A class, which displays raster data 更多...

#include <qwt_plot_rasteritem.h>

类 QwtPlotRasterItem 继承关系图:

类
class	PrivateData

Public 类型
enum	CachePolicy { NoCache , PaintCache }
	Cache policy 更多...

enum	PaintAttribute { PaintInDeviceResolution = 1 }
	Paint attributes 更多...

Public 类型继承自 QwtPlotItem
enum	RttiValues { Rtti_PlotItem = 0 , Rtti_PlotGrid , Rtti_PlotScale , Rtti_PlotLegend , Rtti_PlotMarker , Rtti_PlotCurve , Rtti_PlotSpectroCurve , Rtti_PlotIntervalCurve , Rtti_PlotHistogram , Rtti_PlotSpectrogram , Rtti_PlotGraphic , Rtti_PlotTradingCurve , Rtti_PlotBarChart , Rtti_PlotMultiBarChart , Rtti_PlotShape , Rtti_PlotTextLabel , Rtti_PlotZone , Rtti_PlotVectorField , Rtti_PlotArrowMarker , Rtti_PlotBoxChart , Rtti_PlotUserItem = 1000 }
	Runtime type information 更多...

enum	ItemAttribute { Legend = 0x01 , AutoScale = 0x02 , Margins = 0x04 }
	Plot Item Attributes 更多...

enum	ItemInterest { ScaleInterest = 0x01 , LegendInterest = 0x02 }
	Plot Item Interests 更多...

enum	RenderHint { RenderAntialiased = 0x1 }
	Render hints 更多...

Public 成员函数
	QwtPlotRasterItem (const QString &title=QString())
	Constructor

	QwtPlotRasterItem (const QwtText &title)

void	setPaintAttribute (PaintAttribute, bool on=true)
	Set a paint attribute

bool	testPaintAttribute (PaintAttribute) const
	Test a paint attribute

void	setAlpha (int alpha)
	Set an alpha value for the raster data

int	alpha () const
	Get the alpha value of the raster item

void	setCachePolicy (CachePolicy)
	Change the cache policy

CachePolicy	cachePolicy () const
	Get the cache policy

void	invalidateCache ()
	Invalidate the paint cache

virtual void	draw (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const override
	Draw the raster data

virtual QRectF	pixelHint (const QRectF &) const
	Pixel hint

virtual QwtInterval	interval (Qt::Axis) const
	Get the bounding interval for an axis

virtual QRectF	boundingRect () const override
	Get the bounding rectangle of the data

Public 成员函数继承自 QwtPlotItem
	QwtPlotItem ()
	Default constructor

	QwtPlotItem (const QString &title)
	Constructor with title as QString

	QwtPlotItem (const QwtText &title)
	Constructor with title as QwtText

virtual	~QwtPlotItem ()
	Destructor

virtual void	attach (QwtPlot *plot)
	Attach the item to a plot

void	detach ()
	Detach the item from the plot

QwtPlot *	plot () const
	Get the plot the item is attached to

void	setTitle (const QString &title)
	Set the title using a QString

void	setTitle (const QwtText &title)
	Set the title using a QwtText

const QwtText &	title () const
	Get the title

virtual int	rtti () const
	Runtime type information

void	setItemAttribute (ItemAttribute, bool on=true)
	Set an item attribute

bool	testItemAttribute (ItemAttribute) const
	Test an item attribute

void	setItemInterest (ItemInterest, bool on=true)
	Set an item interest

bool	testItemInterest (ItemInterest) const
	Test an item interest

void	setRenderHint (RenderHint, bool on=true)
	Set a render hint

bool	testRenderHint (RenderHint) const
	Test a render hint

void	setRenderThreadCount (uint numThreads)
	Set the number of render threads

uint	renderThreadCount () const
	Get the number of render threads

void	setLegendIconSize (const QSize &)
	Set the legend icon size

QSize	legendIconSize () const
	Get the legend icon size

double	z () const
	Get the z-value

void	setZ (double z)
	Set the z-value

void	show ()
	Show the item

void	hide ()
	Hide the item

virtual void	setVisible (bool)
	Set the visibility

bool	isVisible () const
	Check if the item is visible

void	setAxes (QwtAxisId xAxis, QwtAxisId yAxis)
	Set both axes

void	setXAxis (QwtAxisId)
	Set the x-axis

QwtAxisId	xAxis () const
	Get the x-axis

void	setYAxis (QwtAxisId)
	Set the y-axis

QwtAxisId	yAxis () const
	Get the y-axis

virtual void	itemChanged ()
	Notify the plot that the item has changed

virtual void	legendChanged ()
	Notify the item that the legend has changed

virtual void	getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, double &left, double &top, double &right, double &bottom) const
	Get margin hints for the canvas

virtual void	updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
	Update the item with new scale divisions

virtual void	updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
	Update the item with changes of the legend

QRectF	scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
	Calculate the scale rectangle

QRectF	paintRect (const QwtScaleMap &, const QwtScaleMap &) const
	Calculate the paint rectangle

virtual QList< QwtLegendData >	legendData () const
	Return legend data

virtual QwtGraphic	legendIcon (int index, const QSizeF &) const
	Return a legend icon

Protected 成员函数
virtual QImage	renderImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &area, const QSize &imageSize) const =0

virtual QwtScaleMap	imageMap (Qt::Orientation, const QwtScaleMap &map, const QRectF &area, const QSize &imageSize, double pixelSize) const
	Get the image map

Protected 成员函数继承自 QwtPlotItem
QwtGraphic	defaultIcon (const QBrush &, const QSizeF &) const
	Create a default icon

详细描述

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. (e.g 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.

参见: QwtPlotSpectrogram

成员枚举类型说明

◆ CachePolicy

enum QwtPlotRasterItem::CachePolicy

Cache policy

The default policy is NoCache

枚举值

NoCache

renderImage() is called each time 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 useful for improving the performance of hide/show operations or manipulations of the alpha value. All other situations are handled by the canvas backing store.

◆ PaintAttribute

enum QwtPlotRasterItem::PaintAttribute

Paint attributes

Attributes to modify the drawing algorithm.

参见: setPaintAttribute(), testPaintAttribute()

枚举值

PaintInDeviceResolution

When the image is rendered according to the data pixels ( QwtRasterData::pixelHint() ) it can be expanded to paint device resolution before it is passed to QPainter. The expansion algorithm rounds the pixel borders in the same way as the axis ticks, what is usually better than the scaling algorithm implemented in Qt. Disabling this flag might make sense, to reduce the size of a document/file. If this is possible for a document format depends on the implementation of the specific QPaintEngine.

构造及析构函数说明

◆ QwtPlotRasterItem()

QwtPlotRasterItem::QwtPlotRasterItem ( const QString & title = QString() )

explicit

Constructor

参数

[in] title Title of the raster item

Constructor with title

参数

[in] title Title of the raster item

Destructor

成员函数说明

◆ alpha()

int QwtPlotRasterItem::alpha ( ) const

Get the alpha value of the raster item

返回: Alpha value of the raster item

参见: setAlpha()

◆ boundingRect()

QRectF QwtPlotRasterItem::boundingRect ( ) const

overridevirtual

Get the bounding rectangle of the data

返回: Bounding rectangle of the data

参见: QwtPlotRasterItem::interval()

重载 QwtPlotItem .

◆ cachePolicy()

QwtPlotRasterItem::CachePolicy QwtPlotRasterItem::cachePolicy ( ) const

Get the cache policy

返回: Cache policy

参见: CachePolicy, setCachePolicy()

◆ draw()

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

overridevirtual

Draw the raster data

参数

[in]	painter	Painter
[in]	xMap	X-Scale Map
[in]	yMap	Y-Scale Map
[in]	canvasRect	Contents rectangle of the plot canvas

实现了 QwtPlotItem.

被 QwtPlotSpectrogram 重载.

◆ imageMap()

QwtScaleMap QwtPlotRasterItem::imageMap	(	Qt::Orientation	orientation,
		const QwtScaleMap &	map,
		const QRectF &	area,
		const QSize &	imageSize,
		double	pixelSize
	)		const

protectedvirtual

Get the image map

Calculate a scale map for painting to an image

参数

orientation	Orientation, Qt::Horizontal means a X axis
map	Scale map for rendering the plot item
area	Area to be painted on the image
imageSize	Image size
pixelSize	Width/Height of a data pixel

返回: Calculated scale map

◆ interval()

QwtInterval QwtPlotRasterItem::interval ( Qt::Axis axis ) const

virtual

Get the bounding interval for an axis

This method is intended to be reimplemented by derived classes. The default implementation returns an invalid interval.

参数

[in] axis X, Y, or Z axis

返回: Bounding interval for an axis

被 QwtPlotSpectrogram 重载.

◆ invalidateCache()

void QwtPlotRasterItem::invalidateCache ( )

Invalidate the paint cache

参见: setCachePolicy()

◆ pixelHint()

QRectF QwtPlotRasterItem::pixelHint ( const QRectF & area ) const

virtual

Pixel hint

The geometry of a pixel is used to calculate the resolution and alignment of the rendered image. Width and height of the hint need to be the horizontal and vertical distances between 2 neighboring points. The center of the hint has to be the position of any point (it doesn't matter which one). Limiting the resolution of the image might significantly improve the performance and heavily reduce the amount of memory when rendering a QImage from the raster data. The default implementation returns an empty rectangle (QRectF()), meaning that the image will be rendered in target device (e.g. screen) resolution.

参数

[in] area In most implementations the resolution of the data doesn't depend on the requested area

返回: Bounding rectangle of a pixel

参见: render(), renderImage()

被 QwtPlotSpectrogram 重载.

◆ renderImage()

virtual QImage QwtPlotRasterItem::renderImage	(	const QwtScaleMap &	xMap,
		const QwtScaleMap &	yMap,
		const QRectF &	area,
		const QSize &	imageSize
	)		const

protectedpure virtual

在 QwtPlotSpectrogram 内被实现.

◆ setAlpha()

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. (e.g. 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.

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.
参数

[in] alpha Alpha value

参见
alpha()

◆ setCachePolicy()

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

Change the cache policy

The default policy is NoCache

参数

[in] policy Cache policy

参见: CachePolicy, cachePolicy()

◆ setPaintAttribute()

void QwtPlotRasterItem::setPaintAttribute	(	PaintAttribute	attribute,
		bool	on = `true`
	)

Set a paint attribute

参数

[in]	attribute	Paint attribute
[in]	on	On/Off

参见: PaintAttribute, testPaintAttribute()

◆ testPaintAttribute()

bool QwtPlotRasterItem::testPaintAttribute ( PaintAttribute attribute ) const

Test a paint attribute

参数

[in] attribute Paint attribute

返回: True, when attribute is enabled

参见: PaintAttribute, setPaintAttribute()

该类的文档由以下文件生成:

/home/runner/work/QWT/QWT/src/plot/qwt_plot_rasteritem.h
/home/runner/work/QWT/QWT/src/plot/qwt_plot_rasteritem.cpp

类

Public 类型

Public 成员函数

Protected 成员函数

详细描述

成员枚举类型说明

◆ CachePolicy

◆ PaintAttribute

构造及析构函数说明

◆ QwtPlotRasterItem()

成员函数说明

◆ alpha()

◆ boundingRect()

◆ cachePolicy()

◆ draw()

◆ imageMap()

◆ interval()

◆ invalidateCache()

◆ pixelHint()

◆ renderImage()

◆ setAlpha()

◆ setCachePolicy()

◆ setPaintAttribute()

◆ testPaintAttribute()