source: vendor/trolltech/current/src/widgets/qgridview.cpp

/****************************************************************************
** $Id: qgridview.cpp 2 2005-11-16 15:49:26Z dmik $
**
** Implementation of QGridView class
**
** Created : 010523
**
** Copyright (C) 1992-2001 Trolltech AS.  All rights reserved.
**
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** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
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**********************************************************************/


#include "qgridview.h"

#ifndef QT_NO_GRIDVIEW

#include "qpainter.h"

/*!
    \class QGridView qgridview.h
    \brief The QGridView class provides an abstract base for
    fixed-size grids.

    \ingroup abstractwidgets

    A grid view consists of a number of abstract cells organized in
    rows and columns. The cells have a fixed size and are identified
    with a row index and a column index. The top-left cell is in row
    0, column 0. The bottom-right cell is in row numRows()-1, column
    numCols()-1.

    You can define \l numRows, \l numCols, \l cellWidth and \l
    cellHeight. Reimplement the pure virtual function paintCell() to
    draw the contents of a cell.

    With ensureCellVisible(), you can ensure a certain cell is
    visible. With rowAt() and columnAt() you can find a cell based on
    the given x- and y-coordinates.

    If you need to monitor changes to the grid's dimensions (i.e. when
    numRows or numCols is changed), reimplement the dimensionChange()
    change handler.

    Note: the row and column indices are always given in the order,
    row (vertical offset) then column (horizontal offset). This order
    is the opposite of all pixel operations, which are given in the
    order x (horizontal offset), y (vertical offset).

    QGridView is a very simple abstract class based on QScrollView. It
    is designed to simplify the task of drawing many cells of the same
    size in a potentially scrollable canvas. If you need rows and
    columns with different sizes, use a QTable instead. If you need a
    simple list of items, use a QListBox. If you need to present
    hierachical data use a QListView, and if you need random objects
    at random positions, consider using either a QIconView or a
    QCanvas.
*/


/*!
    Constructs a grid view.

    The \a parent, \a name and widget flag, \a f, arguments are passed
    to the QScrollView constructor.
*/
QGridView::QGridView( QWidget *parent, const char *name, WFlags f )
    :QScrollView( parent, name, f | WStaticContents ),
     nrows( 5 ), ncols( 5 ), cellw( 12 ), cellh( 12 )
{
    viewport()->setBackgroundMode( PaletteBase );
    setBackgroundMode( PaletteBackground, PaletteBase );
    viewport()->setFocusProxy( this );
}

/*!
    Destroys the grid view.
*/
QGridView::~QGridView()
{
}

void QGridView::updateGrid()
{
    resizeContents( ncols * cellw, nrows * cellh );
}

/*!
    \property QGridView::numRows
    \brief The number of rows in the grid

    \sa numCols
*/
void QGridView::setNumRows( int numRows )
{
    int oldnrows = nrows;
    nrows = numRows;
    dimensionChange( oldnrows, ncols );
    updateGrid();
}

/*!
    \property QGridView::numCols
    \brief The number of columns in the grid

    \sa numRows
*/
void QGridView::setNumCols( int numCols )
{
    int oldncols = ncols;
    ncols = numCols;
    dimensionChange( nrows, oldncols );
    updateGrid();
}

/*!
    \property QGridView::cellWidth
    \brief The width of a grid column

    All columns in a grid view have the same width.

    \sa cellHeight
*/
void QGridView::setCellWidth( int cellWidth )
{
    cellw = cellWidth;
    updateGrid();
    updateContents();
}

/*!
    \property QGridView::cellHeight
    \brief The height of a grid row

    All rows in a grid view have the same height.

    \sa cellWidth
*/
void QGridView::setCellHeight( int cellHeight )
{
    cellh = cellHeight;
    updateGrid();
    updateContents();
}

/*!
    Returns the geometry of cell (\a row, \a column) in the content
    coordinate system.

    \sa cellRect()
 */
QRect QGridView::cellGeometry( int row, int column )
{
    QRect r;
    if ( row >= 0 && row < nrows && column >= 0 && column < ncols )
        r.setRect( cellw * column, cellh * row, cellw, cellh );
    return r;
}

/*!
    Repaints cell (\a row, \a column).

    If \a erase is TRUE, Qt erases the area of the cell before the
    paintCell() call; otherwise no erasing takes place.

    \sa QWidget::repaint()
*/
void QGridView::repaintCell( int row, int column, bool erase )
{
    repaintContents( cellGeometry( row, column ), erase );
}

/*!
    Updates cell (\a row, \a column).

    \sa QWidget::update()
*/
void QGridView::updateCell( int row, int column )
{
    updateContents( cellGeometry( row, column ) );
}

/*!
    Ensures cell (\a row, \a column) is visible, scrolling the grid
    view if necessary.
*/
void QGridView::ensureCellVisible( int row, int column )
{
    QRect r = cellGeometry( row, column );
    ensureVisible( r.x(), r.y(), r.width(), r.height() );
}

/*!
    This function fills the \a cw pixels wide and \a ch pixels high
    rectangle starting at position (\a cx, \a cy) with the background
    color using the painter \a p.

    paintEmptyArea() is invoked by drawContents() to erase or fill
    unused areas.
*/

void QGridView::paintEmptyArea( QPainter *p, int cx ,int cy, int cw, int ch)
{
    if ( gridSize().width() >= contentsWidth() && gridSize().height() >= contentsHeight() )
        return;
    // Region of the rect we should draw
    contentsToViewport( cx, cy, cx, cy );
    QRegion reg( QRect( cx, cy, cw, ch ) );
    // Subtract the table from it
    reg = reg.subtract( QRect( contentsToViewport( QPoint( 0, 0 ) ), gridSize() ) );

    // And draw the rectangles (transformed as needed)
    QMemArray<QRect> r = reg.rects();
    const QBrush &brush = backgroundBrush();
    for ( int i = 0; i < (int)r.count(); ++i)
        p->fillRect( r[ i ], brush );
}

/*!\reimp
 */
void QGridView::drawContents( QPainter *p, int cx, int cy, int cw, int ch )
{
    int colfirst = columnAt( cx );
    int collast = columnAt( cx + cw );
    int rowfirst = rowAt( cy );
    int rowlast = rowAt( cy + ch );

    if ( rowfirst == -1 || colfirst == -1 ) {
        paintEmptyArea( p, cx, cy, cw, ch );
        return;
    }

    if ( collast < 0 || collast >= ncols )
        collast = ncols-1;
    if ( rowlast < 0 || rowlast >= nrows )
        rowlast = nrows-1;

    // Go through the rows
    for ( int r = rowfirst; r <= rowlast; ++r ) {
        // get row position and height
        int rowp = r * cellh;

        // Go through the columns in the row r
        // if we know from where to where, go through [colfirst, collast],
        // else go through all of them
        for ( int c = colfirst; c <= collast; ++c ) {
            // get position and width of column c
            int colp = c * cellw;
            // Translate painter and draw the cell
            p->translate( colp, rowp );
            paintCell( p, r, c );
            p->translate( -colp, -rowp );
        }
    }

    // Paint empty rects
    paintEmptyArea( p, cx, cy, cw, ch );
}

/*!
    \reimp

    (Implemented to get rid of a compiler warning.)
*/
void QGridView::drawContents( QPainter * )
{
}

/*!
    \fn void QGridView::dimensionChange( int oldNumRows, int oldNumCols )

    This change handler is called whenever any of the grid's
    dimensions change. \a oldNumRows and \a oldNumCols contain the
    old dimensions, numRows() and numCols() contain the new
    dimensions.
*/
void QGridView::dimensionChange( int, int ) {}



/*!
    \fn int QGridView::rowAt( int y ) const

    Returns the number of the row at position \a y. \a y must be given
    in content coordinates.

    \sa columnAt()
*/

/*!
    \fn int QGridView::columnAt( int x ) const

    Returns the number of the column at position \a x. \a x must be
    given in content coordinates.

    \sa rowAt()
*/

/*!
    \fn void QGridView::paintCell( QPainter *p, int row, int col )

    This pure virtual function is called to paint the single cell at
    (\a row, \a col) using painter \a p. The painter must be open when
    paintCell() is called and must remain open.

    The coordinate system is \link QPainter::translate() translated
    \endlink so that the origin is at the top-left corner of the cell
    to be painted, i.e. \e cell coordinates. Do not scale or shear
    the coordinate system (or if you do, restore the transformation
    matrix before you return).

    The painter is not clipped by default in order to get maximum
    efficiency. If you want clipping, use

    \code
    p->setClipRect( cellRect(), QPainter::CoordPainter );
    //... your drawing code
    p->setClipping( FALSE );

    \endcode
*/

/*!
    \fn  QRect QGridView::cellRect() const

    Returns the geometry of a cell in a cell's coordinate system. This
    is a convenience function useful in paintCell(). It is equivalent
    to QRect( 0, 0, cellWidth(), cellHeight() ).

    \sa cellGeometry()

*/

/*!
    \fn  QSize QGridView::gridSize() const

    Returns the size of the grid in pixels.

*/

#endif // QT_NO_GRIDVIEW