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 // ct_lvtqtw_backgroundeventfilter.cpp                               -*-C++-*-
 
 /*
 // Copyright 2023 Codethink Ltd <codethink@codethink.co.uk>
 // SPDX-License-Identifier: Apache-2.0
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 */
 
 #include <ct_lvtqtw_backgroundeventfilter.h>
 
 #include <QAbstractItemModel>
 #include <QAbstractItemView>
 #include <QBrush>
 #include <QDebug>
 #include <QEvent>
 #include <QFontMetrics>
 #include <QPaintEvent>
 #include <QPainter>
 #include <QPen>
 
 namespace Codethink::lvtqtw {
 
 struct BackgroundEventFilter::Private {
     QString backgroundString;
 };
 
 BackgroundEventFilter::BackgroundEventFilter(QObject *parent):
     QObject(parent), d(std::make_unique<BackgroundEventFilter::Private>())
 {
 }
 
 BackgroundEventFilter::~BackgroundEventFilter() = default;
 
 void BackgroundEventFilter::setBackgroundText(const QString& bgString)
 {
     d->backgroundString = bgString;
 }
 
 bool BackgroundEventFilter::eventFilter(QObject *obj, QEvent *ev)
 {
     if (d->backgroundString.isEmpty()) {
         return false;
     }
 
     if (!obj || !ev) {
         return false;
     }
 
     auto *view = qobject_cast<QWidget *>(obj);
     if (!view) {
         return false;
     }
 
     auto *viewParent = qobject_cast<QAbstractItemView *>(view->parentWidget());
     if (!viewParent) {
         return false;
     }
 
     if (ev->type() != QEvent::Paint) {
         if (ev->type() == QEvent::EnabledChange) {
             view->update();
             return false;
         }
         return false;
     }
 
     auto *model = viewParent->model();
     if (!model) {
         return false;
     }
 
     if (model->rowCount() != 0) {
         return false;
     }
 
     QFontMetrics fm(view->font());
     const int width = fm.horizontalAdvance(d->backgroundString);
     const int height = fm.height();
     const int xPos = (view->width() / 2) - (width / 2);
     const int yPos = (view->height() / 2) - (height / 2);
 
     QPainter painter;
     painter.begin(view);
     painter.setPen(QPen(QBrush(Qt::gray), 2));
     painter.drawText(xPos, yPos, d->backgroundString);
     painter.end();
 
     return true;
 }
 
 } // namespace Codethink::lvtqtw