feat: add scroll animtion on mobile (#1154)

Author: LucasXu0

lib/src/editor/editor_component/service/scroll_service_widget.dart

@@ -135,21 +135,34 @@ class _ScrollServiceWidgetState extends State<ScrollServiceWidget>
       final endTouchPoint = targetRect.centerRight;
 
       if (PlatformExtension.isMobile) {
+        // Determine if this is a drag operation
+        final bool isDragOperation = dragMode != null &&
+            (dragMode.toString() ==
+                    'MobileSelectionDragMode.leftSelectionHandle' ||
+                dragMode.toString() ==
+                    'MobileSelectionDragMode.rightSelectionHandle');
+
+        // Use animation for drag operations, instant for others
+        final scrollDuration =
+            isDragOperation ? const Duration(milliseconds: 2) : Duration.zero;
+
         // soft keyboard
         // workaround: wait for the soft keyboard to show up
-        final duration = KeyboardHeightObserver.currentKeyboardHeight == 0
+        final keyboardDelay = KeyboardHeightObserver.currentKeyboardHeight == 0
             ? const Duration(milliseconds: 250)
             : Duration.zero;
 
-        Future.delayed(duration, () {
+        Future.delayed(keyboardDelay, () {
           if (_forwardKey.currentContext == null) {
             return;
           }
+          // Mobile needs to continuously update scroll position/direction during drag
+          // Don't skip even if already scrolling, because direction may have changed
           startAutoScroll(
             endTouchPoint,
             edgeOffset: editorState.autoScrollEdgeOffset,
             direction: direction,
-            duration: Duration.zero,
+            duration: scrollDuration,
           );
         });
       } else {

lib/src/editor_state.dart

@@ -636,9 +636,9 @@ class EditorState {
       late AutoScroller scroller;
       scroller = AutoScroller(
         scrollableState,
-        velocityScalar: isDesktopOrWeb ? 0.15 : 0.02,
-        minimumAutoScrollDelta: isDesktopOrWeb ? 0.07 : 0.004,
-        maxAutoScrollDelta: isDesktopOrWeb ? 3.5 : 0.053,
+        velocityScalar: 0.15,
+        minimumAutoScrollDelta: 0.07,
+        maxAutoScrollDelta: 3.5,
         animationDuration: Duration.zero,
         onScrollViewScrolled: () {
           _notifyScrollViewScrolledListeners();