153,51 @@ class _HtmlContentViewerOnWebState extends State<HtmlContentViewerOnWeb>
     ScrollController controller,
   ) {
     final deltaY = data['deltaY'] ?? 0.0;
-    final newOffset = controller.offset + deltaY;
+    final target = controller.offset + deltaY;
-    log('_HtmlContentViewerOnWebState::_handleIframeOnScrollChangedListener:deltaY = $deltaY | newOffset = $newOffset');
+
-    if (newOffset < controller.position.minScrollExtent) {
+    if (PlatformInfo.isWebTouchDevice) {
-      controller.jumpTo(controller.position.minScrollExtent);
+      final newOffset = target.clamp(
-    } else if (newOffset > controller.position.maxScrollExtent) {
+        controller.position.minScrollExtent,
-      controller.jumpTo(controller.position.maxScrollExtent);
+        controller.position.maxScrollExtent,
+      );
+
+      controller.animateTo(
+        newOffset,
+        duration: const Duration(milliseconds: 50),
+        curve: Curves.linear,
+      );
     } else {
-      controller.jumpTo(newOffset);
+      if (target < controller.position.minScrollExtent) {
+        controller.jumpTo(controller.position.minScrollExtent);
+      } else if (target > controller.position.maxScrollExtent) {
+        controller.jumpTo(controller.position.maxScrollExtent);
+      } else {
+        controller.jumpTo(target);
+      }
     }
   }
 
+  void _handleIframeOnScrollEndListener(
+    dynamic data,
+    ScrollController controller,
+  ) {
+    final velocity = data['velocity'] ?? 0.0;
+
+    final distance = velocity * 800;
+    final target = controller.offset + distance;
+
+    final newOffset = target.clamp(
+      controller.position.minScrollExtent,
+      controller.position.maxScrollExtent,
+    );
+
+    controller.animateTo(
+      newOffset,
+      duration: const Duration(milliseconds: 600),
+      curve: Curves.decelerate,
+    );
+  }
+
   bool _isHtmlContentHeightEventTriggered(String? type) =>
       type?.contains('toDart: htmlHeight') == true;
 
@@ -319,17 +365,6 @@ class _HtmlContentViewerOnWebState extends State<HtmlContentViewerOnWeb>
           
           ${!widget.autoAdjustHeight ? 'resizeObserver.observe(document.body);' : ''}
         }
-        
-        ${widget.scrollController != null ? '''
-          window.addEventListener('wheel', function (event) {
-            const deltaY = event.deltaY;
-            window.parent.postMessage(JSON.stringify({
-              "view": "$_createdViewId",
-              "type": "toDart: $onScrollChangedEvent",
-              "deltaY": deltaY
-            }), "*");
-          });
-        ''' : ''}
       </script>
     ''';
 
@@ -349,6 +384,17 @@ class _HtmlContentViewerOnWebState extends State<HtmlContentViewerOnWeb>
       HtmlInteraction.scriptsHandleLazyLoadingBackgroundImage,
       HtmlInteraction.generateNormalizeImageScript(widget.widthContent),
       if (widget.enableQuoteToggle) HtmlUtils.quoteToggleScript,
+      if (widget.scrollController != null)
+        PlatformInfo.isWebTouchDevice
+            ? HtmlInteraction.scriptsTouchEventListener(
+                viewId: _createdViewId,
+                onScrollChangedEvent: onScrollChangedEvent,
+                onScrollEndEvent: onScrollEndEvent,
+              )
+            : HtmlInteraction.scriptsWheelEventListener(
+                viewId: _createdViewId,
+                onScrollChangedEvent: onScrollChangedEvent,
+              ),
     ].join();
 
     final htmlTemplate = HtmlUtils.generateHtmlDocument(

core/lib/utils/html/html_interaction.dart

@@ -298,4 +298,84 @@ class HtmlInteraction {
       });
     </script>
   ''';
+
+  static String scriptsWheelEventListener({
+    required String viewId,
+    required String onScrollChangedEvent,
+  }) => '''
+    <script type="text/javascript">
+      function onWheel(e) { 
+        const deltaY = event.deltaY;
+        window.parent.postMessage(JSON.stringify({
+          "view": "$viewId",
+          "type": "toDart: $onScrollChangedEvent",
+          "deltaY": deltaY
+        }), "*");
+      }
+      
+      window.addEventListener('wheel', onWheel, { passive: true });
+      
+      window.addEventListener('pagehide', (event) => {
+        window.removeEventListener('wheel', onWheel);
+      });
+    </script>
+  ''';
+
+  static String scriptsTouchEventListener({
+    required String viewId,
+    required String onScrollChangedEvent,
+    required String onScrollEndEvent,
+  }) => '''
+    <script type="text/javascript">
+      let lastY = 0;
+      let lastTime = 0;
+      let velocity = 0;
+    
+      function onTouchStart(e) { 
+        lastY = e.touches[0].clientY;
+        lastTime = performance.now();
+        velocity = 0;
+      }
+    
+      function onTouchMove(e) { 
+        const now = performance.now();
+        const y = e.touches[0].clientY;
+        const dy = lastY - y;
+        const dt = now - lastTime;
+    
+        if (dt > 0) {
+          velocity = dy / dt; // px per ms
+          velocity = Math.max(Math.min(velocity, 2), -2); // clamp velocity
+        }
+    
+        lastY = y;
+        lastTime = now;
+    
+        window.parent.postMessage(JSON.stringify({
+          view: "$viewId",
+          type: "toDart: $onScrollChangedEvent",
+          deltaY: dy,
+        }), '*');
+      }
+    
+      function onTouchEnd(e) { 
+        window.parent.postMessage(JSON.stringify({
+          view: "$viewId",
+          type: "toDart: $onScrollEndEvent",
+          velocity: velocity,
+        }), '*');
+      }
+    
+      window.addEventListener('touchstart', onTouchStart, { passive: true });
+      window.addEventListener('touchmove', onTouchMove, { passive: true });
+      window.addEventListener('touchend', onTouchEnd, { passive: true });
+    
+      window.addEventListener('pagehide', () => {
+        window.removeEventListener('touchstart', onTouchStart);
+        window.removeEventListener('touchmove', onTouchMove);
+        window.removeEventListener('touchend', onTouchEnd);
+      });
+    </script>
+
+  ''';
 }

core/lib/utils/platform_info.dart

@@ -1,6 +1,7 @@
 import 'package:core/utils/app_logger.dart';
 import 'package:core/utils/web_renderer/canvas_kit.dart';
 import 'package:flutter/foundation.dart';
+import 'package:universal_html/html.dart' as universal_html;
 
 abstract class PlatformInfo {
   @visibleForTesting
@@ -44,4 +45,25 @@ abstract class PlatformInfo {
     log('PlatformInfo::platformNameOS(): $platformName');
     return platformName;
   }
+
+  static String get userAgent =>
+      isWeb ? universal_html.window.navigator.userAgent.toLowerCase() : '';
+
+  /// Web browser on a mobile phone
+  static bool get isWebMobile =>
+      isWeb && (userAgent.contains('iphone') ||
+          (userAgent.contains('android') && userAgent.contains('mobile')));
+
+  /// Web browser on a tablet device
+  static bool get isWebTablet =>
+      isWeb && (userAgent.contains('ipad') ||
+          (userAgent.contains('android') && !userAgent.contains('mobile')));
+
+  /// Web browser on a desktop (PC/Mac)
+  static bool get isWebDesktop =>
+      isWeb && !isWebMobile && !isWebTablet;
+
+  /// Touch devices
+  static bool get isWebTouchDevice =>
+      isWeb && (isWebMobile || isWebTablet);
 }