UI/Qt: Reduce flicker when populating autocomplete

Previously, autocomplete was cleared before the results for the current
query were retrieved. The new results would then be added when the
network request completed. This resulted in a noticable flicker. The
results are now updated when the request for the current query is
completed.

There is a small behavior change in that the query itself is no longer
included in the autocomplete dropdown unless the list would otherwise
be empty.

Author: tcl3

Ladybird/Qt/AutoComplete.cpp

@@ -38,7 +38,7 @@ AutoComplete::AutoComplete(QWidget* parent)
     });
 }
 
-ErrorOr<void> AutoComplete::parse_google_autocomplete(Vector<JsonValue> const& json)
+ErrorOr<Vector<String>> AutoComplete::parse_google_autocomplete(Vector<JsonValue> const& json)
 {
     if (json.size() != 5)
         return Error::from_string_view("Invalid JSON, expected 5 elements in array"sv);
@@ -54,26 +54,28 @@ ErrorOr<void> AutoComplete::parse_google_autocomplete(Vector<JsonValue> const& j
     if (query != m_query)
         return Error::from_string_view("Invalid JSON, query does not match"sv);
 
-    for (auto& suggestion : suggestions_array) {
-        m_auto_complete_model->add(TRY(String::from_byte_string(suggestion.as_string())));
-    }
+    Vector<String> results;
+    results.ensure_capacity(suggestions_array.size());
+    for (auto& suggestion : suggestions_array)
+        results.unchecked_append(MUST(String::from_byte_string(suggestion.as_string())));
 
-    return {};
+    return results;
 }
 
-ErrorOr<void> AutoComplete::parse_duckduckgo_autocomplete(Vector<JsonValue> const& json)
+ErrorOr<Vector<String>> AutoComplete::parse_duckduckgo_autocomplete(Vector<JsonValue> const& json)
 {
+    Vector<String> results;
     for (auto const& suggestion : json) {
         auto maybe_value = suggestion.as_object().get("phrase"sv);
         if (!maybe_value.has_value())
             continue;
-        m_auto_complete_model->add(TRY(String::from_byte_string(maybe_value->as_string())));
+        results.append(MUST(String::from_byte_string(maybe_value->as_string())));
     }
 
-    return {};
+    return results;
 }
 
-ErrorOr<void> AutoComplete::parse_yahoo_autocomplete(JsonObject const& json)
+ErrorOr<Vector<String>> AutoComplete::parse_yahoo_autocomplete(JsonObject const& json)
 {
     if (!json.get("q"sv).has_value() || !json.get("q"sv)->is_string())
         return Error::from_string_view("Invalid JSON, expected \"q\" to be a string"sv);
@@ -86,6 +88,8 @@ ErrorOr<void> AutoComplete::parse_yahoo_autocomplete(JsonObject const& json)
     if (query != m_query)
         return Error::from_string_view("Invalid JSON, query does not match"sv);
 
+    Vector<String> results;
+    results.ensure_capacity(suggestions_object.size());
     for (auto& suggestion_object : suggestions_object) {
         if (!suggestion_object.is_object())
             return Error::from_string_view("Invalid JSON, expected value to be an object"sv);
@@ -94,10 +98,10 @@ ErrorOr<void> AutoComplete::parse_yahoo_autocomplete(JsonObject const& json)
         if (!suggestion.get("k"sv).has_value() || !suggestion.get("k"sv)->is_string())
             return Error::from_string_view("Invalid JSON, expected \"k\" to be a string"sv);
 
-        m_auto_complete_model->add(TRY(String::from_byte_string(suggestion.get("k"sv)->as_string())));
-    };
+        results.unchecked_append(MUST(String::from_byte_string(suggestion.get("k"sv)->as_string())));
+    }
 
-    return {};
+    return results;
 }
 
 ErrorOr<void> AutoComplete::got_network_response(QNetworkReply* reply)
@@ -109,16 +113,23 @@ ErrorOr<void> AutoComplete::got_network_response(QNetworkReply* reply)
     auto json = TRY(parser.parse());
 
     auto engine_name = Settings::the()->autocomplete_engine().name;
-    if (engine_name == "Google")
-        return parse_google_autocomplete(json.as_array().values());
-
-    if (engine_name == "DuckDuckGo")
-        return parse_duckduckgo_autocomplete(json.as_array().values());
+    Vector<String> results;
+    if (engine_name == "Google") {
+        results = TRY(parse_google_autocomplete(json.as_array().values()));
+    } else if (engine_name == "DuckDuckGo") {
+        results = TRY(parse_duckduckgo_autocomplete(json.as_array().values()));
+    } else if (engine_name == "Yahoo")
+        results = TRY(parse_yahoo_autocomplete(json.as_object()));
+    else {
+        return Error::from_string_view("Invalid engine name"sv);
+    }
 
-    if (engine_name == "Yahoo")
-        return parse_yahoo_autocomplete(json.as_object());
+    if (results.is_empty()) {
+        results.append(m_query);
+    }
 
-    return Error::from_string_view("Invalid engine name"sv);
+    m_auto_complete_model->replace_suggestions(move(results));
+    return {};
 }
 
 String AutoComplete::auto_complete_url_from_query(StringView query)
@@ -138,9 +149,6 @@ void AutoComplete::get_search_suggestions(String search_string)
     if (m_reply)
         m_reply->abort();
 
-    m_auto_complete_model->clear();
-    m_auto_complete_model->add(m_query);
-
     QNetworkRequest request { QUrl(qstring_from_ak_string(auto_complete_url_from_query(m_query))) };
     m_reply = m_manager->get(request);
 }

Ladybird/Qt/AutoComplete.h

@@ -45,6 +45,13 @@ class AutoCompleteModel final : public QAbstractListModel {
         endResetModel();
     }
 
+    void replace_suggestions(Vector<String> suggestions)
+    {
+        beginInsertRows({}, m_suggestions.size(), m_suggestions.size());
+        m_suggestions = suggestions;
+        endInsertRows();
+    }
+
 private:
     AK::Vector<String> m_suggestions;
 };
@@ -71,9 +78,9 @@ class AutoComplete final : public QCompleter {
 
     ErrorOr<void> got_network_response(QNetworkReply* reply);
 
-    ErrorOr<void> parse_google_autocomplete(Vector<JsonValue> const&);
-    ErrorOr<void> parse_duckduckgo_autocomplete(Vector<JsonValue> const&);
-    ErrorOr<void> parse_yahoo_autocomplete(JsonObject const&);
+    ErrorOr<Vector<String>> parse_google_autocomplete(Vector<JsonValue> const&);
+    ErrorOr<Vector<String>> parse_duckduckgo_autocomplete(Vector<JsonValue> const&);
+    ErrorOr<Vector<String>> parse_yahoo_autocomplete(JsonObject const&);
 
     QNetworkAccessManager* m_manager;
     AutoCompleteModel* m_auto_complete_model;