source: trunk/src/gui/kernel/qboxlayout.cpp@ 808

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#include "qboxlayout.h"
#include "qapplication.h"
#include "qwidget.h"
#include "qlist.h"
#include "qsizepolicy.h"
#include "qvector.h"

#include "qlayoutengine_p.h"
#include "qlayout_p.h"

QT_BEGIN_NAMESPACE

/*
    Returns true if the \a widget can be added to the \a layout;
    otherwise returns false.
*/
static bool checkWidget(QLayout *layout, QWidget *widget)
{
    if (!widget) {
        qWarning("QLayout: Cannot add null widget to %s/%s", layout->metaObject()->className(),
                  layout->objectName().toLocal8Bit().data());
        return false;
    }
    return true;
}

struct QBoxLayoutItem
{
    QBoxLayoutItem(QLayoutItem *it, int stretch_ = 0)
        : item(it), stretch(stretch_), magic(false) { }
    ~QBoxLayoutItem() { delete item; }

    int hfw(int w) {
        if (item->hasHeightForWidth()) {
            return item->heightForWidth(w);
        } else {
            return item->sizeHint().height();
        }
    }
    int mhfw(int w) {
        if (item->hasHeightForWidth()) {
            return item->heightForWidth(w);
        } else {
            return item->minimumSize().height();
        }
    }
    int hStretch() {
        if (stretch == 0 && item->widget()) {
            return item->widget()->sizePolicy().horizontalStretch();
        } else {
            return stretch;
        }
    }
    int vStretch() {
        if (stretch == 0 && item->widget()) {
            return item->widget()->sizePolicy().verticalStretch();
        } else {
            return stretch;
        }
    }

    QLayoutItem *item;
    int stretch;
    bool magic;
};

class QBoxLayoutPrivate : public QLayoutPrivate
{
    Q_DECLARE_PUBLIC(QBoxLayout)
public:
    QBoxLayoutPrivate() : hfwWidth(-1), dirty(true), spacing(-1) { }
    ~QBoxLayoutPrivate();

    void setDirty() {
        geomArray.clear();
        hfwWidth = -1;
        hfwHeight = -1;
        dirty = true;
    }

    QList<QBoxLayoutItem *> list;
    QVector<QLayoutStruct> geomArray;
    int hfwWidth;
    int hfwHeight;
    int hfwMinHeight;
    QSize sizeHint;
    QSize minSize;
    QSize maxSize;
    int leftMargin, topMargin, rightMargin, bottomMargin;
    Qt::Orientations expanding;
    uint hasHfw : 1;
    uint dirty : 1;
    QBoxLayout::Direction dir;
    int spacing;

    inline void deleteAll() { while (!list.isEmpty()) delete list.takeFirst(); }

    void setupGeom();
    void calcHfw(int);

    void effectiveMargins(int *left, int *top, int *right, int *bottom) const;
};

QBoxLayoutPrivate::~QBoxLayoutPrivate()
{
}

static inline bool horz(QBoxLayout::Direction dir)
{
    return dir == QBoxLayout::RightToLeft || dir == QBoxLayout::LeftToRight;
}

/**
 * The purpose of this function is to make sure that widgets are not laid out outside its layout.
 * E.g. the layoutItemRect margins are only meant to take of the surrounding margins/spacings.
 * However, if the margin is 0, it can easily cover the area of a widget above it.
 */
void QBoxLayoutPrivate::effectiveMargins(int *left, int *top, int *right, int *bottom) const
{
    int l = leftMargin;
    int t = topMargin;
    int r = rightMargin;
    int b = bottomMargin;
#ifdef Q_WS_MAC
    Q_Q(const QBoxLayout);
    if (horz(dir)) {
        QBoxLayoutItem *leftBox = 0;
        QBoxLayoutItem *rightBox = 0;

        if (left || right) {
            leftBox = list.value(0);
            rightBox = list.value(list.count() - 1);
            if (dir == QBoxLayout::RightToLeft)
                qSwap(leftBox, rightBox);

            int leftDelta = 0;
            int rightDelta = 0;
            if (leftBox) {
                QLayoutItem *itm = leftBox->item;
                if (QWidget *w = itm->widget())
                    leftDelta = itm->geometry().left() - w->geometry().left();
            }
            if (rightBox) {
                QLayoutItem *itm = rightBox->item;
                if (QWidget *w = itm->widget())
                    rightDelta = w->geometry().right() - itm->geometry().right();
            }
            QWidget *w = q->parentWidget();
            Qt::LayoutDirection layoutDirection = w ? w->layoutDirection() : QApplication::layoutDirection();
            if (layoutDirection == Qt::RightToLeft)
                qSwap(leftDelta, rightDelta);

            l = qMax(l, leftDelta);
            r = qMax(r, rightDelta);
        }

        int count = top || bottom ? list.count() : 0;
        for (int i = 0; i < count; ++i) {
            QBoxLayoutItem *box = list.at(i);
            QLayoutItem *itm = box->item;
            QWidget *w = itm->widget();
            if (w) {
                QRect lir = itm->geometry();
                QRect wr = w->geometry();
                if (top)
                    t = qMax(t, lir.top() - wr.top());
                if (bottom)
                    b = qMax(b, wr.bottom() - lir.bottom());
            }
        }
    } else {    // vertical layout
        QBoxLayoutItem *topBox = 0;
        QBoxLayoutItem *bottomBox = 0;

        if (top || bottom) {
            topBox = list.value(0);
            bottomBox = list.value(list.count() - 1);
            if (dir == QBoxLayout::BottomToTop) {
                qSwap(topBox, bottomBox);
            }

            if (top && topBox) {
                QLayoutItem *itm = topBox->item;
                QWidget *w = itm->widget();
                if (w)
                    t = qMax(t, itm->geometry().top() - w->geometry().top());
            }

            if (bottom && bottomBox) {
                QLayoutItem *itm = bottomBox->item;
                QWidget *w = itm->widget();
                if (w)
                    b = qMax(b, w->geometry().bottom() - itm->geometry().bottom());
            }
        }

        int count = left || right ? list.count() : 0;
        for (int i = 0; i < count; ++i) {
            QBoxLayoutItem *box = list.at(i);
            QLayoutItem *itm = box->item;
            QWidget *w = itm->widget();
            if (w) {
                QRect lir = itm->geometry();
                QRect wr = w->geometry();
                if (left)
                    l = qMax(l, lir.left() - wr.left());
                if (right)
                    r = qMax(r, wr.right() - lir.right());
            }
        }        
    }
#endif
    if (left)
        *left = l;
    if (top)
        *top = t;
    if (right)
        *right = r;
    if (bottom)
        *bottom = b;
}


/*
    Initializes the data structure needed by qGeomCalc and
    recalculates max/min and size hint.
*/
void QBoxLayoutPrivate::setupGeom()
{
    if (!dirty)
        return;

    Q_Q(QBoxLayout);
    int maxw = horz(dir) ? 0 : QLAYOUTSIZE_MAX;
    int maxh = horz(dir) ? QLAYOUTSIZE_MAX : 0;
    int minw = 0;
    int minh = 0;
    int hintw = 0;
    int hinth = 0;

    bool horexp = false;
    bool verexp = false;

    hasHfw = false;

    int n = list.count();
    geomArray.clear();
    QVector<QLayoutStruct> a(n);

    QSizePolicy::ControlTypes controlTypes1;
    QSizePolicy::ControlTypes controlTypes2;
    int fixedSpacing = q->spacing();
    int previousNonEmptyIndex = -1;

    QStyle *style = 0;
    if (fixedSpacing < 0) {
        if (QWidget *parentWidget = q->parentWidget())
            style = parentWidget->style();
    }

    for (int i = 0; i < n; i++) {
        QBoxLayoutItem *box = list.at(i);
        QSize max = box->item->maximumSize();
        QSize min = box->item->minimumSize();
        QSize hint = box->item->sizeHint();
        Qt::Orientations exp = box->item->expandingDirections();
        bool empty = box->item->isEmpty();
        int spacing = 0;

        if (!empty) {
            if (fixedSpacing >= 0) {
                spacing = (previousNonEmptyIndex >= 0) ? fixedSpacing : 0;
#ifdef Q_WS_MAC
                if (!horz(dir) && previousNonEmptyIndex >= 0) {
                    QBoxLayoutItem *sibling = (dir == QBoxLayout::TopToBottom  ? box : list.at(previousNonEmptyIndex));
                    if (sibling) {
                        QWidget *wid = sibling->item->widget();
                        if (wid)
                            spacing = qMax(spacing, sibling->item->geometry().top() - wid->geometry().top());
                    }
                }
#endif
            } else {
                controlTypes1 = controlTypes2;
                controlTypes2 = box->item->controlTypes();
                if (previousNonEmptyIndex >= 0) {
                    QSizePolicy::ControlTypes actual1 = controlTypes1;
                    QSizePolicy::ControlTypes actual2 = controlTypes2;
                    if (dir == QBoxLayout::RightToLeft || dir == QBoxLayout::BottomToTop)
                        qSwap(actual1, actual2);

                    if (style) {
                        spacing = style->combinedLayoutSpacing(actual1, actual2,
                                             horz(dir) ? Qt::Horizontal : Qt::Vertical,
                                             0, q->parentWidget());
                        if (spacing < 0)
                            spacing = 0;
                    }
                }
            }

            if (previousNonEmptyIndex >= 0)
                a[previousNonEmptyIndex].spacing = spacing;
            previousNonEmptyIndex = i;
        }

        bool ignore = empty && box->item->widget(); // ignore hidden widgets
        bool dummy = true;
        if (horz(dir)) {
            bool expand = (exp & Qt::Horizontal || box->stretch > 0);
            horexp = horexp || expand;
            maxw += spacing + max.width();
            minw += spacing + min.width();
            hintw += spacing + hint.width();
            if (!ignore)
                qMaxExpCalc(maxh, verexp, dummy,
                            max.height(), exp & Qt::Vertical, box->item->isEmpty());
            minh = qMax(minh, min.height());
            hinth = qMax(hinth, hint.height());

            a[i].sizeHint = hint.width();
            a[i].maximumSize = max.width();
            a[i].minimumSize = min.width();
            a[i].expansive = expand;
            a[i].stretch = box->stretch ? box->stretch : box->hStretch();
        } else {
            bool expand = (exp & Qt::Vertical || box->stretch > 0);
            verexp = verexp || expand;
            maxh += spacing + max.height();
            minh += spacing + min.height();
            hinth += spacing + hint.height();
            if (!ignore)
                qMaxExpCalc(maxw, horexp, dummy,
                            max.width(), exp & Qt::Horizontal, box->item->isEmpty());
            minw = qMax(minw, min.width());
            hintw = qMax(hintw, hint.width());

            a[i].sizeHint = hint.height();
            a[i].maximumSize = max.height();
            a[i].minimumSize = min.height();
            a[i].expansive = expand;
            a[i].stretch = box->stretch ? box->stretch : box->vStretch();
        }

        a[i].empty = empty;
        a[i].spacing = 0;   // might be be initialized with a non-zero value in a later iteration
        hasHfw = hasHfw || box->item->hasHeightForWidth();
    }

    geomArray = a;

    expanding = (Qt::Orientations)
                       ((horexp ? Qt::Horizontal : 0)
                         | (verexp ? Qt::Vertical : 0));

    minSize = QSize(minw, minh);
    maxSize = QSize(maxw, maxh).expandedTo(minSize);
    sizeHint = QSize(hintw, hinth).expandedTo(minSize).boundedTo(maxSize);

    q->getContentsMargins(&leftMargin, &topMargin, &rightMargin, &bottomMargin);
    int left, top, right, bottom;
    effectiveMargins(&left, &top, &right, &bottom);
    QSize extra(left + right, top + bottom);

    minSize += extra;
    maxSize += extra;
    sizeHint += extra;

    dirty = false;
}

/*
  Calculates and stores the preferred height given the width \a w.
*/
void QBoxLayoutPrivate::calcHfw(int w)
{
    QVector<QLayoutStruct> &a = geomArray;
    int n = a.count();
    int h = 0;
    int mh = 0;

    Q_ASSERT(n == list.size());

    if (horz(dir)) {
        qGeomCalc(a, 0, n, 0, w);
        for (int i = 0; i < n; i++) {
            QBoxLayoutItem *box = list.at(i);
            h = qMax(h, box->hfw(a.at(i).size));
            mh = qMax(mh, box->mhfw(a.at(i).size));
        }
    } else {
        for (int i = 0; i < n; ++i) {
            QBoxLayoutItem *box = list.at(i);
            int spacing = a.at(i).spacing;
            h += box->hfw(w);
            mh += box->mhfw(w);
            h += spacing;
            mh += spacing;
        }
    }
    hfwWidth = w;
    hfwHeight = h;
    hfwMinHeight = mh;
}


/*!
    \class QBoxLayout

    \brief The QBoxLayout class lines up child widgets horizontally or
    vertically.

    \ingroup geomanagement

    QBoxLayout takes the space it gets (from its parent layout or from
    the parentWidget()), divides it up into a row of boxes, and makes
    each managed widget fill one box.

    \image qhboxlayout-with-5-children.png Horizontal box layout with five child widgets

    If the QBoxLayout's orientation is Qt::Horizontal the boxes are
    placed in a row, with suitable sizes. Each widget (or other box)
    will get at least its minimum size and at most its maximum size.
    Any excess space is shared according to the stretch factors (more
    about that below).

    \image qvboxlayout-with-5-children.png Vertical box layout with five child widgets

    If the QBoxLayout's orientation is Qt::Vertical, the boxes are
    placed in a column, again with suitable sizes.

    The easiest way to create a QBoxLayout is to use one of the
    convenience classes, e.g. QHBoxLayout (for Qt::Horizontal boxes)
    or QVBoxLayout (for Qt::Vertical boxes). You can also use the
    QBoxLayout constructor directly, specifying its direction as
    LeftToRight, RightToLeft, TopToBottom, or BottomToTop.

    If the QBoxLayout is not the top-level layout (i.e. it is not
    managing all of the widget's area and children), you must add it
    to its parent layout before you can do anything with it. The
    normal way to add a layout is by calling
    parentLayout-\>addLayout().

    Once you have done this, you can add boxes to the QBoxLayout using
    one of four functions:

    \list
    \o addWidget() to add a widget to the QBoxLayout and set the
    widget's stretch factor. (The stretch factor is along the row of
    boxes.)

    \o addSpacing() to create an empty box; this is one of the
    functions you use to create nice and spacious dialogs. See below
    for ways to set margins.

    \o addStretch() to create an empty, stretchable box.

    \o addLayout() to add a box containing another QLayout to the row
    and set that layout's stretch factor.
    \endlist

    Use insertWidget(), insertSpacing(), insertStretch() or
    insertLayout() to insert a box at a specified position in the
    layout.

    QBoxLayout also includes two margin widths:

    \list
    \o setContentsMargins() sets the width of the outer border on 
       each side of the widget. This is the width of the reserved space 
       along each of the QBoxLayout's four sides.
    \o setSpacing() sets the width between neighboring boxes. (You
       can use addSpacing() to get more space at a particular spot.)
    \endlist

    The margin default is provided by the style. The default margin
    most Qt styles specify is 9 for child widgets and 11 for windows.
    The spacing defaults to the same as the margin width for a
    top-level layout, or to the same as the parent layout.

    To remove a widget from a layout, call removeWidget(). Calling
    QWidget::hide() on a widget also effectively removes the widget
    from the layout until QWidget::show() is called.

    You will almost always want to use QVBoxLayout and QHBoxLayout
    rather than QBoxLayout because of their convenient constructors.

    \sa QGridLayout, QStackedLayout, {Layout Management}
*/

/*!
    \enum QBoxLayout::Direction

    This type is used to determine the direction of a box layout.

    \value LeftToRight  Horizontal from left to right.
    \value RightToLeft  Horizontal from right to left.
    \value TopToBottom  Vertical from top to bottom.
    \value BottomToTop  Vertical from bottom to top.

    \omitvalue Down
    \omitvalue Up
*/

/*!
    Constructs a new QBoxLayout with direction \a dir and parent widget \a
    parent.

    \sa direction()
*/
QBoxLayout::QBoxLayout(Direction dir, QWidget *parent)
    : QLayout(*new QBoxLayoutPrivate, 0, parent)
{
    Q_D(QBoxLayout);
    d->dir = dir;
}