qquickgridview.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qquickgridview_p.h"
#include "qquickflickable_p_p.h"
#include "qquickitemview_p_p.h"
 
#include <private/qqmlobjectmodel_p.h>
#include <private/qquicksmoothedanimation_p_p.h>
 
#include <QtGui/qevent.h>
#include <QtCore/qmath.h>
#include <QtCore/qcoreapplication.h>
#include "qplatformdefs.h"
 
#include <cmath>
 
QT_BEGIN_NAMESPACE
 
#ifndef QML_FLICK_SNAPONETHRESHOLD
#define QML_FLICK_SNAPONETHRESHOLD 30
#endif
 
//----------------------------------------------------------------------------
 
class FxGridItemSG : public FxViewItem
{
public:
    FxGridItemSG(QQuickItem *i, QQuickGridView *v, bool own) : FxViewItem(i, v, own, static_cast<QQuickItemViewAttached*>(qmlAttachedPropertiesObject<QQuickGridView>(i))), view(v)
    {
    }
 
    qreal position() const override {
        return rowPos();
    }
 
    qreal endPosition() const override {
        return endRowPos();
    }
 
    qreal size() const override {
        return view->flow() == QQuickGridView::FlowLeftToRight ? view->cellHeight() : view->cellWidth();
    }
 
    qreal sectionSize() const override {
        return 0.0;
    }
 
    qreal rowPos() const {
        if (view->flow() == QQuickGridView::FlowLeftToRight)
            return (view->verticalLayoutDirection() == QQuickItemView::BottomToTop ? -view->cellHeight()-itemY() : itemY());
        else
            return (view->effectiveLayoutDirection() == Qt::RightToLeft ? -view->cellWidth()-itemX() : itemX());
    }
 
    qreal colPos() const {
        if (view->flow() == QQuickGridView::FlowLeftToRight) {
            if (view->effectiveLayoutDirection() == Qt::RightToLeft) {
                qreal colSize = view->cellWidth();
                int columns = view->width()/colSize;
                return colSize * (columns-1) - itemX();
            } else {
                return itemX();
            }
        } else {
            if (view->verticalLayoutDirection() == QQuickItemView::BottomToTop) {
                return -view->cellHeight() - itemY();
            } else {
                return itemY();
            }
        }
    }
    qreal endRowPos() const {
        if (view->flow() == QQuickGridView::FlowLeftToRight) {
            if (view->verticalLayoutDirection() == QQuickItemView::BottomToTop)
                return -itemY();
            else
                return itemY() + view->cellHeight();
        } else {
            if (view->effectiveLayoutDirection() == Qt::RightToLeft)
                return -itemX();
            else
                return itemX() + view->cellWidth();
        }
    }
    void setPosition(qreal col, qreal row, bool immediate = false) {
        moveTo(pointForPosition(col, row), immediate);
    }
    bool contains(qreal x, qreal y) const override {
        return (x >= itemX() && x < itemX() + view->cellWidth() &&
                y >= itemY() && y < itemY() + view->cellHeight());
    }
 
    QQuickGridView *view;
 
private:
    QPointF pointForPosition(qreal col, qreal row) const {
        qreal x;
        qreal y;
        if (view->flow() == QQuickGridView::FlowLeftToRight) {
            x = col;
            y = row;
            if (view->effectiveLayoutDirection() == Qt::RightToLeft) {
                int columns = view->width()/view->cellWidth();
                x = view->cellWidth() * (columns-1) - col;
            }
        } else {
            x = row;
            y = col;
            if (view->effectiveLayoutDirection() == Qt::RightToLeft)
                x = -view->cellWidth() - row;
        }
        if (view->verticalLayoutDirection() == QQuickItemView::BottomToTop)
            y = -view->cellHeight() - y;
        return QPointF(x, y);
    }
};
 
//----------------------------------------------------------------------------
 
class QQuickGridViewPrivate : public QQuickItemViewPrivate
{
    Q_DECLARE_PUBLIC(QQuickGridView)
 
public:
    Qt::Orientation layoutOrientation() const override;
    bool isContentFlowReversed() const override;
 
    qreal positionAt(int index) const override;
    qreal endPositionAt(int index) const override;
    qreal originPosition() const override;
    qreal lastPosition() const override;
 
    qreal rowSize() const;
    qreal colSize() const;
    qreal colPosAt(int modelIndex) const;
    qreal rowPosAt(int modelIndex) const;
    qreal snapPosAt(qreal pos) const;
    FxViewItem *snapItemAt(qreal pos) const;
    int snapIndex() const;
    qreal contentXForPosition(qreal pos) const;
    qreal contentYForPosition(qreal pos) const;
 
    void resetColumns();
 
    bool addVisibleItems(qreal fillFrom, qreal fillTo, qreal bufferFrom, qreal bufferTo, bool doBuffer) override;
    bool removeNonVisibleItems(qreal bufferFrom, qreal bufferTo) override;
 
    void removeItem(FxViewItem *item);
 
    FxViewItem *newViewItem(int index, QQuickItem *item) override;
    void initializeViewItem(FxViewItem *item) override;
    void repositionItemAt(FxViewItem *item, int index, qreal sizeBuffer) override;
    void repositionPackageItemAt(QQuickItem *item, int index) override;
    void resetFirstItemPosition(qreal pos = 0.0) override;
    void adjustFirstItem(qreal forwards, qreal backwards, int changeBeforeVisible) override;
 
    void createHighlight(bool onDestruction = false) override;
    void updateHighlight() override;
    void resetHighlightPosition() override;
 
    void setPosition(qreal pos) override;
    void layoutVisibleItems(int fromModelIndex = 0) override;
    bool applyInsertionChange(const QQmlChangeSet::Change &insert, ChangeResult *changeResult, QList<FxViewItem *> *addedItems, QList<MovedItem> *movingIntoView) override;
#if QT_CONFIG(quick_viewtransitions)
    void translateAndTransitionItemsAfter(int afterModelIndex, const ChangeResult &insertionResult, const ChangeResult &removalResult) override;
#endif
    bool needsRefillForAddedOrRemovedIndex(int index) const override;
 
    qreal headerSize() const override;
    qreal footerSize() const override;
    bool showHeaderForIndex(int index) const override;
    bool showFooterForIndex(int index) const override;
    void updateHeader() override;
    void updateFooter() override;
 
    void initializeComponentItem(QQuickItem *item) const override;
 
    void changedVisibleIndex(int newIndex) override;
    void initializeCurrentItem() override;
 
    void updateViewport() override;
    void fixupPosition() override;
    void fixup(AxisData &data, qreal minExtent, qreal maxExtent) override;
    bool flick(QQuickItemViewPrivate::AxisData &data, qreal minExtent, qreal maxExtent, qreal vSize,
               QQuickTimeLineCallback::Callback fixupCallback, QEvent::Type eventType, qreal velocity) override;
 
    QQuickGridView::Flow flow;
    qreal cellWidth;
    qreal cellHeight;
    int columns;
    QQuickGridView::SnapMode snapMode;
 
    QSmoothedAnimation *highlightXAnimator;
    QSmoothedAnimation *highlightYAnimator;
 
    QQuickGridViewPrivate()
        : flow(QQuickGridView::FlowLeftToRight)
        , cellWidth(100), cellHeight(100), columns(1)
        , snapMode(QQuickGridView::NoSnap)
        , highlightXAnimator(nullptr), highlightYAnimator(nullptr)
    {}
    ~QQuickGridViewPrivate()
    {
        delete highlightXAnimator;
        delete highlightYAnimator;
    }
};
 
Qt::Orientation QQuickGridViewPrivate::layoutOrientation() const
{
    return flow == QQuickGridView::FlowLeftToRight ? Qt::Vertical : Qt::Horizontal;
}
 
bool QQuickGridViewPrivate::isContentFlowReversed() const
{
    Q_Q(const QQuickGridView);
 
    return (flow == QQuickGridView::FlowLeftToRight && verticalLayoutDirection == QQuickItemView::BottomToTop)
            || (flow == QQuickGridView::FlowTopToBottom && q->effectiveLayoutDirection() == Qt::RightToLeft);
}
 
void QQuickGridViewPrivate::changedVisibleIndex(int newIndex)
{
    visibleIndex = newIndex / columns * columns;
}
 
void QQuickGridViewPrivate::setPosition(qreal pos)
{
    Q_Q(QQuickGridView);
    q->QQuickFlickable::setContentX(contentXForPosition(pos));
    q->QQuickFlickable::setContentY(contentYForPosition(pos));
}
 
qreal QQuickGridViewPrivate::originPosition() const
{
    qreal pos = 0;
    if (!visibleItems.isEmpty())
        pos = static_cast<FxGridItemSG*>(visibleItems.first())->rowPos() - visibleIndex / columns * rowSize();
    return pos;
}
 
qreal QQuickGridViewPrivate::lastPosition() const
{
    qreal pos = 0;
    if (model && (model->count() || !visibleItems.isEmpty())) {
        qreal lastRowPos = model->count() ? rowPosAt(model->count() - 1) : 0;
        if (!visibleItems.isEmpty()) {
            // If there are items in delayRemove state, they may be after any items linked to the model
            lastRowPos = qMax(lastRowPos, static_cast<FxGridItemSG*>(visibleItems.last())->rowPos());
        }
        pos = lastRowPos + rowSize();
    }
    return pos;
}
 
qreal QQuickGridViewPrivate::positionAt(int index) const
{
    return rowPosAt(index);
}
 
qreal QQuickGridViewPrivate::endPositionAt(int index) const
{
    return rowPosAt(index) + rowSize();
}
 
qreal QQuickGridViewPrivate::rowSize() const {
    return flow == QQuickGridView::FlowLeftToRight ? cellHeight : cellWidth;
}
qreal QQuickGridViewPrivate::colSize() const {
    return flow == QQuickGridView::FlowLeftToRight ? cellWidth : cellHeight;
}
 
qreal QQuickGridViewPrivate::colPosAt(int modelIndex) const
{
    if (FxViewItem *item = visibleItem(modelIndex))
        return static_cast<FxGridItemSG*>(item)->colPos();
    if (!visibleItems.isEmpty()) {
        if (modelIndex == visibleIndex) {
            FxGridItemSG *firstItem = static_cast<FxGridItemSG*>(visibleItems.first());
            return firstItem->colPos();
        } else if (modelIndex < visibleIndex) {
            int count = (visibleIndex - modelIndex) % columns;
            int col = static_cast<FxGridItemSG*>(visibleItems.first())->colPos() / colSize();
            col = (columns - count + col) % columns;
            return col * colSize();
        } else {
            FxGridItemSG *lastItem = static_cast<FxGridItemSG*>(visibleItems.last());
            int count = modelIndex - lastItem->index;
            int col = lastItem->colPos() / colSize();
            col = (col + count) % columns;
            return col * colSize();
        }
    }
    return (modelIndex % columns) * colSize();
}
 
qreal QQuickGridViewPrivate::rowPosAt(int modelIndex) const
{
    if (FxViewItem *item = visibleItem(modelIndex))
        return static_cast<FxGridItemSG*>(item)->rowPos();
    if (!visibleItems.isEmpty()) {
        if (modelIndex == visibleIndex) {
            FxGridItemSG *firstItem = static_cast<FxGridItemSG*>(visibleItems.first());
            return firstItem->rowPos();
        } else if (modelIndex < visibleIndex) {
            FxGridItemSG *firstItem = static_cast<FxGridItemSG*>(visibleItems.first());
            int firstCol = firstItem->colPos() / colSize();
            int col = visibleIndex - modelIndex + (columns - firstCol - 1);
            int rows = col / columns;
            return firstItem->rowPos() - rows * rowSize();
        } else {
            FxGridItemSG *lastItem = static_cast<FxGridItemSG*>(visibleItems.last());
            int count = modelIndex - lastItem->index;
            int col = lastItem->colPos() + count * colSize();
            int rows = col / (columns * colSize());
            return lastItem->rowPos() + rows * rowSize();
        }
    }
 
    qreal rowPos = ((modelIndex / columns) * rowSize());
 
    if (flow == QQuickGridView::FlowLeftToRight && verticalLayoutDirection == QQuickItemView::TopToBottom) {
        // Add the effective startpos of row 0. Start by subtracting minExtent, which will contain the
        // height of the rows outside the beginning of the content item. (Rows can end up outside if
        // e.g flicking the viewport a long way down, changing cellSize, and then flick back).
        // NOTE: It's not clearly understood why the flow == QQuickGridView::FlowLeftToRight guard is
        // needed, since the flow shouldn't normally affect the y postition of an index. But without
        // it, several auto tests start failing, so we keep it until this part is better understood.
        rowPos -= minExtent;
        // minExtent will also contain the size of the topMargin (vData.startMargin), the header, and
        // the highlightRangeStart. Those should be added before the start of row 0. So we need to subtract
        // them from the rowPos. But only the largest of topMargin and highlightRangeStart will need
        // to be taken into account, since having a topMargin will also ensure that currentItem ends
        // up within the requested highlight range when view is positioned at the beginning.
        rowPos += qMax(vData.startMargin, highlightRangeStart) + headerSize();
    }
 
    return rowPos;
}
 
qreal QQuickGridViewPrivate::snapPosAt(qreal pos) const
{
    Q_Q(const QQuickGridView);
    qreal snapPos = 0;
    if (!visibleItems.isEmpty()) {
        qreal highlightStart = highlightRangeStart;
        pos += highlightStart;
        pos += rowSize()/2;
        snapPos = static_cast<FxGridItemSG*>(visibleItems.first())->rowPos() - visibleIndex / columns * rowSize();
        snapPos = pos - std::fmod(pos - snapPos, qreal(rowSize()));
        snapPos -= highlightStart;
        qreal maxExtent;
        qreal minExtent;
        if (isContentFlowReversed()) {
            maxExtent = q->minXExtent()-size();
            minExtent = q->maxXExtent()-size();
        } else {
            maxExtent = flow == QQuickGridView::FlowLeftToRight ? -q->maxYExtent() : -q->maxXExtent();
            minExtent = flow == QQuickGridView::FlowLeftToRight ? -q->minYExtent() : -q->minXExtent();
        }
        if (snapPos > maxExtent)
            snapPos = maxExtent;
        if (snapPos < minExtent)
            snapPos = minExtent;
    }
    return snapPos;
}
 
FxViewItem *QQuickGridViewPrivate::snapItemAt(qreal pos) const
{
    for (FxViewItem *item : visibleItems) {
        if (item->index == -1)
            continue;
        qreal itemTop = item->position();
        if (itemTop+rowSize()/2 >= pos && itemTop - rowSize()/2 <= pos)
            return item;
    }
    return nullptr;
}
 
int QQuickGridViewPrivate::snapIndex() const
{
    int index = currentIndex;
    for (FxViewItem *item : visibleItems) {
        if (item->index == -1)
            continue;
        qreal itemTop = item->position();
        FxGridItemSG *hItem = static_cast<FxGridItemSG*>(highlight.get());
        if (itemTop >= hItem->rowPos()-rowSize()/2 && itemTop < hItem->rowPos()+rowSize()/2) {
            FxGridItemSG *gridItem = static_cast<FxGridItemSG*>(item);
            index = gridItem->index;
            if (gridItem->colPos() >= hItem->colPos()-colSize()/2 && gridItem->colPos() < hItem->colPos()+colSize()/2)
                return gridItem->index;
        }
    }
    return index;
}
 
qreal QQuickGridViewPrivate::contentXForPosition(qreal pos) const
{
    Q_Q(const QQuickGridView);
    if (flow == QQuickGridView::FlowLeftToRight) {
        // vertical scroll
        if (q->effectiveLayoutDirection() == Qt::LeftToRight) {
            return -q->leftMargin();
        } else {
            qreal colSize = cellWidth;
            int columns = (q->width() - q->leftMargin() - q->rightMargin()) / colSize;
            return -q->width() + q->rightMargin() + (cellWidth * columns);
        }
    } else {
        // horizontal scroll
        if (q->effectiveLayoutDirection() == Qt::LeftToRight)
            return pos;
        else
            return -pos - q->width();
    }
}
 
qreal QQuickGridViewPrivate::contentYForPosition(qreal pos) const
{
    Q_Q(const QQuickGridView);
    if (flow == QQuickGridView::FlowLeftToRight) {
        // vertical scroll
        if (verticalLayoutDirection == QQuickItemView::TopToBottom)
            return pos;
        else
            return -pos - q->height();
    } else {
        // horizontal scroll
        if (verticalLayoutDirection == QQuickItemView::TopToBottom)
            return -q->topMargin();
        else
            return -q->height() + q->bottomMargin();
    }
}
 
void QQuickGridViewPrivate::resetColumns()
{
    Q_Q(QQuickGridView);
    qreal length = flow == QQuickGridView::FlowLeftToRight
            ? q->width() - q->leftMargin() - q->rightMargin()
            : q->height() - q->topMargin() - q->bottomMargin();
    columns = qMax(1, qFloor(length / colSize()));
}
 
FxViewItem *QQuickGridViewPrivate::newViewItem(int modelIndex, QQuickItem *item)
{
    Q_Q(QQuickGridView);
    Q_UNUSED(modelIndex);
    return new FxGridItemSG(item, q, false);
}
 
void QQuickGridViewPrivate::initializeViewItem(FxViewItem *item)
{
    QQuickItemViewPrivate::initializeViewItem(item);
 
    // need to track current items that are animating
    item->trackGeometry(true);
}
 
bool QQuickGridViewPrivate::addVisibleItems(qreal fillFrom, qreal fillTo, qreal bufferFrom, qreal bufferTo, bool doBuffer)
{
    qreal colPos = colPosAt(visibleIndex);
    qreal rowPos = rowPosAt(visibleIndex);
    if (visibleItems.size()) {
        FxGridItemSG *lastItem = static_cast<FxGridItemSG*>(visibleItems.constLast());
        rowPos = lastItem->rowPos();
        int colNum = qFloor((lastItem->colPos()+colSize()/2) / colSize());
        if (++colNum >= columns) {
            colNum = 0;
            rowPos += rowSize();
        }
        colPos = colNum * colSize();
    }
 
    int modelIndex = findLastVisibleIndex();
    modelIndex = modelIndex < 0 ? visibleIndex : modelIndex + 1;
 
    if (visibleItems.size() && (bufferFrom > rowPos + rowSize()*2
        || bufferTo < rowPosAt(visibleIndex) - rowSize())) {
        // We've jumped more than a page.  Estimate which items are now
        // visible and fill from there.
        int count = (fillFrom - (rowPos + rowSize())) / (rowSize()) * columns;
        releaseVisibleItems(reusableFlag);
        modelIndex += count;
        if (modelIndex >= model->count())
            modelIndex = model->count() - 1;
        else if (modelIndex < 0)
            modelIndex = 0;
        modelIndex = modelIndex / columns * columns;
        visibleIndex = modelIndex;
        colPos = colPosAt(visibleIndex);
        rowPos = rowPosAt(visibleIndex);
    }
 
    int colNum = qFloor((colPos+colSize()/2) / colSize());
    FxGridItemSG *item = nullptr;
    bool changed = false;
 
    QQmlIncubator::IncubationMode incubationMode = doBuffer ? QQmlIncubator::Asynchronous : QQmlIncubator::AsynchronousIfNested;
 
    while (modelIndex < model->count() && rowPos <= fillTo + rowSize()*(columns - colNum)/(columns+1)) {
        qCDebug(lcItemViewDelegateLifecycle) << "refill: append item" << modelIndex << colPos << rowPos;
        if (!(item = static_cast<FxGridItemSG*>(createItem(modelIndex, incubationMode))))
            break;
#if QT_CONFIG(quick_viewtransitions)
        if (!transitioner || !transitioner->canTransition(QQuickItemViewTransitioner::PopulateTransition, true)) // pos will be set by layoutVisibleItems()
            item->setPosition(colPos, rowPos, true);
#endif
        QQuickItemPrivate::get(item->item)->setCulled(doBuffer);
        visibleItems.append(item);
        if (++colNum >= columns) {
            colNum = 0;
            rowPos += rowSize();
        }
        colPos = colNum * colSize();
        ++modelIndex;
        changed = true;
    }
 
    if (doBuffer && requestedIndex != -1) // already waiting for an item
        return changed;
 
    // Find first column
    if (visibleItems.size()) {
        FxGridItemSG *firstItem = static_cast<FxGridItemSG*>(visibleItems.constFirst());
        rowPos = firstItem->rowPos();
        colPos = firstItem->colPos();
    }
    colNum = qFloor((colPos+colSize()/2) / colSize());
    if (--colNum < 0) {
        colNum = columns - 1;
        rowPos -= rowSize();
    }
 
    // Prepend
    colPos = colNum * colSize();
    while (visibleIndex > 0 && rowPos + rowSize() - 1 >= fillFrom - rowSize()*(colNum+1)/(columns+1)){
        qCDebug(lcItemViewDelegateLifecycle) << "refill: prepend item" << visibleIndex-1 << "top pos" << rowPos << colPos;
        if (!(item = static_cast<FxGridItemSG*>(createItem(visibleIndex-1, incubationMode))))
            break;
        --visibleIndex;
#if QT_CONFIG(quick_viewtransitions)
        if (!transitioner || !transitioner->canTransition(QQuickItemViewTransitioner::PopulateTransition, true)) // pos will be set by layoutVisibleItems()
            item->setPosition(colPos, rowPos, true);
#endif
        QQuickItemPrivate::get(item->item)->setCulled(doBuffer);
        visibleItems.prepend(item);
        if (--colNum < 0) {
            colNum = columns-1;
            rowPos -= rowSize();
        }
        colPos = colNum * colSize();
        changed = true;
    }
 
    return changed;
}
 
void QQuickGridViewPrivate::removeItem(FxViewItem *item)
{
#if QT_CONFIG(quick_viewtransitions)
    if (item->transitionScheduledOrRunning()) {
        qCDebug(lcItemViewDelegateLifecycle) << "\tnot releasing animating item:" << item->index << item->item->objectName();
        item->releaseAfterTransition = true;
        releasePendingTransition.append(item);
    } else
#endif
    {
        releaseItem(item, QQmlDelegateModel::NotReusable);
    }
}
 
bool QQuickGridViewPrivate::removeNonVisibleItems(qreal bufferFrom, qreal bufferTo)
{
    FxGridItemSG *item = nullptr;
    bool changed = false;
 
    while (visibleItems.size() > 1
           && (item = static_cast<FxGridItemSG*>(visibleItems.constFirst()))
                && item->rowPos()+rowSize()-1 < bufferFrom - rowSize()*(item->colPos()/colSize()+1)/(columns+1)) {
        if (item->attached->delayRemove())
            break;
        qCDebug(lcItemViewDelegateLifecycle) << "refill: remove first" << visibleIndex << "top end pos" << item->endRowPos();
        if (item->index != -1)
            visibleIndex++;
        visibleItems.removeFirst();
        removeItem(item);
        changed = true;
    }
    while (visibleItems.size() > 1
           && (item = static_cast<FxGridItemSG*>(visibleItems.constLast()))
                && item->rowPos() > bufferTo + rowSize()*(columns - item->colPos()/colSize())/(columns+1)) {
        if (item->attached->delayRemove())
            break;
        qCDebug(lcItemViewDelegateLifecycle) << "refill: remove last" << visibleIndex+visibleItems.size()-1;
        visibleItems.removeLast();
        removeItem(item);
        changed = true;
    }
 
    return changed;
}
 
void QQuickGridViewPrivate::updateViewport()
{
    resetColumns();
    QQuickItemViewPrivate::updateViewport();
}
 
void QQuickGridViewPrivate::layoutVisibleItems(int fromModelIndex)
{
    if (visibleItems.size()) {
        const qreal from = isContentFlowReversed() ? -position()-displayMarginBeginning-size() : position()-displayMarginBeginning;
        const qreal to = isContentFlowReversed() ? -position()+displayMarginEnd : position()+size()+displayMarginEnd;
 
        FxGridItemSG *firstItem = static_cast<FxGridItemSG*>(visibleItems.constFirst());
        qreal rowPos = firstItem->rowPos();
        qreal colPos = firstItem->colPos();
        int col = visibleIndex % columns;
        if (colPos != col * colSize()) {
            colPos = col * colSize();
            firstItem->setPosition(colPos, rowPos);
        }
        firstItem->setVisible(firstItem->rowPos() + rowSize() >= from && firstItem->rowPos() <= to);
        for (int i = 1; i < visibleItems.size(); ++i) {
            FxGridItemSG *item = static_cast<FxGridItemSG*>(visibleItems.at(i));
            if (++col >= columns) {
                col = 0;
                rowPos += rowSize();
            }
            colPos = col * colSize();
            if (item->index >= fromModelIndex) {
                item->setPosition(colPos, rowPos);
                item->setVisible(item->rowPos() + rowSize() >= from && item->rowPos() <= to);
            }
        }
    }
}
 
void QQuickGridViewPrivate::repositionItemAt(FxViewItem *item, int index, qreal sizeBuffer)
{
    int count = sizeBuffer / rowSize();
    static_cast<FxGridItemSG *>(item)->setPosition(colPosAt(index + count), rowPosAt(index + count));
}
 
void QQuickGridViewPrivate::repositionPackageItemAt(QQuickItem *item, int index)
{
    Q_Q(QQuickGridView);
    qreal pos = position();
    if (flow == QQuickGridView::FlowLeftToRight) {
        if (item->y() + item->height() > pos && item->y() < pos + q->height()) {
            qreal y = (verticalLayoutDirection == QQuickItemView::TopToBottom)
                    ? rowPosAt(index)
                    : -rowPosAt(index) - item->height();
            item->setPosition(QPointF(colPosAt(index), y));
        }
    } else {
        if (item->x() + item->width() > pos && item->x() < pos + q->width()) {
            qreal y = (verticalLayoutDirection == QQuickItemView::TopToBottom)
                    ? colPosAt(index)
                    : -colPosAt(index) - item->height();
            if (flow == QQuickGridView::FlowTopToBottom && q->effectiveLayoutDirection() == Qt::RightToLeft)
                item->setPosition(QPointF(-rowPosAt(index)-item->width(), y));
            else
                item->setPosition(QPointF(rowPosAt(index), y));
        }
    }
}
 
void QQuickGridViewPrivate::resetFirstItemPosition(qreal pos)
{
    FxGridItemSG *item = static_cast<FxGridItemSG*>(visibleItems.constFirst());
    item->setPosition(0, pos);
}
 
void QQuickGridViewPrivate::adjustFirstItem(qreal forwards, qreal backwards, int changeBeforeVisible)
{
    if (!visibleItems.size())
        return;
 
    int moveCount = (forwards - backwards) / rowSize();
    if (moveCount == 0 && changeBeforeVisible != 0)
        moveCount += (changeBeforeVisible % columns) - (columns - 1);
 
    FxGridItemSG *gridItem = static_cast<FxGridItemSG*>(visibleItems.constFirst());
    gridItem->setPosition(gridItem->colPos(), gridItem->rowPos() + ((moveCount / columns) * rowSize()));
}
 
void QQuickGridViewPrivate::createHighlight(bool onDestruction)
{
    bool changed = false;
    if (highlight) {
        if (trackedItem == highlight.get())
            trackedItem = nullptr;
        highlight.reset();
 
        delete highlightXAnimator;
        delete highlightYAnimator;
        highlightXAnimator = nullptr;
        highlightYAnimator = nullptr;
 
        changed = true;
    }
 
    if (onDestruction)
        return;
 
    Q_Q(QQuickGridView);
    if (currentItem) {
        QQuickItem *item = createHighlightItem();
        if (item) {
            std::unique_ptr<FxGridItemSG> newHighlight
                    = std::make_unique<FxGridItemSG>(item, q, true);
            newHighlight->trackGeometry(true);
            if (autoHighlight)
                resetHighlightPosition();
            highlightXAnimator = new QSmoothedAnimation;
            highlightXAnimator->target = QQmlProperty(item, QLatin1String("x"));
            highlightXAnimator->userDuration = highlightMoveDuration;
            highlightYAnimator = new QSmoothedAnimation;
            highlightYAnimator->target = QQmlProperty(item, QLatin1String("y"));
            highlightYAnimator->userDuration = highlightMoveDuration;
 
            highlight = std::move(newHighlight);
            changed = true;
        }
    }
    if (changed)
        emit q->highlightItemChanged();
}
 
void QQuickGridViewPrivate::updateHighlight()
{
    applyPendingChanges();
 
    if ((!currentItem && highlight) || (currentItem && !highlight))
        createHighlight();
    bool strictHighlight = haveHighlightRange && highlightRange == QQuickGridView::StrictlyEnforceRange;
    if (currentItem && autoHighlight && highlight && (!strictHighlight || !pressed)) {
        // auto-update highlight
        highlightXAnimator->to = currentItem->itemX();
        highlightYAnimator->to = currentItem->itemY();
        highlight->item->setSize(currentItem->item->size());
 
        highlightXAnimator->restart();
        highlightYAnimator->restart();
    }
    updateTrackedItem();
}
 
void QQuickGridViewPrivate::resetHighlightPosition()
{
    if (highlight && currentItem) {
        FxGridItemSG *cItem = static_cast<FxGridItemSG*>(currentItem);
        static_cast<FxGridItemSG *>(highlight.get())->setPosition(cItem->colPos(), cItem->rowPos());
    }
}
 
qreal QQuickGridViewPrivate::headerSize() const
{
    if (!header)
        return 0.0;
    return flow == QQuickGridView::FlowLeftToRight ? header->item->height() : header->item->width();
}
 
qreal QQuickGridViewPrivate::footerSize() const
{
    if (!footer)
        return 0.0;
    return flow == QQuickGridView::FlowLeftToRight? footer->item->height() : footer->item->width();
}
 
bool QQuickGridViewPrivate::showHeaderForIndex(int index) const
{
    return index / columns == 0;
}
 
bool QQuickGridViewPrivate::showFooterForIndex(int index) const
{
    return index / columns == (model->count()-1) / columns;
}
 
void QQuickGridViewPrivate::updateFooter()
{
    Q_Q(QQuickGridView);
    bool created = false;
    if (!footer) {
        QQuickItem *item = createComponentItem(footerComponent, 1.0);
        if (!item)
            return;
        footer = new FxGridItemSG(item, q, true);
        footer->trackGeometry(true);
        created = true;
    }
 
    FxGridItemSG *gridItem = static_cast<FxGridItemSG*>(footer);
    qreal colOffset = 0;
    qreal rowOffset = 0;
    if (q->effectiveLayoutDirection() == Qt::RightToLeft) {
        if (flow == QQuickGridView::FlowTopToBottom)
            rowOffset += gridItem->item->width() - cellWidth;
        else
            colOffset += gridItem->item->width() - cellWidth;
    }
    if (verticalLayoutDirection == QQuickItemView::BottomToTop) {
        if (flow == QQuickGridView::FlowTopToBottom)
            colOffset += gridItem->item->height() - cellHeight;
        else
            rowOffset += gridItem->item->height() - cellHeight;
    }
    if (visibleItems.size()) {
        qreal endPos = lastPosition();
        if (findLastVisibleIndex() == model->count()-1) {
            gridItem->setPosition(colOffset, endPos + rowOffset);
        } else {
            qreal visiblePos = isContentFlowReversed() ? -position() : position() + size();
            if (endPos <= visiblePos || gridItem->endPosition() <= endPos + rowOffset)
                gridItem->setPosition(colOffset, endPos + rowOffset);
        }
    } else {
        gridItem->setPosition(colOffset, rowOffset);
    }
 
    if (created)
        emit q->footerItemChanged();
}
 
void QQuickGridViewPrivate::initializeComponentItem(QQuickItem *item) const
{
    QQuickGridViewAttached *attached = static_cast<QQuickGridViewAttached *>(
        qmlAttachedPropertiesObject<QQuickGridView>(item));
    if (attached)
        attached->setView(const_cast<QQuickGridView*>(q_func()));
}
 
void QQuickGridViewPrivate::updateHeader()
{
    Q_Q(QQuickGridView);
    bool created = false;
    if (!header) {
        QQuickItem *item = createComponentItem(headerComponent, 1.0);
        if (!item)
            return;
        header = new FxGridItemSG(item, q, true);
        header->trackGeometry(true);
        created = true;
    }
 
    FxGridItemSG *gridItem = static_cast<FxGridItemSG*>(header);
    qreal colOffset = 0;
    qreal rowOffset = -headerSize();
    if (q->effectiveLayoutDirection() == Qt::RightToLeft) {
        if (flow == QQuickGridView::FlowTopToBottom)
            rowOffset += gridItem->item->width() - cellWidth;
        else
            colOffset += gridItem->item->width() - cellWidth;
    }
    if (verticalLayoutDirection == QQuickItemView::BottomToTop) {
        if (flow == QQuickGridView::FlowTopToBottom)
            colOffset += gridItem->item->height() - cellHeight;
        else
            rowOffset += gridItem->item->height() - cellHeight;
    }
    if (visibleItems.size()) {
        qreal startPos = originPosition();
        if (visibleIndex == 0) {
            gridItem->setPosition(colOffset, startPos + rowOffset);
        } else {
            qreal tempPos = isContentFlowReversed() ? -position()-size() : position();
            qreal headerPos = isContentFlowReversed() ? gridItem->rowPos() + cellWidth - headerSize() : gridItem->rowPos();
            if (tempPos <= startPos || headerPos > startPos + rowOffset)
                gridItem->setPosition(colOffset, startPos + rowOffset);
        }
    } else {
        if (isContentFlowReversed())
            gridItem->setPosition(colOffset, rowOffset);
        else
            gridItem->setPosition(colOffset, -headerSize());
    }
 
    if (created)
        emit q->headerItemChanged();
}
 
void QQuickGridViewPrivate::initializeCurrentItem()
{
    if (currentItem && currentIndex >= 0) {
        FxGridItemSG *gridItem = static_cast<FxGridItemSG*>(currentItem);
        FxViewItem *actualItem = visibleItem(currentIndex);
 
        // don't reposition the item if it's about to be transitioned to another position
        if ((!actualItem
#if QT_CONFIG(quick_viewtransitions)
             || !actualItem->transitionScheduledOrRunning()
#endif
             ))
            gridItem->setPosition(colPosAt(currentIndex), rowPosAt(currentIndex));
    }
}
 
void QQuickGridViewPrivate::fixupPosition()
{
    if (flow == QQuickGridView::FlowLeftToRight)
        fixupY();
    else
        fixupX();
}
 
void QQuickGridViewPrivate::fixup(AxisData &data, qreal minExtent, qreal maxExtent)
{
    if ((flow == QQuickGridView::FlowTopToBottom && &data == &vData)
        || (flow == QQuickGridView::FlowLeftToRight && &data == &hData))
        return;
 
    fixupMode = moveReason == Mouse ? fixupMode : Immediate;
 
    qreal viewPos = isContentFlowReversed() ? -position()-size() : position();
 
    bool strictHighlightRange = haveHighlightRange && highlightRange == QQuickGridView::StrictlyEnforceRange;
    if (snapMode != QQuickGridView::NoSnap) {
        qreal tempPosition = isContentFlowReversed() ? -position()-size() : position();
        if (snapMode == QQuickGridView::SnapOneRow && moveReason == Mouse) {
            // if we've been dragged < rowSize()/2 then bias towards the next row
            qreal dist = data.move.value() - data.pressPos;
            qreal bias = 0;
            if (data.velocity > 0 && dist > QML_FLICK_SNAPONETHRESHOLD && dist < rowSize()/2)
                bias = rowSize()/2;
            else if (data.velocity < 0 && dist < -QML_FLICK_SNAPONETHRESHOLD && dist > -rowSize()/2)
                bias = -rowSize()/2;
            if (isContentFlowReversed())
                bias = -bias;
            tempPosition -= bias;
        }
        FxViewItem *topItem = snapItemAt(tempPosition+highlightRangeStart);
        if (strictHighlightRange && currentItem && (!topItem || (topItem->index != currentIndex && fixupMode == Immediate))) {
            // StrictlyEnforceRange always keeps an item in range
            updateHighlight();
            topItem = currentItem;
        }
        FxViewItem *bottomItem = snapItemAt(tempPosition+highlightRangeEnd);
        if (strictHighlightRange && currentItem && (!bottomItem || (bottomItem->index != currentIndex && fixupMode == Immediate))) {
            // StrictlyEnforceRange always keeps an item in range
            updateHighlight();
            bottomItem = currentItem;
        }
        qreal pos;
        bool isInBounds = -position() > maxExtent && -position() <= minExtent;
        if (topItem && (isInBounds || strictHighlightRange)) {
            qreal headerPos = header ? static_cast<FxGridItemSG*>(header)->rowPos() : 0;
            if (topItem->index == 0 && header && tempPosition+highlightRangeStart < headerPos+headerSize()/2 && !strictHighlightRange) {
                pos = isContentFlowReversed() ? - headerPos + highlightRangeStart - size() : headerPos - highlightRangeStart;
            } else {
                if (isContentFlowReversed())
                    pos = qMax(qMin(-topItem->position() + highlightRangeStart - size(), -maxExtent), -minExtent);
                else
                    pos = qMax(qMin(topItem->position() - highlightRangeStart, -maxExtent), -minExtent);
            }
        } else if (bottomItem && isInBounds) {
            if (isContentFlowReversed())
                pos = qMax(qMin(-bottomItem->position() + highlightRangeEnd - size(), -maxExtent), -minExtent);
            else
                pos = qMax(qMin(bottomItem->position() - highlightRangeEnd, -maxExtent), -minExtent);
        } else {
            QQuickItemViewPrivate::fixup(data, minExtent, maxExtent);
            return;
        }
 
        qreal dist = qAbs(data.move + pos);
        if (dist > 0) {
            timeline.reset(data.move);
            if (fixupMode != Immediate) {
                timeline.move(data.move, -pos, QEasingCurve(QEasingCurve::InOutQuad), fixupDuration/2);
                data.fixingUp = true;
            } else {
                timeline.set(data.move, -pos);
            }
            vTime = timeline.time();
        }
    } else if (haveHighlightRange && highlightRange == QQuickGridView::StrictlyEnforceRange) {
        if (currentItem) {
            updateHighlight();
            qreal pos = static_cast<FxGridItemSG*>(currentItem)->rowPos();
            if (viewPos < pos + rowSize() - highlightRangeEnd)
                viewPos = pos + rowSize() - highlightRangeEnd;
            if (viewPos > pos - highlightRangeStart)
                viewPos = pos - highlightRangeStart;
            if (isContentFlowReversed())
                viewPos = -viewPos-size();
            timeline.reset(data.move);
            if (viewPos != position()) {
                if (fixupMode != Immediate) {
                    timeline.move(data.move, -viewPos, QEasingCurve(QEasingCurve::InOutQuad), fixupDuration/2);
                    data.fixingUp = true;
                } else {
                    timeline.set(data.move, -viewPos);
                }
            }
            vTime = timeline.time();
        }
    } else {
        QQuickItemViewPrivate::fixup(data, minExtent, maxExtent);
    }
    data.inOvershoot = false;
    fixupMode = Normal;
}
 
bool QQuickGridViewPrivate::flick(AxisData &data, qreal minExtent, qreal maxExtent, qreal vSize,
                                  QQuickTimeLineCallback::Callback fixupCallback, QEvent::Type eventType, qreal velocity)
{
    data.fixingUp = false;
    moveReason = Mouse;
    if ((!haveHighlightRange || highlightRange != QQuickGridView::StrictlyEnforceRange)
        && snapMode == QQuickGridView::NoSnap) {
        return QQuickItemViewPrivate::flick(data, minExtent, maxExtent, vSize, fixupCallback, eventType, velocity);
    }
    qreal maxDistance = 0;
    qreal dataValue = isContentFlowReversed() ? -data.move.value()+size() : data.move.value();
    // -ve velocity means list is moving up/left
    if (velocity > 0) {
        if (data.move.value() < minExtent) {
            if (snapMode == QQuickGridView::SnapOneRow) {
                // if we've been dragged < averageSize/2 then bias towards the next item
                qreal dist = data.move.value() - data.pressPos;
                qreal bias = dist < rowSize()/2 ? rowSize()/2 : 0;
                if (isContentFlowReversed())
                    bias = -bias;
                data.flickTarget = -snapPosAt(-dataValue - bias);
                maxDistance = qAbs(data.flickTarget - data.move.value());
                velocity = maxVelocity;
            } else {
                maxDistance = qAbs(minExtent - data.move.value());
            }
        }
        if (snapMode == QQuickGridView::NoSnap && highlightRange != QQuickGridView::StrictlyEnforceRange)
            data.flickTarget = minExtent;
    } else {
        if (data.move.value() > maxExtent) {
            if (snapMode == QQuickGridView::SnapOneRow) {
                // if we've been dragged < averageSize/2 then bias towards the next item
                qreal dist = data.move.value() - data.pressPos;
                qreal bias = -dist < rowSize()/2 ? rowSize()/2 : 0;
                if (isContentFlowReversed())
                    bias = -bias;
                data.flickTarget = -snapPosAt(-dataValue + bias);
                maxDistance = qAbs(data.flickTarget - data.move.value());
                velocity = -maxVelocity;
            } else {
                maxDistance = qAbs(maxExtent - data.move.value());
            }
        }
        if (snapMode == QQuickGridView::NoSnap && highlightRange != QQuickGridView::StrictlyEnforceRange)
            data.flickTarget = maxExtent;
    }
    bool overShoot = boundsBehavior & QQuickFlickable::OvershootBounds;
    if (maxDistance > 0 || overShoot) {
        // This mode requires the grid to stop exactly on a row boundary.
        qreal v = velocity;
        if (maxVelocity != -1 && maxVelocity < qAbs(v)) {
            if (v < 0)
                v = -maxVelocity;
            else
                v = maxVelocity;
        }
        qreal accel = eventType == QEvent::Wheel ? wheelDeceleration : deceleration;
        qreal v2 = v * v;
        qreal overshootDist = 0.0;
        if ((maxDistance > 0.0 && v2 / (2.0f * maxDistance) < accel) || snapMode == QQuickGridView::SnapOneRow) {
            // + rowSize()/4 to encourage moving at least one item in the flick direction
            qreal dist = v2 / (accel * 2.0) + rowSize()/4;
            dist = qMin(dist, maxDistance);
            if (v > 0)
                dist = -dist;
            if (snapMode != QQuickGridView::SnapOneRow) {
                qreal distTemp = isContentFlowReversed() ? -dist : dist;
                data.flickTarget = -snapPosAt(-dataValue + distTemp);
            }
            data.flickTarget = isContentFlowReversed() ? -data.flickTarget+size() : data.flickTarget;
            if (overShoot) {
                if (data.flickTarget >= minExtent) {
                    overshootDist = overShootDistance(vSize);
                    data.flickTarget += overshootDist;
                } else if (data.flickTarget <= maxExtent) {
                    overshootDist = overShootDistance(vSize);
                    data.flickTarget -= overshootDist;
                }
            }
            qreal adjDist = -data.flickTarget + data.move.value();
            if (qAbs(adjDist) > qAbs(dist)) {
                // Prevent painfully slow flicking - adjust velocity to suit flickDeceleration
                qreal adjv2 = accel * 2.0f * qAbs(adjDist);
                if (adjv2 > v2) {
                    v2 = adjv2;
                    v = qSqrt(v2);
                    if (dist > 0)
                        v = -v;
                }
            }
            dist = adjDist;
            accel = v2 / (2.0f * qAbs(dist));
        } else {
            data.flickTarget = velocity > 0 ? minExtent : maxExtent;
            overshootDist = overShoot ? overShootDistance(vSize) : 0;
        }
        timeline.reset(data.move);
        timeline.accel(data.move, v, accel, maxDistance + overshootDist);
        timeline.callback(QQuickTimeLineCallback(&data.move, fixupCallback, this));
        return true;
    } else {
        timeline.reset(data.move);
        fixup(data, minExtent, maxExtent);
        return false;
    }
}
 
 
//----------------------------------------------------------------------------
QQuickGridView::QQuickGridView(QQuickItem *parent)
    : QQuickItemView(*(new QQuickGridViewPrivate), parent)
{
}
 
void QQuickGridView::setHighlightFollowsCurrentItem(bool autoHighlight)
{
    Q_D(QQuickGridView);
    if (d->autoHighlight != autoHighlight) {
        if (!autoHighlight && d->highlightXAnimator) {
            d->highlightXAnimator->stop();
            d->highlightYAnimator->stop();
        }
        QQuickItemView::setHighlightFollowsCurrentItem(autoHighlight);
    }
}
 
void QQuickGridView::setHighlightMoveDuration(int duration)
{
    Q_D(QQuickGridView);
    if (d->highlightMoveDuration != duration) {
        if (d->highlightYAnimator) {
            d->highlightXAnimator->userDuration = duration;
            d->highlightYAnimator->userDuration = duration;
        }
        QQuickItemView::setHighlightMoveDuration(duration);
    }
}
 
QQuickGridView::Flow QQuickGridView::flow() const
{
    Q_D(const QQuickGridView);
    return d->flow;
}
 
void QQuickGridView::setFlow(Flow flow)
{
    Q_D(QQuickGridView);
    if (d->flow != flow) {
        d->flow = flow;
        if (d->flow == FlowLeftToRight) {
            setContentWidth(-1);
            setFlickableDirection(VerticalFlick);
        } else {
            setContentHeight(-1);
            setFlickableDirection(HorizontalFlick);
        }
        setContentX(0);
        setContentY(0);
        d->regenerate(true);
        emit flowChanged();
    }
}
 
 
qreal QQuickGridView::cellWidth() const
{
    Q_D(const QQuickGridView);
    return d->cellWidth;
}
 
void QQuickGridView::setCellWidth(qreal cellWidth)
{
    Q_D(QQuickGridView);
    if (cellWidth != d->cellWidth && cellWidth > 0) {
        d->cellWidth = qMax(qreal(1), cellWidth);
        d->updateViewport();
        emit cellWidthChanged();
        d->forceLayoutPolish();
        QQuickFlickable::setContentX(d->contentXForPosition(d->position()));
    }
}
 
qreal QQuickGridView::cellHeight() const
{
    Q_D(const QQuickGridView);
    return d->cellHeight;
}
 
void QQuickGridView::setCellHeight(qreal cellHeight)
{
    Q_D(QQuickGridView);
    if (cellHeight != d->cellHeight && cellHeight > 0) {
        d->cellHeight = qMax(qreal(1), cellHeight);
        d->updateViewport();
        emit cellHeightChanged();
        d->forceLayoutPolish();
        QQuickFlickable::setContentY(d->contentYForPosition(d->position()));
    }
}
QQuickGridView::SnapMode QQuickGridView::snapMode() const
{
    Q_D(const QQuickGridView);
    return d->snapMode;
}
 
void QQuickGridView::setSnapMode(SnapMode mode)
{
    Q_D(QQuickGridView);
    if (d->snapMode != mode) {
        d->snapMode = mode;
        emit snapModeChanged();
    }
}
 
 
void QQuickGridView::viewportMoved(Qt::Orientations orient)
{
    Q_D(QQuickGridView);
    QQuickItemView::viewportMoved(orient);
    if (!d->itemCount)
        return;
    if (d->inViewportMoved)
        return;
    d->inViewportMoved = true;
 
    if (yflick()) {
        if (d->isContentFlowReversed())
            d->bufferMode = d->vData.smoothVelocity < 0 ? QQuickItemViewPrivate::BufferAfter : QQuickItemViewPrivate::BufferBefore;
        else
            d->bufferMode = d->vData.smoothVelocity < 0 ? QQuickItemViewPrivate::BufferBefore : QQuickItemViewPrivate::BufferAfter;
    } else {
        if (d->isContentFlowReversed())
            d->bufferMode = d->hData.smoothVelocity < 0 ? QQuickItemViewPrivate::BufferAfter : QQuickItemViewPrivate::BufferBefore;
        else
            d->bufferMode = d->hData.smoothVelocity < 0 ? QQuickItemViewPrivate::BufferBefore : QQuickItemViewPrivate::BufferAfter;
    }
 
    d->refillOrLayout();
 
    // Set visibility of items to eliminate cost of items outside the visible area.
    qreal from = d->isContentFlowReversed() ? -d->position()-d->displayMarginBeginning-d->size() : d->position()-d->displayMarginBeginning;
    qreal to = d->isContentFlowReversed() ? -d->position()+d->displayMarginEnd : d->position()+d->size()+d->displayMarginEnd;
    for (FxViewItem *item : std::as_const(d->visibleItems)) {
        FxGridItemSG *gridItem = static_cast<FxGridItemSG*>(item);
        QQuickItemPrivate::get(gridItem->item)->setCulled(gridItem->rowPos() + d->rowSize() < from || gridItem->rowPos() > to);
    }
    if (d->currentItem) {
        FxGridItemSG *item = static_cast<FxGridItemSG*>(d->currentItem);
        QQuickItemPrivate::get(item->item)->setCulled(item->rowPos() + d->rowSize() < from || item->rowPos() > to);
    }
 
    if (d->hData.flicking || d->vData.flicking || d->hData.moving || d->vData.moving)
        d->moveReason = QQuickGridViewPrivate::Mouse;
    if (d->moveReason != QQuickGridViewPrivate::SetIndex) {
        if (d->haveHighlightRange && d->highlightRange == StrictlyEnforceRange && d->highlight) {
            // reposition highlight
            qreal pos = d->highlight->position();
            qreal viewPos = d->isContentFlowReversed() ? -d->position()-d->size() : d->position();
            if (pos > viewPos + d->highlightRangeEnd - d->highlight->size())
                pos = viewPos + d->highlightRangeEnd - d->highlight->size();
            if (pos < viewPos + d->highlightRangeStart)
                pos = viewPos + d->highlightRangeStart;
 
            if (pos != d->highlight->position()) {
                d->highlightXAnimator->stop();
                d->highlightYAnimator->stop();
                FxGridItemSG *sgHighlight = static_cast<FxGridItemSG *>(d->highlight.get());
                sgHighlight->setPosition(sgHighlight->colPos(), pos);
            } else {
                d->updateHighlight();
            }
 
            // update current index
            int idx = d->snapIndex();
            if (idx >= 0 && idx != d->currentIndex) {
                d->updateCurrent(idx);
                if (d->currentItem
                        && static_cast<FxGridItemSG*>(d->currentItem)->colPos()
                            != static_cast<FxGridItemSG*>(d->highlight.get())->colPos()
                        && d->autoHighlight) {
                    if (d->flow == FlowLeftToRight)
                        d->highlightXAnimator->to = d->currentItem->itemX();
                    else
                        d->highlightYAnimator->to = d->currentItem->itemY();
                }
            }
        }
    }
 
    d->inViewportMoved = false;
}
 
void QQuickGridView::keyPressEvent(QKeyEvent *event)
{
    Q_D(QQuickGridView);
    if (d->model && d->model->count() && ((d->interactive && !d->explicitKeyNavigationEnabled)
        || (d->explicitKeyNavigationEnabled && d->keyNavigationEnabled))) {
        d->moveReason = QQuickGridViewPrivate::SetIndex;
        int oldCurrent = currentIndex();
        switch (event->key()) {
        case Qt::Key_Up:
            moveCurrentIndexUp();
            break;
        case Qt::Key_Down:
            moveCurrentIndexDown();
            break;
        case Qt::Key_Left:
            moveCurrentIndexLeft();
            break;
        case Qt::Key_Right:
            moveCurrentIndexRight();
            break;
        default:
            break;
        }
        if (oldCurrent != currentIndex() || d->wrap) {
            event->accept();
            return;
        }
    }
    event->ignore();
    QQuickItemView::keyPressEvent(event);
}
 
void QQuickGridView::geometryChange(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_D(QQuickGridView);
    d->resetColumns();
 
    if (newGeometry.width() != oldGeometry.width()
            && newGeometry.height() != oldGeometry.height()) {
        d->setPosition(d->position());
    } else if (newGeometry.width() != oldGeometry.width()) {
        QQuickFlickable::setContentX(d->contentXForPosition(d->position()));
    } else if (newGeometry.height() != oldGeometry.height()) {
        QQuickFlickable::setContentY(d->contentYForPosition(d->position()));
    }
 
    QQuickItemView::geometryChange(newGeometry, oldGeometry);
}
 
void QQuickGridView::initItem(int index, QObject *obj)
{
    QQuickItemView::initItem(index, obj);
 
    // setting the view from the FxViewItem wrapper is too late if the delegate
    // needs access to the view in Component.onCompleted
    QQuickItem *item = qmlobject_cast<QQuickItem*>(obj);
    if (item) {
        QQuickGridViewAttached *attached = static_cast<QQuickGridViewAttached *>(
                qmlAttachedPropertiesObject<QQuickGridView>(item));
        if (attached)
            attached->setView(this);
    }
}
 
void QQuickGridView::moveCurrentIndexUp()
{
    Q_D(QQuickGridView);
    const int count = d->model ? d->model->count() : 0;
    if (!count)
        return;
    if (d->verticalLayoutDirection == QQuickItemView::TopToBottom) {
        if (d->flow == QQuickGridView::FlowLeftToRight) {
            if (currentIndex() >= d->columns || d->wrap) {
                int index = currentIndex() - d->columns;
                setCurrentIndex((index >= 0 && index < count) ? index : count-1);
            }
        } else {
            if (currentIndex() > 0 || d->wrap) {
                int index = currentIndex() - 1;
                setCurrentIndex((index >= 0 && index < count) ? index : count-1);
            }
        }
    } else {
        if (d->flow == QQuickGridView::FlowLeftToRight) {
            if (currentIndex() < count - d->columns || d->wrap) {
                int index = currentIndex()+d->columns;
                setCurrentIndex((index >= 0 && index < count) ? index : 0);
            }
        } else {
            if (currentIndex() < count - 1 || d->wrap) {
                int index = currentIndex() + 1;
                setCurrentIndex((index >= 0 && index < count) ? index : 0);
            }
        }
    }
}
 
void QQuickGridView::moveCurrentIndexDown()
{
    Q_D(QQuickGridView);
    const int count = d->model ? d->model->count() : 0;
    if (!count)
        return;
 
    if (d->verticalLayoutDirection == QQuickItemView::TopToBottom) {
        if (d->flow == QQuickGridView::FlowLeftToRight) {
            if (currentIndex() < count - d->columns || d->wrap) {
                int index = currentIndex()+d->columns;
                setCurrentIndex((index >= 0 && index < count) ? index : 0);
            }
        } else {
            if (currentIndex() < count - 1 || d->wrap) {
                int index = currentIndex() + 1;
                setCurrentIndex((index >= 0 && index < count) ? index : 0);
            }
        }
    } else {
        if (d->flow == QQuickGridView::FlowLeftToRight) {
            if (currentIndex() >= d->columns || d->wrap) {
                int index = currentIndex() - d->columns;
                setCurrentIndex((index >= 0 && index < count) ? index : count-1);
            }
        } else {
            if (currentIndex() > 0 || d->wrap) {
                int index = currentIndex() - 1;
                setCurrentIndex((index >= 0 && index < count) ? index : count-1);
            }
        }
    }
}
 
void QQuickGridView::moveCurrentIndexLeft()
{
    Q_D(QQuickGridView);
    const int count = d->model ? d->model->count() : 0;
    if (!count)
        return;
    if (effectiveLayoutDirection() == Qt::LeftToRight) {
        if (d->flow == QQuickGridView::FlowLeftToRight) {
            if (currentIndex() > 0 || d->wrap) {
                int index = currentIndex() - 1;
                setCurrentIndex((index >= 0 && index < count) ? index : count-1);
            }
        } else {
            if (currentIndex() >= d->columns || d->wrap) {
                int index = currentIndex() - d->columns;
                setCurrentIndex((index >= 0 && index < count) ? index : count-1);
            }
        }
    } else {
        if (d->flow == QQuickGridView::FlowLeftToRight) {
            if (currentIndex() < count - 1 || d->wrap) {
                int index = currentIndex() + 1;
                setCurrentIndex((index >= 0 && index < count) ? index : 0);
            }
        } else {
            if (currentIndex() < count - d->columns || d->wrap) {
                int index = currentIndex() + d->columns;
                setCurrentIndex((index >= 0 && index < count) ? index : 0);
            }
        }
    }
}
 
 
void QQuickGridView::moveCurrentIndexRight()
{
    Q_D(QQuickGridView);
    const int count = d->model ? d->model->count() : 0;
    if (!count)
        return;
    if (effectiveLayoutDirection() == Qt::LeftToRight) {
        if (d->flow == QQuickGridView::FlowLeftToRight) {
            if (currentIndex() < count - 1 || d->wrap) {
                int index = currentIndex() + 1;
                setCurrentIndex((index >= 0 && index < count) ? index : 0);
            }
        } else {
            if (currentIndex() < count - d->columns || d->wrap) {
                int index = currentIndex()+d->columns;
                setCurrentIndex((index >= 0 && index < count) ? index : 0);
            }
        }
    } else {
        if (d->flow == QQuickGridView::FlowLeftToRight) {
            if (currentIndex() > 0 || d->wrap) {
                int index = currentIndex() - 1;
                setCurrentIndex((index >= 0 && index < count) ? index : count-1);
            }
        } else {
            if (currentIndex() >= d->columns || d->wrap) {
                int index = currentIndex() - d->columns;
                setCurrentIndex((index >= 0 && index < count) ? index : count-1);
            }
        }
    }
}
 
bool QQuickGridViewPrivate::applyInsertionChange(const QQmlChangeSet::Change &change, ChangeResult *insertResult, QList<FxViewItem *> *addedItems, QList<MovedItem> *movingIntoView)
{
    Q_Q(QQuickGridView);
 
    if (q->size().isEmpty())
        return false;
 
    int modelIndex = change.index;
    int count = change.count;
 
    int index = visibleItems.size() ? mapFromModel(modelIndex) : 0;
 
    if (index < 0) {
        int i = visibleItems.size() - 1;
        while (i > 0 && visibleItems.at(i)->index == -1)
            --i;
        if (visibleItems.at(i)->index + 1 == modelIndex) {
            // Special case of appending an item to the model.
            index = visibleItems.size();
        } else {
            if (modelIndex <= visibleIndex) {
                // Insert before visible items
                visibleIndex += count;
                for (FxViewItem *item : std::as_const(visibleItems)) {
                    if (item->index != -1 && item->index >= modelIndex)
                        item->index += count;
                }
            }
            return true;
        }
    }
 
    qreal tempPos = isContentFlowReversed() ? -position()-size()+q->width()+1 : position();
    qreal colPos = 0;
    qreal rowPos = 0;
    int colNum = 0;
    if (visibleItems.size()) {
        if (index < visibleItems.size()) {
            FxGridItemSG *gridItem = static_cast<FxGridItemSG*>(visibleItems.at(index));
            colPos = gridItem->colPos();
            rowPos = gridItem->rowPos();
            colNum = qFloor((colPos+colSize()/2) / colSize());
        } else {
            // appending items to visible list
            FxGridItemSG *gridItem = static_cast<FxGridItemSG*>(visibleItems.at(index-1));
            rowPos = gridItem->rowPos();
            colNum = qFloor((gridItem->colPos()+colSize()/2) / colSize());
            if (++colNum >= columns) {
                colNum = 0;
                rowPos += rowSize();
            }
            colPos = colNum * colSize();
        }
    }
 
#if QT_CONFIG(quick_viewtransitions)
    // Update the indexes of the following visible items.
    for (FxViewItem *item : std::as_const(visibleItems)) {
        if (item->index != -1 && item->index >= modelIndex) {
            item->index += count;
            if (change.isMove())
                item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::MoveTransition, false);
            else
                item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::AddTransition, false);
        }
    }
#endif
 
    int prevVisibleCount = visibleItems.size();
    if (insertResult->visiblePos.isValid() && rowPos < insertResult->visiblePos) {
        // Insert items before the visible item.
        int insertionIdx = index;
        int i = count - 1;
        int from = tempPos - buffer - displayMarginBeginning;
 
        if (rowPos > from && insertionIdx < visibleIndex) {
                // items won't be visible, just note the size for repositioning
                insertResult->countChangeBeforeVisible += count;
                insertResult->sizeChangesBeforeVisiblePos += ((count + columns - 1) / columns) * rowSize();
        } else {
            while (i >= 0) {
                // item is before first visible e.g. in cache buffer
                FxViewItem *item = nullptr;
                if (change.isMove() && (item = currentChanges.removedItems.take(change.moveKey(modelIndex + i))))
                    item->index = modelIndex + i;
                if (!item)
                    item = createItem(modelIndex + i, QQmlIncubator::Synchronous);
                if (!item)
                    return false;
 
                QQuickItemPrivate::get(item->item)->setCulled(false);
                visibleItems.insert(insertionIdx, item);
                if (insertionIdx == 0)
                    insertResult->changedFirstItem = true;
                if (!change.isMove()) {
                    addedItems->append(item);
#if QT_CONFIG(quick_viewtransitions)
                    if (transitioner)
                        item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::AddTransition, true);
                    else
#endif
                        item->moveTo(QPointF(colPos, rowPos), true);
                }
                insertResult->sizeChangesBeforeVisiblePos += rowSize();
 
                if (--colNum < 0 ) {
                    colNum = columns - 1;
                    rowPos -= rowSize();
                }
                colPos = colNum * colSize();
                index++;
                i--;
            }
        }
 
        // There may be gaps in the index sequence of visibleItems because
        // of the index shift/update done before the insertion just above.
        // Find if there is any...
        int firstOkIdx = -1;
        for (int i = 0; i <= insertionIdx && i < visibleItems.size() - 1; i++) {
            if (visibleItems.at(i)->index + 1 != visibleItems.at(i + 1)->index) {
                firstOkIdx = i + 1;
                break;
            }
        }
        // ... and remove all the items before that one
        for (int i = 0; i < firstOkIdx; i++) {
            FxViewItem *nvItem = visibleItems.takeFirst();
            addedItems->removeOne(nvItem);
            removeItem(nvItem);
        }
 
    } else {
        int i = 0;
        int to = buffer+displayMarginEnd+tempPos+size()-1;
        while (i < count && rowPos <= to + rowSize()*(columns - colNum)/qreal(columns+1)) {
            FxViewItem *item = nullptr;
            if (change.isMove() && (item = currentChanges.removedItems.take(change.moveKey(modelIndex + i))))
                item->index = modelIndex + i;
            bool newItem = !item;
            if (!item)
                item = createItem(modelIndex + i, QQmlIncubator::Synchronous);
            if (!item)
                return false;
 
            QQuickItemPrivate::get(item->item)->setCulled(false);
            visibleItems.insert(index, item);
            if (index == 0)
                insertResult->changedFirstItem = true;
            if (change.isMove()) {
                // we know this is a move target, since move displaced items that are
                // shuffled into view due to a move would be added in refill()
                if (newItem
#if QT_CONFIG(quick_viewtransitions)
                        && transitioner && transitioner->canTransition(QQuickItemViewTransitioner::MoveTransition, true)
#endif
                        )
                    movingIntoView->append(MovedItem(item, change.moveKey(item->index)));
            } else {
                addedItems->append(item);
#if QT_CONFIG(quick_viewtransitions)
                if (transitioner)
                    item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::AddTransition, true);
                else
#endif
                    item->moveTo(QPointF(colPos, rowPos), true);
            }
            insertResult->sizeChangesAfterVisiblePos += rowSize();
 
            if (++colNum >= columns) {
                colNum = 0;
                rowPos += rowSize();
            }
            colPos = colNum * colSize();
            ++index;
            ++i;
        }
    }
 
    updateVisibleIndex();
 
    return visibleItems.size() > prevVisibleCount;
}
 
#if QT_CONFIG(quick_viewtransitions)
void QQuickGridViewPrivate::translateAndTransitionItemsAfter(int afterModelIndex, const ChangeResult &insertionResult, const ChangeResult &removalResult)
{
    if (!transitioner)
        return;
 
    int markerItemIndex = -1;
    for (int i=0; i<visibleItems.size(); i++) {
        if (visibleItems.at(i)->index == afterModelIndex) {
            markerItemIndex = i;
            break;
        }
    }
    if (markerItemIndex < 0)
        return;
 
    const qreal viewEndPos = isContentFlowReversed() ? -position() : position() + size();
    int countItemsRemoved = -(removalResult.sizeChangesAfterVisiblePos / rowSize());
 
    // account for whether first item has changed if < 1 row was removed before visible
    int changeBeforeVisible = insertionResult.countChangeBeforeVisible - removalResult.countChangeBeforeVisible;
    if (changeBeforeVisible != 0)
        countItemsRemoved += (changeBeforeVisible % columns) - (columns - 1);
 
    countItemsRemoved -= removalResult.countChangeAfterVisibleItems;
 
    for (int i=markerItemIndex+1; i<visibleItems.size(); i++) {
        FxGridItemSG *gridItem = static_cast<FxGridItemSG *>(visibleItems.at(i));
        if (gridItem->position() >= viewEndPos)
            break;
        if (!gridItem->transitionScheduledOrRunning()) {
            qreal origRowPos = gridItem->colPos();
            qreal origColPos = gridItem->rowPos();
            int indexDiff = gridItem->index - countItemsRemoved;
            gridItem->setPosition((indexDiff % columns) * colSize(), (indexDiff / columns) * rowSize());
            gridItem->transitionNextReposition(transitioner, QQuickItemViewTransitioner::RemoveTransition, false);
            gridItem->setPosition(origRowPos, origColPos);
        }
    }
}
#endif
 
bool QQuickGridViewPrivate::needsRefillForAddedOrRemovedIndex(int modelIndex) const
{
    // If we add or remove items before visible items, a layout may be
    // required to ensure item 0 is in the first column.
    return modelIndex < visibleIndex;
}
 
QQuickGridViewAttached *QQuickGridView::qmlAttachedProperties(QObject *obj)
{
    return new QQuickGridViewAttached(obj);
}
 
QT_END_NAMESPACE
 
#include "moc_qquickgridview_p.cpp"