qgraphicslayout.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qapplication.h"
 
#include "qgraphicslayout.h"
#include "qgraphicslayout_p.h"
#include "qgraphicslayoutitem.h"
#include "qgraphicslayoutitem_p.h"
#include "qgraphicswidget.h"
#include "qgraphicswidget_p.h"
#include "qgraphicsscene.h"
 
QT_BEGIN_NAMESPACE
 
QGraphicsLayout::QGraphicsLayout(QGraphicsLayoutItem *parent)
    : QGraphicsLayoutItem(*new QGraphicsLayoutPrivate)
{
    setParentLayoutItem(parent);
    if (parent && !parent->isLayout()) {
        // If a layout has a parent that is not a layout it must be a QGraphicsWidget.
        QGraphicsItem *itemParent = parent->graphicsItem();
        if (itemParent && itemParent->isWidget()) {
            static_cast<QGraphicsWidget *>(itemParent)->d_func()->setLayout_helper(this);
        } else {
            qWarning("QGraphicsLayout::QGraphicsLayout: Attempt to create a layout with a parent that is"
                    " neither a QGraphicsWidget nor QGraphicsLayout");
        }
    }
    d_func()->sizePolicy = QSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding, QSizePolicy::DefaultType);
    setOwnedByLayout(true);
}
 
QGraphicsLayout::QGraphicsLayout(QGraphicsLayoutPrivate &dd, QGraphicsLayoutItem *parent)
    : QGraphicsLayoutItem(dd)
{
    setParentLayoutItem(parent);
    if (parent && !parent->isLayout()) {
        // If a layout has a parent that is not a layout it must be a QGraphicsWidget.
        QGraphicsItem *itemParent = parent->graphicsItem();
        if (itemParent && itemParent->isWidget()) {
            static_cast<QGraphicsWidget *>(itemParent)->d_func()->setLayout_helper(this);
        } else {
            qWarning("QGraphicsLayout::QGraphicsLayout: Attempt to create a layout with a parent that is"
                    " neither a QGraphicsWidget nor QGraphicsLayout");
        }
    }
    d_func()->sizePolicy = QSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding, QSizePolicy::DefaultType);
    setOwnedByLayout(true);
}
 
QGraphicsLayout::~QGraphicsLayout()
{
}
 
void QGraphicsLayout::setContentsMargins(qreal left, qreal top, qreal right, qreal bottom)
{
    Q_D(QGraphicsLayout);
    if (d->left == left && d->top == top && d->right == right && d->bottom == bottom)
        return;
    d->left = left;
    d->right = right;
    d->top = top;
    d->bottom = bottom;
    invalidate();
}
 
void QGraphicsLayout::getContentsMargins(qreal *left, qreal *top, qreal *right, qreal *bottom) const
{
    Q_D(const QGraphicsLayout);
    d->getMargin(left, d->left, QStyle::PM_LayoutLeftMargin);
    d->getMargin(top, d->top, QStyle::PM_LayoutTopMargin);
    d->getMargin(right, d->right, QStyle::PM_LayoutRightMargin);
    d->getMargin(bottom, d->bottom, QStyle::PM_LayoutBottomMargin);
}
 
void QGraphicsLayout::activate()
{
    Q_D(QGraphicsLayout);
    if (d->activated)
        return;
 
    d->activateRecursive(this);
 
    // we don't call activate on a sublayout, but somebody might.
    // Therefore, we walk to the parentitem of the toplevel layout.
    QGraphicsLayoutItem *parentItem = this;
    while (parentItem && parentItem->isLayout())
        parentItem = parentItem->parentLayoutItem();
    if (!parentItem)
        return;
    Q_ASSERT(!parentItem->isLayout());
 
    if (QGraphicsLayout::instantInvalidatePropagation()) {
        QGraphicsWidget *parentWidget = static_cast<QGraphicsWidget*>(parentItem);
        if (!parentWidget->parentLayoutItem()) {
            // we've reached the topmost widget, resize it
            bool wasResized = parentWidget->testAttribute(Qt::WA_Resized);
            parentWidget->resize(parentWidget->size());
            parentWidget->setAttribute(Qt::WA_Resized, wasResized);
        }
 
        setGeometry(parentItem->contentsRect());    // relayout children
    } else {
        setGeometry(parentItem->contentsRect());    // relayout children
        parentLayoutItem()->updateGeometry();
    }
}
 
bool QGraphicsLayout::isActivated() const
{
    Q_D(const QGraphicsLayout);
    return d->activated;
}
 
void QGraphicsLayout::invalidate()
{
    if (QGraphicsLayout::instantInvalidatePropagation()) {
        updateGeometry();
    } else {
        // only mark layouts as invalid (activated = false) if we can post a LayoutRequest event.
        QGraphicsLayoutItem *layoutItem = this;
        while (layoutItem && layoutItem->isLayout()) {
            // we could call updateGeometry(), but what if that method
            // does not call the base implementation? In addition, updateGeometry()
            // does more than we need.
            layoutItem->d_func()->sizeHintCacheDirty = true;
            layoutItem->d_func()->sizeHintWithConstraintCacheDirty = true;
            layoutItem = layoutItem->parentLayoutItem();
        }
        if (layoutItem) {
            layoutItem->d_func()->sizeHintCacheDirty = true;
            layoutItem->d_func()->sizeHintWithConstraintCacheDirty = true;
        }
 
        bool postIt = layoutItem ? !layoutItem->isLayout() : false;
        if (postIt) {
            layoutItem = this;
            while (layoutItem && layoutItem->isLayout()
                    && static_cast<QGraphicsLayout*>(layoutItem)->d_func()->activated) {
                static_cast<QGraphicsLayout*>(layoutItem)->d_func()->activated = false;
                layoutItem = layoutItem->parentLayoutItem();
            }
            if (layoutItem && !layoutItem->isLayout()) {
                // If a layout has a parent that is not a layout it must be a QGraphicsWidget.
                QCoreApplication::postEvent(static_cast<QGraphicsWidget *>(layoutItem), new QEvent(QEvent::LayoutRequest));
            }
        }
    }
}
 
void QGraphicsLayout::updateGeometry()
{
    Q_D(QGraphicsLayout);
    if (QGraphicsLayout::instantInvalidatePropagation()) {
        d->activated = false;
        QGraphicsLayoutItem::updateGeometry();
 
        QGraphicsLayoutItem *parentItem = parentLayoutItem();
        if (!parentItem)
            return;
 
        if (parentItem->isLayout())
            static_cast<QGraphicsLayout *>(parentItem)->invalidate();
        else
            parentItem->updateGeometry();
    } else {
        QGraphicsLayoutItem::updateGeometry();
        if (QGraphicsLayoutItem *parentItem = parentLayoutItem()) {
            if (parentItem->isLayout()) {
                parentItem->updateGeometry();
            } else {
                invalidate();
            }
        }
    }
}
 
void QGraphicsLayout::widgetEvent(QEvent *e)
{
    switch (e->type()) {
    case QEvent::GraphicsSceneResize:
        if (isActivated()) {
            setGeometry(parentLayoutItem()->contentsRect());
        } else {
            activate(); // relies on that activate() will call updateGeometry()
        }
        break;
    case QEvent::LayoutRequest:
        activate();
        break;
    case QEvent::LayoutDirectionChange:
        invalidate();
        break;
    default:
        break;
    }
}
 
void QGraphicsLayout::addChildLayoutItem(QGraphicsLayoutItem *layoutItem)
{
    Q_D(QGraphicsLayout);
    d->addChildLayoutItem(layoutItem);
}
 
static bool g_instantInvalidatePropagation = false;
 
void QGraphicsLayout::setInstantInvalidatePropagation(bool enable)
{
    g_instantInvalidatePropagation = enable;
}
 
bool QGraphicsLayout::instantInvalidatePropagation()
{
    return g_instantInvalidatePropagation;
}
 
QT_END_NAMESPACE