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Q3GridView Class Reference
[Qt3Support module]

The Q3GridView class provides an abstract base for fixed-size grids. More...

 #include <Q3GridView>

This class is part of the Qt 3 support library. It is provided to keep old source code working. We strongly advise against using it in new code. See Porting to Qt 4 for more information.

Inherits Q3ScrollView.


Public Functions

Protected Functions

Additional Inherited Members

Detailed Description

The Q3GridView 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 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).

Q3GridView is a very simple abstract class based on Q3ScrollView. 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 Q3Table instead. If you need a simple list of items, use a Q3ListBox. If you need to present hierachical data use a Q3ListView, and if you need random objects at random positions, consider using either a Q3IconView or a Q3Canvas.

Property Documentation

cellHeight : int

This property holds the height of a grid row.

All rows in a grid view have the same height.

Access functions:

See also cellWidth.

cellWidth : int

This property holds the width of a grid column.

All columns in a grid view have the same width.

Access functions:

See also cellHeight.

numCols : int

This property holds the number of columns in the grid.

Access functions:

See also numRows.

numRows : int

This property holds the number of rows in the grid.

Access functions:

See also numCols.

Member Function Documentation

Q3GridView::Q3GridView ( QWidget * parent = 0, const char * name = 0, Qt::WindowFlags f = 0 )

Constructs a grid view.

The parent, name and widget flag, f, arguments are passed to the Q3ScrollView constructor.

Q3GridView::~Q3GridView ()

Destroys the grid view.

QRect Q3GridView::cellGeometry ( int row, int column )

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

See also cellRect().

QRect Q3GridView::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()).

See also cellGeometry().

int Q3GridView::columnAt ( int x ) const

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

See also rowAt().

void Q3GridView::dimensionChange ( int oldNumRows, int oldNumCols )   [virtual protected]

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

void Q3GridView::ensureCellVisible ( int row, int column )

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

QSize Q3GridView::gridSize () const

Returns the size of the grid in pixels.

void Q3GridView::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

void Q3GridView::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 Q3GridView::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.

See also QWidget::repaint().

int Q3GridView::rowAt ( int y ) const

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

See also columnAt().

void Q3GridView::updateCell ( int row, int column )

Updates cell (row, column).

See also QWidget::update().

Copyright © 2008 Trolltech Trademarks
Qt 4.3.5