trusty (3) QwtScaleEngine.3.gz
NAME
QwtScaleEngine -
Base class for scale engines.
SYNOPSIS
#include <qwt_scale_engine.h>
Inherited by QwtLinearScaleEngine, and QwtLog10ScaleEngine.
Public Types
enum Attribute { NoAttribute = 0x00, IncludeReference = 0x01, Symmetric = 0x02, Floating = 0x04,
Inverted = 0x08 }
typedef QFlags< Attribute > Attributes
Public Member Functions
QwtScaleEngine ()
virtual ~QwtScaleEngine ()
void setAttribute (Attribute, bool on=true)
bool testAttribute (Attribute) const
void setAttributes (Attributes)
Attributes attributes () const
void setReference (double reference)
double reference () const
void setMargins (double lower, double upper)
double lowerMargin () const
double upperMargin () const
virtual void autoScale (int maxNumSteps, double &x1, double &x2, double &stepSize) const =0
virtual QwtScaleDiv divideScale (double x1, double x2, int maxMajSteps, int maxMinSteps, double
stepSize=0.0) const =0
virtual QwtScaleTransformation * transformation () const =0
Protected Member Functions
bool contains (const QwtInterval &, double val) const
QList< double > strip (const QList< double > &, const QwtInterval &) const
double divideInterval (double interval, int numSteps) const
QwtInterval buildInterval (double v) const
Detailed Description
Base class for scale engines.
A scale engine trys to find 'reasonable' ranges and step sizes for scales.
The layout of the scale can be varied with setAttribute().
Qwt offers implementations for logarithmic (log10) and linear scales. Contributions for other types of
scale engines (date/time, log2 ... ) are welcome.
Member Typedef Documentation
typedef QFlags<Attribute> QwtScaleEngine::Attributes
Layout attributes.
Member Enumeration Documentation
enum QwtScaleEngine::Attribute Layout attributes
See also:
setAttribute(), testAttribute(), reference(), lowerMargin(), upperMargin()
Enumerator:
NoAttribute
No attributes.
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.
Constructor & Destructor Documentation
QwtScaleEngine::QwtScaleEngine () [explicit]
Constructor.
QwtScaleEngine::~QwtScaleEngine () [virtual]
Destructor.
Member Function Documentation
QwtScaleEngine::Attributes QwtScaleEngine::attributes () const Return the scale attributes
See also:
Attribute, setAttributes(), testAttribute()
virtual void QwtScaleEngine::autoScale (intmaxNumSteps, double &x1, double &x2, double &stepSize) const [pure
virtual] Align and divide an interval
Parameters:
maxNumSteps Max. number of steps
x1 First limit of the interval (In/Out)
x2 Second limit of the interval (In/Out)
stepSize Step size (Return value)
Implemented in QwtLinearScaleEngine, and QwtLog10ScaleEngine.
QwtInterval QwtScaleEngine::buildInterval (doublev) const [protected]
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 QwtInterval &interval, doublevalue) const [protected] Check if an
interval 'contains' a value
Parameters:
interval Interval
value Value
See also:
QwtScaleArithmetic::compareEps()
double QwtScaleEngine::divideInterval (doubleintervalSize, intnumSteps) const [protected] Calculate a step
size for an interval size
Parameters:
intervalSize Interval size
numSteps Number of steps
Returns:
Step size
virtual QwtScaleDiv QwtScaleEngine::divideScale (doublex1, doublex2, intmaxMajSteps, intmaxMinSteps,
doublestepSize = 0.0) const [pure virtual]
Calculate a scale division. Parameters:
x1 First interval limit
x2 Second interval limit
maxMajSteps Maximum for the number of major steps
maxMinSteps Maximum number of minor steps
stepSize Step size. If stepSize == 0.0, the scaleEngine calculates one.
Implemented in QwtLinearScaleEngine, and QwtLog10ScaleEngine.
double QwtScaleEngine::lowerMargin () const Returns:
the margin at the lower end of the scale The default margin is 0.
See also:
setMargins()
double QwtScaleEngine::reference () const Returns:
the reference value
See also:
setReference(), setAttribute()
void QwtScaleEngine::setAttribute (Attributeattribute, boolon = true) Change a scale attribute
Parameters:
attribute Attribute to change
on On/Off
See also:
Attribute, testAttribute()
void QwtScaleEngine::setAttributes (Attributesattributes) Change the scale attribute
Parameters:
attributes Set scale attributes
See also:
Attribute, attributes()
void QwtScaleEngine::setMargins (doublelower, doubleupper)
Specify margins at the scale's endpoints. Parameters:
lower minimum distance between the scale's lower boundary and the smallest enclosed value
upper minimum 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:
• QwtLog10ScaleEngine measures the margins in decades.
See also:
upperMargin(), lowerMargin()
void QwtScaleEngine::setReference (doubler)
Specify a reference point. Parameters:
r new reference value
The reference point is needed if options IncludeReference or Symmetric are active. Its default value is
0.0.
See also:
Attribute
QList< double > QwtScaleEngine::strip (const QList< double > &ticks, const QwtInterval &interval) const
[protected] Remove ticks from a list, that are not inside an interval
Parameters:
ticks Tick list
interval Interval
Returns:
Stripped tick list
bool QwtScaleEngine::testAttribute (Attributeattribute) const Check if a attribute is set.
Parameters:
attribute Attribute to be tested
See also:
Attribute, setAttribute()
virtual QwtScaleTransformation* QwtScaleEngine::transformation () const [pure virtual] Returns:
a transformation
Implemented in QwtLinearScaleEngine, and QwtLog10ScaleEngine.
double QwtScaleEngine::upperMargin () const Returns:
the margin at the upper end of the scale The default margin is 0.
See also:
setMargins()
Author
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