Qwt User's Guide  6.1.3
QwtRoundScaleDraw Class Reference

A class for drawing round scales. More...

#include <qwt_round_scale_draw.h>

Inheritance diagram for QwtRoundScaleDraw:

Public Member Functions

 QwtRoundScaleDraw ()
 Constructor. More...
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. More...
virtual double extent (const QFont &) const
- Public Member Functions inherited from QwtAbstractScaleDraw
 QwtAbstractScaleDraw ()
 Constructor. More...
virtual ~QwtAbstractScaleDraw ()
void setScaleDiv (const QwtScaleDiv &s)
const QwtScaleDivscaleDiv () const
void setTransformation (QwtTransform *)
const QwtScaleMapscaleMap () const
QwtScaleMapscaleMap ()
void enableComponent (ScaleComponent, bool enable=true)
bool hasComponent (ScaleComponent) const
void setTickLength (QwtScaleDiv::TickType, double length)
double tickLength (QwtScaleDiv::TickType) const
double maxTickLength () const
void setSpacing (double margin)
 Set the spacing between tick and labels. More...
double spacing () const
 Get the spacing. More...
void setPenWidth (int width)
 Specify the width of the scale pen. More...
int penWidth () const
virtual void draw (QPainter *, const QPalette &) const
 Draw the scale. More...
virtual QwtText label (double) const
 Convert a value into its representing label. More...
void setMinimumExtent (double)
 Set a minimum for the extent. More...
double minimumExtent () 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
- Protected Member Functions inherited from QwtAbstractScaleDraw
void invalidateCache ()
const QwtTexttickLabel (const QFont &, double value) const
 Convert a value into its representing label and cache it. More...

Additional Inherited Members

- Public Types inherited from QwtAbstractScaleDraw
enum  ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
typedef QFlags< ScaleComponentScaleComponents
 Scale components.

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 ( )


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

Draws the baseline of the scale

See also
drawTick(), drawLabel()

Implements QwtAbstractScaleDraw.

void QwtRoundScaleDraw::drawLabel ( QPainter *  painter,
double  value 
) const

Draws the label for a major scale tick

See also
drawTick(), drawBackbone()

Implements QwtAbstractScaleDraw.

void QwtRoundScaleDraw::drawTick ( QPainter *  painter,
double  value,
double  len 
) const

Draw a tick

valueValue of the tick
lenLenght of the tick
See also
drawBackbone(), drawLabel()

Implements QwtAbstractScaleDraw.

double QwtRoundScaleDraw::extent ( const QFont &  font) const

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.

fontFont 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

centerNew 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 ( double  angle1,
double  angle2 

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.

angle2boundaries 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 ( double  radius)

Change of radius the scale

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

radiusNew Radius
See also