feat: copy underline

frontend/app_flowy/packages/flowy_editor/lib/src/document/selection.dart

@@ -46,6 +46,13 @@ class Selection {
       (start.path <= end.path && !pathEquals(start.path, end.path)) ||
       (isSingle && start.offset < end.offset);
 
+  Selection normalize() {
+    if (isForward) {
+      return Selection(start: end, end: start);
+    }
+    return this;
+  }
+
   Selection get reversed => copyWith(start: end, end: start);
 
   Selection collapse({bool atStart = false}) {

frontend/app_flowy/packages/flowy_editor/lib/src/infra/html_converter.dart

@@ -18,6 +18,7 @@ const String tagParagraph = "p";
 const String tagImage = "img";
 const String tagAnchor = "a";
 const String tagBold = "b";
+const String tagUnderline = "u";
 const String tagStrong = "strong";
 const String tagSpan = "span";
 const String tagCode = "code";
@@ -54,7 +55,8 @@ class HTMLToNodesConverter {
         if (child.localName == tagAnchor ||
             child.localName == tagSpan ||
             child.localName == tagCode ||
-            child.localName == tagStrong) {
+            child.localName == tagStrong ||
+            child.localName == tagUnderline) {
           _handleRichTextElement(delta, child);
         } else if (child.localName == tagBold) {
           // Google docs wraps the the content inside the `<b></b>` tag.
@@ -203,6 +205,8 @@ class HTMLToNodesConverter {
       delta.insert(element.text, attributes);
     } else if (element.localName == tagStrong || element.localName == tagBold) {
       delta.insert(element.text, {"bold": true});
+    } else if (element.localName == tagUnderline) {
+      delta.insert(element.text, {"underline": true});
     } else {
       delta.insert(element.text);
     }
@@ -454,6 +458,11 @@ class NodesToHTMLConverter {
             final strong = html.Element.tag(tagStrong);
             strong.append(html.Text(op.content));
             childNodes.add(strong);
+          } else if (attributes.length == 1 &&
+              attributes[StyleKey.underline] == true) {
+            final strong = html.Element.tag(tagUnderline);
+            strong.append(html.Text(op.content));
+            childNodes.add(strong);
           } else {
             final span = html.Element.tag(tagSpan);
             final cssString = _attributesToCssStyle(attributes);

frontend/app_flowy/packages/flowy_editor/lib/src/service/internal_key_event_handlers/copy_paste_handler.dart

@@ -6,10 +6,11 @@ import 'package:flutter/services.dart';
 import 'package:rich_clipboard/rich_clipboard.dart';
 
 _handleCopy(EditorState editorState) async {
-  final selection = editorState.cursorSelection;
+  var selection = editorState.cursorSelection;
   if (selection == null || selection.isCollapsed) {
     return;
   }
+  selection = selection.normalize();
   if (pathEquals(selection.start.path, selection.end.path)) {
     final nodeAtPath = editorState.document.nodeAtPath(selection.end.path)!;
     if (nodeAtPath.type == "text") {