#include <qwt_plot_rasteritem.h>

Inheritance diagram for QwtPlotRasterItem:

Public Types
enum	CachePolicy { NoCache, PaintCache, ScreenCache }
Public Types inherited from QwtPlotItem
enum	ItemAttribute { Legend = 1, AutoScale = 2 }
enum	RenderHint { RenderAntialiased = 1 }
enum	RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG, Rtti_PlotUserItem = 1000 }

Public Member Functions
	QwtPlotRasterItem (const QString &title=QString::null)
	QwtPlotRasterItem (const QwtText &title)
virtual	~QwtPlotRasterItem ()
int	alpha () const
CachePolicy	cachePolicy () const
virtual void	draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &rect) const
void	invalidateCache ()
virtual QSize	rasterHint (const QwtDoubleRect &) const
void	setAlpha (int alpha)
void	setCachePolicy (CachePolicy)
Public Member Functions inherited from QwtPlotItem
	QwtPlotItem (const QwtText &title=QwtText())
virtual	~QwtPlotItem ()
void	attach (QwtPlot *plot)
virtual QwtDoubleRect	boundingRect () const
void	detach ()
void	hide ()
QwtDoubleRect	invTransform (const QwtScaleMap &, const QwtScaleMap &, const QRect &) const
bool	isVisible () const
virtual void	itemChanged ()
virtual QWidget *	legendItem () const
QRect	paintRect (const QwtScaleMap &, const QwtScaleMap &) const
QwtPlot *	plot () const
virtual int	rtti () const
QwtDoubleRect	scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
void	setAxis (int xAxis, int yAxis)
void	setItemAttribute (ItemAttribute, bool on=true)
void	setRenderHint (RenderHint, bool on=true)
void	setTitle (const QString &title)
void	setTitle (const QwtText &title)
virtual void	setVisible (bool)
void	setXAxis (int axis)
void	setYAxis (int axis)
void	setZ (double z)
void	show ()
bool	testItemAttribute (ItemAttribute) const
bool	testRenderHint (RenderHint) const
const QwtText &	title () const
QRect	transform (const QwtScaleMap &, const QwtScaleMap &, const QwtDoubleRect &) const
virtual void	updateLegend (QwtLegend *) const
virtual void	updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
int	xAxis () const
int	yAxis () const
double	z () const
Public Member Functions inherited from QwtLegendItemManager
	QwtLegendItemManager ()
virtual	~QwtLegendItemManager ()

Protected Member Functions
virtual QImage	renderImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtDoubleRect &area) const =0

Detailed Description

A class, which displays raster data.

Raster data is a grid of pixel values, that can be represented as a QImage. It is used for many types of information like spectrograms, cartograms, geographical maps ...

Often a plot has several types of raster data organized in layers. ( f.e a geographical map, with weather statistics ). Using setAlpha() raster items can be stacked easily.

QwtPlotRasterItem is only implemented for images of the following formats: QImage::Format_Indexed8, QImage::Format_ARGB32.

See also:: QwtPlotSpectrogram

Member Enumeration Documentation

enum QwtPlotRasterItem::CachePolicy

NoCache
renderImage() is called, whenever the item has to be repainted
PaintCache
renderImage() is called, whenever the image cache is not valid, or the scales, or the size of the canvas has changed. This type of cache is only useful for improving the performance of hide/show operations. All other situations are already handled by the plot canvas cache.
ScreenCache
The screen cache is an image in size of the screen. As long as the scales don't change the target image is scaled from the cache. This might improve the performance when resizing the plot widget, but suffers from scaling effects.

The default policy is NoCache

Member Function Documentation

int QwtPlotRasterItem::alpha ( ) const

Returns:: Alpha value of the raster item

See also:: setAlpha()

QwtPlotRasterItem::CachePolicy QwtPlotRasterItem::cachePolicy ( ) const

Returns:: Cache policy

See also:: CachePolicy, setCachePolicy()

void QwtPlotRasterItem::draw	(	QPainter *	painter,
		const QwtScaleMap &	xMap,
		const QwtScaleMap &	yMap,
		const QRect &	canvasRect
	)		const

virtual

Draw the raster data.

Parameters:

painter	Painter
xMap	X-Scale Map
yMap	Y-Scale Map
canvasRect	Contents rect of the plot canvas

Implements QwtPlotItem.

Reimplemented in QwtPlotSpectrogram.

void QwtPlotRasterItem::invalidateCache ( )

Invalidate the paint cache

See also:: setCachePolicy()

QSize QwtPlotRasterItem::rasterHint ( const QwtDoubleRect & ) const

virtual

Returns the recommended raster for a given rect.

F.e the raster hint can be used to limit the resolution of the image that is rendered.

The default implementation returns an invalid size (QSize()), what means: no hint.

Reimplemented in QwtPlotSpectrogram.

virtual QImage QwtPlotRasterItem::renderImage	(	const QwtScaleMap &	xMap,
		const QwtScaleMap &	yMap,
		const QwtDoubleRect &	area
	)		const

protectedpure virtual

Renders an image for an area

The format of the image must be QImage::Format_Indexed8, QImage::Format_RGB32 or QImage::Format_ARGB32

Parameters:

xMap	Maps x-values into pixel coordinates.
yMap	Maps y-values into pixel coordinates.
area	Requested area for the image in scale coordinates

Implemented in QwtPlotSpectrogram.

void QwtPlotRasterItem::setAlpha ( int alpha )

Set an alpha value for the raster data.

Often a plot has several types of raster data organized in layers. ( f.e a geographical map, with weather statistics ). Using setAlpha() raster items can be stacked easily.

The alpha value is a value [0, 255] to control the transparency of the image. 0 represents a fully transparent color, while 255 represents a fully opaque color.

Parameters:

alpha Alpha value

alpha >= 0
All alpha values of the pixels returned by renderImage() will be set to alpha, beside those with an alpha value of 0 (invalid pixels).
alpha < 0 The alpha values returned by renderImage() are not changed.

The default alpha value is -1.

See also:: alpha()

void QwtPlotRasterItem::setCachePolicy ( QwtPlotRasterItem::CachePolicy policy )

Change the cache policy

The default policy is NoCache

Parameters:

policy Cache policy

See also:: CachePolicy, cachePolicy()

Public Types

Public Member Functions

Protected Member Functions

Detailed Description

Member Enumeration Documentation

Member Function Documentation