Qwt User's Guide  6.1.3
QwtNullPaintDevice Class Referenceabstract

A null paint device doing nothing. More...

#include <qwt_null_paintdevice.h>

Inheritance diagram for QwtNullPaintDevice:

Public Types

enum  Mode { NormalMode, PolygonPathMode, PathMode }
 Render mode. More...

Public Member Functions

 QwtNullPaintDevice ()
virtual ~QwtNullPaintDevice ()
void setMode (Mode)
Mode mode () const
virtual QPaintEngine * paintEngine () const
 See QPaintDevice::paintEngine()
virtual int metric (PaintDeviceMetric metric) const
virtual void drawRects (const QRect *, int)
 See QPaintEngine::drawRects()
virtual void drawRects (const QRectF *, int)
 See QPaintEngine::drawRects()
virtual void drawLines (const QLine *, int)
 See QPaintEngine::drawLines()
virtual void drawLines (const QLineF *, int)
 See QPaintEngine::drawLines()
virtual void drawEllipse (const QRectF &)
 See QPaintEngine::drawEllipse()
virtual void drawEllipse (const QRect &)
 See QPaintEngine::drawEllipse()
virtual void drawPath (const QPainterPath &)
 See QPaintEngine::drawPath()
virtual void drawPoints (const QPointF *, int)
 See QPaintEngine::drawPoints()
virtual void drawPoints (const QPoint *, int)
 See QPaintEngine::drawPoints()
virtual void drawPolygon (const QPointF *, int, QPaintEngine::PolygonDrawMode)
 See QPaintEngine::drawPolygon()
virtual void drawPolygon (const QPoint *, int, QPaintEngine::PolygonDrawMode)
 See QPaintEngine::drawPolygon()
virtual void drawPixmap (const QRectF &, const QPixmap &, const QRectF &)
 See QPaintEngine::drawPixmap()
virtual void drawTextItem (const QPointF &, const QTextItem &)
 See QPaintEngine::drawTextItem()
virtual void drawTiledPixmap (const QRectF &, const QPixmap &, const QPointF &s)
 See QPaintEngine::drawTiledPixmap()
virtual void drawImage (const QRectF &, const QImage &, const QRectF &, Qt::ImageConversionFlags)
 See QPaintEngine::drawImage()
virtual void updateState (const QPaintEngineState &state)
 See QPaintEngine::updateState()

Protected Member Functions

virtual QSize sizeMetrics () const =0

Detailed Description

A null paint device doing nothing.

Sometimes important layout/rendering geometries are not available or changeable from the public Qt class interface. ( f.e hidden in the style implementation ).

QwtNullPaintDevice can be used to manipulate or filter out this information by analyzing the stream of paint primitives.

F.e. QwtNullPaintDevice is used by QwtPlotCanvas to identify styled backgrounds with rounded corners.

Member Enumeration Documentation

Render mode.

See also
setMode(), mode()

All vector graphic primitives are painted by the corresponding draw methods


Vector graphic primitives ( beside polygons ) are mapped to a QPainterPath and are painted by drawPath. In PathMode mode only a few draw methods are called:


Vector graphic primitives are mapped to a QPainterPath and are painted by drawPath. In PathMode mode only a few draw methods are called:

Member Function Documentation

int QwtNullPaintDevice::metric ( PaintDeviceMetric  deviceMetric) const

See QPaintDevice::metric()

deviceMetricType of metric
Metric information for the given paint device metric.
See also
QwtNullPaintDevice::Mode QwtNullPaintDevice::mode ( ) const
Render mode
See also
void QwtNullPaintDevice::setMode ( Mode  mode)

Set the render mode

modeNew mode
See also
virtual QSize QwtNullPaintDevice::sizeMetrics ( ) const
protectedpure virtual
Size needed to implement metric()

Implemented in QwtGraphic.