[plasma/plasma-setup] modules: Improve language search in Plasma Setup

Git commit b5a0a068ff74f4c69cfcc664dd454fc19312d53e by Kristen McWilliam, on behalf of Tiziano Gaia.
Committed on 21/07/2026 at 17:23.
Pushed by merritt into branch 'master'.

Improve language search in Plasma Setup

Use QSortFilterProxyModel for language filtering

M  +21   -28   modules/language/contents/ui/main.qml
M  +1    -0    modules/languageutil/CMakeLists.txt
A  +56   -0    modules/languageutil/languagesortfilterproxymodel.cpp     [License: LGPL(v2.1+)]
A  +32   -0    modules/languageutil/languagesortfilterproxymodel.h     [License: LGPL(v2.1+)]
M  +28   -0    modules/languageutil/languageutil.cpp
M  +28   -0    modules/languageutil/languageutil.h

https://invent.kde.org/plasma/plasma-setup/-/commit/b5a0a068ff74f4c69cfcc664dd454fc19312d53e

diff --git a/modules/language/contents/ui/main.qml b/modules/language/contents/ui/main.qml
index 3d7f767..a52eaa0 100644
--- a/modules/language/contents/ui/main.qml
+++ b/modules/language/contents/ui/main.qml
@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: 2025 Kristen McWilliam <[email protected]>
+// SPDX-FileCopyrightText: 2026 Tiziano Gaia <[email protected]>
 // SPDX-License-Identifier: LGPL-2.1-or-later
 
 pragma ComponentBehavior: Bound
@@ -49,10 +50,9 @@ PlasmaSetupComponents.SetupModule {
                 id: searchField
                 Layout.fillWidth: true
                 placeholderText: i18n("Search languages…")
-                property string filterString: ""
 
                 onTextChanged: {
-                    filterString = text.toLowerCase();
+                    Language.LanguageUtil.languageFilter = text;
                 }
             }
 
@@ -69,45 +69,35 @@ PlasmaSetupComponents.SetupModule {
                 ListView {
                     id: languageListView
                     clip: true
-                    model: Language.LanguageUtil.availableLanguages
-
-                    // Filter languages based on search text
-                    function matchesFilter(language) {
-                        if (!searchField.filterString) {
-                            return true;
-                        }
-
-                        // Get language name from locale code
-                        const localeName = Qt.locale(language).nativeLanguageName;
-                        return language.toLowerCase().includes(searchField.filterString) || localeName.toLowerCase().includes(searchField.filterString);
-                    }
+                    model: Language.LanguageUtil.languageModel
 
                     currentIndex: -1 // Ensure focus is not on the listview
 
                     delegate: RadioDelegate {
-                        required property string modelData
+                        required property string languageCode
 
-                        // Show and hide based on filter
-                        readonly property bool matchesFilter: languageListView.matchesFilter(modelData)
-                        height: matchesFilter ? implicitHeight : 0
                         width: ListView.view.width
-                        visible: matchesFilter
 
                         // Get language name from locale code (e.g., "en_US" -> "English (United States)")
                         text: {
-                            const locale = Qt.locale(modelData);
+                            const locale = Qt.locale(languageCode);
                             const localeName = locale.nativeLanguageName;
+
                             // First letter to uppercase
-                            return localeName.charAt(0).toUpperCase() + localeName.slice(1) + " (" + locale.nativeCountryName + ")";
+                            return localeName.charAt(0).toUpperCase()
+                                + localeName.slice(1)
+                                + " ("
+                                + locale.nativeCountryName
+                                + ")";
                         }
 
-                        checked: Language.LanguageUtil.currentLanguage === modelData
+                        checked: Language.LanguageUtil.currentLanguage === languageCode
 
                         onToggled: {
-                            if (checked && modelData !== Language.LanguageUtil.currentLanguage) {
-                                Language.LanguageUtil.currentLanguage = modelData;
+                            if (checked && languageCode !== Language.LanguageUtil.currentLanguage) {
+                                Language.LanguageUtil.currentLanguage = languageCode;
                                 Language.LanguageUtil.applyLanguage();
-                                checked = Qt.binding(() => Language.LanguageUtil.currentLanguage === modelData);
+                                checked = Qt.binding(() => Language.LanguageUtil.currentLanguage === languageCode);
                             }
                         }
                     }
@@ -115,10 +105,13 @@ PlasmaSetupComponents.SetupModule {
                     function scrollToCurrentLanguage() {
                         // Find the index of the current language
                         const currentLang = Language.LanguageUtil.currentLanguage;
-                        for (let i = 0; i < model.length; i++) {
-                            if (model[i] === currentLang) {
+
+                        for (let i = 0; i < languageListView.count; i++) {
+                            const item = languageListView.itemAtIndex(i);
+
+                            if (item && item.languageCode === currentLang) {
                                 // Position the view at the current language with some offset
-                                positionViewAtIndex(i, ListView.Center);
+                                languageListView.positionViewAtIndex(i, ListView.Center);
                                 break;
                             }
                         }
diff --git a/modules/languageutil/CMakeLists.txt b/modules/languageutil/CMakeLists.txt
index 73fda76..af807bf 100644
--- a/modules/languageutil/CMakeLists.txt
+++ b/modules/languageutil/CMakeLists.txt
@@ -16,6 +16,7 @@ ecm_add_qml_module(plasmasetup_languageutil
     GENERATE_PLUGIN_SOURCE
     SOURCES
         languageutil.cpp
+        languagesortfilterproxymodel.cpp
         ${logging_SRCS}
 )
 
diff --git a/modules/languageutil/languagesortfilterproxymodel.cpp b/modules/languageutil/languagesortfilterproxymodel.cpp
new file mode 100644
index 0000000..fc4f1b3
--- /dev/null
+++ b/modules/languageutil/languagesortfilterproxymodel.cpp
@@ -0,0 +1,56 @@
+// SPDX-FileCopyrightText: 2026 Tiziano Gaia <[email protected]>
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#include "languagesortfilterproxymodel.h"
+
+#include <QLocale>
+
+LanguageSortFilterProxyModel::LanguageSortFilterProxyModel(QObject *parent)
+    : QSortFilterProxyModel(parent)
+{
+}
+
+void LanguageSortFilterProxyModel::setFilterString(const QString &filter)
+{
+    if (m_filterString == filter) {
+        return;
+    }
+
+    beginFilterChange();
+    m_filterString = filter;
+    endFilterChange();
+}
+
+bool LanguageSortFilterProxyModel::filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const
+{
+    if (m_filterString.isEmpty()) {
+        return true;
+    }
+
+    const QModelIndex index = sourceModel()->index(sourceRow, 0, sourceParent);
+    const QString language = sourceModel()->data(index, Qt::DisplayRole).toString();
+
+    const QLocale locale(language);
+
+    const QString nativeName = locale.nativeLanguageName();
+    const QString englishName = QLocale::languageToString(locale.language());
+
+    return language.contains(m_filterString, Qt::CaseInsensitive) || nativeName.contains(m_filterString, Qt::CaseInsensitive)
+        || englishName.contains(m_filterString, Qt::CaseInsensitive);
+}
+
+QHash<int, QByteArray> LanguageSortFilterProxyModel::roleNames() const
+{
+    auto roles = QSortFilterProxyModel::roleNames();
+    roles[Qt::UserRole + 1] = "languageCode";
+    return roles;
+}
+
+QVariant LanguageSortFilterProxyModel::data(const QModelIndex &index, int role) const
+{
+    if (role == Qt::UserRole + 1) {
+        return sourceModel()->data(mapToSource(index), Qt::DisplayRole);
+    }
+
+    return QSortFilterProxyModel::data(index, role);
+}
diff --git a/modules/languageutil/languagesortfilterproxymodel.h b/modules/languageutil/languagesortfilterproxymodel.h
new file mode 100644
index 0000000..0089b98
--- /dev/null
+++ b/modules/languageutil/languagesortfilterproxymodel.h
@@ -0,0 +1,32 @@
+// SPDX-FileCopyrightText: 2026 Tiziano Gaia <[email protected]>
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#pragma once
+
+#include <QSortFilterProxyModel>
+#include <QString>
+
+class QModelIndex;
+class QVariant;
+
+/**
+ * A proxy model that filters the list of available languages
+ * by locale code, native language name, and English language name.
+ */
+class LanguageSortFilterProxyModel : public QSortFilterProxyModel
+{
+    Q_OBJECT
+
+public:
+    explicit LanguageSortFilterProxyModel(QObject *parent = nullptr);
+
+    void setFilterString(const QString &filter);
+
+protected:
+    bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override;
+    QHash<int, QByteArray> roleNames() const override;
+    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+
+private:
+    QString m_filterString;
+};
diff --git a/modules/languageutil/languageutil.cpp b/modules/languageutil/languageutil.cpp
index 9d3f01e..6bcd1b3 100644
--- a/modules/languageutil/languageutil.cpp
+++ b/modules/languageutil/languageutil.cpp
@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: 2025 Kristen McWilliam <[email protected]>
+// SPDX-FileCopyrightText: 2026 Tiziano Gaia <[email protected]>
 // SPDX-License-Identifier: LGPL-2.1-or-later
 
 #include "languageutil.h"
@@ -9,12 +10,17 @@
 #include <QCoreApplication>
 #include <QDBusConnection>
 #include <QDBusReply>
+#include <QLocale>
 #include <QTimer>
 
 LanguageUtil::LanguageUtil(QObject *parent)
     : QObject(parent)
 {
     loadAvailableLanguages();
+
+    m_languageModel.setStringList(m_availableLanguages);
+    m_languageProxyModel.setSourceModel(&m_languageModel);
+
     m_currentLanguage = QLocale::system().name();
     qCInfo(PlasmaSetupLanguageUtil) << "System language detected as:" << m_currentLanguage;
     overrideInitialLanguageIfNeeded();
@@ -25,6 +31,28 @@ QStringList LanguageUtil::availableLanguages() const
     return m_availableLanguages;
 }
 
+QString LanguageUtil::languageFilter() const
+{
+    return m_languageFilter;
+}
+
+QAbstractItemModel *LanguageUtil::languageModel()
+{
+    return &m_languageProxyModel;
+}
+
+void LanguageUtil::setLanguageFilter(const QString &filter)
+{
+    if (m_languageFilter == filter) {
+        return;
+    }
+
+    m_languageFilter = filter;
+    m_languageProxyModel.setFilterString(filter);
+
+    Q_EMIT languageFilterChanged();
+}
+
 QString LanguageUtil::currentLanguage() const
 {
     return m_currentLanguage;
diff --git a/modules/languageutil/languageutil.h b/modules/languageutil/languageutil.h
index 51c967f..bbf4954 100644
--- a/modules/languageutil/languageutil.h
+++ b/modules/languageutil/languageutil.h
@@ -1,10 +1,14 @@
 // SPDX-FileCopyrightText: 2025 Kristen McWilliam <[email protected]>
+// SPDX-FileCopyrightText: 2026 Tiziano Gaia <[email protected]>
 // SPDX-License-Identifier: LGPL-2.1-or-later
 
 #pragma once
 
 #include <QObject>
 #include <QQmlEngine>
+#include <QStringListModel>
+
+#include "languagesortfilterproxymodel.h"
 
 /**
  * Handles language choice.
@@ -28,6 +32,22 @@ class LanguageUtil : public QObject
      */
     Q_PROPERTY(QStringList availableLanguages READ availableLanguages NOTIFY availableLanguagesChanged)
 
+    /**
+     * Model containing the available languages.
+     *
+     * This model supports filtering through languageFilter and is exposed
+     * directly to QML views that display the available language choices.
+     */
+    Q_PROPERTY(QAbstractItemModel *languageModel READ languageModel CONSTANT)
+
+    /**
+     * Search filter applied to the language model.
+     *
+     * Updating this value filters languages by their code, native name,
+     * or English name.
+     */
+    Q_PROPERTY(QString languageFilter READ languageFilter WRITE setLanguageFilter NOTIFY languageFilterChanged)
+
     /**
      * The language code of the currently selected language.
      */
@@ -37,6 +57,10 @@ public:
     explicit LanguageUtil(QObject *parent = nullptr);
 
     QStringList availableLanguages() const;
+    QAbstractItemModel *languageModel();
+    QString languageFilter() const;
+    void setLanguageFilter(const QString &filter);
+
     QString currentLanguage() const;
     void setCurrentLanguage(const QString &language);
 
@@ -47,6 +71,7 @@ public:
 
 Q_SIGNALS:
     void availableLanguagesChanged();
+    void languageFilterChanged();
     void currentLanguageChanged();
     void initialLanguageOverrideApplied();
 
@@ -84,5 +109,8 @@ private:
     void overrideInitialLanguageIfNeeded();
 
     QStringList m_availableLanguages;
+    QStringListModel m_languageModel;
+    LanguageSortFilterProxyModel m_languageProxyModel;
+    QString m_languageFilter;
     QString m_currentLanguage;
 };