[SuperText] - Add support for inline widgets (Resolves #2441)

super_text_layout/lib/src/inline_widgets.dart

@@ -0,0 +1,31 @@
+/// A placeholder to be given to an `AttributedText`, and later replaced
+/// within an inline network image.
+class InlineNetworkImagePlaceholder {
+  const InlineNetworkImagePlaceholder(this.url);
+
+  final String url;
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is InlineNetworkImagePlaceholder && runtimeType == other.runtimeType && url == other.url;
+
+  @override
+  int get hashCode => url.hashCode;
+}
+
+/// A placeholder to be given to an `AttributedText`, and later replaced
+/// within an inline asset image.
+class InlineAssetImagePlaceholder {
+  const InlineAssetImagePlaceholder(this.assetPath);
+
+  final String assetPath;
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is InlineAssetImagePlaceholder && runtimeType == other.runtimeType && assetPath == other.assetPath;
+
+  @override
+  int get hashCode => assetPath.hashCode;
+}

super_text_layout/lib/src/super_text_layout_with_selection.dart

@@ -246,7 +246,13 @@ class _RebuildOptimizedSuperTextWithSelectionState extends State<_RebuildOptimiz
                   style: userSelection.caretStyle,
                   blinkCaret: userSelection.blinkCaret,
                   blinkTimingMode: userSelection.blinkTimingMode,
-                  position: userSelection.selection.extent,
+                  position: TextPosition(
+                    offset: userSelection.selection.extent.offset,
+                    affinity: TextAffinity.downstream,
+                  ),
+                  // ^ We force downstream, instead of upstream, to reduce the buggyness
+                  //   of caret sizing in Flutter when placed near an inline widget.
+                  //   Issue: https://github.com/flutter/flutter/issues/159932
                   caretTracker: userSelection.caretFollower,
                 ),
           ],

super_text_layout/lib/src/text_selection_layer.dart

@@ -1,3 +1,5 @@
+import 'dart:ui';
+
 import 'package:flutter/widgets.dart';
 
 import 'text_layout.dart';
@@ -160,7 +162,10 @@ class TextSelectionPainter extends CustomPainter {
       return;
     }
 
-    final selectionBoxes = textLayout!.getBoxesForSelection(textSelection!);
+    final selectionBoxes = textLayout!.getBoxesForSelection(
+      textSelection!,
+      boxHeightStyle: BoxHeightStyle.max,
+    );
 
     for (final box in selectionBoxes) {
       final rawRect = box.toRect();

super_text_layout/lib/super_text_layout.dart

@@ -1,4 +1,5 @@
 export 'src/caret_layer.dart';
+export 'src/inline_widgets.dart';
 export 'src/super_text.dart';
 export 'src/super_text_layout_with_selection.dart';
 export 'src/text_layout.dart';