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QwtScaleEngine(3)              Qwt User's Guide              QwtScaleEngine(3)


QwtScaleEngine -


#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 o IncludeReference Build a scale which includes the reference() value. o Symmetric Build a scale which is symmetric to the reference() value. o 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. o Inverted Turn the scale upside down. See also: setAttribute(), testAttribute(), reference(), lowerMargin(), upperMargin() Member Function Documentation int 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 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 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 QwtLog10ScaleEngine, and QwtLinearScaleEngine. 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 (intattributes) 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: o 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 QwtValueList QwtScaleEngine::strip (const QwtValueList &ticks, const QwtDoubleInterval &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 QwtLog10ScaleEngine, and QwtLinearScaleEngine. double QwtScaleEngine::upperMargin () const Returns: the margin at the upper end of the scale The default margin is 0. See also: setMargins() Author Generated automatically by Doxygen for Qwt User's Guide from the source code. Version 5.2.3 Tue Nov 20 2012 QwtScaleEngine(3)

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