1.修复android11图片预览滑动异常的问题

lib/util/photo_preview/photo_preview.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:io';
 import 'package:flutter/material.dart';
 import 'package:loading_indicator/loading_indicator.dart';
@@ -12,54 +13,41 @@ class PhotoPreview extends StatefulWidget {
   int index;
   String heroTagSuffix;
 
-  PhotoPreview(
-      {Key key,
-      this.previewImageDatas,
-      this.index = 0,
-      this.heroTagSuffix = ""})
-      : super(key: key);
-
-  PhotoPreview._showPhotoViewByData(
-      {Key key,
-      this.previewImageDatas,
-      this.index = 0,
-      this.heroTagSuffix = ""})
-      : super(key: key) {
-  }
+  PhotoPreview({Key key, this.previewImageDatas, this.index = 0, this.heroTagSuffix = ""}) : super(key: key);
+
+  PhotoPreview._showPhotoViewByData({Key key, this.previewImageDatas, this.index = 0, this.heroTagSuffix = ""}) : super(key: key) {}
 
-  PhotoPreview._showPhotoViewByImages(
-      {Key key, List<String> images, this.index = 0, this.heroTagSuffix = ""})
-      : super(key: key) {
+  PhotoPreview._showPhotoViewByImages({Key key, List<String> images, this.index = 0, this.heroTagSuffix = ""}) : super(key: key) {
     if (images != null) {
       previewImageDatas = List();
       for (var img in images) {
-        previewImageDatas.add(PreviewImageData(
-            previewImageType: PreviewImageType.netUrl, data: img));
+        previewImageDatas.add(PreviewImageData(previewImageType: PreviewImageType.netUrl, data: img));
       }
     }
   }
 
   ///显示类型的一些预览
-  static showPhotoPreview(
-      BuildContext context, List<PreviewImageData> previewImageDatas,
-      {int currentIndex = 0, String heroTagSuffix}) {
-    Navigator.of(context).push(new FadeRoute(
-        page: PhotoPreview._showPhotoViewByData(
-      previewImageDatas: previewImageDatas,
-      index: currentIndex,
-      heroTagSuffix: heroTagSuffix,
-    )));
+  static showPhotoPreview(BuildContext context, List<PreviewImageData> previewImageDatas, {int currentIndex = 0, String heroTagSuffix}) {
+    Navigator.push(
+        context,
+        MaterialPageRoute(
+            builder: (_) => PhotoPreview._showPhotoViewByData(
+              previewImageDatas: previewImageDatas,
+              index: currentIndex,
+              heroTagSuffix: heroTagSuffix,
+            )));
   }
 
   ///显示仅仅是一组list<String>类型的图片预览
-  static showPhotoPreviewByimages(BuildContext context, List<String> images,
-      {int currentIndex = 0, String heroTagSuffix = ""}) {
-    Navigator.of(context).push(new FadeRoute(
-        page: PhotoPreview._showPhotoViewByImages(
-      images: images,
-      index: currentIndex,
-      heroTagSuffix: heroTagSuffix,
-    )));
+  static showPhotoPreviewByimages(BuildContext context, List<String> images, {int currentIndex = 0, String heroTagSuffix = ""}) {
+    Navigator.push(
+        context,
+        MaterialPageRoute(
+            builder: (_) => PhotoPreview._showPhotoViewByImages(
+                  images: images,
+                  index: currentIndex,
+                  heroTagSuffix: heroTagSuffix,
+                )));
   }
 
   @override
@@ -67,24 +55,23 @@ class PhotoPreview extends StatefulWidget {
 }
 
 class _PhotoPreviewState extends State<PhotoPreview> {
-  PageController pageController;
-
   @override
   void initState() {
-    pageController = PageController(keepPage: true, initialPage: widget.index);
     super.initState();
   }
 
   @override
   Widget build(BuildContext context) {
-    return Scaffold(
-        backgroundColor: Colors.transparent,
-        body: PhotoViewGalleryScreen(
+    return  PhotoViewGalleryScreen(
           images: widget.previewImageDatas,
           index: widget.index,
-          controller: pageController,
           heroTagSuffix: widget.heroTagSuffix ?? "",
-        ));
+        );
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
   }
 }
 
@@ -95,8 +82,7 @@ class PreviewImageData {
   bool isSelect;
   String tag;
 
-  PreviewImageData(
-      {this.previewImageType, this.data, this.isSelect = false, this.tag});
+  PreviewImageData({this.previewImageType, this.data, this.isSelect = false, this.tag});
 }
 
 ///预览类型
@@ -113,35 +99,38 @@ class PhotoViewGalleryScreen extends StatefulWidget {
   List<PreviewImageData> images = [];
   int index = 0;
   String heroTagSuffix;
-  PageController controller;
-
-  PhotoViewGalleryScreen(
-      {Key key,
-      @required this.images,
-      this.index,
-      this.controller,
-      this.heroTagSuffix})
-      : super(key: key) {
-    controller = PageController(initialPage: index);
-  }
+
+  PhotoViewGalleryScreen({Key key, @required this.images, this.index, this.heroTagSuffix}) : super(key: key);
 
   @override
   _PhotoViewGalleryScreenState createState() => _PhotoViewGalleryScreenState();
 }
 
-class _PhotoViewGalleryScreenState extends State<PhotoViewGalleryScreen> {
+class _PhotoViewGalleryScreenState extends State<PhotoViewGalleryScreen> with AutomaticKeepAliveClientMixin {
   int currentIndex = 0;
+  PageController pageController;
+  PhotoViewScaleStateController scaleStateController;
 
   @override
   void initState() {
+    scaleStateController = PhotoViewScaleStateController();
     // TODO: implement initState
-    super.initState();
+    pageController = PageController(initialPage: widget?.index ?? 0);
     currentIndex = widget.index;
+    super.initState();
+  }
+
+  @override
+  void dispose() {
+    scaleStateController.dispose();
+    pageController.dispose();
+    super.dispose();
   }
 
   @override
   Widget build(BuildContext context) {
     return Scaffold(
+      backgroundColor: Colors.black,
       body: Stack(
         children: <Widget>[
           GestureDetector(
@@ -149,45 +138,45 @@ class _PhotoViewGalleryScreenState extends State<PhotoViewGalleryScreen> {
               Navigator.pop(context);
             },
             child: Container(
-                color: Colors.black,
-                child: PhotoViewGallery.builder(
-                  scrollPhysics: const BouncingScrollPhysics(),
-                  builder: (BuildContext context, int index) {
-                    return PhotoViewGalleryPageOptions(
-                      imageProvider: _buildPage(context, index),
-                      heroAttributes: widget.heroTagSuffix.isNotEmpty
-                          ? PhotoViewHeroAttributes(
-                              tag: (widget.images[index].data ?? "") +
-                                  widget.heroTagSuffix)
-                          : null,
-                    );
-                  },
-                  itemCount: widget.images.length,
-                  loadFailedChild: Container(
-                    child: Text("加载失败"),
-                  ),
-                  loadingBuilder: (context,event){
-                    return Column(
-                      mainAxisAlignment: MainAxisAlignment.center,
-                      children: <Widget>[
-                        Container(
+              margin: EdgeInsets.all(1),
+              child: PhotoViewGallery.builder(
+                scrollPhysics: const BouncingScrollPhysics(),
+                builder: (BuildContext context, int index) {
+                  return PhotoViewGalleryPageOptions(
+                    scaleStateController: scaleStateController,
+                    imageProvider: _buildPage(context, index),
+                    heroAttributes: widget.heroTagSuffix.isNotEmpty ? PhotoViewHeroAttributes(tag: (widget.images[index].data ?? "") + widget.heroTagSuffix) : null,
+                  );
+                },
+                itemCount: widget.images.length,
+                loadFailedChild: Container(
+                  child: Text("加载失败"),
+                ),
+                loadingBuilder: (context, event) {
+                  return Column(
+                    mainAxisAlignment: MainAxisAlignment.center,
+                    children: <Widget>[
+                      Container(
                           width: 48,
-                          constraints: BoxConstraints(maxWidth: 48,maxHeight: 48),
+                          constraints: BoxConstraints(maxWidth: 48, maxHeight: 48),
                           height: 48,
-                          child: LoadingIndicator(indicatorType: Indicator.ballSpinFadeLoader,color: Colors.white,)
-                        ),
-                      ],
-                    );
-                  },
-                  backgroundDecoration: BoxDecoration(color: Colors.black),
-                  pageController: widget.controller,
-                  enableRotation: true,
-                  onPageChanged: (index) {
-                    setState(() {
-                      currentIndex = index;
-                    });
-                  },
-                )),
+                          child: LoadingIndicator(
+                            indicatorType: Indicator.ballSpinFadeLoader,
+                            color: Colors.white,
+                          )),
+                    ],
+                  );
+                },
+                backgroundDecoration: BoxDecoration(color: Colors.black),
+                pageController: pageController,
+                enableRotation: true,
+                onPageChanged: (index) {
+                  setState(() {
+                    currentIndex = index;
+                  });
+                },
+              ),
+            ),
           ),
           Positioned(
             //图片index显示
@@ -195,8 +184,7 @@ class _PhotoViewGalleryScreenState extends State<PhotoViewGalleryScreen> {
             width: MediaQuery.of(context).size.width,
             child: Container(
               child: Center(
-                child: Text("${currentIndex + 1}/${widget.images.length}",
-                    style: TextStyle(color: Colors.white, fontSize: 16)),
+                child: Text("${currentIndex + 1}/${widget.images.length}", style: TextStyle(color: Colors.white, fontSize: 16)),
               ),
             ),
           ),
@@ -228,6 +216,10 @@ class _PhotoViewGalleryScreenState extends State<PhotoViewGalleryScreen> {
       return Image.file(File(item.data)).image;
     }
   }
+
+  @override
+  // TODO: implement wantKeepAlive
+  bool get wantKeepAlive => true;
 }
 
 class FadeRoute extends PageRouteBuilder {