folio: Use dynamic list insert/delete for changes

Should help reduce the effect of https://invent.kde.org/plasma/plasma-mobile/-/issues/440

Instead of fully resetting the application list when the ksycoca db
changes, calculate which items are removed and added based on the
storageId and emit targeted signals for them.

containments/homescreens/folio/applicationlistmodel.cpp

@@ -1,5 +1,5 @@
 // SPDX-FileCopyrightText: 2014 Antonis Tsiapaliokas <antonis.tsiapaliokas@kde.org>
-// SPDX-FileCopyrightText: 2022 Devin Lin <devin@kde.org>
+// SPDX-FileCopyrightText: 2022-2024 Devin Lin <devin@kde.org>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "applicationlistmodel.h"
@@ -53,13 +53,12 @@ void ApplicationListModel::sycocaDbChanged()
     load();
 }
 
-void ApplicationListModel::load()
+KService::List ApplicationListModel::queryApplications()
 {
     auto cfg = KSharedConfig::openConfig(QStringLiteral("applications-blacklistrc"));
     auto blgroup = KConfigGroup(cfg, QStringLiteral("Applications"));
 
     const QStringList blacklist = blgroup.readEntry("blacklist", QStringList());
-
     auto filter = [blacklist](const KService::Ptr &service) -> bool {
         if (service->noDisplay()) {
             return false;
@@ -76,27 +75,61 @@ void ApplicationListModel::load()
         return true;
     };
 
-    beginResetModel();
+    return KApplicationTrader::query(filter);
+}
 
-    m_delegates.clear();
+void ApplicationListModel::load()
+{
+    qDebug() << "Reloading folio app list...";
 
-    QList<FolioDelegate::Ptr> unorderedList;
+    // This function supports dynamic insertions and deletions to the existing
+    // list depending on what is given from queryApplications().
 
-    const KService::List apps = KApplicationTrader::query(filter);
-
-    for (const KService::Ptr &service : apps) {
-        FolioApplication::Ptr app = std::make_shared<FolioApplication>(m_homeScreen, service);
-        FolioDelegate::Ptr delegate = std::make_shared<FolioDelegate>(app, m_homeScreen);
-        unorderedList << delegate;
+    QMap<QString, int> storageIdMap; // <storageId, index>
+    for (int i = 0; i < m_delegates.size(); ++i) {
+        const auto &delegate = m_delegates[i];
+        storageIdMap.insert(delegate->application()->storageId(), i);
     }
 
-    std::sort(unorderedList.begin(), unorderedList.end(), [](FolioDelegate::Ptr &a1, FolioDelegate::Ptr &a2) {
-        return a1->application()->name().compare(a2->application()->name(), Qt::CaseInsensitive) < 0;
-    });
+    const KService::List currentApps = queryApplications();
+    QList<KService::Ptr> toInsert;
 
-    m_delegates << unorderedList;
+    for (const KService::Ptr &service : currentApps) {
+        auto it = storageIdMap.find(service->storageId());
+        if (it != storageIdMap.end()) {
+            // Service already in m_delegates
+            storageIdMap.erase(it);
+        } else {
+            // Service needs to be inserted into m_delegates
+            toInsert.append(std::move(service));
+        }
+    }
 
-    endResetModel();
+    QList<int> toRemove;
+    for (int index : storageIdMap.values()) {
+        toRemove.append(index);
+    }
+
+    std::sort(toRemove.begin(), toRemove.end());
+
+    // Remove indices first, from end to start to avoid indicies changing
+    for (int i = toRemove.size() - 1; i >= 0; --i) {
+        int ind = toRemove[i];
+
+        beginRemoveRows({}, ind, ind);
+        m_delegates.removeAt(ind);
+        endRemoveRows();
+    }
+
+    // Append new elements
+    for (const KService::Ptr &service : toInsert) {
+        FolioApplication::Ptr app = std::make_shared<FolioApplication>(m_homeScreen, service);
+        FolioDelegate::Ptr delegate = std::make_shared<FolioDelegate>(app, m_homeScreen);
+
+        beginInsertRows({}, m_delegates.size(), m_delegates.size());
+        m_delegates.append(delegate);
+        endInsertRows();
+    }
 }
 
 QVariant ApplicationListModel::data(const QModelIndex &index, int role) const
@@ -115,7 +148,7 @@ QVariant ApplicationListModel::data(const QModelIndex &index, int role) const
         if (!delegate->application()) {
             return QVariant();
         }
-        return m_delegates.at(index.row())->application()->name();
+        return delegate->application()->name();
     default:
         return QVariant();
     }
@@ -133,7 +166,13 @@ int ApplicationListModel::rowCount(const QModelIndex &parent) const
 ApplicationListSearchModel::ApplicationListSearchModel(HomeScreen *parent, ApplicationListModel *model)
     : QSortFilterProxyModel(parent)
 {
-    setFilterCaseSensitivity(Qt::CaseInsensitive);
     setSourceModel(model);
+
     setFilterRole(ApplicationListModel::NameRole);
+    setFilterCaseSensitivity(Qt::CaseInsensitive);
+
+    setSortRole(ApplicationListModel::NameRole);
+    setSortCaseSensitivity(Qt::CaseInsensitive);
+
+    sort(0, Qt::AscendingOrder);
 }

containments/homescreens/folio/applicationlistmodel.h

@@ -10,6 +10,8 @@
 #include <QQuickItem>
 #include <QSet>
 
+#include <KService>
+
 #include "foliodelegate.h"
 #include "homescreen.h"
 
@@ -42,6 +44,8 @@ public Q_SLOTS:
     void sycocaDbChanged();
 
 protected:
+    KService::List queryApplications();
+
     HomeScreen *m_homeScreen{nullptr};
 
     QList<std::shared_ptr<FolioDelegate>> m_delegates;