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;