File indexing completed on 2024-04-14 03:54:01

 /*
     This file is part of the KDE libraries
     SPDX-FileCopyrightText: 2006, 2007 Andreas Hartmetz <ahartmetz@gmail.com>
     SPDX-FileCopyrightText: 2008 Urs Wolfer <uwolfer@kde.org>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 
 #include "kextendableitemdelegate.h"
 
 #include <QApplication>
 #include <QModelIndex>
 #include <QPainter>
 #include <QScrollBar>
 #include <QTreeView>
 
 class KExtendableItemDelegatePrivate
 {
 public:
     KExtendableItemDelegatePrivate(KExtendableItemDelegate *parent)
         : q(parent)
         , stateTick(0)
         , cachedStateTick(-1)
         , cachedRow(-20)
         , // Qt uses -1 for invalid indices
         extenderHeight(0)
 
     {
     }
 
     void _k_extenderDestructionHandler(QObject *destroyed);
     void _k_verticalScroll();
 
     QSize maybeExtendedSize(const QStyleOptionViewItem &option, const QModelIndex &index) const;
     QModelIndex indexOfExtendedColumnInSameRow(const QModelIndex &index) const;
     void scheduleUpdateViewLayout();
 
     KExtendableItemDelegate *const q;
 
     /**
      * Delete all active extenders
      */
     void deleteExtenders();
 
     // this will trigger a lot of auto-casting QModelIndex <-> QPersistentModelIndex
     QHash<QPersistentModelIndex, QWidget *> extenders;
     QHash<QWidget *, QPersistentModelIndex> extenderIndices;
     QMultiHash<QWidget *, QPersistentModelIndex> deletionQueue;
     QPixmap extendPixmap;
     QPixmap contractPixmap;
     int stateTick;
     int cachedStateTick;
     int cachedRow;
     QModelIndex cachedParentIndex;
     QWidget *extender = nullptr;
     int extenderHeight;
 };
 
 KExtendableItemDelegate::KExtendableItemDelegate(QAbstractItemView *parent)
     : QStyledItemDelegate(parent)
     , d(new KExtendableItemDelegatePrivate(this))
 {
     connect(parent->verticalScrollBar(), SIGNAL(valueChanged(int)), this, SLOT(_k_verticalScroll()));
 }
 
 KExtendableItemDelegate::~KExtendableItemDelegate() = default;
 
 void KExtendableItemDelegate::extendItem(QWidget *ext, const QModelIndex &index)
 {
     // qDebug() << "Creating extender at " << ext << " for item " << index.model()->data(index,Qt::DisplayRole).toString();
 
     if (!ext || !index.isValid()) {
         return;
     }
     // maintain the invariant "zero or one extender per row"
     d->stateTick++;
     contractItem(d->indexOfExtendedColumnInSameRow(index));
     d->stateTick++;
     // reparent, as promised in the docs
     QAbstractItemView *aiv = qobject_cast<QAbstractItemView *>(parent());
     if (!aiv) {
         return;
     }
     ext->setParent(aiv->viewport());
     d->extenders.insert(index, ext);
     d->extenderIndices.insert(ext, index);
     connect(ext, SIGNAL(destroyed(QObject *)), this, SLOT(_k_extenderDestructionHandler(QObject *)));
     Q_EMIT extenderCreated(ext, index);
     d->scheduleUpdateViewLayout();
 }
 
 void KExtendableItemDelegate::contractItem(const QModelIndex &index)
 {
     QWidget *extender = d->extenders.value(index);
     if (!extender) {
         return;
     }
     // qDebug() << "Collapse extender at " << extender << " for item " << index.model()->data(index,Qt::DisplayRole).toString();
     extender->hide();
     extender->deleteLater();
 
     QPersistentModelIndex persistentIndex = d->extenderIndices.take(extender);
     d->extenders.remove(persistentIndex);
 
     d->deletionQueue.insert(extender, persistentIndex);
 
     d->scheduleUpdateViewLayout();
 }
 
 void KExtendableItemDelegate::contractAll()
 {
     d->deleteExtenders();
 }
 
 // slot
 void KExtendableItemDelegatePrivate::_k_extenderDestructionHandler(QObject *destroyed)
 {
     // qDebug() << "Removing extender at " << destroyed;
 
     QWidget *extender = static_cast<QWidget *>(destroyed);
     stateTick++;
 
     QPersistentModelIndex persistentIndex = deletionQueue.take(extender);
     if (persistentIndex.isValid() && q->receivers(SIGNAL(extenderDestroyed(QWidget *, QModelIndex))) != 0) {
         QModelIndex index = persistentIndex;
         Q_EMIT q->extenderDestroyed(extender, index);
     }
 
     scheduleUpdateViewLayout();
 }
 
 // slot
 void KExtendableItemDelegatePrivate::_k_verticalScroll()
 {
     for (QWidget *extender : std::as_const(extenders)) {
         // Fast scrolling can lead to artifacts where extenders stay in the viewport
         // of the parent's scroll area even though their items are scrolled out.
         // Therefore we hide all extenders when scrolling.
         // In paintEvent() show() will be called on actually visible extenders and
         // Qt's double buffering takes care of eliminating flicker.
         // ### This scales badly to many extenders. There are probably better ways to
         //     avoid the artifacts.
         extender->hide();
     }
 }
 
 bool KExtendableItemDelegate::isExtended(const QModelIndex &index) const
 {
     return d->extenders.value(index);
 }
 
 QSize KExtendableItemDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     QSize ret;
 
     if (!d->extenders.isEmpty()) {
         ret = d->maybeExtendedSize(option, index);
     } else {
         ret = QStyledItemDelegate::sizeHint(option, index);
     }
 
     bool showExtensionIndicator = index.model() ? index.model()->data(index, ShowExtensionIndicatorRole).toBool() : false;
     if (showExtensionIndicator) {
         ret.rwidth() += d->extendPixmap.width() / d->extendPixmap.devicePixelRatio();
     }
 
     return ret;
 }
 
 void KExtendableItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     int indicatorX = 0;
     int indicatorY = 0;
 
     QStyleOptionViewItem indicatorOption(option);
     initStyleOption(&indicatorOption, index);
     if (index.column() == 0) {
         indicatorOption.viewItemPosition = QStyleOptionViewItem::Beginning;
     } else if (index.column() == index.model()->columnCount() - 1) {
         indicatorOption.viewItemPosition = QStyleOptionViewItem::End;
     } else {
         indicatorOption.viewItemPosition = QStyleOptionViewItem::Middle;
     }
 
     QStyleOptionViewItem itemOption(option);
     initStyleOption(&itemOption, index);
     if (index.column() == 0) {
         itemOption.viewItemPosition = QStyleOptionViewItem::Beginning;
     } else if (index.column() == index.model()->columnCount() - 1) {
         itemOption.viewItemPosition = QStyleOptionViewItem::End;
     } else {
         itemOption.viewItemPosition = QStyleOptionViewItem::Middle;
     }
 
     const bool showExtensionIndicator = index.model()->data(index, ShowExtensionIndicatorRole).toBool();
 
     if (showExtensionIndicator) {
         const QSize extendPixmapSize = d->extendPixmap.size() / d->extendPixmap.devicePixelRatio();
         if (QApplication::isRightToLeft()) {
             indicatorX = option.rect.right() - extendPixmapSize.width();
             itemOption.rect.setRight(indicatorX);
             indicatorOption.rect.setLeft(indicatorX);
         } else {
             indicatorX = option.rect.left();
             indicatorOption.rect.setRight(indicatorX + extendPixmapSize.width());
             itemOption.rect.setLeft(indicatorX + extendPixmapSize.width());
         }
         indicatorY = option.rect.top() + ((option.rect.height() - extendPixmapSize.height()) >> 1);
     }
 
     // fast path
     if (d->extenders.isEmpty()) {
         QStyledItemDelegate::paint(painter, itemOption, index);
         if (showExtensionIndicator) {
             painter->save();
             QApplication::style()->drawPrimitive(QStyle::PE_PanelItemViewItem, &indicatorOption, painter);
             painter->restore();
             painter->drawPixmap(indicatorX, indicatorY, d->extendPixmap);
         }
         return;
     }
 
     int row = index.row();
     QModelIndex parentIndex = index.parent();
 
     // indexOfExtendedColumnInSameRow() is very expensive, try to avoid calling it.
     if (row != d->cachedRow //
         || d->cachedStateTick != d->stateTick //
         || d->cachedParentIndex != parentIndex) {
         d->extender = d->extenders.value(d->indexOfExtendedColumnInSameRow(index));
         d->cachedStateTick = d->stateTick;
         d->cachedRow = row;
         d->cachedParentIndex = parentIndex;
         if (d->extender) {
             d->extenderHeight = d->extender->sizeHint().height();
         }
     }
 
     if (!d->extender) {
         QStyledItemDelegate::paint(painter, itemOption, index);
         if (showExtensionIndicator) {
             painter->save();
             QApplication::style()->drawPrimitive(QStyle::PE_PanelItemViewItem, &indicatorOption, painter);
             painter->restore();
             painter->drawPixmap(indicatorX, indicatorY, d->extendPixmap);
         }
         return;
     }
 
     // an extender is present - make two rectangles: one to paint the original item, one for the extender
     if (isExtended(index)) {
         QStyleOptionViewItem extOption(option);
         initStyleOption(&extOption, index);
         extOption.rect = extenderRect(d->extender, option, index);
         updateExtenderGeometry(d->extender, extOption, index);
         // if we show it before, it will briefly flash in the wrong location.
         // the downside is, of course, that an api user effectively can't hide it.
         d->extender->show();
     }
 
     indicatorOption.rect.setHeight(option.rect.height() - d->extenderHeight);
     itemOption.rect.setHeight(option.rect.height() - d->extenderHeight);
     // tricky:make sure that the modified options' rect really has the
     // same height as the unchanged option.rect if no extender is present
     //(seems to work OK)
     QStyledItemDelegate::paint(painter, itemOption, index);
 
     if (showExtensionIndicator) {
         const int extendPixmapHeight = d->extendPixmap.height() / d->extendPixmap.devicePixelRatio();
         // indicatorOption's height changed, change this too
         indicatorY = indicatorOption.rect.top() + ((indicatorOption.rect.height() - extendPixmapHeight) >> 1);
         painter->save();
         QApplication::style()->drawPrimitive(QStyle::PE_PanelItemViewItem, &indicatorOption, painter);
         painter->restore();
 
         if (d->extenders.contains(index)) {
             painter->drawPixmap(indicatorX, indicatorY, d->contractPixmap);
         } else {
             painter->drawPixmap(indicatorX, indicatorY, d->extendPixmap);
         }
     }
 }
 
 QRect KExtendableItemDelegate::extenderRect(QWidget *extender, const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     Q_ASSERT(extender);
     QRect rect(option.rect);
     rect.setTop(rect.bottom() + 1 - extender->sizeHint().height());
 
     int indentation = 0;
     if (QTreeView *tv = qobject_cast<QTreeView *>(parent())) {
         int indentSteps = 0;
         for (QModelIndex idx(index.parent()); idx.isValid(); idx = idx.parent()) {
             indentSteps++;
         }
         if (tv->rootIsDecorated()) {
             indentSteps++;
         }
         indentation = indentSteps * tv->indentation();
     }
 
     QAbstractScrollArea *container = qobject_cast<QAbstractScrollArea *>(parent());
     Q_ASSERT(container);
     if (qApp->isLeftToRight()) {
         rect.setLeft(indentation);
         rect.setRight(container->viewport()->width() - 1);
     } else {
         rect.setRight(container->viewport()->width() - 1 - indentation);
         rect.setLeft(0);
     }
     return rect;
 }
 
 QSize KExtendableItemDelegatePrivate::maybeExtendedSize(const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     QWidget *extender = extenders.value(index);
     QSize size(q->QStyledItemDelegate::sizeHint(option, index));
     if (!extender) {
         return size;
     }
     // add extender height to maximum height of any column in our row
     int itemHeight = size.height();
 
     int row = index.row();
     int thisColumn = index.column();
 
     // this is quite slow, but Qt is smart about when to call sizeHint().
     for (int column = 0; index.model()->columnCount() < column; column++) {
         if (column == thisColumn) {
             continue;
         }
         QModelIndex neighborIndex(index.sibling(row, column));
         if (!neighborIndex.isValid()) {
             break;
         }
         itemHeight = qMax(itemHeight, q->QStyledItemDelegate::sizeHint(option, neighborIndex).height());
     }
 
     // we only want to reserve vertical space, the horizontal extender layout is our private business.
     size.rheight() = itemHeight + extender->sizeHint().height();
     return size;
 }
 
 QModelIndex KExtendableItemDelegatePrivate::indexOfExtendedColumnInSameRow(const QModelIndex &index) const
 {
     const QAbstractItemModel *const model = index.model();
     const QModelIndex parentIndex(index.parent());
     const int row = index.row();
     const int columnCount = model->columnCount();
 
     // slow, slow, slow
     for (int column = 0; column < columnCount; column++) {
         QModelIndex indexOfExt(model->index(row, column, parentIndex));
         if (extenders.value(indexOfExt)) {
             return indexOfExt;
         }
     }
 
     return QModelIndex();
 }
 
 void KExtendableItemDelegate::updateExtenderGeometry(QWidget *extender, const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     Q_UNUSED(index);
     extender->setGeometry(option.rect);
 }
 
 void KExtendableItemDelegatePrivate::deleteExtenders()
 {
     for (QWidget *ext : std::as_const(extenders)) {
         ext->hide();
         ext->deleteLater();
     }
     deletionQueue.unite(extenderIndices);
     extenders.clear();
     extenderIndices.clear();
 }
 
 // make the view re-ask for sizeHint() and redisplay items with their new size
 //### starting from Qt 4.4 we could emit sizeHintChanged() instead
 void KExtendableItemDelegatePrivate::scheduleUpdateViewLayout()
 {
     QAbstractItemView *aiv = qobject_cast<QAbstractItemView *>(q->parent());
     // prevent crashes during destruction of the view
     if (aiv) {
         // dirty hack to call aiv's protected scheduleDelayedItemsLayout()
         aiv->setRootIndex(aiv->rootIndex());
     }
 }
 
 void KExtendableItemDelegate::setExtendPixmap(const QPixmap &pixmap)
 {
     d->extendPixmap = pixmap;
 }
 
 void KExtendableItemDelegate::setContractPixmap(const QPixmap &pixmap)
 {
     d->contractPixmap = pixmap;
 }
 
 QPixmap KExtendableItemDelegate::extendPixmap()
 {
     return d->extendPixmap;
 }
 
 QPixmap KExtendableItemDelegate::contractPixmap()
 {
     return d->contractPixmap;
 }
 
 #include "moc_kextendableitemdelegate.cpp"