widgets/graphicsview/qgraphicsgridlayout.cpp

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtWidgets module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \class QGraphicsGridLayout
    \brief The QGraphicsGridLayout class provides a grid layout for managing
    widgets in Graphics View.
    \since 4.4

    \ingroup graphicsview-api
    \inmodule QtWidgets

    The most common way to use QGraphicsGridLayout is to construct an object
    on the heap with no parent, add widgets and layouts by calling addItem(),
    and finally assign the layout to a widget by calling
    QGraphicsWidget::setLayout(). QGraphicsGridLayout automatically computes
    the dimensions of the grid as you add items.

    \snippet code/src_gui_graphicsview_qgraphicsgridlayout.cpp 0

    The layout takes ownership of the items. In some cases when the layout
    item also inherits from QGraphicsItem (such as QGraphicsWidget) there will be a
    ambiguity in ownership because the layout item belongs to two ownership hierarchies.
    See the documentation of QGraphicsLayoutItem::setOwnedByLayout() how to handle
    this.
    You can access each item in the layout by calling count() and itemAt(). Calling
    removeAt() will remove an item from the layout, without
    destroying it.

    \section1 Size Hints and Size Policies in QGraphicsGridLayout

    QGraphicsGridLayout respects each item's size hints and size policies,
    and when a cell in the grid has more space than the items can fill, each item
    is arranged according to the layout's alignment for that item. You can set
    an alignment for each item by calling setAlignment(), and check the
    alignment for any item by calling alignment(). You can also set the alignment
    for an entire row or column by calling setRowAlignment() and setColumnAlignment()
    respectively.  By default, items are aligned to the top left.


    \sa QGraphicsLinearLayout, QGraphicsWidget
*/

#include "qglobal.h"

#include "qapplication.h"
#include "qwidget.h"
#include "qgraphicslayout_p.h"
#include "qgraphicslayoutitem.h"
#include "qgraphicsgridlayout.h"
#include "qgraphicswidget.h"
#include "qgraphicsgridlayoutengine_p.h"
#include "qgraphicslayoutstyleinfo_p.h"
#include "qscopedpointer.h"
#ifdef QT_DEBUG
# include <QtCore/qdebug.h>
#endif

QT_BEGIN_NAMESPACE

class QGraphicsGridLayoutPrivate : public QGraphicsLayoutPrivate
{
public:
    QGraphicsGridLayoutPrivate() { }
    QGraphicsLayoutStyleInfo *styleInfo() const;

    mutable QScopedPointer<QGraphicsLayoutStyleInfo> m_styleInfo;
    QGraphicsGridLayoutEngine engine;

#ifdef QGRIDLAYOUTENGINE_DEBUG
    void dump(int indent) const;
#endif
};


QGraphicsLayoutStyleInfo *QGraphicsGridLayoutPrivate::styleInfo() const
{
    if (!m_styleInfo)
        m_styleInfo.reset(new QGraphicsLayoutStyleInfo(this));
    return m_styleInfo.data();
}

/*!
    Constructs a QGraphicsGridLayout instance.  \a parent is passed to
    QGraphicsLayout's constructor.
*/
QGraphicsGridLayout::QGraphicsGridLayout(QGraphicsLayoutItem *parent)
    : QGraphicsLayout(*new QGraphicsGridLayoutPrivate(), parent)
{
}

/*!
    Destroys the QGraphicsGridLayout object.
*/
QGraphicsGridLayout::~QGraphicsGridLayout()
{
    for (int i = count() - 1; i >= 0; --i) {
        QGraphicsLayoutItem *item = itemAt(i);
        // The following lines can be removed, but this removes the item
        // from the layout more efficiently than the implementation of
        // ~QGraphicsLayoutItem.
        removeAt(i);
        if (item) {
            item->setParentLayoutItem(nullptr);
            if (item->ownedByLayout())
                delete item;
        }
    }
}

/*!
    Adds \a item to the grid on \a row and \a column. You can specify a
    \a rowSpan and \a columnSpan and an optional \a alignment.
*/
void QGraphicsGridLayout::addItem(QGraphicsLayoutItem *item, int row, int column,
                                  int rowSpan, int columnSpan, Qt::Alignment alignment)
{
    Q_D(QGraphicsGridLayout);
    if (row < 0 || column < 0) {
        qWarning("QGraphicsGridLayout::addItem: invalid row/column: %d",
                 row < 0 ? row : column);
        return;
    }
    if (columnSpan < 1 || rowSpan < 1) {
        qWarning("QGraphicsGridLayout::addItem: invalid row span/column span: %d",
                 rowSpan < 1 ? rowSpan : columnSpan);
        return;
    }
    if (!item) {
        qWarning("QGraphicsGridLayout::addItem: cannot add null item");
        return;
    }
    if (item == this) {
        qWarning("QGraphicsGridLayout::addItem: cannot insert itself");
        return;
    }

    d->addChildLayoutItem(item);

    QGraphicsGridLayoutEngineItem *gridEngineItem = new QGraphicsGridLayoutEngineItem(item, row, column, rowSpan, columnSpan, alignment);
    d->engine.insertItem(gridEngineItem, -1);
    invalidate();
}

/*!
    \fn QGraphicsGridLayout::addItem(QGraphicsLayoutItem *item, int row, int column, Qt::Alignment alignment = 0)

    Adds \a item to the grid on \a row and \a column. You can specify
    an optional \a alignment for \a item.
*/

/*!
    Sets the default horizontal spacing for the grid layout to \a spacing.
*/
void QGraphicsGridLayout::setHorizontalSpacing(qreal spacing)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setSpacing(spacing, Qt::Horizontal);
    invalidate();
}

/*!
    Returns the default horizontal spacing for the grid layout.
*/
qreal QGraphicsGridLayout::horizontalSpacing() const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.spacing(Qt::Horizontal, d->styleInfo());
}

/*!
    Sets the default vertical spacing for the grid layout to \a spacing.
*/
void QGraphicsGridLayout::setVerticalSpacing(qreal spacing)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setSpacing(spacing, Qt::Vertical);
    invalidate();
}

/*!
    Returns the default vertical spacing for the grid layout.
*/
qreal QGraphicsGridLayout::verticalSpacing() const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.spacing(Qt::Vertical, d->styleInfo());
}

/*!
    Sets the grid layout's default spacing, both vertical and
    horizontal, to \a spacing.

    \sa rowSpacing(), columnSpacing()
*/
void QGraphicsGridLayout::setSpacing(qreal spacing)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setSpacing(spacing, Qt::Horizontal | Qt::Vertical);
    invalidate();
}

/*!
    Sets the spacing for \a row to \a spacing.
*/
void QGraphicsGridLayout::setRowSpacing(int row, qreal spacing)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSpacing(row, spacing, Qt::Vertical);
    invalidate();
}

/*!
    Returns the row spacing for \a row.
*/
qreal QGraphicsGridLayout::rowSpacing(int row) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowSpacing(row, Qt::Vertical);
}

/*!
    Sets the spacing for \a column to \a spacing.
*/
void QGraphicsGridLayout::setColumnSpacing(int column, qreal spacing)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSpacing(column, spacing, Qt::Horizontal);
    invalidate();
}

/*!
    Returns the column spacing for \a column.
*/
qreal QGraphicsGridLayout::columnSpacing(int column) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowSpacing(column, Qt::Horizontal);
}

/*!
    Sets the stretch factor for \a row to \a stretch.
*/
void QGraphicsGridLayout::setRowStretchFactor(int row, int stretch)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowStretchFactor(row, stretch, Qt::Vertical);
    invalidate();
}

/*!
    Returns the stretch factor for \a row.
*/
int QGraphicsGridLayout::rowStretchFactor(int row) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowStretchFactor(row, Qt::Vertical);
}

/*!
    Sets the stretch factor for \a column to \a stretch.
*/
void QGraphicsGridLayout::setColumnStretchFactor(int column, int stretch)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowStretchFactor(column, stretch, Qt::Horizontal);
    invalidate();
}

/*!
    Returns the stretch factor for \a column.
*/
int QGraphicsGridLayout::columnStretchFactor(int column) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowStretchFactor(column, Qt::Horizontal);
}

/*!
    Sets the minimum height for row, \a row, to \a height.
*/
void QGraphicsGridLayout::setRowMinimumHeight(int row, qreal height)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSizeHint(Qt::MinimumSize, row, height, Qt::Vertical);
    invalidate();
}

/*!
    Returns the minimum height for row, \a row.
*/
qreal QGraphicsGridLayout::rowMinimumHeight(int row) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowSizeHint(Qt::MinimumSize, row, Qt::Vertical);
}

/*!
    Sets the preferred height for row, \a row, to \a height.
*/
void QGraphicsGridLayout::setRowPreferredHeight(int row, qreal height)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSizeHint(Qt::PreferredSize, row, height, Qt::Vertical);
    invalidate();
}

/*!
    Returns the preferred height for row, \a row.
*/
qreal QGraphicsGridLayout::rowPreferredHeight(int row) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowSizeHint(Qt::PreferredSize, row, Qt::Vertical);
}

/*!
    Sets the maximum height for row, \a row, to \a height.
*/
void QGraphicsGridLayout::setRowMaximumHeight(int row, qreal height)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSizeHint(Qt::MaximumSize, row, height, Qt::Vertical);
    invalidate();
}

/*!
    Returns the maximum height for row, \a row.
*/
qreal QGraphicsGridLayout::rowMaximumHeight(int row) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowSizeHint(Qt::MaximumSize, row, Qt::Vertical);
}

/*!
    Sets the fixed height for row, \a row, to \a height.
*/
void QGraphicsGridLayout::setRowFixedHeight(int row, qreal height)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSizeHint(Qt::MinimumSize, row, height, Qt::Vertical);
    d->engine.setRowSizeHint(Qt::MaximumSize, row, height, Qt::Vertical);
    invalidate();
}

/*!
    Sets the minimum width for \a column to \a width.
*/
void QGraphicsGridLayout::setColumnMinimumWidth(int column, qreal width)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSizeHint(Qt::MinimumSize, column, width, Qt::Horizontal);
    invalidate();
}

/*!
    Returns the minimum width for \a column.
*/
qreal QGraphicsGridLayout::columnMinimumWidth(int column) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowSizeHint(Qt::MinimumSize, column, Qt::Horizontal);
}

/*!
    Sets the preferred width for \a column to \a width.
*/
void QGraphicsGridLayout::setColumnPreferredWidth(int column, qreal width)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSizeHint(Qt::PreferredSize, column, width, Qt::Horizontal);
    invalidate();
}

/*!
    Returns the preferred width for \a column.
*/
qreal QGraphicsGridLayout::columnPreferredWidth(int column) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowSizeHint(Qt::PreferredSize, column, Qt::Horizontal);
}

/*!
    Sets the maximum width of \a column to \a width.
*/
void QGraphicsGridLayout::setColumnMaximumWidth(int column, qreal width)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSizeHint(Qt::MaximumSize, column, width, Qt::Horizontal);
    invalidate();
}

/*!
    Returns the maximum width for \a column.
*/
qreal QGraphicsGridLayout::columnMaximumWidth(int column) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowSizeHint(Qt::MaximumSize, column, Qt::Horizontal);
}

/*!
    Sets the fixed width of \a column to \a width.
*/
void QGraphicsGridLayout::setColumnFixedWidth(int column, qreal width)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowSizeHint(Qt::MinimumSize, column, width, Qt::Horizontal);
    d->engine.setRowSizeHint(Qt::MaximumSize, column, width, Qt::Horizontal);
    invalidate();
}

/*!
    Sets the alignment of \a row to \a alignment.
*/
void QGraphicsGridLayout::setRowAlignment(int row, Qt::Alignment alignment)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowAlignment(row, alignment, Qt::Vertical);
    invalidate();
}

/*!
    Returns the alignment of \a row.
*/
Qt::Alignment QGraphicsGridLayout::rowAlignment(int row) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowAlignment(row, Qt::Vertical);
}

/*!
    Sets the alignment for \a column to \a alignment.
*/
void QGraphicsGridLayout::setColumnAlignment(int column, Qt::Alignment alignment)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setRowAlignment(column, alignment, Qt::Horizontal);
    invalidate();
}

/*!
    Returns the alignment for \a column.
*/
Qt::Alignment QGraphicsGridLayout::columnAlignment(int column) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.rowAlignment(column, Qt::Horizontal);
}

/*!
    Sets the alignment for \a item to \a alignment.
*/
void QGraphicsGridLayout::setAlignment(QGraphicsLayoutItem *item, Qt::Alignment alignment)
{
    Q_D(QGraphicsGridLayout);
    d->engine.setAlignment(item, alignment);
    invalidate();
}

/*!
    Returns the alignment for \a item.
*/
Qt::Alignment QGraphicsGridLayout::alignment(QGraphicsLayoutItem *item) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.alignment(item);
}

/*!
    Returns the number of rows in the grid layout. This is always one more
    than the index of the last row that is occupied by a layout item (empty
    rows are counted except for those at the end).
*/
int QGraphicsGridLayout::rowCount() const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.effectiveLastRow(Qt::Vertical) + 1;
}

/*!
    Returns the number of columns in the grid layout. This is always one more
    than the index of  the last column that is occupied by a layout item (empty
    columns are counted except for those at the end).
*/
int QGraphicsGridLayout::columnCount() const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.effectiveLastRow(Qt::Horizontal) + 1;
}

/*!
    Returns a pointer to the layout item at (\a row, \a column).
*/
QGraphicsLayoutItem *QGraphicsGridLayout::itemAt(int row, int column) const
{
    Q_D(const QGraphicsGridLayout);
    if (row < 0 || row >= rowCount() || column < 0 || column >= columnCount()) {
        qWarning("QGraphicsGridLayout::itemAt: invalid row, column %d, %d", row, column);
        return nullptr;
    }
    if (QGraphicsGridLayoutEngineItem *engineItem = static_cast<QGraphicsGridLayoutEngineItem*>(d->engine.itemAt(row, column)))
        return engineItem->layoutItem();
    return nullptr;
}

/*!
    Returns the number of layout items in this grid layout.
*/
int QGraphicsGridLayout::count() const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.itemCount();
}

/*!
    Returns the layout item at \a index, or \nullptr if there is no
    layout item at this index.
*/
QGraphicsLayoutItem *QGraphicsGridLayout::itemAt(int index) const
{
    Q_D(const QGraphicsGridLayout);
    if (index < 0 || index >= d->engine.itemCount()) {
        qWarning("QGraphicsGridLayout::itemAt: invalid index %d", index);
        return nullptr;
    }
    if (QGraphicsGridLayoutEngineItem *engineItem = static_cast<QGraphicsGridLayoutEngineItem*>(d->engine.itemAt(index)))
        return engineItem->layoutItem();
    return nullptr;
}

/*!
    Removes the layout item at \a index without destroying it. Ownership of
    the item is transferred to the caller.

    \sa addItem()
*/
void QGraphicsGridLayout::removeAt(int index)
{
    Q_D(QGraphicsGridLayout);
    if (index < 0 || index >= d->engine.itemCount()) {
        qWarning("QGraphicsGridLayout::removeAt: invalid index %d", index);
        return;
    }

    if (QGraphicsGridLayoutEngineItem *gridItem = static_cast<QGraphicsGridLayoutEngineItem*>(d->engine.itemAt(index))) {
        if (QGraphicsLayoutItem *layoutItem = gridItem->layoutItem())
            layoutItem->setParentLayoutItem(nullptr);
        d->engine.removeItem(gridItem);

        // recalculate rowInfo.count if we remove an item that is on the right/bottommost row
        for (int j = 0; j < NOrientations; ++j) {
            // 0: Hor, 1: Ver
            const Qt::Orientation orient = (j == 0 ? Qt::Horizontal : Qt::Vertical);
            const int oldCount = d->engine.rowCount(orient);
            if (gridItem->lastRow(orient) == oldCount - 1) {
                const int newCount = d->engine.effectiveLastRow(orient) + 1;
                d->engine.removeRows(newCount, oldCount - newCount, orient);
            }
        }

        delete gridItem;
        invalidate();
    }
}

/*!
    Removes the layout item \a item without destroying it.
    Ownership of the item is transferred to the caller.

    \sa addItem()
*/
void QGraphicsGridLayout::removeItem(QGraphicsLayoutItem *item)
{
    Q_D(QGraphicsGridLayout);
    int index = d->engine.indexOf(item);
    removeAt(index);
}
/*!
    \reimp
*/
void QGraphicsGridLayout::invalidate()
{
    Q_D(QGraphicsGridLayout);
    d->engine.invalidate();
    if (d->m_styleInfo)
        d->m_styleInfo->invalidate();
    QGraphicsLayout::invalidate();
}

#ifdef QGRIDLAYOUTENGINE_DEBUG
void QGraphicsGridLayoutPrivate::dump(int indent) const
{
    if (qt_graphicsLayoutDebug()) {
        engine.dump(indent + 1);
    }
}
#endif

/*!
    Sets the bounding geometry of the grid layout to \a rect.
*/
void QGraphicsGridLayout::setGeometry(const QRectF &rect)
{
    Q_D(QGraphicsGridLayout);
    QGraphicsLayout::setGeometry(rect);
    QRectF effectiveRect = geometry();
    qreal left, top, right, bottom;
    getContentsMargins(&left, &top, &right, &bottom);
    Qt::LayoutDirection visualDir = d->visualDirection();
    d->engine.setVisualDirection(visualDir);
    if (visualDir == Qt::RightToLeft)
        qSwap(left, right);
    effectiveRect.adjust(+left, +top, -right, -bottom);
    d->engine.setGeometries(effectiveRect, d->styleInfo());
#ifdef QGRIDLAYOUTENGINE_DEBUG
    if (qt_graphicsLayoutDebug()) {
        static int counter = 0;
        qDebug("==== BEGIN DUMP OF QGraphicsGridLayout (%d)====", counter++);
        d->dump(1);
        qDebug("==== END DUMP OF QGraphicsGridLayout ====");
    }
#endif
}

/*!
    \reimp
*/
QSizeF QGraphicsGridLayout::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const
{
    Q_D(const QGraphicsGridLayout);
    qreal left, top, right, bottom;
    getContentsMargins(&left, &top, &right, &bottom);
    const QSizeF extraMargins(left + right, top + bottom);
    return d->engine.sizeHint(which , constraint - extraMargins, d->styleInfo()) + extraMargins;
}


#if 0
// ### kill? (implement and kill?)
QRect QGraphicsGridLayout::cellRect(int row, int column, int rowSpan, int columnSpan) const
{
    Q_D(const QGraphicsGridLayout);
    return QRect();
//    return d->engine.cellRect(parentLayoutable(), contentsGeometry(), row, column, rowSpan, columnSpan);
}

QSizePolicy::ControlTypes QGraphicsGridLayout::controlTypes(LayoutSide side) const
{
    Q_D(const QGraphicsGridLayout);
    return d->engine.controlTypes(side);
}
#endif

QT_END_NAMESPACE