qquicklinearlayout.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 "qquicklinearlayout_p.h"
#include "qquickgridlayoutengine_p.h"
#include "qquicklayoutstyleinfo_p.h"
#include <QtCore/private/qnumeric_p.h>
#include <QtQml/qqmlinfo.h>
#include "qdebug.h"
#include <limits>
 
 
 
 
QT_BEGIN_NAMESPACE
 
QQuickGridLayoutBase::QQuickGridLayoutBase()
    : QQuickLayout(*new QQuickGridLayoutBasePrivate)
{
 
}
 
QQuickGridLayoutBase::QQuickGridLayoutBase(QQuickGridLayoutBasePrivate &dd,
                                           Qt::Orientation orientation,
                                           QQuickItem *parent /*= nullptr */)
    : QQuickLayout(dd, parent)
{
    Q_D(QQuickGridLayoutBase);
    d->orientation = orientation;
    d->styleInfo = new QQuickLayoutStyleInfo;
}
 
Qt::Orientation QQuickGridLayoutBase::orientation() const
{
    Q_D(const QQuickGridLayoutBase);
    return d->orientation;
}
 
void QQuickGridLayoutBase::setOrientation(Qt::Orientation orientation)
{
    Q_D(QQuickGridLayoutBase);
    if (d->orientation == orientation)
        return;
 
    d->orientation = orientation;
    invalidate();
}
 
QSizeF QQuickGridLayoutBase::sizeHint(Qt::SizeHint whichSizeHint) const
{
    Q_D(const QQuickGridLayoutBase);
    return d->engine.sizeHint(whichSizeHint, QSizeF(), d->styleInfo);
}
 
Qt::LayoutDirection QQuickGridLayoutBase::layoutDirection() const
{
    Q_D(const QQuickGridLayoutBase);
    return d->m_layoutDirection;
}
 
void QQuickGridLayoutBase::setLayoutDirection(Qt::LayoutDirection dir)
{
    Q_D(QQuickGridLayoutBase);
    if (d->m_layoutDirection == dir)
        return;
    d->m_layoutDirection = dir;
    invalidate();
    emit layoutDirectionChanged();
}
 
Qt::LayoutDirection QQuickGridLayoutBase::effectiveLayoutDirection() const
{
    Q_D(const QQuickGridLayoutBase);
    return !d->effectiveLayoutMirror == (layoutDirection() == Qt::LeftToRight)
                                      ? Qt::LeftToRight : Qt::RightToLeft;
}
 
void QQuickGridLayoutBase::setAlignment(QQuickItem *item, Qt::Alignment alignment)
{
    Q_D(QQuickGridLayoutBase);
    d->engine.setAlignment(item, alignment);
    maybeSubscribeToBaseLineOffsetChanges(item);
}
 
void QQuickGridLayoutBase::setStretchFactor(QQuickItem *item, int stretchFactor, Qt::Orientation orient)
{
    Q_D(QQuickGridLayoutBase);
    d->engine.setStretchFactor(item, stretchFactor, orient);
}
 
QQuickGridLayoutBase::~QQuickGridLayoutBase()
{
    Q_D(QQuickGridLayoutBase);
 
    // Remove item listeners so we do not act on signalling unnecessarily
    // (there is no point, as the layout will be torn down anyway).
    deactivateRecur();
    delete d->styleInfo;
}
 
void QQuickGridLayoutBase::componentComplete()
{
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::componentComplete()" << this << parent();
    QQuickLayout::componentComplete();
 
    /* The layout is invalid when it is constructed, but during construction of the layout and
       its children (in the "static/from QML" case which this is trying to cover) things
       change and as a consequence invalidate() and ensureLayoutItemsUpdated() might be called.
       As soon as ensureLayoutItemsUpdated() is called it will set d->dirty = false.
       However, a subsequent invalidate() will return early if the component is not completed
       because it knows that componentComplete() will take care of doing the proper layouting
       (so it won't set d->dirty = true). When we then call ensureLayoutItemsUpdated() again here
       it sees that its not dirty and assumes everything up-to-date. For those cases we therefore
       need to call invalidate() in advance
    */
    invalidate();
    ensureLayoutItemsUpdated(QQuickLayout::ApplySizeHints);
 
    QQuickItem *par = parentItem();
    if (qobject_cast<QQuickLayout*>(par))
        return;
    rearrange(QSizeF(width(), height()));
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::componentComplete(). COMPLETED" << this << parent();
}
 
/*
  Invalidation happens like this as a reaction to that a size hint changes on an item "a":
 
  Suppose we have the following Qml document:
    RowLayout {
        id: l1
        RowLayout {
            id: l2
            Item {
                id: a
            }
            Item {
                id: b
            }
        }
    }
 
  1.    l2->invalidate(a) is called on l2, where item refers to "a".
        (this will dirty the cached size hints of item "a")
  2.    The layout engine will invalidate:
            i)  invalidate the layout engine
            ii) dirty the cached size hints of item "l2" (by calling parentLayout()->invalidate(l2)
        The recursion continues to the topmost layout
 */
void QQuickGridLayoutBase::invalidate(QQuickItem *childItem)
{
    Q_D(QQuickGridLayoutBase);
    if (!isReady())
        return;
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::invalidate()" << this << ", invalidated:" << invalidated();
    if (childItem) {
        if (d->m_rearranging) {
            if (!d->m_invalidateAfterRearrange.contains(childItem))
                d->m_invalidateAfterRearrange << childItem;
            return;
        }
        if (QQuickGridLayoutItem *layoutItem = d->engine.findLayoutItem(childItem)) {
            layoutItem->invalidate();
        }
    }
 
    // invalidate engine
    d->engine.invalidate();
 
    qCDebug(lcQuickLayouts) << "calling QQuickLayout::invalidate();";
    QQuickLayout::invalidate();
 
    if (auto *parentLayout = qobject_cast<QQuickLayout *>(parentItem()))
        parentLayout->invalidate(this);
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::invalidate() LEAVING" << this;
}
 
void QQuickGridLayoutBase::updateLayoutItems()
{
    Q_D(QQuickGridLayoutBase);
    if (!isReady())
        return;
 
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::updateLayoutItems ENTERING" << this;
    d->engine.deleteItems();
    insertLayoutItems();
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::updateLayoutItems() LEAVING" << this;
}
 
QQuickItem *QQuickGridLayoutBase::itemAt(int index) const
{
    Q_D(const QQuickGridLayoutBase);
    return static_cast<QQuickGridLayoutItem*>(d->engine.itemAt(index))->layoutItem();
}
 
int QQuickGridLayoutBase::itemCount() const
{
    Q_D(const QQuickGridLayoutBase);
    return d->engine.itemCount();
}
 
void QQuickGridLayoutBase::removeGridItem(QGridLayoutItem *gridItem)
{
    Q_D(QQuickGridLayoutBase);
    const int index = gridItem->firstRow(d->orientation);
    d->engine.removeItem(gridItem);
    d->engine.removeRows(index, 1, d->orientation);
}
 
void QQuickGridLayoutBase::itemDestroyed(QQuickItem *item)
{
    if (!isReady())
        return;
    Q_D(QQuickGridLayoutBase);
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::itemDestroyed";
    if (QQuickGridLayoutItem *gridItem = d->engine.findLayoutItem(item)) {
        removeGridItem(gridItem);
        delete gridItem;
        invalidate();
    }
}
 
void QQuickGridLayoutBase::itemVisibilityChanged(QQuickItem *item)
{
    Q_UNUSED(item);
 
    if (!isReady())
        return;
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::itemVisibilityChanged()";
    invalidate(item);
}
 
void QQuickGridLayoutBase::rearrange(const QSizeF &size)
{
    Q_D(QQuickGridLayoutBase);
    if (!isReady() || !size.isValid())
        return;
 
    qCDebug(lcQuickLayouts) << "QQuickGridLayoutBase::rearrange" << d->m_recurRearrangeCounter << this;
    const auto refCounter = qScopeGuard([&d] {
        --(d->m_recurRearrangeCounter);
    });
    if (d->m_recurRearrangeCounter++ == 2) {
        // allow a recursive depth of two in order to respond to height-for-width
        // (e.g QQuickText changes implicitHeight when its width gets changed)
        qWarning() << "Qt Quick Layouts: Detected recursive rearrange. Aborting after two iterations.";
        return;
    }
 
    // Should normally not be needed, but there might be an incoming window resize event that we
    // will process before we process updatePolish()
    ensureLayoutItemsUpdated(QQuickLayout::ApplySizeHints | QQuickLayout::Recursive);
 
    d->m_rearranging = true;
    qCDebug(lcQuickLayouts) << objectName() << "QQuickGridLayoutBase::rearrange()" << size;
    Qt::LayoutDirection visualDir = effectiveLayoutDirection();
    d->engine.setVisualDirection(visualDir);
 
    /*
    qreal left, top, right, bottom;
    left = top = right = bottom = 0;                    // ### support for margins?
    if (visualDir == Qt::RightToLeft)
        qSwap(left, right);
    */
 
    // Set m_dirty to false in case size hint changes during arrangement.
    // This could happen if there is a binding like implicitWidth: height
    QQuickLayout::rearrange(size);
    d->engine.setGeometries(QRectF(QPointF(0,0), size), d->styleInfo);
    d->m_rearranging = false;
 
    for (auto childItem : std::as_const(d->m_invalidateAfterRearrange))
        invalidate(childItem);
    d->m_invalidateAfterRearrange.clear();
}
 
/**********************************
 **
 ** QQuickGridLayout
 **
 **/
QQuickGridLayout::QQuickGridLayout(QQuickItem *parent /* = nullptr*/)
    : QQuickGridLayoutBase(*new QQuickGridLayoutPrivate, Qt::Horizontal, parent)
{
}
 
qreal QQuickGridLayout::columnSpacing() const
{
    Q_D(const QQuickGridLayout);
    return d->engine.spacing(Qt::Horizontal, d->styleInfo);
}
 
void QQuickGridLayout::setColumnSpacing(qreal spacing)
{
    Q_D(QQuickGridLayout);
    if (qt_is_nan(spacing) || columnSpacing() == spacing)
        return;
 
    d->engine.setSpacing(spacing, Qt::Horizontal);
    invalidate();
    emit columnSpacingChanged();
}
 
qreal QQuickGridLayout::rowSpacing() const
{
    Q_D(const QQuickGridLayout);
    return d->engine.spacing(Qt::Vertical, d->styleInfo);
}
 
void QQuickGridLayout::setRowSpacing(qreal spacing)
{
    Q_D(QQuickGridLayout);
    if (qt_is_nan(spacing) || rowSpacing() == spacing)
        return;
 
    d->engine.setSpacing(spacing, Qt::Vertical);
    invalidate();
    emit rowSpacingChanged();
}
 
int QQuickGridLayout::columns() const
{
    Q_D(const QQuickGridLayout);
    return d->columns;
}
 
void QQuickGridLayout::setColumns(int columns)
{
    Q_D(QQuickGridLayout);
    if (d->columns == columns)
        return;
    d->columns = columns;
    invalidate();
    emit columnsChanged();
}
 
 
int QQuickGridLayout::rows() const
{
    Q_D(const QQuickGridLayout);
    return d->rows;
}
 
void QQuickGridLayout::setRows(int rows)
{
    Q_D(QQuickGridLayout);
    if (d->rows == rows)
        return;
    d->rows = rows;
    invalidate();
    emit rowsChanged();
}
 
 
QQuickGridLayout::Flow QQuickGridLayout::flow() const
{
    Q_D(const QQuickGridLayout);
    return d->flow;
}
 
void QQuickGridLayout::setFlow(QQuickGridLayout::Flow flow)
{
    Q_D(QQuickGridLayout);
    if (d->flow == flow)
        return;
    d->flow = flow;
    // If flow is changed, the layout needs to be repopulated
    invalidate();
    emit flowChanged();
}
 
bool QQuickGridLayout::uniformCellWidths() const
{
    Q_D(const QQuickGridLayout);
    return d->engine.uniformCellWidths();
}
 
void QQuickGridLayout::setUniformCellWidths(bool uniformCellWidths)
{
    Q_D(QQuickGridLayout);
    if (d->engine.uniformCellWidths() == uniformCellWidths)
        return;
    d->engine.setUniformCellWidths(uniformCellWidths);
    invalidate();
    emit uniformCellWidthsChanged();
}
 
bool QQuickGridLayout::uniformCellHeights() const
{
    Q_D(const QQuickGridLayout);
    return d->engine.uniformCellHeights();
}
 
void QQuickGridLayout::setUniformCellHeights(bool uniformCellHeights)
{
    Q_D(QQuickGridLayout);
    if (d->engine.uniformCellHeights() == uniformCellHeights)
        return;
    d->engine.setUniformCellHeights(uniformCellHeights);
    invalidate();
    emit uniformCellHeightsChanged();
}
 
 
void QQuickGridLayout::insertLayoutItems()
{
    Q_D(QQuickGridLayout);
 
    int nextCellPos[2] = {0,0};
    int &nextColumn = nextCellPos[0];
    int &nextRow = nextCellPos[1];
 
    const QSize gridSize(columns(), rows());
    const int flowOrientation = flow();
    int &flowColumn = nextCellPos[flowOrientation];
    int &flowRow = nextCellPos[1 - flowOrientation];
    int flowBound = (flowOrientation == QQuickGridLayout::LeftToRight) ? columns() : rows();
 
    if (flowBound < 0)
        flowBound = std::numeric_limits<int>::max();
 
    const auto items = childItems();
    for (QQuickItem *child : items) {
        checkAnchors(child);
        // Will skip all items with effective maximum width/height == 0
        if (shouldIgnoreItem(child))
            continue;
        QQuickLayoutAttached *info = attachedLayoutObject(child, false);
 
        Qt::Alignment alignment;
        int hStretch = -1;
        int vStretch = -1;
        int row = -1;
        int column = -1;
        int span[2] = {1,1};
        int &columnSpan = span[0];
        int &rowSpan = span[1];
 
        if (info) {
            if (info->isRowSet() || info->isColumnSet()) {
                // If row is specified and column is not specified (or vice versa),
                // the unspecified component of the cell position should default to 0
                // The getters do this for us, as they will return 0 for an
                // unset (or negative) value.
                // In addition, if \a rows is less than Layout.row, treat Layout.row as if it was not set
                // This will basically make it find the next available cell (potentially wrapping to
                // the next line). Likewise for an invalid Layout.column
 
                if (gridSize.height() >= 0 && row >= gridSize.height()) {
                    qmlWarning(child) << QString::fromLatin1("Layout: row (%1) should be less than the number of rows (%2)").arg(info->row()).arg(rows());
                } else {
                    row = info->row();
                }
 
                if (gridSize.width() >= 0 && info->column() >= gridSize.width()) {
                    qmlWarning(child) << QString::fromLatin1("Layout: column (%1) should be less than the number of columns (%2)").arg(info->column()).arg(columns());
                } else {
                    column = info->column();
                }
            }
            rowSpan = info->rowSpan();
            columnSpan = info->columnSpan();
            if (columnSpan < 1) {
                qmlWarning(child) << "Layout: invalid column span: " << columnSpan;
                return;
 
            } else if (rowSpan < 1) {
                qmlWarning(child) << "Layout: invalid row span: " << rowSpan;
                return;
            }
            alignment = info->alignment();
            hStretch = info->horizontalStretchFactor();
            if (hStretch >= 0 && !info->fillWidth())
                qmlWarning(child) << "horizontalStretchFactor requires fillWidth to also be set to true";
            vStretch = info->verticalStretchFactor();
            if (vStretch >= 0 && !info->fillHeight())
                qmlWarning(child) << "verticalStretchFactor requires fillHeight to also be set to true";
        }
 
        Q_ASSERT(columnSpan >= 1);
        Q_ASSERT(rowSpan >= 1);
        const int sp = span[flowOrientation];
        if (sp > flowBound)
            return;
 
        if (row >= 0)
            nextRow = row;
        if (column >= 0)
            nextColumn = column;
 
        if (row < 0 || column < 0) {
            /* if row or column is not specified, find next position by
               advancing in the flow direction until there is a cell that
               can accept the item.
 
               The acceptance rules are pretty simple, but complexity arises
               when an item requires several cells (due to spans):
               1. Check if the cells that the item will require
                  does not extend beyond columns (for LeftToRight) or
                  rows (for TopToBottom).
               2. Check if the cells that the item will require is not already
                  taken by another item.
            */
            bool cellAcceptsItem;
            while (true) {
                // Check if the item does not span beyond the layout bound
                cellAcceptsItem = (flowColumn + sp) <= flowBound;
 
                // Check if all the required cells are not taken
                for (int rs = 0; cellAcceptsItem && rs < rowSpan; ++rs) {
                    for (int cs = 0; cellAcceptsItem && cs < columnSpan; ++cs) {
                        if (d->engine.itemAt(nextRow + rs, nextColumn + cs)) {
                            cellAcceptsItem = false;
                        }
                    }
                }
                if (cellAcceptsItem)
                    break;
                ++flowColumn;
                if (flowColumn == flowBound) {
                    flowColumn = 0;
                    ++flowRow;
                }
            }
        }
        column = nextColumn;
        row = nextRow;
        QQuickGridLayoutItem *layoutItem = new QQuickGridLayoutItem(child, row, column, rowSpan, columnSpan, alignment);
        if (hStretch >= 0)
            layoutItem->setStretchFactor(hStretch, Qt::Horizontal);
        if (vStretch >= 0)
            layoutItem->setStretchFactor(vStretch, Qt::Vertical);
 
        d->engine.insertItem(layoutItem, -1);
    }
}
 
/**********************************
 **
 ** QQuickLinearLayout
 **
 **/
QQuickLinearLayout::QQuickLinearLayout(Qt::Orientation orientation,
                                        QQuickItem *parent /*= nullptr*/)
    : QQuickGridLayoutBase(*new QQuickLinearLayoutPrivate, orientation, parent)
{
}
 
bool QQuickLinearLayout::uniformCellSizes() const
{
    Q_D(const QQuickLinearLayout);
    Q_ASSERT(d->engine.uniformCellWidths() == d->engine.uniformCellHeights());
    return d->engine.uniformCellWidths();
}
 
void QQuickLinearLayout::setUniformCellSizes(bool uniformCellSizes)
{
    Q_D(QQuickLinearLayout);
    Q_ASSERT(d->engine.uniformCellWidths() == d->engine.uniformCellHeights());
    if (d->engine.uniformCellHeights() == uniformCellSizes)
        return;
    d->engine.setUniformCellWidths(uniformCellSizes);
    d->engine.setUniformCellHeights(uniformCellSizes);
    invalidate();
    emit uniformCellSizesChanged();
}
 
 
qreal QQuickLinearLayout::spacing() const
{
    Q_D(const QQuickLinearLayout);
    return d->engine.spacing(d->orientation, d->styleInfo);
}
 
void QQuickLinearLayout::setSpacing(qreal space)
{
    Q_D(QQuickLinearLayout);
    if (qt_is_nan(space) || spacing() == space)
        return;
 
    d->engine.setSpacing(space, Qt::Horizontal | Qt::Vertical);
    invalidate();
    emit spacingChanged();
}
 
void QQuickLinearLayout::insertLayoutItems()
{
    Q_D(QQuickLinearLayout);
    const auto items = childItems();
    for (QQuickItem *child : items) {
        Q_ASSERT(child);
        checkAnchors(child);
 
        // Will skip all items with effective maximum width/height == 0
        if (shouldIgnoreItem(child))
            continue;
        QQuickLayoutAttached *info = attachedLayoutObject(child, false);
 
        Qt::Alignment alignment;
        int hStretch = -1;
        int vStretch = -1;
        bool fillWidth = false;
        bool fillHeight = false;
        if (info) {
            alignment = info->alignment();
            hStretch = info->horizontalStretchFactor();
            vStretch = info->verticalStretchFactor();
            fillWidth = info->fillWidth();
            fillHeight = info->fillHeight();
        }
 
        const int index = d->engine.rowCount(d->orientation);
        d->engine.insertRow(index, d->orientation);
 
        int gridRow = 0;
        int gridColumn = index;
        if (d->orientation == Qt::Vertical)
            qSwap(gridRow, gridColumn);
        QQuickGridLayoutItem *layoutItem = new QQuickGridLayoutItem(child, gridRow, gridColumn, 1, 1, alignment);
 
        if (hStretch >= 0) {
            if (!fillWidth)
                qmlWarning(child) << "horizontalStretchFactor requires fillWidth to also be set to true";
            layoutItem->setStretchFactor(hStretch, Qt::Horizontal);
        }
        if (vStretch >= 0) {
            if (!fillHeight)
                qmlWarning(child) << "verticalStretchFactor requires fillHeight to also be set to true";
            layoutItem->setStretchFactor(vStretch, Qt::Vertical);
        }
        d->engine.insertItem(layoutItem, index);
    }
}
 
QT_END_NAMESPACE
 
#include "moc_qquicklinearlayout_p.cpp"