qlayoutengine.cpp File Reference

#include "qlayout.h"
#include "private/qlayoutengine_p.h"
#include "qvector.h"
#include "qwidget.h"
#include <qlist.h>
#include <qalgorithms.h>
#include <qdebug.h>

Go to the source code of this file.

Typedefs
typedef qint64	Fixed64

Functions
static int	fRound (Fixed64 i)
void	qGeomCalc (QVector< QLayoutStruct > &chain, int start, int count, int pos, int space, int spacer)
Q_GUI_EXPORT QSize	qSmartMaxSize (const QSize &sizeHint, const QSize &minSize, const QSize &maxSize, const QSizePolicy &sizePolicy, Qt::Alignment align)
Q_GUI_EXPORT QSize	qSmartMaxSize (const QWidgetItem *i, Qt::Alignment align)
Q_GUI_EXPORT QSize	qSmartMaxSize (const QWidget *w, Qt::Alignment align)
Q_GUI_EXPORT QSize	qSmartMinSize (const QSize &sizeHint, const QSize &minSizeHint, const QSize &minSize, const QSize &maxSize, const QSizePolicy &sizePolicy)
Q_GUI_EXPORT QSize	qSmartMinSize (const QWidgetItem *i)
Q_GUI_EXPORT QSize	qSmartMinSize (const QWidget *w)
Q_GUI_EXPORT int	qSmartSpacing (const QLayout *layout, QStyle::PixelMetric pm)
static Fixed64	toFixed (int i)

Typedef Documentation

Fixed64

typedef qint64 Fixed64

Definition at line 57 of file qlayoutengine.cpp.

Function Documentation

fRound()

static int fRound ( Fixed64  i )

inlinestatic

Definition at line 59 of file qlayoutengine.cpp.

Referenced by qGeomCalc().

                                    {
    return (i % 256 < 128) ? i / 256 : 1 + i / 256;
}

qGeomCalc()

void qGeomCalc	(	QVector< QLayoutStruct > &	chain,
		int	start,
		int	count,
		int	pos,
		int	space,
		int	spacer
	)

Definition at line 78 of file qlayoutengine.cpp.

Referenced by QBoxLayoutPrivate::calcHfw(), QGridLayoutPrivate::distribute(), distributeMultiBox(), QSplitterPrivate::doResize(), QDockAreaLayoutInfo::fitItems(), QDockAreaLayout::fitLayout(), QGridLayoutPrivate::heightForWidth(), QToolBarLayout::layoutActions(), QTabBarPrivate::layoutTabs(), QBoxLayout::setGeometry(), and QFormLayout::setGeometry().

{
    int cHint = 0;
    int cMin = 0;
    int cMax = 0;
    int sumStretch = 0;
    int sumSpacing = 0;
    int expandingCount = 0;

    bool allEmptyNonstretch = true;
    int pendingSpacing = -1;
    int spacerCount = 0;
    int i;

    for (i = start; i < start + count; i++) {
        QLayoutStruct *data = &chain[i];

        data->done = false;
        cHint += data->smartSizeHint();
        cMin += data->minimumSize;
        cMax += data->maximumSize;
        sumStretch += data->stretch;
        if (!data->empty) {
            /*
                Using pendingSpacing, we ensure that the spacing for the last
                (non-empty) item is ignored.
            */
            if (pendingSpacing >= 0) {
                sumSpacing += pendingSpacing;
                ++spacerCount;
            }
            pendingSpacing = data->effectiveSpacer(spacer);
        }
        if (data->expansive)
            expandingCount++;
        allEmptyNonstretch = allEmptyNonstretch && data->empty && !data->expansive && data->stretch <= 0;
    }

    int extraspace = 0;

    if (space < cMin + sumSpacing) {
        /*
          Less space than minimumSize; take from the biggest first
        */

        int minSize = cMin + sumSpacing;

        // shrink the spacers proportionally
        if (spacer >= 0) {
            spacer = minSize > 0 ? spacer * space / minSize : 0;
            sumSpacing = spacer * spacerCount;
        }

        QList<int> list;

        for (i = start; i < start + count; i++)
            list << chain.at(i).minimumSize;

        qSort(list);

        int space_left = space - sumSpacing;

        int sum = 0;
        int idx = 0;
        int space_used=0;
        int current = 0;
        while (idx < count && space_used < space_left) {
            current = list.at(idx);
            space_used = sum + current * (count - idx);
            sum += current;
            ++idx;
        }
        --idx;
        int deficit = space_used - space_left;

        int items = count - idx;
        /*
         * If we truncate all items to "current", we would get "deficit" too many pixels. Therefore, we have to remove
         * deficit/items from each item bigger than maxval. The actual value to remove is deficitPerItem + remainder/items
         * "rest" is the accumulated error from using integer arithmetic.
        */
        int deficitPerItem = deficit/items;
        int remainder = deficit % items;
        int maxval = current - deficitPerItem;

        int rest = 0;
        for (i = start; i < start + count; i++) {
            int maxv = maxval;
            rest += remainder;
            if (rest >= items) {
                maxv--;
                rest-=items;
            }
            QLayoutStruct *data = &chain[i];
            data->size = qMin(data->minimumSize, maxv);
            data->done = true;
        }
    } else if (space < cHint + sumSpacing) {
        /*
          Less space than smartSizeHint(), but more than minimumSize.
          Currently take space equally from each, as in Qt 2.x.
          Commented-out lines will give more space to stretchier
          items.
        */
        int n = count;
        int space_left = space - sumSpacing;
        int overdraft = cHint - space_left;

        // first give to the fixed ones:
        for (i = start; i < start + count; i++) {
            QLayoutStruct *data = &chain[i];
            if (!data->done
                 && data->minimumSize >= data->smartSizeHint()) {
                data->size = data->smartSizeHint();
                data->done = true;
                space_left -= data->smartSizeHint();
                // sumStretch -= data->stretch;
                n--;
            }
        }
        bool finished = n == 0;
        while (!finished) {
            finished = true;
            Fixed64 fp_over = toFixed(overdraft);
            Fixed64 fp_w = 0;

            for (i = start; i < start+count; i++) {
                QLayoutStruct *data = &chain[i];
                if (data->done)
                    continue;
                // if (sumStretch <= 0)
                fp_w += fp_over / n;
                // else
                //    fp_w += (fp_over * data->stretch) / sumStretch;
                int w = fRound(fp_w);
                data->size = data->smartSizeHint() - w;
                fp_w -= toFixed(w); // give the difference to the next
                if (data->size < data->minimumSize) {
                    data->done = true;
                    data->size = data->minimumSize;
                    finished = false;
                    overdraft -= data->smartSizeHint() - data->minimumSize;
                    // sumStretch -= data->stretch;
                    n--;
                    break;
                }
            }
        }
    } else { // extra space
        int n = count;
        int space_left = space - sumSpacing;
        // first give to the fixed ones, and handle non-expansiveness
        for (i = start; i < start + count; i++) {
            QLayoutStruct *data = &chain[i];
            if (!data->done
                && (data->maximumSize <= data->smartSizeHint()
                    || (!allEmptyNonstretch && data->empty &&
                        !data->expansive && data->stretch == 0))) {
                data->size = data->smartSizeHint();
                data->done = true;
                space_left -= data->size;
                sumStretch -= data->stretch;
                 if (data->expansive)
                     expandingCount--;
                n--;
            }
        }
        extraspace = space_left;

        /*
          Do a trial distribution and calculate how much it is off.
          If there are more deficit pixels than surplus pixels, give
          the minimum size items what they need, and repeat.
          Otherwise give to the maximum size items, and repeat.

          Paul Olav Tvete has a wonderful mathematical proof of the
          correctness of this principle, but unfortunately this
          comment is too small to contain it.
        */
        int surplus, deficit;
        do {
            surplus = deficit = 0;
            Fixed64 fp_space = toFixed(space_left);
            Fixed64 fp_w = 0;
            for (i = start; i < start + count; i++) {
                QLayoutStruct *data = &chain[i];
                if (data->done)
                    continue;
                extraspace = 0;
                if (sumStretch > 0) {
                    fp_w += (fp_space * data->stretch) / sumStretch;
                } else if (expandingCount > 0) {
                    fp_w += (fp_space * (data->expansive ? 1 : 0)) / expandingCount;
                } else {
                    fp_w += fp_space * 1 / n;
                }
                int w = fRound(fp_w);
                data->size = w;
                fp_w -= toFixed(w); // give the difference to the next
                if (w < data->smartSizeHint()) {
                    deficit +=  data->smartSizeHint() - w;
                } else if (w > data->maximumSize) {
                    surplus += w - data->maximumSize;
                }
            }
            if (deficit > 0 && surplus <= deficit) {
                // give to the ones that have too little
                for (i = start; i < start+count; i++) {
                    QLayoutStruct *data = &chain[i];
                    if (!data->done && data->size < data->smartSizeHint()) {
                        data->size = data->smartSizeHint();
                        data->done = true;
                        space_left -= data->smartSizeHint();
                        sumStretch -= data->stretch;
                        if (data->expansive)
                            expandingCount--;
                        n--;
                    }
                }
            }
            if (surplus > 0 && surplus >= deficit) {
                // take from the ones that have too much
                for (i = start; i < start + count; i++) {
                    QLayoutStruct *data = &chain[i];
                    if (!data->done && data->size > data->maximumSize) {
                        data->size = data->maximumSize;
                        data->done = true;
                        space_left -= data->maximumSize;
                        sumStretch -= data->stretch;
                        if (data->expansive)
                            expandingCount--;
                        n--;
                    }
                }
            }
        } while (n > 0 && surplus != deficit);
        if (n == 0)
            extraspace = space_left;
    }

    /*
      As a last resort, we distribute the unwanted space equally
      among the spacers (counting the start and end of the chain). We
      could, but don't, attempt a sub-pixel allocation of the extra
      space.
    */
    int extra = extraspace / (spacerCount + 2);
    int p = pos + extra;
    for (i = start; i < start+count; i++) {
        QLayoutStruct *data = &chain[i];
        data->pos = p;
        p += data->size;
        if (!data->empty)
            p += data->effectiveSpacer(spacer) + extra;
    }

#ifdef QLAYOUT_EXTRA_DEBUG
    qDebug() << "qGeomCalc" << "start" << start <<  "count" << count <<  "pos" << pos
             <<  "space" << space <<  "spacer" << spacer;
    for (i = start; i < start + count; ++i) {
        qDebug() << i << ':' << chain[i].minimumSize << chain[i].smartSizeHint()
                 << chain[i].maximumSize << "stretch" << chain[i].stretch
                 << "empty" << chain[i].empty << "expansive" << chain[i].expansive
                 << "spacing" << chain[i].spacing;
        qDebug() << "result pos" << chain[i].pos << "size" << chain[i].size;
    }
#endif
}

qSmartMaxSize() [1/3]

Q_GUI_EXPORT QSize qSmartMaxSize	(	const QSize &	sizeHint,
		const QSize &	minSize,
		const QSize &	maxSize,
		const QSizePolicy &	sizePolicy,
		Qt::Alignment	align
	)

Definition at line 393 of file qlayoutengine.cpp.

Referenced by QLayout::closestAcceptableSize(), QWidgetItem::maximumSize(), qSmartMaxSize(), QWidgetItemV2::updateCacheIfNecessary(), and QScrollAreaPrivate::updateScrollBars().

{
    if (align & Qt::AlignHorizontal_Mask && align & Qt::AlignVertical_Mask)
        return QSize(QLAYOUTSIZE_MAX, QLAYOUTSIZE_MAX);
    QSize s = maxSize;
    QSize hint = sizeHint.expandedTo(minSize);
    if (s.width() == QWIDGETSIZE_MAX && !(align & Qt::AlignHorizontal_Mask))
        if (!(sizePolicy.horizontalPolicy() & QSizePolicy::GrowFlag))
            s.setWidth(hint.width());

    if (s.height() == QWIDGETSIZE_MAX && !(align & Qt::AlignVertical_Mask))
        if (!(sizePolicy.verticalPolicy() & QSizePolicy::GrowFlag))
            s.setHeight(hint.height());

    if (align & Qt::AlignHorizontal_Mask)
        s.setWidth(QLAYOUTSIZE_MAX);
    if (align & Qt::AlignVertical_Mask)
        s.setHeight(QLAYOUTSIZE_MAX);
    return s;
}

qSmartMaxSize() [2/3]

Q_GUI_EXPORT QSize qSmartMaxSize	(	const QWidgetItem *	i,
		Qt::Alignment	align
	)

Definition at line 416 of file qlayoutengine.cpp.

{
    QWidget *w = ((QWidgetItem*)i)->widget();

    return qSmartMaxSize(w->sizeHint().expandedTo(w->minimumSizeHint()), w->minimumSize(), w->maximumSize(),
                            w->sizePolicy(), align);
}

qSmartMaxSize() [3/3]

Q_GUI_EXPORT QSize qSmartMaxSize	(	const QWidget *	w,
		Qt::Alignment	align
	)

Definition at line 424 of file qlayoutengine.cpp.

{
    return qSmartMaxSize(w->sizeHint().expandedTo(w->minimumSizeHint()), w->minimumSize(), w->maximumSize(),
                            w->sizePolicy(), align);
}

qSmartMinSize() [1/3]

Q_GUI_EXPORT QSize qSmartMinSize	(	const QSize &	sizeHint,
		const QSize &	minSizeHint,
		const QSize &	minSize,
		const QSize &	maxSize,
		const QSizePolicy &	sizePolicy
	)

Definition at line 348 of file qlayoutengine.cpp.

Referenced by QSplitterPrivate::addContribution(), QMdiAreaPrivate::appendChild(), QWorkspace::cascade(), QLayout::closestAcceptableSize(), QSplitterPrivate::doMove(), QSplitterPrivate::doResize(), QStatusBar::event(), QSplitterPrivate::findWidgetJustBeforeOrJustAfter(), menuBarHeightForWidth(), QStackedLayout::minimumSize(), QToolBarAreaLayoutItem::minimumSize(), QWidgetItem::minimumSize(), QSplitter::minimumSizeHint(), QWidgetResizeHandler::mouseMoveEvent(), qSmartMinSize(), QSplitterPrivate::recalc(), QStatusBar::reformat(), QSplitterPrivate::setGeo(), QSplitterPrivate::setSizes_helper(), QMdiArea::showEvent(), QWidgetItemV2::updateCacheIfNecessary(), QStyledItemDelegate::updateEditorGeometry(), and QScrollAreaPrivate::updateScrollBars().

{
    QSize s(0, 0);

    if (sizePolicy.horizontalPolicy() != QSizePolicy::Ignored) {
        if (sizePolicy.horizontalPolicy() & QSizePolicy::ShrinkFlag)
            s.setWidth(minSizeHint.width());
        else
            s.setWidth(qMax(sizeHint.width(), minSizeHint.width()));
    }

    if (sizePolicy.verticalPolicy() != QSizePolicy::Ignored) {
        if (sizePolicy.verticalPolicy() & QSizePolicy::ShrinkFlag) {
            s.setHeight(minSizeHint.height());
        } else {
            s.setHeight(qMax(sizeHint.height(), minSizeHint.height()));
        }
    }

    s = s.boundedTo(maxSize);
    if (minSize.width() > 0)
        s.setWidth(minSize.width());
    if (minSize.height() > 0)
        s.setHeight(minSize.height());

    return s.expandedTo(QSize(0,0));
}

qSmartMinSize() [2/3]

Q_GUI_EXPORT QSize qSmartMinSize

(

const QWidgetItem *

i

)

Definition at line 378 of file qlayoutengine.cpp.

{
    QWidget *w = ((QWidgetItem *)i)->widget();
    return qSmartMinSize(w->sizeHint(), w->minimumSizeHint(),
                            w->minimumSize(), w->maximumSize(),
                            w->sizePolicy());
}

qSmartMinSize() [3/3]

Q_GUI_EXPORT QSize qSmartMinSize

(

const QWidget *

w

)

Definition at line 386 of file qlayoutengine.cpp.

{
    return qSmartMinSize(w->sizeHint(), w->minimumSizeHint(),
                            w->minimumSize(), w->maximumSize(),
                            w->sizePolicy());
}

qSmartSpacing()

Q_GUI_EXPORT int qSmartSpacing	(	const QLayout *	layout,
		QStyle::PixelMetric	pm
	)

Definition at line 430 of file qlayoutengine.cpp.

Referenced by QGridLayout::horizontalSpacing(), QLayout::setAlignment(), QFormLayout::setHorizontalSpacing(), QFormLayout::setVerticalSpacing(), QBoxLayout::spacing(), and QGridLayout::verticalSpacing().

{
    QObject *parent = layout->parent();
    if (!parent) {
        return -1;
    } else if (parent->isWidgetType()) {
        QWidget *pw = static_cast<QWidget *>(parent);
        return pw->style()->pixelMetric(pm, 0, pw);
    } else {
        return static_cast<QLayout *>(parent)->spacing();
    }
}

toFixed()

static Fixed64 toFixed ( int  i )

inlinestatic

Definition at line 58 of file qlayoutengine.cpp.

Referenced by qGeomCalc().

{ return (Fixed64)i * 256; }