qlayout.cpp

奇趣公司比较新的qt/emd版本

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#include "qlayout.h"

#include "qapplication.h"
#include "qlayoutengine_p.h"
#include "qmenubar.h"
#include "qtoolbar.h"
#include "qevent.h"
#include "qstyle.h"
#include "qvariant.h"
#include "qwidget_p.h"
#include "qlayout_p.h"

static int menuBarHeightForWidth(QWidget *menubar, int w)
{
    if (menubar && !menubar->isHidden() && !menubar->isWindow()) {
        int result = menubar->heightForWidth(qMax(w, menubar->minimumWidth()));
        if (result != -1)
            return result;
        result = menubar->sizeHint().height();
        if (result != -1)
            return result;
    }
    return 0;
}

/*!
    \class QLayout
    \brief The QLayout class is the base class of geometry managers.

    \ingroup appearance
    \ingroup geomanagement

    This is an abstract base class inherited by the concrete classes
    QBoxLayout, QGridLayout, and QStackedLayout.

    For users of QLayout subclasses or of QMainWindow there is seldom
    any need to use the basic functions provided by QLayout, such as
    setSizeConstraint() or setMenuBar(). See \l{Layout Classes}
    for more information.

    To make your own layout manager, implement the functions
    addItem(), sizeHint(), setGeometry(), itemAt() and takeAt(). You
    should also implement minimumSize() to ensure your layout isn't
    resized to zero size if there is too little space. To support
    children whose heights depend on their widths, implement
    hasHeightForWidth() and heightForWidth(). See the
    \l{layouts/borderlayout}{Border Layout} and
    \l{layouts/flowlayout}{Flow Layout} examples for
    more information about implementing custom layout managers.

    Geometry management stops when the layout manager is deleted.

    \sa QLayoutItem, {Layout Classes}, {Basic Layouts Example},
        {Border Layout Example}, {Flow Layout Example}
*/


/*!
    Constructs a new top-level QLayout, with parent \a parent.
    \a parent may not be 0.

    There can be only one top-level layout for a widget. It is
    returned by QWidget::layout().
*/
QLayout::QLayout(QWidget *parent)
    : QObject(*new QLayoutPrivate, parent)
{
    if (!parent)
        return;
    parent->setLayout(this);
}

/*!
    Constructs a new child QLayout.

    This layout has to be inserted into another layout before geometry
    management will work.
*/
QLayout::QLayout()
    : QObject(*new QLayoutPrivate, 0)
{
}


/*! \internal
 */
QLayout::QLayout(QLayoutPrivate &dd, QLayout *lay, QWidget *w)
    : QObject(dd, lay ? static_cast<QObject*>(lay) : static_cast<QObject*>(w))
{
    Q_D(QLayout);
    if (lay) {
        lay->addItem(this);
    } else if (w) {
        if (w->layout()) {
            qWarning("QLayout: Attempting to add QLayout \"%s\" to %s \"%s\", which"
                     " already has a layout",
                     qPrintable(QObject::objectName()), w->metaObject()->className(),
                     w->objectName().toLocal8Bit().data());
            setParent(0);
        } else {
            d->topLevel = true;
            w->d_func()->layout = this;
            invalidate();
        }
    }
}

QLayoutPrivate::QLayoutPrivate()
    : QObjectPrivate(), insideSpacing(-1), userLeftMargin(-1), userTopMargin(-1), userRightMargin(-1),
      userBottomMargin(-1), topLevel(false), enabled(true), activated(true), autoNewChild(false),
      constraint(QLayout::SetDefaultConstraint), menubar(0)
{
}

void QLayoutPrivate::getMargin(int *result, int userMargin, QStyle::PixelMetric pm) const
{
    if (!result)
        return;

    Q_Q(const QLayout);
    if (userMargin >= 0) {
        *result = userMargin;
    } else if (!topLevel) {
        *result = 0;
    } else if (QWidget *pw = q->parentWidget()) {
        *result = pw->style()->pixelMetric(pm, 0, pw);
    } else {
        *result = 0;
    }
}

#ifdef QT3_SUPPORT
/*!
    Constructs a new top-level QLayout called \a name, with parent
    widget \a parent. \a parent may not be 0.

    The \a margin is the number of pixels between the edge of the
    widget and the managed children. The \a spacing sets the value of
    spacing(), which gives the spacing between the managed widgets. If
    \a spacing is -1 (the default), spacing is set to the value of \a
    margin.

    There can be only one top-level layout for a widget. It is
    returned by QWidget::layout()

    \sa QWidget::setLayout()
*/
QLayout::QLayout(QWidget *parent, int margin, int spacing, const char *name)
    : QObject(*new QLayoutPrivate,parent)
{
    Q_D(QLayout);
    setObjectName(QString::fromAscii(name));
    setMargin(margin);
    if (spacing < 0)
        d->insideSpacing = margin;
    else
        d->insideSpacing = spacing;
    if (parent) {
        if (parent->layout()) {
            qWarning("QLayout \"%s\" added to %s \"%s\", which already has a layout",
                     QObject::objectName().toLocal8Bit().data(), parent->metaObject()->className(),
                     parent->objectName().toLocal8Bit().data());
            parent->layout()->setParent(0);
        } else {
            d->topLevel = true;
            parent->d_func()->layout = this;
            invalidate();
        }
    }
}

/*!
    Constructs a new child QLayout called \a name, and places it
    inside \a parentLayout by using the default placement defined by
    addItem().

    If \a spacing is -1, this QLayout inherits \a parentLayout's
    spacing(), otherwise the value of \a spacing is used.
*/
QLayout::QLayout(QLayout *parentLayout, int spacing, const char *name)
    : QObject(*new QLayoutPrivate,parentLayout)

{
    Q_D(QLayout);
    setObjectName(QString::fromAscii(name));
    d->insideSpacing = spacing;
    parentLayout->addItem(this);
}

/*!
    Constructs a new child QLayout called \a name. If \a spacing is
    -1, this QLayout inherits its parent's spacing(); otherwise the
    value of \a spacing is used.

    This layout has to be inserted into another layout before geometry
    management will work.
*/
QLayout::QLayout(int spacing, const char *name)
    : QObject(*new QLayoutPrivate, 0)
{
    Q_D(QLayout);
    setObjectName(QString::fromAscii(name));
    d->insideSpacing = spacing;
}

/*!
    Automatically adding widgets is deprecated. Use addWidget() or
    addLayout() instead.
*/
void QLayout::setAutoAdd(bool a) { Q_D(QLayout); d->autoNewChild = a; }

/*!
    Automatically adding widgets is deprecated. Use addWidget() or
    addLayout() instead.
*/
bool QLayout::autoAdd() const { Q_D(const QLayout); return d->autoNewChild; }
#endif


/*!
    \fn void QLayout::addItem(QLayoutItem *item)

    Implemented in subclasses to add an \a item. How it is added is
    specific to each subclass.

    This function is not usually called in application code. To add a widget
    to a layout, use the addWidget() function; to add a child layout, use the
    addLayout() function provided by the relevant QLayout subclass.

    \bold{Note:} The ownership of \a item is transferred to the layout, and it's
    the layout's responsibility to delete it.

    \sa addWidget(), QBoxLayout::addLayout(), QGridLayout::addLayout()
*/

/*!
    Adds widget \a w to this layout in a manner specific to the
    layout. This function uses addItem().
*/
void QLayout::addWidget(QWidget *w)
{
    addChildWidget(w);
    addItem(new QWidgetItem(w));
}



/*!
    Sets the alignment for widget \a w to \a alignment and returns
    true if \a w is found in this layout (not including child
    layouts); otherwise returns false.
*/
bool QLayout::setAlignment(QWidget *w, Qt::Alignment alignment)
{
    int i = 0;
    QLayoutItem *item = itemAt(i);
    while (item) {
        if (item->widget() == w) {
            item->setAlignment(alignment);
            invalidate();
            return true;
        }
        ++i;
        item = itemAt(i);
    }
    return false;
}

/*!
  \overload

  Sets the alignment for the layout \a l to \a alignment and
  returns true if \a l is found in this layout (not including child
  layouts); otherwise returns false.
*/
bool QLayout::setAlignment(QLayout *l, Qt::Alignment alignment)
{
    int i = 0;
    QLayoutItem *item = itemAt(i);
    while (item) {
        if (item->layout() == l) {
            item->setAlignment(alignment);
            invalidate();
            return true;
        }
        ++i;
        item = itemAt(i);
    }
    return false;
}

/*!
    \fn void QLayout::setAlignment(Qt::Alignment alignment)

    Sets the alignment of this item to \a alignment.

    \sa QLayoutItem::setAlignment()
*/

/*!
    \fn bool QLayout::isTopLevel() const

    Returns true if this layout is a top-level layout, i.e. not a
    child of another layout; otherwise returns false.
*/

/*!
    \property QLayout::margin
    \brief the width of the outside border of the layout
    \obsolete

    Use setContentsMargins() and getContentsMargins() instead.

    \sa contentsRect(), spacing
*/

/*!
    \obsolete
*/
int QLayout::margin() const
{
    int left, top, right, bottom;
    getContentsMargins(&left, &top, &right, &bottom);
    if (left == top && top == right && right == bottom) {
        return left;
    } else {
        return -1;
    }
}

/*!
    \property QLayout::spacing
    \brief the spacing between widgets inside the layout

    If no value is explicitly set, the layout's spacing is inherited
    from the parent layout, or from the style settings for the parent
    widget.

    For QGridLayout, it is possible to set different horizontal and
    vertical spacings using \l{QGridLayout::}{setHorizontalSpacing()}
    and \l{QGridLayout::}{setVerticalSpacing()}. In that case,
    spacing() returns -1.

    \sa contentsRect(), getContentsMargins(), QStyle::layoutSpacing(),
        QStyle::pixelMetric()
*/

int QLayout::spacing() const
{
    if (const QBoxLayout* boxlayout = qobject_cast<const QBoxLayout*>(this)) {
        return boxlayout->spacing();
    } else if (const QGridLayout* gridlayout = qobject_cast<const QGridLayout*>(this)) {
        return gridlayout->spacing();
    } else {
        Q_D(const QLayout);
        if (d->insideSpacing >=0) {
            return d->insideSpacing;
        } else {
            // arbitrarily prefer horizontal spacing to vertical spacing
            return qSmartSpacing(this, QStyle::PM_LayoutHorizontalSpacing);
        }
    }
}

/*!
    \obsolete
*/
void QLayout::setMargin(int margin)
{
    setContentsMargins(margin, margin, margin, margin);
}

void QLayout::setSpacing(int spacing)
{
    if (QBoxLayout* boxlayout = qobject_cast<QBoxLayout*>(this)) {
        boxlayout->setSpacing(spacing);
    } else if (QGridLayout* gridlayout = qobject_cast<QGridLayout*>(this)) {
        gridlayout->setSpacing(spacing);
    } else {
        Q_D(QLayout);
        d->insideSpacing = spacing;
        invalidate();
    }
}

/*!
    \since 4.3

    Sets the \a left, \a top, \a right, and \a bottom margins to use
    around the layout.

    By default, QLayout uses the values provided by the style. On
    most platforms, the margin is 11 pixels in all directions.

    \sa getContentsMargins(), QStyle::pixelMetric(),
        {QStyle::}{PM_LayoutLeftMargin},
        {QStyle::}{PM_LayoutTopMargin},
        {QStyle::}{PM_LayoutRightMargin},
        {QStyle::}{PM_LayoutBottomMargin}
*/
void QLayout::setContentsMargins(int left, int top, int right, int bottom)
{
    Q_D(QLayout);
    d->userLeftMargin = left;
    d->userTopMargin = top;
    d->userRightMargin = right;
    d->userBottomMargin = bottom;
    invalidate();
}

/*!
    \since 4.3

    Extracts the left, top, right, and bottom margins used around the
    layout, and assigns them to *\a left, *\a top, *\a right, and *\a
    bottom (unless they are null pointers).

    By default, QLayout uses the values provided by the style. On
    most platforms, the margin is 11 pixels in all directions.

    \sa setContentsMargins(), QStyle::pixelMetric(),
        {QStyle::}{PM_LayoutLeftMargin},
        {QStyle::}{PM_LayoutTopMargin},
        {QStyle::}{PM_LayoutRightMargin},
        {QStyle::}{PM_LayoutBottomMargin}
*/
void QLayout::getContentsMargins(int *left, int *top, int *right, int *bottom) const
{
    Q_D(const QLayout);
    d->getMargin(left, d->userLeftMargin, QStyle::PM_LayoutLeftMargin);
    d->getMargin(top, d->userTopMargin, QStyle::PM_LayoutTopMargin);
    d->getMargin(right, d->userRightMargin, QStyle::PM_LayoutRightMargin);
    d->getMargin(bottom, d->userBottomMargin, QStyle::PM_LayoutBottomMargin);
}

/*!
    \since 4.3

    Returns the layout's geometry() rectangle, but taking into account the
    contents margins.

    \sa setContentsMargins(), getContentsMargins()
*/
QRect QLayout::contentsRect() const
{
    Q_D(const QLayout);
    int left, top, right, bottom;
    getContentsMargins(&left, &top, &right, &bottom);
    return d->rect.adjusted(+left, +top, -right, -bottom);
}

#ifdef QT3_SUPPORT
bool QLayout::isTopLevel() const
{
    Q_D(const QLayout);
    return d->topLevel;
}
#endif

/*!
    Returns the parent widget of this layout, or 0 if this layout is
    not installed on any widget.

    If the layout is a sub-layout, this function returns the parent
    widget of the parent layout.

    \sa parent()
*/
QWidget *QLayout::parentWidget() const
{
    Q_D(const QLayout);
    if (!d->topLevel) {
        if (parent()) {
            QLayout *parentLayout = ::qobject_cast<QLayout*>(parent());
            Q_ASSERT(parentLayout);
            return parentLayout->parentWidget();
        } else {
            return 0;
        }
    } else {
        Q_ASSERT(parent() && parent()->isWidgetType());
        return static_cast<QWidget *>(parent());
    }