QGridView Class

Qt 3.0.5

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QGridView Class Reference

The QGridView class provides an abstract base for fixed-size grids. More...

#include <qgridview.h>

Inherits QScrollView.

List of all member functions.

Public Members

QGridView ( QWidget * parent = 0, const char * name = 0, WFlags f = 0 )
~QGridView ()
int numRows () const
virtual void setNumRows ( int )
int numCols () const
virtual void setNumCols ( int )
int cellWidth () const
virtual void setCellWidth ( int )
int cellHeight () const
virtual void setCellHeight ( int )
QRect cellRect () const
QRect cellGeometry ( int row, int column )
QSize gridSize () const
int rowAt ( int y ) const
int columnAt ( int x ) const
void repaintCell ( int row, int column, bool erase = TRUE )
void updateCell ( int row, int column )
void ensureCellVisible ( int row, int column )

Properties

int cellHeight - the height of a grid row
int cellWidth - the width of a grid column
int numCols - the number of columns in the grid
int numRows - the number of rows in the grid

Protected Members

virtual void paintCell ( QPainter * p, int row, int col ) = 0
virtual void paintEmptyArea ( QPainter * p, int cx, int cy, int cw, int ch )
virtual void dimensionChange ( int oldNumRows, int oldNumCols )

Detailed Description

The QGridView class provides an abstract base for fixed-size grids.

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 numRows, numCols, cellWidth and cellHeight. Reimplement the pure virtual function paintCell() to draw the content 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, 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 in 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.

Member Function Documentation

QGridView::QGridView ( QWidget * parent = 0, const char * name = 0, WFlags f = 0 )

Constructs a grid view.

The parent, name and widget flag, f, arguments are passed to the QScrollView constructor.

QGridView::~QGridView ()

Destroys the grid view.

QRect QGridView::cellGeometry ( int row, int column )

Returns the geometry of cell (row, column) in the content coordinate system.

int QGridView::cellHeight () const

Returns the height of a grid row. See the "cellHeight" property for details.

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() ).

int QGridView::cellWidth () const

Returns the width of a grid column. See the "cellWidth" property for details.

int QGridView::columnAt ( int x ) const

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

void QGridView::dimensionChange ( int oldNumRows, int oldNumCols ) `[virtual protected]`

This change handler is called whenever any of the grid's dimensions changes. oldNumRows and oldNumCols contain the old dimensions, numRows() and numCols() contain the new dimensions.

void QGridView::ensureCellVisible ( int row, int column )

Ensure cell (row, column) is visible, scrolling the grid view if necessary.

QSize QGridView::gridSize () const

Returns the size of the grid in pixels.

int QGridView::numCols () const

Returns the number of columns in the grid. See the "numCols" property for details.

int QGridView::numRows () const

Returns the number of rows in the grid. See the "numRows" property for details.

void QGridView::paintCell ( QPainter * p, int row, int col ) `[pure virtual protected]`

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

The coordinate system is translated so that the origin is at the top-left corner of the cell to be painted, i.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

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

void QGridView::paintEmptyArea ( QPainter * p, int cx, int cy, int cw, int ch ) `[virtual protected]`

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

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

void QGridView::repaintCell ( int row, int column, bool erase = TRUE )

Repaints cell (row, column).

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

int QGridView::rowAt ( int y ) const

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

void QGridView::setCellHeight ( int ) `[virtual]`

Sets the height of a grid row. See the "cellHeight" property for details.

void QGridView::setCellWidth ( int ) `[virtual]`

Sets the width of a grid column. See the "cellWidth" property for details.

void QGridView::setNumCols ( int ) `[virtual]`

Sets the number of columns in the grid. See the "numCols" property for details.

void QGridView::setNumRows ( int ) `[virtual]`

Sets the number of rows in the grid. See the "numRows" property for details.

void QGridView::updateCell ( int row, int column )

Updates cell (row, column).

Property Documentation

int cellHeight

This property holds the height of a grid row.

All rows in a grid view have the same height.

int cellWidth

This property holds the width of a grid column.

All columns in a grid view have the same width.

int numCols

This property holds the number of columns in the grid.

Set this property's value with setNumCols() and get this property's value with numCols().

int numRows

This property holds the number of rows in the grid.

Set this property's value with setNumRows() and get this property's value with numRows().