QwtScaleEngine(3) | Qwt User's Guide | QwtScaleEngine(3) |
NAME¶
QwtScaleEngine -SYNOPSIS¶
#include <qwt_scale_engine.h>
Inherited by QwtLinearScaleEngine, and QwtLog10ScaleEngine.
Public Types¶
enum Attribute { NoAttribute = 0, IncludeReference = 1, Symmetric = 2, Floating = 4, Inverted = 8 }
Public Member Functions¶
QwtScaleEngine ()
virtual ~QwtScaleEngine ()
int 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
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 QwtScaleTransformation * transformation () const =0
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
QwtValueList strip (const QwtValueList &, const QwtDoubleInterval &) 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 Enumeration Documentation¶
enum QwtScaleEngine::Attribute¶
- 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:
Member Function Documentation¶
int QwtScaleEngine::attributes () const¶
Return the scale attributesSee also:
virtual void QwtScaleEngine::autoScale (intmaxNumSteps, double &x1, double &x2, double &stepSize) const [pure virtual]¶
Align and divide an intervalParameters:
x1 First limit of the interval (In/Out)
x2 Second limit of the interval (In/Out)
stepSize Step size (Return value)
Implemented in QwtLog10ScaleEngine, and QwtLinearScaleEngine.
QwtDoubleInterval 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 QwtDoubleInterval &interval, doublevalue) const [protected]¶
Check if an interval 'contains' a valueParameters:
value Value
See also:
double QwtScaleEngine::divideInterval (doubleintervalSize, intnumSteps) const [protected]¶
Calculate a step size for an interval sizeParameters:
numSteps Number of steps
Returns:
virtual QwtScaleDiv QwtScaleEngine::divideScale (doublex1, doublex2, intmaxMajSteps, intmaxMinSteps, doublestepSize = 0.0) const [pure virtual]¶
Calculate a scale division. Parameters: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 QwtLog10ScaleEngine, and QwtLinearScaleEngine.
double QwtScaleEngine::lowerMargin () const¶
Returns:See also:
double QwtScaleEngine::reference () const¶
Returns:See also:
void QwtScaleEngine::setAttribute (Attributeattribute, boolon = true)¶
Change a scale attributeParameters:
on On/Off
See also:
void QwtScaleEngine::setAttributes (intattributes)¶
Change the scale attributeParameters:
See also:
void QwtScaleEngine::setMargins (doublelower, doubleupper)¶
Specify margins at the scale's endpoints. Parameters: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:
void QwtScaleEngine::setReference (doubler)¶
Specify a reference point. Parameters:The reference point is needed if options IncludeReference or Symmetric are active. Its default value is 0.0.
See also:
QwtValueList QwtScaleEngine::strip (const QwtValueList &ticks, const QwtDoubleInterval &interval) const [protected]¶
Remove ticks from a list, that are not inside an intervalParameters:
interval Interval
Returns:
bool QwtScaleEngine::testAttribute (Attributeattribute) const¶
Check if a attribute is set.Parameters:
See also:
virtual QwtScaleTransformation* QwtScaleEngine::transformation () const [pure virtual]¶
Returns:Implemented in QwtLog10ScaleEngine, and QwtLinearScaleEngine.
double QwtScaleEngine::upperMargin () const¶
Returns:See also:
Author¶
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