qwt_dyngrid_layout.cpp

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/* -*- 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*>::const_iterator it = itemList.constBegin();
        it != itemList.constEnd(); ++it, index++ )
    {
        itemSizeHints[ index ] = ( *it )->sizeHint();
    }

    isDirty = false;
}

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

    setSpacing( spacing );
    setMargin( margin );
}

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

void QwtDynGridLayout::init()
{
    d_data = new QwtDynGridLayout::PrivateData;
    d_data->maxColumns = d_data->numRows = d_data->numColumns = 0;
    d_data->expanding = 0;
}


QwtDynGridLayout::~QwtDynGridLayout()
{
    qDeleteAll( d_data->itemList );
    delete d_data;
}

void QwtDynGridLayout::invalidate()
{
    d_data->isDirty = true;
    QLayout::invalidate();
}

void QwtDynGridLayout::setMaxColumns( uint maxColumns )
{
    d_data->maxColumns = maxColumns;
}

uint QwtDynGridLayout::maxColumns() const
{
    return d_data->maxColumns;
}

void QwtDynGridLayout::addItem( QLayoutItem *item )
{
    d_data->itemList.append( item );
    invalidate();
}

bool QwtDynGridLayout::isEmpty() const
{
    return d_data->itemList.isEmpty();
}

uint QwtDynGridLayout::itemCount() const
{
    return d_data->itemList.count();
}

QLayoutItem *QwtDynGridLayout::itemAt( int index ) const
{
    if ( index < 0 || index >= d_data->itemList.count() )
        return NULL;

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

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 );
}

int QwtDynGridLayout::count() const
{
    return d_data->itemList.count();
}

void QwtDynGridLayout::setExpandingDirections( Qt::Orientations expanding )
{
    d_data->expanding = expanding;
}

Qt::Orientations QwtDynGridLayout::expandingDirections() const
{
    return d_data->expanding;
}

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++;

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

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

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
}

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;
}

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;
}

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();
#if QT_VERSION >= 0x040700
    itemGeometries.reserve( itemCount );
#endif

    for ( int i = 0; i < itemCount; i++ )
    {
        const int row = i / numColumns;
        const int col = i % numColumns;

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

    return itemGeometries;
}


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() );
    }
}

bool QwtDynGridLayout::hasHeightForWidth() const
{
    return true;
}

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;
}

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;
            }
        }
    }
}

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 );
}

uint QwtDynGridLayout::numRows() const
{
    return d_data->numRows;
}

uint QwtDynGridLayout::numColumns() const
{
    return d_data->numColumns;
}