QwtPolarGrid Class Reference

An item which draws scales and grid lines on a polar plot. More...

#include <qwt_polar_grid.h>

Inheritance diagram for QwtPolarGrid:

[legend]

List of all members.

Public Types
enum	DisplayFlag {   SmartOriginLabel = 1,   HideMaxRadiusLabel = 2,   ClipAxisBackground = 4,   SmartScaleDraw = 8,   ClipGridLines = 16 }
enum	GridAttribute { AutoScaling = 1 }
Public Member Functions
	QwtPolarGrid ()
virtual	~QwtPolarGrid ()
virtual int	rtti () const
void	setDisplayFlag (DisplayFlag, bool on=true)
bool	testDisplayFlag (DisplayFlag) const
void	setGridAttribute (GridAttribute, bool on=true)
bool	testGridAttribute (GridAttribute) const
void	showGrid (int scaleId, bool show=true)
bool	isGridVisible (int scaleId) const
void	showMinorGrid (int scaleId, bool show=true)
bool	isMinorGridVisible (int scaleId) const
void	showAxis (int axisId, bool show=true)
bool	isAxisVisible (int axisId) const
void	setPen (const QPen &p)
void	setFont (const QFont &)
void	setMajorGridPen (const QPen &p)
void	setMajorGridPen (int scaleId, const QPen &p)
QPen	majorGridPen (int scaleId) const
void	setMinorGridPen (const QPen &p)
void	setMinorGridPen (int scaleId, const QPen &p)
QPen	minorGridPen (int scaleId) const
void	setAxisPen (int axisId, const QPen &p)
QPen	axisPen (int axisId) const
void	setAxisFont (int axisId, const QFont &p)
QFont	axisFont (int axisId) const
virtual void	draw (QPainter *p, const QwtScaleMap &azimuthMap, const QwtScaleMap &radialMap, const QwtDoublePoint &pole, double radius, const QwtDoubleRect &rect) const
virtual void	updateScaleDiv (const QwtScaleDiv &azimuthMap, const QwtScaleDiv &radialMap, const QwtDoubleInterval &)
virtual int	marginHint () const
Protected Member Functions
void	drawRays (QPainter *, const QwtDoubleRect &, const QwtDoublePoint &pole, double radius, const QwtScaleMap &azimuthMap, const QwtValueList &) const
void	drawCircles (QPainter *, const QwtDoubleRect &, const QwtDoublePoint &pole, const QwtScaleMap &radialMap, const QwtValueList &) const
void	drawAxis (QPainter *, int axisId) const

---

Detailed Description

An item which draws scales and grid lines on a polar plot.

The QwtPolarGrid class can be used to draw a coordinate grid. A coordinate grid consists of major and minor gridlines. The locations of the gridlines are determined by the azimuth and radial scale divisions.

QwtPolarGrid is also responsible for drawing the axis representing the scales. It is possible to display 4 radial and one azimuth axis.

Whenever the scale divisions of the plot widget changes the grid is synchronized by updateScaleDiv().

See also:

QwtPolarPlot, QwtPolar::Axis

---

Member Enumeration Documentation

enum QwtPolarGrid::DisplayFlag

Mysterious flags trying to avoid conflicts, when painting the scales and grid lines.

• SmartOriginLabel
  Try to avoid situations, where the label of the origin is painted over another axis.
• HideMaxRadiusLabel
  Often the outermost tick of the radial scale is close to the canvas border. With HideMaxRadiusLabel enabled it is not painted.
• ClipAxisBackground
  The tick labels of the radial scales might be hard to read, when they are painted on top of the radial grid lines ( or on top of a curve/spectrogram ). When ClipAxisBackground the bounding rect of each label is added to the clip region.
• SmartScaleDraw
  Don't paint the backbone of the radial axes, when they are very close to a line of the azimuth grid.
• ClipGridLines
  All grid lines are clipped against the plot area before being painted. When the plot is zoomed in this will have an significant impact on the performance of the painting cde.

The default setting enables all flags.

enum QwtPolarGrid::GridAttribute

Grid attributes.

• AutoScaling
  When AutoScaling is enabled, the radial axes will be adjusted to the interval, that is currently visible on the canvas plot.

---

Constructor & Destructor Documentation

QwtPolarGrid::QwtPolarGrid

(

)

[explicit]

Constructor.

Enables major and disables minor grid lines. The azimuth and right radial axis are visible. all other axes are hidden. Autoscaling is enabled.

QwtPolarGrid::~QwtPolarGrid

(

)

[virtual]

Destructor.

---

Member Function Documentation

int QwtPolarGrid::rtti

(

)

const [virtual]

Returns:

QwtPlotItem::Rtti_PolarGrid

Reimplemented from QwtPolarItem.

void QwtPolarGrid::setDisplayFlag	(	DisplayFlag	flag,
		bool	on = true
	)

Change the display flags

Parameters:

	flag	See DisplayFlag
	on	true/false

bool QwtPolarGrid::testDisplayFlag

(

DisplayFlag

flag

)

const

Returns:

true, if flag is enabled

Parameters:

flag

See DisplayFlag

void QwtPolarGrid::setGridAttribute	(	GridAttribute	attribute,
		bool	on = true
	)

Specify an attribute for the grid.

Parameters:

	attribute	Grid attribute
	on	On/Off

/sa GridAttribute, testGridAttribute(), updateScaleDiv(), QwtPolarPlot::zoom(), QwtPolarPlot::scaleDiv()

bool QwtPolarGrid::testGridAttribute

(

GridAttribute

attribute

)

const

Returns:

true, if attribute is enabled

See also:

GridAttribute, setGridAttribute()

void QwtPolarGrid::showGrid	(	int	scaleId,
		bool	show = true
	)

Show/Hide grid lines for a scale

Parameters:

	scaleId	Scale id ( QwtPolar::Scale )
	show	true/false

bool QwtPolarGrid::isGridVisible

(

int

scaleId

)

const

Returns:

true if grid lines are enabled

Parameters:

scaleId

Scale id ( QwtPolar::Scale )

See also:

QwtPolar::Scale, showGrid()

void QwtPolarGrid::showMinorGrid	(	int	scaleId,
		bool	show = true
	)

Show/Hide minor grid lines for a scale

To display minor grid lines. showGrid() needs to be enabled too.

Parameters:

	scaleId	Scale id ( QwtPolar::Scale )
	show	true/false

See also:

showGrid

bool QwtPolarGrid::isMinorGridVisible

(

int

scaleId

)

const

Returns:

true if minor grid lines are enabled

Parameters:

scaleId

Scale id ( QwtPolar::Scale )

See also:

showMinorGrid()

void QwtPolarGrid::showAxis	(	int	axisId,
		bool	show = true
	)

Show/Hide an axis

Parameters:

	axisId	Axis id (QwtPolar::Axis)
	show	true/false

See also:

isAxisVisible()

bool QwtPolarGrid::isAxisVisible

(

int

axisId

)

const

Returns:

true if the axis is visible

Parameters:

axisId

Axis id (QwtPolar::Axis)

See also:

showAxis()

void QwtPolarGrid::setPen

(

const QPen &

pen

)

Assign a pen for all axes and grid lines

Parameters:

pen

Pen

See also:

setMajorGridPen(), setMinorGridPen(), setAxisPen()

void QwtPolarGrid::setFont

(

const QFont &

font

)

Assign a font for all scale tick labels

Parameters:

font

Font

See also:

setAxisFont()

void QwtPolarGrid::setMajorGridPen

(

const QPen &

pen

)

Assign a pen for the major grid lines

Parameters:

pen

Pen

See also:

setPen(), setMinorGridPen(), majorGridPen

void QwtPolarGrid::setMajorGridPen	(	int	scaleId,
		const QPen &	pen
	)

Assign a pen for the major grid lines of a specific scale

Parameters:

	scaleId	Scale id ( QwtPolar::Scale )
	pen	Pen

See also:

setPen(), setMinorGridPen(), majorGridPen

QPen QwtPolarGrid::majorGridPen

(

int

scaleId

)

const

Returns:

Pen for painting the major grid lines of a specific scale

Parameters:

scaleId

Scale id ( QwtPolar::Scale )

See also:

setMajorGridPen(), minorGridPen()

void QwtPolarGrid::setMinorGridPen

(

const QPen &

pen

)

Assign a pen for the minor grid lines

Parameters:

pen

Pen

See also:

setPen(), setMajorGridPen(), minorGridPen()

void QwtPolarGrid::setMinorGridPen	(	int	scaleId,
		const QPen &	pen
	)

Assign a pen for the minor grid lines of a specific scale

Parameters:

	scaleId	Scale id ( QwtPolar::Scale )
	pen	Pen

See also:

setPen(), setMajorGridPen(), minorGridPen

QPen QwtPolarGrid::minorGridPen

(

int

scaleId

)

const

Returns:

Pen for painting the minor grid lines of a specific scale

Parameters:

scaleId

Scale id ( QwtPolar::Scale )

void QwtPolarGrid::setAxisPen	(	int	axisId,
		const QPen &	pen
	)

Assign a pen for painting an axis

Parameters:

	axisId	Axis id (QwtPolar::Axis)
	pen	Pen

See also:

axisPen()

QPen QwtPolarGrid::axisPen

(

int

axisId

)

const

Returns:

Pen for painting a specific axis

Parameters:

axisId

Axis id (QwtPolar::Axis)

See also:

setAxisPen()

void QwtPolarGrid::setAxisFont	(	int	axisId,
		const QFont &	font
	)

Assign a font for the tick labels of a specific axis

Parameters:

	axisId	Axis id (QwtPolar::Axis)
	font	new Font

QFont QwtPolarGrid::axisFont

(

int

axisId

)

const

Returns:

Font for the tick labels of a specific axis

Parameters:

axisId

Axis id (QwtPolar::Axis)

void QwtPolarGrid::draw	(	QPainter *	painter,
		const QwtScaleMap &	azimuthMap,
		const QwtScaleMap &	radialMap,
		const QwtDoublePoint &	pole,
		double	radius,
		const QwtDoubleRect &	canvasRect
	)			const [virtual]

Draw the grid and axes

Parameters:

	painter	Painter
	azimuthMap	Maps azimuth values to values related to 0.0, M_2PI
	radialMap	Maps radius values into painter coordinates.
	pole	Position of the pole in painter coordinates
	radius	Radius of the complete plot area in painter coordinates
	canvasRect	Contents rect of the canvas in painter coordinates

Implements QwtPolarItem.

void QwtPolarGrid::updateScaleDiv	(	const QwtScaleDiv &	azimuthScaleDiv,
		const QwtScaleDiv &	radialScaleDiv,
		const QwtDoubleInterval &	interval
	)			[virtual]

Update the item to changes of the axes scale division.

If AutoScaling is enabled the radial scale is calculated from the interval, otherwise the scales are adopted to the plot scales.

Parameters:

	azimuthScaleDiv	Scale division of the azimuth-scale
	radialScaleDiv	Scale division of the radius-axis
	interval	The interval of the radius-axis, that is visible on the canvas

See also:

QwtPolarPlot::setGridAttributes()

Reimplemented from QwtPolarItem.

int QwtPolarGrid::marginHint

(

)

const [virtual]

Returns:

Number of pixels, that are necessary to paint the azimuth scale

See also:

QwtRoundScaleDraw::extent()

Reimplemented from QwtPolarItem.

void QwtPolarGrid::drawRays	(	QPainter *	painter,
		const QwtDoubleRect &	canvasRect,
		const QwtDoublePoint &	pole,
		double	radius,
		const QwtScaleMap &	azimuthMap,
		const QwtValueList &	values
	)			const [protected]

Draw lines from the pole

Parameters:

	painter	Painter
	canvasRect	Contents rect of the canvas in painter coordinates
	pole	Position of the pole in painter coordinates
	radius	Length of the lines in painter coordinates
	azimuthMap	Maps azimuth values to values related to 0.0, M_2PI
	values	Azimuth values, indicating the direction of the lines

void QwtPolarGrid::drawCircles	(	QPainter *	painter,
		const QwtDoubleRect &	canvasRect,
		const QwtDoublePoint &	pole,
		const QwtScaleMap &	radialMap,
		const QwtValueList &	values
	)			const [protected]

Draw circles

Parameters:

	painter	Painter
	canvasRect	Contents rect of the canvas in painter coordinates
	pole	Position of the pole in painter coordinates
	radialMap	Maps radius values into painter coordinates.
	values	Radial values, indicating the distances from the pole

void QwtPolarGrid::drawAxis	(	QPainter *	painter,
		int	axisId
	)			const [protected]

Paint an axis

Parameters:

	painter	Painter
	axisId	Axis id (QwtPolar::Axis)