QwtRasterData defines an interface to any type of raster data. 更多...

#include <qwt_raster_data.h>

类 QwtRasterData 继承关系图:

类
class	ContourPlane

class	PrivateData

Public 类型
enum	Attribute { WithoutGaps = 0x01 }
	Raster data attributes 更多...

enum	ConrecFlag { IgnoreAllVerticesOnLevel = 0x01 , IgnoreOutOfRange = 0x02 }
	Flags to modify the contour algorithm 更多...

using	ContourLines = QMap< double, QPolygonF >
	Contour lines

Public 成员函数
	QwtRasterData ()
	Constructor

virtual	~QwtRasterData ()
	Destructor

void	setAttribute (Attribute, bool on=true)
	Set an attribute

bool	testAttribute (Attribute) const
	Test an attribute

virtual QwtInterval	interval (Qt::Axis) const =0

virtual QRectF	pixelHint (const QRectF &) const
	Return a hint for the raster item, about how to align the pixels

virtual void	initRaster (const QRectF &, const QSize &raster)
	Initialize the raster

virtual void	discardRaster ()
	Discard the raster

virtual double	value (double x, double y) const =0

virtual ContourLines	contourLines (const QRectF &rect, const QSize &raster, const QList< double > &levels, ConrecFlags) const
	Calculate contour lines

详细描述

QwtRasterData defines an interface to any type of raster data.

QwtRasterData is an abstract interface, that is used by QwtPlotRasterItem to find the values at the pixels of its raster.

Gaps inside the bounding rectangle of the data can be indicated by NaN values ( when WithoutGaps is disabled ).

Often a raster item is used to display values from a matrix. Then the derived raster data class needs to implement some sort of resampling, that maps the raster of the matrix into the requested raster of the raster item ( depending on resolution and scales of the canvas ).

QwtMatrixRasterData implements raster data, that returns values from a given 2D matrix.

参见: QwtMatrixRasterData

成员枚举类型说明

◆ Attribute

enum QwtRasterData::Attribute

Raster data attributes

Additional information that is used to improve processing of the data.

枚举值

WithoutGaps

The bounding rectangle of the data is spanned by the interval(Qt::XAxis) and interval(Qt::YAxis).

WithoutGaps indicates, that the data has no gaps ( unknown values ) in this area and the result of value() does not need to be checked for NaN values.

Enabling this flag will have an positive effect on the performance of rendering a QwtPlotSpectrogram.

The default setting is false.

注解: NaN values indicate an undefined value

◆ ConrecFlag

enum QwtRasterData::ConrecFlag

Flags to modify the contour algorithm

枚举值
IgnoreAllVerticesOnLevel	Ignore all vertices on the same level
IgnoreOutOfRange	Ignore all values, that are out of range

构造及析构函数说明

◆ QwtRasterData()

QwtRasterData::QwtRasterData ( )

Constructor

Creates a QwtRasterData object with default attributes.

Destructor

成员函数说明

◆ contourLines()

QwtRasterData::ContourLines QwtRasterData::contourLines	(	const QRectF &	rect,
		const QSize &	raster,
		const QList< double > &	levels,
		ConrecFlags	flags
	)		const

virtual

Calculate contour lines

An adaption of CONREC, a simple contouring algorithm. http://local.wasp.uwa.edu.au/~pbourke/papers/conrec/

参数

[in]	rect	Bounding rectangle for the contour lines
[in]	raster	Number of data pixels of the raster data
[in]	levels	List of limits, where to insert contour lines
[in]	flags	Flags to customize the contouring algorithm

返回: Calculated contour lines

◆ discardRaster()

void QwtRasterData::discardRaster ( )

virtual

Discard the raster

Discard a raster

After the composition of an image QwtPlotSpectrogram calls discardRaster().

     The default implementation does nothing, but if data has been loaded
     in initRaster(), it could be deleted now.

参见: initRaster(), value()

◆ initRaster()

void QwtRasterData::initRaster	(	const QRectF &	area,
		const QSize &	raster
	)

virtual

Initialize the raster

Initialize a raster

Before the composition of an image QwtPlotSpectrogram calls initRaster(), announcing the area and its resolution that will be requested.

The default implementation does nothing, but for data sets that are stored in files, it might be good idea to reimplement initRaster(), where the data is resampled and loaded into memory.

参数

[in]	area	Area of the raster
[in]	raster	Number of horizontal and vertical pixels

参见: discardRaster(), value()

◆ interval()

virtual QwtInterval QwtRasterData::interval ( Qt::Axis ) const

pure virtual

在 QwtGridRasterData , 以及 QwtMatrixRasterData 内被实现.

◆ pixelHint()

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

virtual

Return a hint for the raster item, about how to align the pixels

Pixel hint

pixelHint() returns the geometry of a pixel, that can be used to calculate the resolution and alignment of the plot item, that is representing the data.

Width and height of the hint need to be the horizontal and vertical distances between 2 neighbored points. The center of the hint has to be the position of any point ( it doesn't matter which one ).

An empty hint indicates, that there are values for any detail level.

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 recommending to render in target device ( f.e. 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

被 QwtGridRasterData , 以及 QwtMatrixRasterData 重载.

◆ setAttribute()

void QwtRasterData::setAttribute	(	Attribute	attribute,
		bool	on = `true`
	)

Set an attribute

Specify an attribute of the data

参数

[in]	attribute	Attribute to set
[in]	on	On/Off state

参见: Attribute, testAttribute()

◆ testAttribute()

bool QwtRasterData::testAttribute ( Attribute attribute ) const

Test an attribute

Test if an attribute is enabled

参数

[in] attribute Attribute to test

返回: True when attribute is enabled

参见: Attribute, setAttribute()

◆ value()

virtual double QwtRasterData::value	(	double	x,
		double	y
	)		const

pure virtual

在 QwtGridRasterData , 以及 QwtMatrixRasterData 内被实现.

该类的文档由以下文件生成:

/home/runner/work/QWT/QWT/src/core/qwt_raster_data.h
/home/runner/work/QWT/QWT/src/core/qwt_raster_data.cpp

类

Public 类型

Public 成员函数

详细描述

成员枚举类型说明

◆ Attribute

◆ ConrecFlag

构造及析构函数说明

◆ QwtRasterData()

成员函数说明

◆ contourLines()

◆ discardRaster()

◆ initRaster()

◆ interval()

◆ pixelHint()

◆ setAttribute()

◆ testAttribute()

◆ value()