qwt_dyngrid_layout.cpp

/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *****************************************************************************/

#include "qwt_dyngrid_layout.h"
#include "qwt_math.h"
#include <qvector.h>
#include <qlist.h>

class QwtDynGridLayout::PrivateData
{
public:
    PrivateData():
        isDirty( true )
    {
    }

    void updateLayoutCache();

    mutable QList<QLayoutItem*> itemList;

    uint maxColumns;
    uint numRows;
    uint numColumns;

    Qt::Orientations expanding;

    bool isDirty;
    QVector<QSize> itemSizeHints;
};

void QwtDynGridLayout::PrivateData::updateLayoutCache()
{
    itemSizeHints.resize( itemList.count() );

    int index = 0;

    for ( QList<QLayoutItem*>::iterator it = itemList.begin();
        it != itemList.end(); ++it, index++ )
    {
        itemSizeHints[ index ] = ( *it )->sizeHint();
    }

    isDirty = false;
}

/*!
  \param parent Parent widget
  \param margin Margin
  \param spacing Spacing
*/

QwtDynGridLayout::QwtDynGridLayout( QWidget *parent,
        int margin, int spacing ):
    QLayout( parent )
{
    init();

    setSpacing( spacing );
    setMargin( margin );
}

/*!
  \param spacing Spacing
*/

QwtDynGridLayout::QwtDynGridLayout( int spacing )
{
    init();
    setSpacing( spacing );
}

/*!
  Initialize the layout with default values.
*/
void QwtDynGridLayout::init()
{
    d_data = new QwtDynGridLayout::PrivateData;
    d_data->maxColumns = d_data->numRows = d_data->numColumns = 0;
    d_data->expanding = 0;
}

//! Destructor

QwtDynGridLayout::~QwtDynGridLayout()
{
    for ( int i = 0; i < d_data->itemList.size(); i++ )
        delete d_data->itemList[i];

    delete d_data;
}

//! Invalidate all internal caches
void QwtDynGridLayout::invalidate()
{
    d_data->isDirty = true;
    QLayout::invalidate();
}

/*!
  Limit the number of columns.
  \param maxColumns upper limit, 0 means unlimited
  \sa maxColumns()
*/
void QwtDynGridLayout::setMaxColumns( uint maxColumns )
{
    d_data->maxColumns = maxColumns;
}

/*!
  \brief Return the upper limit for the number of columns.

  0 means unlimited, what is the default.

  \return Upper limit for the number of columns
  \sa setMaxColumns()
*/
uint QwtDynGridLayout::maxColumns() const
{
    return d_data->maxColumns;
}

/*! 
  \brief Add an item to the next free position.
  \param item Layout item
 */
void QwtDynGridLayout::addItem( QLayoutItem *item )
{
    d_data->itemList.append( item );
    invalidate();
}

/*!
  \return true if this layout is empty.
*/
bool QwtDynGridLayout::isEmpty() const
{
    return d_data->itemList.isEmpty();
}

/*!
  \return number of layout items
*/
uint QwtDynGridLayout::itemCount() const
{
    return d_data->itemList.count();
}

/*!
  Find the item at a specific index

  \param index Index
  \return Item at a specific index
  \sa takeAt()
*/
QLayoutItem *QwtDynGridLayout::itemAt( int index ) const
{
    if ( index < 0 || index >= d_data->itemList.count() )
        return NULL;

    return d_data->itemList.at( index );
}

/*!
  Find the item at a specific index and remove it from the layout

  \param index Index
  \return Layout item, removed from the layout
  \sa itemAt()
*/
QLayoutItem *QwtDynGridLayout::takeAt( int index )
{
    if ( index < 0 || index >= d_data->itemList.count() )
        return NULL;

    d_data->isDirty = true;
    return d_data->itemList.takeAt( index );
}

//! \return Number of items in the layout
int QwtDynGridLayout::count() const
{
    return d_data->itemList.count();
}

/*!
  Set whether this layout can make use of more space than sizeHint().
  A value of Qt::Vertical or Qt::Horizontal means that it wants to grow in only
  one dimension, while Qt::Vertical | Qt::Horizontal means that it wants
  to grow in both dimensions. The default value is 0.

  \param expanding Or'd orientations
  \sa expandingDirections()
*/
void QwtDynGridLayout::setExpandingDirections( Qt::Orientations expanding )
{
    d_data->expanding = expanding;
}

/*!
  \brief Returns whether this layout can make use of more space than sizeHint().

  A value of Qt::Vertical or Qt::Horizontal means that it wants to grow in only
  one dimension, while Qt::Vertical | Qt::Horizontal means that it wants
  to grow in both dimensions.

  \return Orientations, where the layout expands
  \sa setExpandingDirections()
*/
Qt::Orientations QwtDynGridLayout::expandingDirections() const
{
    return d_data->expanding;
}

/*!
  Reorganizes columns and rows and resizes managed items within
  a rectangle.

  \param rect Layout geometry
*/
void QwtDynGridLayout::setGeometry( const QRect &rect )
{
    QLayout::setGeometry( rect );

    if ( isEmpty() )
        return;

    d_data->numColumns = columnsForWidth( rect.width() );
    d_data->numRows = itemCount() / d_data->numColumns;
    if ( itemCount() % d_data->numColumns )
        d_data->numRows++;

    QList<QRect> itemGeometries = layoutItems( rect, d_data->numColumns );

    int index = 0;
    for ( QList<QLayoutItem*>::iterator it = d_data->itemList.begin();
        it != d_data->itemList.end(); ++it )
    {
        ( *it )->setGeometry( itemGeometries[index] );
        index++;
    }
}

/*!
  \brief Calculate the number of columns for a given width. 

  The calculation tries to use as many columns as possible 
  ( limited by maxColumns() )

  \param width Available width for all columns
  \return Number of columns for a given width

  \sa maxColumns(), setMaxColumns()
*/
uint QwtDynGridLayout::columnsForWidth( int width ) const
{
    if ( isEmpty() )
        return 0;

    uint maxColumns = itemCount();
    if ( d_data->maxColumns > 0 ) 
        maxColumns = qMin( d_data->maxColumns, maxColumns );

    if ( maxRowWidth( maxColumns ) <= width )
        return maxColumns;

    for ( uint numColumns = 2; numColumns <= maxColumns; numColumns++ )
    {
        const int rowWidth = maxRowWidth( numColumns );
        if ( rowWidth > width )
            return numColumns - 1;
    }

    return 1; // At least 1 column
}

/*!
  Calculate the width of a layout for a given number of
  columns.

  \param numColumns Given number of columns
  \param itemWidth Array of the width hints for all items
*/
int QwtDynGridLayout::maxRowWidth( int numColumns ) const
{
    int col;

    QVector<int> colWidth( numColumns );
    for ( col = 0; col < numColumns; col++ )
        colWidth[col] = 0;

    if ( d_data->isDirty )
        d_data->updateLayoutCache();

    for ( int index = 0;
        index < d_data->itemSizeHints.count(); index++ )
    {
        col = index % numColumns;
        colWidth[col] = qMax( colWidth[col],
            d_data->itemSizeHints[int( index )].width() );
    }

    int rowWidth = 2 * margin() + ( numColumns - 1 ) * spacing();
    for ( col = 0; col < numColumns; col++ )
        rowWidth += colWidth[col];

    return rowWidth;
}

/*!
  \return the maximum width of all layout items
*/
int QwtDynGridLayout::maxItemWidth() const
{
    if ( isEmpty() )
        return 0;

    if ( d_data->isDirty )
        d_data->updateLayoutCache();

    int w = 0;
    for ( int i = 0; i < d_data->itemSizeHints.count(); i++ )
    {
        const int itemW = d_data->itemSizeHints[i].width();
        if ( itemW > w )
            w = itemW;
    }

    return w;
}

/*!
  Calculate the geometries of the layout items for a layout
  with numColumns columns and a given rectangle.

  \param rect Rect where to place the items
  \param numColumns Number of columns
  \return item geometries
*/

QList<QRect> QwtDynGridLayout::layoutItems( const QRect &rect,
    uint numColumns ) const
{
    QList<QRect> itemGeometries;
    if ( numColumns == 0 || isEmpty() )
        return itemGeometries;

    uint numRows = itemCount() / numColumns;
    if ( numColumns % itemCount() )
        numRows++;

    if ( numRows == 0 )
        return itemGeometries;

    QVector<int> rowHeight( numRows );
    QVector<int> colWidth( numColumns );

    layoutGrid( numColumns, rowHeight, colWidth );

    bool expandH, expandV;
    expandH = expandingDirections() & Qt::Horizontal;
    expandV = expandingDirections() & Qt::Vertical;

    if ( expandH || expandV )
        stretchGrid( rect, numColumns, rowHeight, colWidth );

    const int maxColumns = d_data->maxColumns;
    d_data->maxColumns = numColumns;
    const QRect alignedRect = alignmentRect( rect );
    d_data->maxColumns = maxColumns;

    const int xOffset = expandH ? 0 : alignedRect.x();
    const int yOffset = expandV ? 0 : alignedRect.y();

    QVector<int> colX( numColumns );
    QVector<int> rowY( numRows );

    const int xySpace = spacing();

    rowY[0] = yOffset + margin();
    for ( uint r = 1; r < numRows; r++ )
        rowY[r] = rowY[r-1] + rowHeight[r-1] + xySpace;

    colX[0] = xOffset + margin();
    for ( uint c = 1; c < numColumns; c++ )
        colX[c] = colX[c-1] + colWidth[c-1] + xySpace;

    const int itemCount = d_data->itemList.size();
    for ( int i = 0; i < itemCount; i++ )
    {
        const int row = i / numColumns;
        const int col = i % numColumns;

        QRect itemGeometry( colX[col], rowY[row],
            colWidth[col], rowHeight[row] );
        itemGeometries.append( itemGeometry );
    }

    return itemGeometries;
}


/*!
  Calculate the dimensions for the columns and rows for a grid
  of numColumns columns.

  \param numColumns Number of columns.
  \param rowHeight Array where to fill in the calculated row heights.
  \param colWidth Array where to fill in the calculated column widths.
*/

void QwtDynGridLayout::layoutGrid( uint numColumns,
    QVector<int>& rowHeight, QVector<int>& colWidth ) const
{
    if ( numColumns <= 0 )
        return;

    if ( d_data->isDirty )
        d_data->updateLayoutCache();

    for ( int index = 0; index < d_data->itemSizeHints.count(); index++ )
    {
        const int row = index / numColumns;
        const int col = index % numColumns;

        const QSize &size = d_data->itemSizeHints[int( index )];

        rowHeight[row] = ( col == 0 )
            ? size.height() : qMax( rowHeight[row], size.height() );
        colWidth[col] = ( row == 0 )
            ? size.width() : qMax( colWidth[col], size.width() );
    }
}

/*!
  \return true: QwtDynGridLayout implements heightForWidth().
  \sa heightForWidth()
*/
bool QwtDynGridLayout::hasHeightForWidth() const
{
    return true;
}

/*!
  \return The preferred height for this layout, given a width.
  \sa hasHeightForWidth()
*/
int QwtDynGridLayout::heightForWidth( int width ) const
{
    if ( isEmpty() )
        return 0;

    const uint numColumns = columnsForWidth( width );
    uint numRows = itemCount() / numColumns;
    if ( itemCount() % numColumns )
        numRows++;

    QVector<int> rowHeight( numRows );
    QVector<int> colWidth( numColumns );

    layoutGrid( numColumns, rowHeight, colWidth );

    int h = 2 * margin() + ( numRows - 1 ) * spacing();
    for ( uint row = 0; row < numRows; row++ )
        h += rowHeight[row];

    return h;
}

/*!
  Stretch columns in case of expanding() & QSizePolicy::Horizontal and
  rows in case of expanding() & QSizePolicy::Vertical to fill the entire
  rect. Rows and columns are stretched with the same factor.

  \param rect Bounding rectangle
  \param numColumns Number of columns
  \param rowHeight Array to be filled with the calculated row heights
  \param colWidth Array to be filled with the calculated column widths

  \sa setExpanding(), expanding()
*/
void QwtDynGridLayout::stretchGrid( const QRect &rect,
    uint numColumns, QVector<int>& rowHeight, QVector<int>& colWidth ) const
{
    if ( numColumns == 0 || isEmpty() )
        return;

    bool expandH, expandV;
    expandH = expandingDirections() & Qt::Horizontal;
    expandV = expandingDirections() & Qt::Vertical;

    if ( expandH )
    {
        int xDelta = rect.width() - 2 * margin() - ( numColumns - 1 ) * spacing();
        for ( uint col = 0; col < numColumns; col++ )
            xDelta -= colWidth[col];

        if ( xDelta > 0 )
        {
            for ( uint col = 0; col < numColumns; col++ )
            {
                const int space = xDelta / ( numColumns - col );
                colWidth[col] += space;
                xDelta -= space;
            }
        }
    }

    if ( expandV )
    {
        uint numRows = itemCount() / numColumns;
        if ( itemCount() % numColumns )
            numRows++;

        int yDelta = rect.height() - 2 * margin() - ( numRows - 1 ) * spacing();
        for ( uint row = 0; row < numRows; row++ )
            yDelta -= rowHeight[row];

        if ( yDelta > 0 )
        {
            for ( uint row = 0; row < numRows; row++ )
            {
                const int space = yDelta / ( numRows - row );
                rowHeight[row] += space;
                yDelta -= space;
            }
        }
    }
}

/*!
   Return the size hint. If maxColumns() > 0 it is the size for
   a grid with maxColumns() columns, otherwise it is the size for
   a grid with only one row.

   \return Size hint
   \sa maxColumns(), setMaxColumns()
*/
QSize QwtDynGridLayout::sizeHint() const
{
    if ( isEmpty() )
        return QSize();

    uint numColumns = itemCount();
    if ( d_data->maxColumns > 0 )
        numColumns = qMin( d_data->maxColumns, numColumns );

    uint numRows = itemCount() / numColumns;
    if ( itemCount() % numColumns )
        numRows++;

    QVector<int> rowHeight( numRows );
    QVector<int> colWidth( numColumns );

    layoutGrid( numColumns, rowHeight, colWidth );

    int h = 2 * margin() + ( numRows - 1 ) * spacing();
    for ( uint row = 0; row < numRows; row++ )
        h += rowHeight[row];

    int w = 2 * margin() + ( numColumns - 1 ) * spacing();
    for ( uint col = 0; col < numColumns; col++ )
        w += colWidth[col];

    return QSize( w, h );
}

/*!
  \return Number of rows of the current layout.
  \sa numColumns()
  \warning The number of rows might change whenever the geometry changes
*/
uint QwtDynGridLayout::numRows() const
{
    return d_data->numRows;
}

/*!
  \return Number of columns of the current layout.
  \sa numRows()
  \warning The number of columns might change whenever the geometry changes
*/
uint QwtDynGridLayout::numColumns() const
{
    return d_data->numColumns;
}