Qwt User's Guide 5.2.2
Public Types | Public Member Functions | Protected Member Functions

QwtLog10ScaleEngine Class Reference

A scale engine for logarithmic (base 10) scales. More...

#include <qwt_scale_engine.h>

Inheritance diagram for QwtLog10ScaleEngine:
Inheritance graph
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List of all members.

Public Types

enum  Attribute {
  NoAttribute = 0,
  IncludeReference = 1,
  Symmetric = 2,
  Floating = 4,
  Inverted = 8
}

Public Member Functions

int attributes () const
virtual void autoScale (int maxSteps, double &x1, double &x2, double &stepSize) const
virtual QwtScaleDiv divideScale (double x1, double x2, int numMajorSteps, int numMinorSteps, double stepSize=0.0) const
double lowerMargin () const
double reference () const
void setAttribute (Attribute, bool on=true)
void setAttributes (int)
void setMargins (double lower, double upper)
void setReference (double reference)
bool testAttribute (Attribute) const
virtual QwtScaleTransformationtransformation () const
double upperMargin () const

Protected Member Functions

QwtDoubleInterval buildInterval (double v) const
bool contains (const QwtDoubleInterval &, double val) const
double divideInterval (double interval, int numSteps) const
QwtDoubleInterval log10 (const QwtDoubleInterval &) const
QwtDoubleInterval pow10 (const QwtDoubleInterval &) const
QwtValueList strip (const QwtValueList &, const QwtDoubleInterval &) const

Detailed Description

A scale engine for logarithmic (base 10) scales.

The step size is measured in *decades* and the major step size will be adjusted to fit the pattern $\left\{ 1,2,3,5\right\} \cdot 10^{n}$, where n is a natural number including zero.

Warning:
the step size as well as the margins are measured in *decades*.

Member Enumeration Documentation

enum QwtScaleEngine::Attribute [inherited]
  • IncludeReference
    Build a scale which includes the reference() value.
  • Symmetric
    Build a scale which is symmetric to the reference() value.
  • Floating
    The endpoints of the scale are supposed to be equal the outmost included values plus the specified margins (see setMargins()). If this attribute is *not* set, the endpoints of the scale will be integer multiples of the step size.
  • Inverted
    Turn the scale upside down.
See also:
setAttribute(), testAttribute(), reference(), lowerMargin(), upperMargin()

Member Function Documentation

int QwtScaleEngine::attributes ( ) const [inherited]

Return the scale attributes

See also:
Attribute, setAttributes(), testAttribute()
void QwtLog10ScaleEngine::autoScale ( int  maxNumSteps,
double &  x1,
double &  x2,
double &  stepSize 
) const [virtual]

Align and divide an interval

Parameters:
maxNumStepsMax. number of steps
x1First limit of the interval (In/Out)
x2Second limit of the interval (In/Out)
stepSizeStep size (Out)
See also:
QwtScaleEngine::setAttribute()

Implements QwtScaleEngine.

QwtDoubleInterval QwtScaleEngine::buildInterval ( double  v) const [protected, inherited]

Build an interval for a value.

In case of v == 0.0 the interval is [-0.5, 0.5], otherwide it is [0.5 * v, 1.5 * v]

bool QwtScaleEngine::contains ( const QwtDoubleInterval interval,
double  value 
) const [protected, inherited]

Check if an interval "contains" a value

Parameters:
intervalInterval
valueValue
See also:
QwtScaleArithmetic::compareEps()
double QwtScaleEngine::divideInterval ( double  intervalSize,
int  numSteps 
) const [protected, inherited]

Calculate a step size for an interval size

Parameters:
intervalSizeInterval size
numStepsNumber of steps
Returns:
Step size
QwtScaleDiv QwtLog10ScaleEngine::divideScale ( double  x1,
double  x2,
int  maxMajSteps,
int  maxMinSteps,
double  stepSize = 0.0 
) const [virtual]

Calculate a scale division.

Parameters:
x1First interval limit
x2Second interval limit
maxMajStepsMaximum for the number of major steps
maxMinStepsMaximum number of minor steps
stepSizeStep size. If stepSize == 0, the scaleEngine calculates one.
See also:
QwtScaleEngine::stepSize(), QwtLog10ScaleEngine::subDivide()

Implements QwtScaleEngine.

QwtDoubleInterval QwtLog10ScaleEngine::log10 ( const QwtDoubleInterval interval) const [protected]

Return the interval [log10(interval.minValue(), log10(interval.maxValue]

double QwtScaleEngine::lowerMargin ( ) const [inherited]
Returns:
the margin at the lower end of the scale The default margin is 0.
See also:
setMargins()
QwtDoubleInterval QwtLog10ScaleEngine::pow10 ( const QwtDoubleInterval interval) const [protected]

Return the interval [pow10(interval.minValue(), pow10(interval.maxValue]

double QwtScaleEngine::reference ( ) const [inherited]
Returns:
the reference value
See also:
setReference(), setAttribute()
void QwtScaleEngine::setAttribute ( Attribute  attribute,
bool  on = true 
) [inherited]

Change a scale attribute

Parameters:
attributeAttribute to change
onOn/Off
See also:
Attribute, testAttribute()
void QwtScaleEngine::setAttributes ( int  attributes) [inherited]

Change the scale attribute

Parameters:
attributesSet scale attributes
See also:
Attribute, attributes()
void QwtScaleEngine::setMargins ( double  lower,
double  upper 
) [inherited]

Specify margins at the scale's endpoints.

Parameters:
lowerminimum distance between the scale's lower boundary and the smallest enclosed value
upperminimum distance between the scale's upper boundary and the greatest enclosed value

Margins can be used to leave a minimum amount of space between the enclosed intervals and the boundaries of the scale.

Warning:
See also:
upperMargin(), lowerMargin()
void QwtScaleEngine::setReference ( double  r) [inherited]

Specify a reference point.

Parameters:
rnew reference value

The reference point is needed if options IncludeReference or Symmetric are active. Its default value is 0.0.

See also:
Attribute
QwtValueList QwtScaleEngine::strip ( const QwtValueList &  ticks,
const QwtDoubleInterval interval 
) const [protected, inherited]

Remove ticks from a list, that are not inside an interval

Parameters:
ticksTick list
intervalInterval
Returns:
Stripped tick list
bool QwtScaleEngine::testAttribute ( Attribute  attribute) const [inherited]

Check if a attribute is set.

Parameters:
attributeAttribute to be tested
See also:
Attribute, setAttribute()
QwtScaleTransformation * QwtLog10ScaleEngine::transformation ( ) const [virtual]

Return a transformation, for logarithmic (base 10) scales

Implements QwtScaleEngine.

double QwtScaleEngine::upperMargin ( ) const [inherited]
Returns:
the margin at the upper end of the scale The default margin is 0.
See also:
setMargins()