added layoutbuilder to optimize code and simplify logic

lib/widgets/post.dart

@@ -99,39 +99,11 @@ class PostWidget extends HookWidget {
     );
   }
 
-  List<ui.LineMetrics> postNeedsToTruncate(
-    String body,
-    Size size,
-    ui.TextDirection textDirection,
-  ) {
-    final span = TextSpan(
-      text: body,
-    );
-    final tp = TextPainter(
-      text: span,
-      maxLines: 20,
-      textDirection: textDirection,
-    )..layout(maxWidth: size.width - 20);
-
-    return tp.computeLineMetrics();
-  }
-
   // == UI ==
 
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
-    final textPostData = post.post.body == null
-        ? []
-        : postNeedsToTruncate(
-            post.post.body,
-            MediaQuery.of(context).size,
-            Directionality.of(context),
-          );
-
-    final textPostLineHeight = textPostData.isNotEmpty
-        ? (textPostData.first as ui.LineMetrics).height
-        : 0.0;
 
     void _openLink() => linkLauncher(
         context: context, url: post.post.url, instanceHost: instanceHost);
@@ -455,16 +427,21 @@ class PostWidget extends HookWidget {
                   padding: const EdgeInsets.all(10),
                   child:
                       MarkdownText(post.post.body, instanceHost: instanceHost)),
-            if (post.post.body != null &&
+            if (post.post.body != null && !fullPost)
-                !fullPost &&
+              LayoutBuilder(
-                textPostData.length <= 20)
+                builder: (context, constraints) {
-              Padding(
+                  final span = TextSpan(
-                  padding: const EdgeInsets.all(10),
+                    text: post.post.body,
-                  child:
+                  );
-                      MarkdownText(post.post.body, instanceHost: instanceHost)),
+                  final tp = TextPainter(
-            if (post.post.body != null && !fullPost && textPostData.length > 20)
+                    text: span,
-              Container(
+                    maxLines: 20,
-                constraints: BoxConstraints(maxHeight: textPostLineHeight * 20),
+                    textDirection: Directionality.of(context),
+                  )..layout(maxWidth: constraints.maxWidth - 20);
+
+                  if (tp.didExceedMaxLines) {
+                    return Container(
+                      constraints: BoxConstraints(maxHeight: tp.height),
                       child: Stack(
                         alignment: Alignment.bottomCenter,
                         children: [
@@ -479,7 +456,7 @@ class PostWidget extends HookWidget {
                             ),
                           ),
                           Container(
-                      height: textPostLineHeight * 4,
+                            height: tp.preferredLineHeight * 4,
                             decoration: BoxDecoration(
                               gradient: LinearGradient(
                                 begin: Alignment.topCenter,
@@ -493,6 +470,14 @@ class PostWidget extends HookWidget {
                           ),
                         ],
                       ),
+                    );
+                  } else {
+                    return Padding(
+                        padding: const EdgeInsets.all(10),
+                        child: MarkdownText(post.post.body,
+                            instanceHost: instanceHost));
+                  }
+                },
               ),
             actions(),
           ],