fix: scroll alignment in remote page

flutter/lib/desktop/pages/remote_page.dart

@@ -286,30 +286,35 @@ class ImagePaint extends StatelessWidget {
         child: child));
 
     if (c.scrollStyle == ScrollStyle.scrollbar) {
+      final imageWidth = c.getDisplayWidth() * s;
+      final imageHeight = c.getDisplayHeight() * s;
       final imageWidget = SizedBox(
-          width: c.getDisplayWidth() * s,
+          width: imageWidth,
-          height: c.getDisplayHeight() * s,
+          height: imageHeight,
           child: CustomPaint(
             painter: ImagePainter(image: m.image, x: 0, y: 0, scale: s),
           ));
 
-      return Center(
+      return NotificationListener<ScrollNotification>(
-        child: NotificationListener<ScrollNotification>(
         onNotification: (notification) {
-            final percentX = _horizontal.position.extentBefore /
+          final percentX = _horizontal.hasClients
+              ? _horizontal.position.extentBefore /
                   (_horizontal.position.extentBefore +
                       _horizontal.position.extentInside +
-                    _horizontal.position.extentAfter);
+                      _horizontal.position.extentAfter)
-            final percentY = _vertical.position.extentBefore /
+              : 0.0;
+          final percentY = _vertical.hasClients
+              ? _vertical.position.extentBefore /
                   (_vertical.position.extentBefore +
                       _vertical.position.extentInside +
-                    _vertical.position.extentAfter);
+                      _vertical.position.extentAfter)
+              : 0.0;
           c.setScrollPercent(percentX, percentY);
           return false;
         },
         child: mouseRegion(
-              child: _buildCrossScrollbar(_buildListener(imageWidget))),
+            child: _buildCrossScrollbar(context, _buildListener(imageWidget),
-        ),
+                Size(imageWidth, imageHeight))),
       );
     } else {
       final imageWidget = SizedBox(
@@ -342,44 +347,96 @@ class ImagePaint extends StatelessWidget {
     }
   }
 
-  Widget _buildCrossScrollbar(Widget child) {
+  Widget _buildCrossScrollbarFromLayout(
+      BuildContext context, Widget child, Size layoutSize, Size size) {
     final scrollConfig = CustomMouseWheelScrollConfig(
         scrollDuration: kDefaultScrollDuration,
         scrollCurve: Curves.linearToEaseOut,
         mouseWheelTurnsThrottleTimeMs:
             kDefaultMouseWheelThrottleDuration.inMilliseconds,
         scrollAmountMultiplier: kDefaultScrollAmountMultiplier);
-    return Obx(() => ImprovedScrolling(
+    var widget = child;
-        scrollController: _vertical,
+    if (layoutSize.width < size.width) {
-        enableCustomMouseWheelScrolling: cursorOverImage.isFalse,
+      widget = ScrollConfiguration(
-        customMouseWheelScrollConfig: scrollConfig,
+        behavior: ScrollConfiguration.of(context).copyWith(scrollbars: false),
-        child: ImprovedScrolling(
-            scrollController: _horizontal,
-            enableCustomMouseWheelScrolling: cursorOverImage.isFalse,
-            customMouseWheelScrollConfig: scrollConfig,
-            child: Scrollbar(
-                controller: _vertical,
-                thumbVisibility: false,
-                trackVisibility: false,
-                child: Scrollbar(
-                    controller: _horizontal,
-                    thumbVisibility: false,
-                    trackVisibility: false,
-                    notificationPredicate: (notif) => notif.depth == 1,
-                    child: SingleChildScrollView(
-                      controller: _vertical,
-                      physics: cursorOverImage.isTrue
-                          ? const NeverScrollableScrollPhysics()
-                          : null,
         child: SingleChildScrollView(
           controller: _horizontal,
           scrollDirection: Axis.horizontal,
           physics: cursorOverImage.isTrue
               ? const NeverScrollableScrollPhysics()
               : null,
-                        child: child,
+          child: widget,
         ),
-                    ))))));
+      );
+    } else {
+      widget = Row(
+        mainAxisAlignment: MainAxisAlignment.center,
+        children: [widget],
+      );
+    }
+    if (layoutSize.height < size.height) {
+      widget = ScrollConfiguration(
+        behavior: ScrollConfiguration.of(context).copyWith(scrollbars: false),
+        child: SingleChildScrollView(
+          controller: _vertical,
+          physics: cursorOverImage.isTrue
+              ? const NeverScrollableScrollPhysics()
+              : null,
+          child: widget,
+        ),
+      );
+    } else {
+      widget = Column(
+        mainAxisAlignment: MainAxisAlignment.center,
+        children: [widget],
+      );
+    }
+    if (layoutSize.width < size.width) {
+      widget = ImprovedScrolling(
+        scrollController: _horizontal,
+        enableCustomMouseWheelScrolling: cursorOverImage.isFalse,
+        customMouseWheelScrollConfig: scrollConfig,
+        child: RawScrollbar(
+          thumbColor: Colors.grey,
+          controller: _horizontal,
+          thumbVisibility: false,
+          trackVisibility: false,
+          notificationPredicate: (notification) => notification.depth == 1,
+          child: widget,
+        ),
+      );
+    }
+    if (layoutSize.height < size.height) {
+      widget = ImprovedScrolling(
+        scrollController: _vertical,
+        enableCustomMouseWheelScrolling: cursorOverImage.isFalse,
+        customMouseWheelScrollConfig: scrollConfig,
+        child: RawScrollbar(
+          thumbColor: Colors.grey,
+          controller: _vertical,
+          thumbVisibility: false,
+          trackVisibility: false,
+          child: widget,
+        ),
+      );
+    }
+
+    return widget;
+  }
+
+  Widget _buildCrossScrollbar(BuildContext context, Widget child, Size size) {
+    var layoutSize = MediaQuery.of(context).size;
+    layoutSize = Size(
+        layoutSize.width - kWindowBorderWidth * 2,
+        layoutSize.height -
+            kWindowBorderWidth * 2 -
+            kDesktopRemoteTabBarHeight);
+    bool overflow =
+        layoutSize.width < size.width || layoutSize.height < size.height;
+    return overflow
+        ? Obx(() =>
+            _buildCrossScrollbarFromLayout(context, child, layoutSize, size))
+        : _buildCrossScrollbarFromLayout(context, child, layoutSize, size);
   }
 
   Widget _buildListener(Widget child) {