QwtScaleEngine Class Reference

Base class for scale engines. More...

#include <qwt_scale_engine.h>

Inheritance diagram for QwtScaleEngine:

Inheritance graph
[legend]

List of all members.

Public Types

enum  Attribute {
  NoAttribute = 0x00,
  IncludeReference = 0x01,
  Symmetric = 0x02,
  Floating = 0x04,
  Inverted = 0x08
}
typedef QFlags< AttributeAttributes

Public Member Functions

Attributes attributes () 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
double lowerMargin () const
 QwtScaleEngine ()
double reference () const
void setAttribute (Attribute, bool on=true)
void setAttributes (Attributes)
void setMargins (double lower, double upper)
void setReference (double reference)
bool testAttribute (Attribute) const
virtual QwtScaleTransformationtransformation () const =0
double upperMargin () const
virtual ~QwtScaleEngine ()

Protected Member Functions

QwtInterval buildInterval (double v) const
bool contains (const QwtInterval &, double val) const
double divideInterval (double interval, int numSteps) const
QList< double > strip (const QList< double > &, const QwtInterval &) const


Detailed Description

Base class for scale engines.

A scale engine tries 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

Layout attributes.


Member Enumeration Documentation

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 ( int  maxNumSteps,
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 ( double  v  )  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,
double  value 
) const [protected]

Check if an interval "contains" a value

Parameters:
interval Interval
value Value
See also:
QwtScaleArithmetic::compareEps()

double QwtScaleEngine::divideInterval ( double  intervalSize,
int  numSteps 
) 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 ( double  x1,
double  x2,
int  maxMajSteps,
int  maxMinSteps,
double  stepSize = 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 ( Attribute  attribute,
bool  on = true 
)

Change a scale attribute

Parameters:
attribute Attribute to change
on On/Off
See also:
Attribute, testAttribute()

void QwtScaleEngine::setAttributes ( Attributes  attributes  ) 

Change the scale attribute

Parameters:
attributes Set scale attributes
See also:
Attribute, attributes()

void QwtScaleEngine::setMargins ( double  lower,
double  upper 
)

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:
See also:
upperMargin(), lowerMargin()

void QwtScaleEngine::setReference ( double  r  ) 

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 ( Attribute  attribute  )  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()


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