path: root/src/layouts/qquicklayout.cpp

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#include "qquicklayout_p.h"
#include <QEvent>
#include <QtCore/qcoreapplication.h>
#include <QtCore/qnumeric.h>
#include <limits>

/*!
    \qmltype Layout
    \instantiates QQuickLayoutAttached
    \inqmlmodule QtQuick.Layouts 1.0
    \ingroup layouts
    \brief Provides attached properties for items pushed onto a \l GridLayout,
    \l RowLayout or \l ColumnLayout.

    An object of type Layout is attached to children of the layout to provide layout specific
    information about the item.
    The properties of the attached object influences how the layout will arrange the items.

    For instance, you can specify \l minimumWidth, \l preferredWidth, and
    \l maximumWidth if the default values are not satisfactory.

    \l fillWidth and \l fillHeight allows you to specify whether an item should
    fill the cell(s) it occupies. This allows it to stretch between \l minimumWidth
    and \l maximumWidth (or \l minimumHeight and \l maximumHeight if \l fillHeight is \c true).

    If \l fillWidth or \l fillHeight is \c false, the items' size will be fixed to its preferred size.

    \sa GridLayout
    \sa RowLayout
    \sa ColumnLayout
*/

QT_BEGIN_NAMESPACE

QQuickLayoutAttached::QQuickLayoutAttached(QObject *parent)
    : QObject(parent),
      m_minimumWidth(0),
      m_minimumHeight(0),
      m_preferredWidth(-1),
      m_preferredHeight(-1),
      m_maximumWidth(std::numeric_limits<qreal>::infinity()),
      m_maximumHeight(std::numeric_limits<qreal>::infinity()),
      m_row(-1),
      m_column(-1),
      m_rowSpan(1),
      m_columnSpan(1),
      m_fillWidth(false),
      m_fillHeight(false),
      m_isFillWidthSet(false),
      m_isFillHeightSet(false),
      m_isMinimumWidthSet(false),
      m_isMinimumHeightSet(false),
      m_isMaximumWidthSet(false),
      m_isMaximumHeightSet(false),
      m_changesNotificationEnabled(true),
      m_alignment(0)
{

}

/*!
    \qmlproperty real Layout::minimumWidth

    This property holds the maximum width of an item in a layout.
    The default value is the items implicit minimum width.

    If the item is a layout, the implicit minimum width will be the minimum width the layout can
    have without any of its items shrink beyond their minimum width.
    The implicit minimum width for any other item is \c 0.

    Setting this value to -1 will reset the width back to its implicit minimum width.


    \sa preferredWidth
    \sa maximumWidth
*/
void QQuickLayoutAttached::setMinimumWidth(qreal width)
{
    if (qIsNaN(width))
        return;
    m_isMinimumWidthSet = width >= 0;
    if (m_minimumWidth == width)
        return;

    m_minimumWidth = width;
    invalidateItem();
    emit minimumWidthChanged();
}

/*!
    \qmlproperty real Layout::minimumHeight

    The default value is the items implicit minimum height.

    If the item is a layout, the implicit minimum height will be the minimum height the layout can
    have without any of its items shrink beyond their minimum height.
    The implicit minimum height for any other item is \c 0.

    Setting this value to -1 will reset the height back to its implicit minimum height.

    \sa preferredHeight
    \sa maximumHeight
*/
void QQuickLayoutAttached::setMinimumHeight(qreal height)
{
    if (qIsNaN(height))
        return;
    m_isMinimumHeightSet = height >= 0;
    if (m_minimumHeight == height)
        return;

    m_minimumHeight = height;
    invalidateItem();
    emit minimumHeightChanged();
}

/*!
    \qmlproperty real Layout::preferredWidth

    This property holds the preferred width of an item in a layout.
    If the preferred width is -1 it will be ignored, and the layout
    will use \l{Item::implicitWidth}{implicitWidth} instead.
    The default is \c -1.

    \sa minimumWidth
    \sa maximumWidth
*/
void QQuickLayoutAttached::setPreferredWidth(qreal width)
{
    if (qIsNaN(width) || m_preferredWidth == width)
        return;

    m_preferredWidth = width;
    invalidateItem();
    emit preferredWidthChanged();
}

/*!
    \qmlproperty real Layout::preferredHeight

    This property holds the preferred height of an item in a layout.
    If the preferred height is -1 it will be ignored, and the layout
    will use \l{Item::implicitHeight}{implicitHeight} instead.
    The default is \c -1.

    \sa minimumHeight
    \sa maximumHeight
*/
void QQuickLayoutAttached::setPreferredHeight(qreal height)
{
    if (qIsNaN(height) || m_preferredHeight == height)
        return;

    m_preferredHeight = height;
    invalidateItem();
    emit preferredHeightChanged();
}

/*!
    \qmlproperty real Layout::maximumWidth

    This property holds the maximum width of an item in a layout.
    The default value is the items implicit maximum width.

    If the item is a layout, the implicit maximum width will be the maximum width the layout can
    have without any of its items grow beyond their maximum width.
    The implicit maximum width for any other item is \c Number.POSITIVE_INFINITE.

    Setting this value to -1 will reset the width back to its implicit maximum width.

    \sa minimumWidth
    \sa preferredWidth
*/
void QQuickLayoutAttached::setMaximumWidth(qreal width)
{
    if (qIsNaN(width))
        return;
    m_isMaximumWidthSet = width >= 0;
    if (m_maximumWidth == width)
        return;

    m_maximumWidth = width;
    invalidateItem();
    emit maximumWidthChanged();
}

/*!
    \qmlproperty real Layout::maximumHeight

    The default value is the items implicit maximum height.

    If the item is a layout, the implicit maximum height will be the maximum height the layout can
    have without any of its items grow beyond their maximum height.
    The implicit maximum height for any other item is \c Number.POSITIVE_INFINITE.

    Setting this value to -1 will reset the height back to its implicit maximum height.

    \sa minimumHeight
    \sa preferredHeight
*/
void QQuickLayoutAttached::setMaximumHeight(qreal height)
{
    if (qIsNaN(height))
        return;
    m_isMaximumHeightSet = height >= 0;
    if (m_maximumHeight == height)
        return;

    m_maximumHeight = height;
    invalidateItem();
    emit maximumHeightChanged();
}

void QQuickLayoutAttached::setMinimumImplicitSize(const QSizeF &sz)
{
    bool emitWidthChanged = false;
    bool emitHeightChanged = false;
    if (!m_isMinimumWidthSet && m_minimumWidth != sz.width()) {
        m_minimumWidth = sz.width();
        emitWidthChanged = true;
    }
    if (!m_isMinimumHeightSet && m_minimumHeight != sz.height()) {
        m_minimumHeight = sz.height();
        emitHeightChanged = true;
    }
    // Only invalidate the item once, and make sure we emit signal changed after the call to
    // invalidateItem()
    if (emitWidthChanged || emitHeightChanged) {
        invalidateItem();
        if (emitWidthChanged)
            emit minimumWidthChanged();
        if (emitHeightChanged)
            emit minimumHeightChanged();
    }
}

void QQuickLayoutAttached::setMaximumImplicitSize(const QSizeF &sz)
{
    bool emitWidthChanged = false;
    bool emitHeightChanged = false;
    if (!m_isMaximumWidthSet && m_maximumWidth != sz.width()) {
        m_maximumWidth = sz.width();
        emitWidthChanged = true;
    }
    if (!m_isMaximumHeightSet && m_maximumHeight != sz.height()) {
        m_maximumHeight = sz.height();
        emitHeightChanged = true;
    }
    // Only invalidate the item once, and make sure we emit changed signal after the call to
    // invalidateItem()
    if (emitWidthChanged || emitHeightChanged) {
        invalidateItem();
        if (emitWidthChanged)
            emit maximumWidthChanged();
        if (emitHeightChanged)
            emit maximumHeightChanged();
    }
}

/*!
    \qmlproperty bool Layout::fillWidth

    If this property is \c true, the item will be as wide as possible while respecting
    the given constraints. If the property is \c false, the item will have a fixed width
    set to the preferred width.
    The default is \c false, except for layouts themselves which defaults to \c true.

    \sa fillHeight
*/
void QQuickLayoutAttached::setFillWidth(bool fill)
{
    m_isFillWidthSet = true;
    if (m_fillWidth != fill) {
        m_fillWidth = fill;
        invalidateItem();
        emit fillWidthChanged();
    }
}

/*!
    \qmlproperty bool Layout::fillHeight

    If this property is \c true, the item will be as tall as possible while respecting
    the given constraints. If the property is \c false, the item will have a fixed height
    set to the preferred height.
    The default is \c false, except for layouts themselves which defaults to \c true.

    \sa fillWidth
*/
void QQuickLayoutAttached::setFillHeight(bool fill)
{
    m_isFillHeightSet = true;
    if (m_fillHeight != fill) {
        m_fillHeight = fill;
        invalidateItem();
        emit fillHeightChanged();
    }
}

/*!
    \qmlproperty int Layout::row

    This property allows you to specify the row position of an item in a \l GridLayout.

    If both \l column and this property are not set, it is up to the layout to assign a cell to the item.

    The default value is \c 0.

    \sa column
    \sa rowSpan
*/
void QQuickLayoutAttached::setRow(int row)
{
    if (row >= 0 && row != m_row)
        m_row = row;
}

/*!
    \qmlproperty int Layout::column

    This property allows you to specify the column position of an item in a \l GridLayout.

    If both \l row and this property are not set, it is up to the layout to assign a cell to the item.

    The default value is \c 0.

    \sa row
    \sa columnSpan
*/
void QQuickLayoutAttached::setColumn(int column)
{
    if (column >= 0 && column != m_column)
        m_column = column;
}


/*!
    \qmlproperty Qt.Alignment Layout::alignment

    This property allows you to specify the alignment of an item within the cell(s) it occupies.

    The default value is \c 0, which means it will be \c{Qt.AlignVCenter | Qt.AlignLeft}
*/


/*!
    \qmlproperty int Layout::rowSpan

    This property allows you to specify the row span of an item in a \l GridLayout.

    The default value is \c 1.

    \sa columnSpan
    \sa row
*/


/*!
    \qmlproperty int Layout::columnSpan

    This property allows you to specify the column span of an item in a \l GridLayout.

    The default value is \c 1.

    \sa rowSpan
    \sa column
*/


qreal QQuickLayoutAttached::sizeHint(Qt::SizeHint which, Qt::Orientation orientation) const
{
    qreal result = 0;
    if (QQuickLayout *layout = qobject_cast<QQuickLayout *>(item())) {
        const QSizeF sz = layout->sizeHint(which);
        result = (orientation == Qt::Horizontal ? sz.width() : sz.height());
    } else {
        if (which == Qt::MaximumSize)
            result = std::numeric_limits<qreal>::infinity();
    }
    return result;
}

void QQuickLayoutAttached::invalidateItem()
{
    if (!m_changesNotificationEnabled)
        return;
    quickLayoutDebug() << "QQuickLayoutAttached::invalidateItem";
    if (QQuickLayout *layout = parentLayout()) {
        layout->invalidate(item());
    }
}

QQuickLayout *QQuickLayoutAttached::parentLayout() const
{
    QQuickItem *parentItem = item();
    if (parentItem) {
        parentItem = parentItem->parentItem();
        return qobject_cast<QQuickLayout *>(parentItem);
    } else {
        qWarning("Layout must be attached to Item elements");
    }
    return 0;
}

QQuickItem *QQuickLayoutAttached::item() const
{
    return qobject_cast<QQuickItem *>(parent());
}





QQuickLayout::QQuickLayout(QQuickLayoutPrivate &dd, QQuickItem *parent)
    : QQuickItem(dd, parent),
      m_dirty(false)
{
}

QQuickLayout::~QQuickLayout()
{

}

QQuickLayoutAttached *QQuickLayout::qmlAttachedProperties(QObject *object)
{
    return new QQuickLayoutAttached(object);
}

bool QQuickLayout::event(QEvent *e)
{
    if (e->type() == QEvent::LayoutRequest)
        rearrange(QSizeF(width(), height()));

    return QQuickItem::event(e);
}

void QQuickLayout::componentComplete()
{
    QQuickItem::componentComplete();
}

void QQuickLayout::invalidate(QQuickItem * /*childItem*/)
{
    if (m_dirty)
        return;

    m_dirty = true;

    if (!qobject_cast<QQuickLayout *>(parentItem())) {
        quickLayoutDebug() << "QQuickLayout::invalidate(), postEvent";
        QCoreApplication::postEvent(this, new QEvent(QEvent::LayoutRequest));
    }
}

void QQuickLayout::rearrange(const QSizeF &/*size*/)
{
    m_dirty = false;
}

QT_END_NAMESPACE