fix: should clean-up no longer valid items in fullscreen mode

全屏模式中，当图标数量变化时，从图标位置数据源中移除不再有效的图标。
已被卸载的图标将不会再占据位置，因应用卸载导致的图标消失后页面留空
的空白页也会被相应移除。

Issue: linuxdeepin/developer-center#6861
Log:

src/models/itemspage.cpp

@@ -4,6 +4,8 @@
 
 #include "itemspage.h"
 
+#include <QSet>
+
 ItemsPage::ItemsPage(const QString &name, int maxItemCountPerPage, QObject *parent)
     : QObject(parent)
     , m_maxItemCountPerPage(maxItemCountPerPage)
@@ -157,6 +159,24 @@ bool ItemsPage::removeItem(const QString id, bool removePageIfPageIsEmpty)
     return false;
 }
 
+void ItemsPage::removeItemsNotIn(const QSet<QString> &itemSet)
+{
+    for (int i = 0; i < m_pages.count(); i++) {
+        for (int j = m_pages.at(i).count() - 1; j >= 0; j--) {
+            const QString & item(m_pages.at(i).at(j));
+            if (itemSet.contains(item)) continue;
+            if (item.startsWith(QLatin1String("internal/"))) continue;
+            m_pages[i].removeAt(j);
+        }
+    }
+    removeEmptyPages();
+}
+
+void ItemsPage::removeEmptyPages()
+{
+    m_pages.removeAll({});
+}
+
 // <page, index>
 std::tuple<int, int> ItemsPage::findItem(const QString &id) const
 {

src/models/itemspage.h

@@ -34,6 +34,8 @@ class ItemsPage : public QObject
     void insertItem(const QString id, int page, int pos = 0);
     void moveItem(int from_page, int from_index, int to_page, int to_index);
     bool removeItem(const QString id, bool removePageIfPageIsEmpty = true);
+    void removeItemsNotIn(const QSet<QString> & itemSet);
+    void removeEmptyPages();
 
     std::tuple<int, int> findItem(const QString & id) const;
     bool contains(const QString & id) const;

src/models/multipageproxymodel.cpp

@@ -283,20 +283,25 @@ std::tuple<int, int, int> MultipageProxyModel::findItem(const QString &id, bool
 
 void MultipageProxyModel::onSourceModelChanged()
 {
-    // add all existing ones if they are not already in
+    QSet<QString> appDesktopIdSet;
     int appsCount = AppsModel::instance().rowCount();
     for (int i = 0; i < appsCount; i++) {
         QString desktopId(AppsModel::instance().data(AppsModel::instance().index(i, 0), AppItem::DesktopIdRole).toString());
+        appDesktopIdSet.insert(desktopId);
         int folder, page, idx;
         std::tie(folder, std::ignore, std::ignore) = findItem(desktopId);
+        // add all existing ones if they are not already in
         if (folder == -1) {
             findItem(desktopId);
             m_topLevel->appendItem(desktopId);
         }
     }
 
-    // TODO: remove the ones that no longer valid out of m_folders
-
+    m_topLevel->removeItemsNotIn(appDesktopIdSet);
+    for (int i = 0; i < m_folderModel.rowCount(); i++) {
+        const QString & folderId = m_folderModel.index(i, 0).data(AppItem::DesktopIdRole).toString();
+        m_folders.value(folderId)->removeItemsNotIn(appDesktopIdSet);
+    }
 
     emit dataChanged(index(0, 0), index(rowCount() - 1, 0), {
         PageRole, IndexInPageRole, FolderIdNumberRole, IconsNameRole