Fix issue where image would keep reloading because we keep trying to recalculate size

Author: tneotia

example/lib/main.dart

@@ -74,7 +74,7 @@ const htmlData = r"""
         <td rowspan='2'>Rowspan\nRowspan\nRowspan\nRowspan\nRowspan\nRowspan\nRowspan\nRowspan\nRowspan\nRowspan</td><td>Data</td><td>Data</td>
       </tr>
       <tr>
-        <td colspan="2"><img alt='Google' src='https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_92x30dp.png' /></td>
+        <td colspan="2"><img alt='Google' src='https://hdwallsource.com/img/2014/7/large-40566-41516-hd-wallpapers.jpg' /></td>
       </tr>
       </tbody>
       <tfoot>
@@ -122,7 +122,7 @@ const htmlData = r"""
       </p>
       <h3>Image support:</h3>
       <h3>Network png</h3>
-      <img alt='Google' src='https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_92x30dp.png' />
+      <img alt='Google' src='https://hdwallsource.com/img/2014/7/large-40566-41516-hd-wallpapers.jpg' />
       <h3>Network svg</h3>
       <img src='https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/android.svg' />
       <h3>Local asset png</h3>
@@ -247,8 +247,9 @@ class _MyHomePageState extends State<MyHomePage> {
         title: Text('flutter_html Example'),
         centerTitle: true,
       ),
-      body: SingleChildScrollView(
-        child: Html(
+      body: ListView.builder(
+        itemCount: 5,
+        itemBuilder: (context, index) => Html(
           data: htmlData,
           tagsList: Html.tags..addAll(["bird", "flutter"]),
           style: {
@@ -273,7 +274,7 @@ class _MyHomePageState extends State<MyHomePage> {
               return SingleChildScrollView(
                 scrollDirection: Axis.horizontal,
                 child:
-                    (context.tree as TableLayoutElement).toWidget(context),
+                (context.tree as TableLayoutElement).toWidget(context),
               );
             },
             "bird": (RenderContext context, Widget child) {
@@ -295,19 +296,19 @@ class _MyHomePageState extends State<MyHomePage> {
               return FlutterLogo(size: 36);
             },
             networkSourceMatcher(domains: ["mydomain.com"]):
-                networkImageRender(
+            networkImageRender(
               headers: {"Custom-Header": "some-value"},
               altWidget: (alt) => Text(alt ?? ""),
               loadingWidget: () => Text("Loading..."),
             ),
             // On relative paths starting with /wiki, prefix with a base url
-            (attr, _) =>
-                    attr["src"] != null && attr["src"]!.startsWith("/wiki"):
-                networkImageRender(
-                    mapUrl: (url) => "https://upload.wikimedia.org" + url!),
+                (attr, _) =>
+            attr["src"] != null && attr["src"]!.startsWith("/wiki"):
+            networkImageRender(
+                mapUrl: (url) => "https://upload.wikimedia.org" + url!),
             // Custom placeholder image for broken links
             networkSourceMatcher():
-                networkImageRender(altWidget: (_) => FlutterLogo()),
+            networkImageRender(altWidget: (_) => FlutterLogo()),
           },
           onLinkTap: (url, _, __, ___) {
             print("Opening $url...");
@@ -326,7 +327,7 @@ class _MyHomePageState extends State<MyHomePage> {
             });
           },
         ),
-      ),
+      )
     );
   }
 }

lib/html_parser.dart

@@ -61,6 +61,8 @@ class HtmlParser extends StatelessWidget {
   final TextSelectionControls? selectionControls;
   final ScrollPhysics? scrollPhysics;
 
+  final Map<String, Size> cachedImageSizes = {};
+
   HtmlParser({
     required this.key,
     required this.htmlData,

lib/image_render.dart

@@ -120,37 +120,43 @@ ImageRender networkImageRender({
         },
       );
       Completer<Size> completer = Completer();
-      Image image = Image.network(src, frameBuilder: (ctx, child, frame, _) {
-        if (frame == null) {
+      if (context.parser.cachedImageSizes[src] != null) {
+        completer.complete(context.parser.cachedImageSizes[src]);
+      } else {
+        Image image = Image.network(src, frameBuilder: (ctx, child, frame, _) {
+          if (frame == null) {
+            if (!completer.isCompleted) {
+              completer.completeError("error");
+            }
+            return child;
+          } else {
+            return child;
+          }
+        });
+
+        ImageStreamListener? listener;
+        listener = ImageStreamListener((ImageInfo imageInfo, bool synchronousCall) {
+          var myImage = imageInfo.image;
+          Size size = Size(myImage.width.toDouble(), myImage.height.toDouble());
           if (!completer.isCompleted) {
-            completer.completeError("error");
+            context.parser.cachedImageSizes[src] = size;
+            completer.complete(size);
+            image.image.resolve(ImageConfiguration()).removeListener(listener!);
           }
-          return child;
-        } else {
-          return child;
-        }
-      });
-
-      var listener =
-          ImageStreamListener((ImageInfo image, bool synchronousCall) {
-        var myImage = image.image;
-        Size size = Size(myImage.width.toDouble(), myImage.height.toDouble());
-        if (!completer.isCompleted) {
-          completer.complete(size);
-        }
-      }, onError: (object, stacktrace) {
-        if (!completer.isCompleted) {
-          completer.completeError(object);
-        }
-      });
-
-      image.image.resolve(ImageConfiguration()).addListener(listener);
+        }, onError: (object, stacktrace) {
+          if (!completer.isCompleted) {
+            completer.completeError(object);
+            image.image.resolve(ImageConfiguration()).removeListener(listener!);
+          }
+        });
+
+        image.image.resolve(ImageConfiguration()).addListener(listener);
+      }
+
       return FutureBuilder<Size>(
         future: completer.future,
+        initialData: context.parser.cachedImageSizes[src],
         builder: (BuildContext buildContext, AsyncSnapshot<Size> snapshot) {
-          if (completer.isCompleted) {
-            image.image.resolve(ImageConfiguration()).removeListener(listener);
-          }
           if (snapshot.hasData) {
             return Container(
               constraints: BoxConstraints(