Minor optimization

@@ -114,7 +114,7 @@ class PdfPreviewCustomState extends State<PdfPreviewCustom>
     with PdfPreviewRaster {
     with PdfPreviewRaster {
   final listView = GlobalKey();
   final listView = GlobalKey();
 
 
-  late List<GlobalKey> _pageGlobalKeys;
+  List<GlobalKey> _pageGlobalKeys = <GlobalKey>[];
 
 
   bool infoLoaded = false;
   bool infoLoaded = false;
 
 
@@ -221,22 +221,15 @@ class PdfPreviewCustomState extends State<PdfPreviewCustom>
           );
           );
     }
     }
 
 
-    _pageGlobalKeys = List.generate(pages.length, (index) => GlobalKey());
+    if (widget.enableScrollToPage) {
+      _pageGlobalKeys = List.generate(pages.length, (_) => GlobalKey());
+    }
 
 
     if (widget.pagesBuilder != null) {
     if (widget.pagesBuilder != null) {
       return widget.pagesBuilder!(context, pages);
       return widget.pagesBuilder!(context, pages);
     }
     }
 
 
-    return widget.enableScrollToPage
-        ? Scrollbar(
-            controller: scrollController,
-            child: SingleChildScrollView(
-              controller: scrollController,
-              physics: widget.scrollPhysics,
-              child: Column(
-                children: List.generate(
-                  pages.length,
-                  (index) => GestureDetector(
+    Widget pageWidget(int index, {Key? key}) => GestureDetector(
           onDoubleTap: () {
           onDoubleTap: () {
             setState(() {
             setState(() {
               updatePosition = scrollController.position.pixels;
               updatePosition = scrollController.position.pixels;
@@ -245,12 +238,24 @@ class PdfPreviewCustomState extends State<PdfPreviewCustom>
             });
             });
           },
           },
           child: PdfPreviewPage(
           child: PdfPreviewPage(
-                      key: getPageKey(index),
+            key: key,
             pageData: pages[index],
             pageData: pages[index],
             pdfPreviewPageDecoration: widget.pdfPreviewPageDecoration,
             pdfPreviewPageDecoration: widget.pdfPreviewPageDecoration,
             pageMargin: widget.previewPageMargin,
             pageMargin: widget.previewPageMargin,
           ),
           ),
-                  ),
+        );
+
+    return widget.enableScrollToPage
+        ? Scrollbar(
+            controller: scrollController,
+            child: SingleChildScrollView(
+              controller: scrollController,
+              physics: widget.scrollPhysics,
+              padding: widget.padding,
+              child: Column(
+                children: List.generate(
+                  pages.length,
+                  (index) => pageWidget(index, key: getPageKey(index)),
                 ),
                 ),
               ),
               ),
             ),
             ),
@@ -261,21 +266,7 @@ class PdfPreviewCustomState extends State<PdfPreviewCustom>
             physics: widget.scrollPhysics,
             physics: widget.scrollPhysics,
             padding: widget.padding,
             padding: widget.padding,
             itemCount: pages.length,
             itemCount: pages.length,
-            itemBuilder: (BuildContext context, int index) => GestureDetector(
-              onDoubleTap: () {
-                setState(() {
-                  updatePosition = scrollController.position.pixels;
-                  preview = index;
-                  transformationController.value.setIdentity();
-                });
-              },
-              child: PdfPreviewPage(
-                key: getPageKey(index),
-                pageData: pages[index],
-                pdfPreviewPageDecoration: widget.pdfPreviewPageDecoration,
-                pageMargin: widget.previewPageMargin,
-              ),
-            ),
+            itemBuilder: (BuildContext context, int index) => pageWidget(index),
           );
           );
   }
   }