qwt_dyngrid_layout.cpp

QWT5.01用于Qt开发的二维图形库程序

  use as many columns as possible (limited by maxCols())

  \param width Available width for all columns
  \sa QwtDynGridLayout::maxCols(), QwtDynGridLayout::setMaxCols()
*/

uint QwtDynGridLayout::columnsForWidth(int width) const
{
    if ( isEmpty() )
        return 0;

    const int maxCols = (d_data->maxCols > 0) ? d_data->maxCols : itemCount();
    if ( maxRowWidth(maxCols) <= width )
        return maxCols;

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

    return 1; // At least 1 column
}

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

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

    QwtArray<int> colWidth(numCols);
    for ( col = 0; col < (int)numCols; col++ )
        colWidth[col] = 0;

    if ( d_data->isDirty )
        ((QwtDynGridLayout*)this)->updateLayoutCache();

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

    int rowWidth = 2 * margin() + (numCols - 1) * spacing();
    for ( col = 0; col < (int)numCols; 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 )
        ((QwtDynGridLayout*)this)->updateLayoutCache();

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

    return w;
}

/*!
  Calculate the geometries of the layout items for a layout
  with numCols columns and a given rect.
  \param rect Rect where to place the items
  \param numCols Number of columns
  \return item geometries
*/

#if QT_VERSION < 0x040000
QValueList<QRect> QwtDynGridLayout::layoutItems(const QRect &rect,
    uint numCols) const
#else
QList<QRect> QwtDynGridLayout::layoutItems(const QRect &rect,
    uint numCols) const
#endif
{
#if QT_VERSION < 0x040000
    QValueList<QRect> itemGeometries;
#else
    QList<QRect> itemGeometries;
#endif
    if ( numCols == 0 || isEmpty() )
        return itemGeometries;

    uint numRows = itemCount() / numCols;
    if ( numRows % itemCount() )
        numRows++;
 
    QwtArray<int> rowHeight(numRows);
    QwtArray<int> colWidth(numCols);
 
    layoutGrid(numCols, rowHeight, colWidth);

    bool expandH, expandV;
#if QT_VERSION >= 0x040000
    expandH = expandingDirections() & Qt::Horizontal;
    expandV = expandingDirections() & Qt::Vertical;
#else
    expandH = expanding() & QSizePolicy::Horizontally;
    expandV = expanding() & QSizePolicy::Vertically;
#endif

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

    QwtDynGridLayout *that = (QwtDynGridLayout *)this;
    const int maxCols = d_data->maxCols;
    that->d_data->maxCols = numCols;
    const QRect alignedRect = alignmentRect(rect);
    that->d_data->maxCols = maxCols;

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

    QwtArray<int> colX(numCols);
    QwtArray<int> rowY(numRows);

    const int xySpace = spacing();

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

    colX[0] = xOffset + margin();
    for ( int c = 1; c < (int)numCols; 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 / numCols;
        const int col = i % numCols;

        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 numCols columns.
  \param numCols 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 numCols, 
    QwtArray<int>& rowHeight, QwtArray<int>& colWidth) const
{
    if ( numCols <= 0 )
        return;

    if ( d_data->isDirty )
        ((QwtDynGridLayout*)this)->updateLayoutCache();

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

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

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

/*!
  \return true: QwtDynGridLayout implements heightForWidth.
  \sa QwtDynGridLayout::heightForWidth()
*/

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

/*!
  \return The preferred height for this layout, given the width w. 
  \sa QwtDynGridLayout::hasHeightForWidth()
*/

int QwtDynGridLayout::heightForWidth(int width) const
{
    if ( isEmpty() )
        return 0;

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

    QwtArray<int> rowHeight(numRows);
    QwtArray<int> colWidth(numCols);

    layoutGrid(numCols, rowHeight, colWidth);

    int h = 2 * margin() + (numRows - 1) * spacing();
    for ( int row = 0; row < (int)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.
  \sa QwtDynGridLayout::setExpanding(), QwtDynGridLayout::expanding()
*/

void QwtDynGridLayout::stretchGrid(const QRect &rect, 
    uint numCols, QwtArray<int>& rowHeight, QwtArray<int>& colWidth) const
{
    if ( numCols == 0 || isEmpty() )
        return;

    bool expandH, expandV;
#if QT_VERSION >= 0x040000
    expandH = expandingDirections() & Qt::Horizontal;
    expandV = expandingDirections() & Qt::Vertical;
#else
    expandH = expanding() & QSizePolicy::Horizontally;
    expandV = expanding() & QSizePolicy::Vertically;
#endif

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

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

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

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

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

/*!
   Return the size hint. If maxCols() > 0 it is the size for
   a grid with maxCols() columns, otherwise it is the size for
   a grid with only one row.
   \sa QwtDynGridLayout::maxCols(), QwtDynGridLayout::setMaxCols()
*/

QSize QwtDynGridLayout::sizeHint() const
{
    if ( isEmpty() )
        return QSize();

    const uint numCols = (d_data->maxCols > 0 ) ? d_data->maxCols : itemCount();
    uint numRows = itemCount() / numCols;
    if ( itemCount() % numCols )
        numRows++;

    QwtArray<int> rowHeight(numRows);
    QwtArray<int> colWidth(numCols);

    layoutGrid(numCols, rowHeight, colWidth);

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

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

    return QSize(w, h);
}

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