QwtRoundScaleDraw (3) - Linux Manuals


QwtRoundScaleDraw -

A class for drawing round scales.


#include <qwt_round_scale_draw.h>

Inherits QwtAbstractScaleDraw.

Inherited by QwtAnalogClockScaleDraw, and QwtCompassScaleDraw.

Public Member Functions

QwtRoundScaleDraw ()
virtual ~QwtRoundScaleDraw ()
void setRadius (double radius)

double radius () const

void moveCenter (double x, double y)
Move the center of the scale draw, leaving the radius unchanged.
void moveCenter (const QPointF &)

QPointF center () const
Get the center of the scale.
void setAngleRange (double angle1, double angle2)
Adjust the baseline circle segment for round scales.
virtual double extent (const QFont &) const

Protected Member Functions

virtual void drawTick (QPainter *, double val, double len) const

virtual void drawBackbone (QPainter *) const

virtual void drawLabel (QPainter *, double val) const

Additional Inherited Members

Detailed Description

A class for drawing round scales.

QwtRoundScaleDraw can be used to draw round scales. The circle segment can be adjusted by setAngleRange(). The geometry of the scale can be specified with moveCenter() and setRadius().

After a scale division has been specified as a QwtScaleDiv object using QwtAbstractScaleDraw::setScaleDiv(const QwtScaleDiv &s), the scale can be drawn with the QwtAbstractScaleDraw::draw() member.

Constructor & Destructor Documentation

QwtRoundScaleDraw::QwtRoundScaleDraw ()

Constructor. The range of the scale is initialized to [0, 100], The center is set to (50, 50) with a radius of 50. The angle range is set to [-135, 135].

Member Function Documentation

void QwtRoundScaleDraw::drawBackbone (QPainter *painter) const [protected], [virtual]

Draws the baseline of the scale


painter Painter

See Also:

drawTick(), drawLabel()

Implements QwtAbstractScaleDraw.

void QwtRoundScaleDraw::drawLabel (QPainter *painter, doublevalue) const [protected], [virtual]

Draws the label for a major scale tick


painter Painter
value Value

See Also:

drawTick(), drawBackbone()

Implements QwtAbstractScaleDraw.

void QwtRoundScaleDraw::drawTick (QPainter *painter, doublevalue, doublelen) const [protected], [virtual]

Draw a tick


painter Painter
value Value of the tick
len Lenght of the tick

See Also:

drawBackbone(), drawLabel()

Implements QwtAbstractScaleDraw.

double QwtRoundScaleDraw::extent (const QFont &font) const [virtual]

Calculate the extent of the scale

The extent is the distance between the baseline to the outermost pixel of the scale draw. radius() + extent() is an upper limit for the radius of the bounding circle.


font Font used for painting the labels


Calculated extent

See Also:

setMinimumExtent(), minimumExtent()


The implemented algorithm is not too smart and calculates only an upper limit, that might be a few pixels too large

Implements QwtAbstractScaleDraw.

void QwtRoundScaleDraw::moveCenter (const QPointF &center)

Move the center of the scale draw, leaving the radius unchanged


center New center

See Also:


double QwtRoundScaleDraw::radius () const

Get the radius

Radius is the radius of the backbone without ticks and labels.


Radius of the scale

See Also:

setRadius(), extent()

void QwtRoundScaleDraw::setAngleRange (doubleangle1, doubleangle2)

Adjust the baseline circle segment for round scales. The baseline will be drawn from min(angle1,angle2) to max(angle1, angle2). The default setting is [ -135, 135 ]. An angle of 0 degrees corresponds to the 12 o'clock position, and positive angles count in a clockwise direction.


angle2 boundaries of the angle interval in degrees.


The angle range is limited to [-360, 360] degrees. Angles exceeding this range will be clipped.
For angles more or equal than 360 degrees above or below min(angle1, angle2), scale marks will not be drawn.
If you need a counterclockwise scale, use QwtScaleDiv::setInterval()

void QwtRoundScaleDraw::setRadius (doubleradius)

Change of radius the scale

Radius is the radius of the backbone without ticks and labels.


radius New Radius

See Also:



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