LibWeb: Delete entire grapheme clusters on backspace/delete key presses

Author: https://github.com/trflynn89
Commit: https://github.com/SerenityOS/serenity/commit/fb6ca386cc
Pull-request: https://github.com/SerenityOS/serenity/pull/17679
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/Page/EditEventHandler.cpp

@@ -6,6 +6,7 @@
 
 #include <AK/StringBuilder.h>
 #include <AK/Utf8View.h>
+#include <LibUnicode/Segmentation.h>
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/DOM/Position.h>
 #include <LibWeb/DOM/Range.h>
@@ -16,20 +17,20 @@
 
 namespace Web {
 
-void EditEventHandler::handle_delete_character_after(const DOM::Position& cursor_position)
+void EditEventHandler::handle_delete_character_after(DOM::Position const& cursor_position)
 {
-    if (cursor_position.offset_is_at_end_of_node()) {
+    auto& node = *static_cast<DOM::Text*>(const_cast<DOM::Node*>(cursor_position.node()));
+    auto& text = node.data();
+
+    auto next_grapheme_offset = Unicode::next_grapheme_segmentation_boundary(Utf8View { text }, cursor_position.offset());
+    if (!next_grapheme_offset.has_value()) {
         // FIXME: Move to the next node and delete the first character there.
         return;
     }
 
-    auto& node = *static_cast<DOM::Text*>(const_cast<DOM::Node*>(cursor_position.node()));
-    auto& text = node.data();
-    auto code_point_length = Utf8View(text).iterator_at_byte_offset(cursor_position.offset()).underlying_code_point_length_in_bytes();
-
     StringBuilder builder;
     builder.append(text.substring_view(0, cursor_position.offset()));
-    builder.append(text.substring_view(cursor_position.offset() + code_point_length));
+    builder.append(text.substring_view(*next_grapheme_offset));
     node.set_data(builder.to_deprecated_string());
 
     // FIXME: When nodes are removed from the DOM, the associated layout nodes become stale and still

Userland/Libraries/LibWeb/Page/EditEventHandler.h

@@ -20,7 +20,7 @@ public:
 
     virtual ~EditEventHandler() = default;
 
-    virtual void handle_delete_character_after(const DOM::Position&);
+    virtual void handle_delete_character_after(DOM::Position const&);
     virtual void handle_delete(DOM::Range&);
     virtual void handle_insert(DOM::Position, u32 code_point);