C++ QSizePolicy::hasHeightForWidth方法代码示例

/*!
  Used to calculate the
  Precondition:
  \a widget should support either hfw or wfh

  If \a heightForWidth is set to false, this function will query the width for height
  instead. \a width will then be interpreted as height, \a minh and \a maxh will be interpreted
  as minimum width and maximum width.
 */
static qreal minimumHeightForWidth(qreal width, qreal minh, qreal maxh,
                                   const QGraphicsWidget *widget,
                                   bool heightForWidth = true)
{
    qreal minimumHeightForWidth = -1;
    const QSizePolicy sp = widget->layout() ? widget->layout()->sizePolicy() : widget->sizePolicy();
    const bool hasHFW = sp.hasHeightForWidth();
    if (hasHFW == heightForWidth) {
        minimumHeightForWidth = hasHFW
                                ? widget->effectiveSizeHint(Qt::MinimumSize, QSizeF(width, -1)).height()
                                : widget->effectiveSizeHint(Qt::MinimumSize, QSizeF(-1, width)).width();    //"width" is here height!
    } else {
        // widthForHeight
        const qreal constraint = width;
        while (maxh - minh > 0.1) {
            qreal middle = minh + (maxh - minh)/2;
            // ### really bad, if we are a widget with a layout it will call
            // layout->effectiveSizeHint(Qt::MiniumumSize), which again will call
            // sizeHint three times because of how the cache works
            qreal hfw = hasHFW
                        ? widget->effectiveSizeHint(Qt::MinimumSize, QSizeF(middle, -1)).height()
                        : widget->effectiveSizeHint(Qt::MinimumSize, QSizeF(-1, middle)).width();
            if (hfw > constraint) {
                minh = middle;
            } else if (hfw <= constraint) {
                maxh = middle;
            }
        }
        minimumHeightForWidth = maxh;
    }
    return minimumHeightForWidth;
}

static QString sizePolicyToString(const QSizePolicy &p)
{
    QString rc; {
        QTextStream str(&rc);
        str << "Control=" << p.controlType() << " expdirs=" << p.expandingDirections()
            << " hasHeightForWidth=" << p.hasHeightForWidth()
            << " H: Policy=" << p.horizontalPolicy()
            << " stretch=" << p.horizontalStretch()
            << " V: Policy=" << p.verticalPolicy()
            << " stretch=" << p.verticalStretch();
    }
    return rc;
}

QString LayoutDumper::toString(const QSizePolicy& policy)
{
    QString result = QString("(%1, %2)")
            .arg(toString(policy.horizontalPolicy()))
            .arg(toString(policy.verticalPolicy()));
    if (policy.hasHeightForWidth()) {
        result += " [hasHeightForWidth]";
    }
    if (policy.hasWidthForHeight()) {
        result += " [hasWidthForHeight]";
    }
    return result;
}

static void _q_boundGeometryToSizeConstraints(const QRectF &startGeometry,
                                              QRectF *rect, Qt::WindowFrameSection section,
                                              const QSizeF &min, const QSizeF &max,
                                              const QGraphicsWidget *widget)
{
    const QRectF proposedRect = *rect;
    qreal width = qBound(min.width(), proposedRect.width(), max.width());
    qreal height = qBound(min.height(), proposedRect.height(), max.height());

    QSizePolicy sp = widget->sizePolicy();
    if (const QGraphicsLayout *l = widget->layout()) {
        sp = l->sizePolicy();
    }
    const bool hasHFW = sp.hasHeightForWidth(); // || sp.hasWidthForHeight();

    const bool widthChanged = proposedRect.width() < widget->size().width();
    const bool heightChanged = proposedRect.height() < widget->size().height();

    if (hasHFW) {
        if (widthChanged || heightChanged) {
            const qreal minh = min.height();
            const qreal maxh = max.height();
            const qreal proposedHFW = minimumHeightForWidth(width, minh, maxh, widget);
            if (proposedHFW > proposedRect.height()) {
                QSizeF effectiveSize = closestAcceptableSize(QSizeF(width, height), widget);
                width = effectiveSize.width();
                height = effectiveSize.height();
            }
        }
    }

    switch (section) {
    case Qt::LeftSection:
        rect->setRect(startGeometry.right() - qRound(width), startGeometry.top(),
                      qRound(width), startGeometry.height());
        break;
    case Qt::TopLeftSection:
        rect->setRect(startGeometry.right() - qRound(width), startGeometry.bottom() - qRound(height),
                      qRound(width), qRound(height));
        break;
    case Qt::TopSection:
        rect->setRect(startGeometry.left(), startGeometry.bottom() - qRound(height),
                      startGeometry.width(), qRound(height));
        break;
    case Qt::TopRightSection:
        rect->setTop(rect->bottom() - qRound(height));
        rect->setWidth(qRound(width));
        break;
    case Qt::RightSection:
        rect->setWidth(qRound(width));
        break;
    case Qt::BottomRightSection:
        rect->setWidth(qRound(width));
        rect->setHeight(qRound(height));
        break;
    case Qt::BottomSection:
        rect->setHeight(qRound(height));
        break;
    case Qt::BottomLeftSection:
        rect->setRect(startGeometry.right() - qRound(width), startGeometry.top(),
                      qRound(width), qRound(height));
        break;
    default:
        break;
    }
}