Move message filtering to C++

The filter callback is called very often (O(messages)). The current
filter model shows some significant overhead in QML internals. Moving
that to C++ makes it quite a bit faster.

src/messagefiltermodel.cpp

@@ -0,0 +1,34 @@
+/*
+ * SPDX-FileCopyrightText: 2021 Nicolas Fella <nicolas.fella@gmx.de>
+ * SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
+ */
+
+#include "messagefiltermodel.h"
+
+#include "messageeventmodel.h"
+#include "neochatconfig.h"
+
+bool MessageFilterModel::filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const
+{
+    const QModelIndex index = sourceModel()->index(sourceRow, 0, sourceParent);
+
+    if (index.data(MessageEventModel::SpecialMarksRole).toInt() == EventStatus::Hidden) {
+        return false;
+    }
+
+    if (index.data(MessageEventModel::MessageRole).toInt() == 0x10) {
+        return false;
+    }
+
+    const QString eventType = index.data(MessageEventModel::EventTypeRole).toString();
+
+    if (eventType == QLatin1String("other")) {
+        return false;
+    }
+
+    if (!NeoChatConfig::self()->showLeaveJoinEvent() && eventType == QLatin1String("state")) {
+        return false;
+    }
+
+    return true;
+}