QwtScaleEngine(3) Qwt User's Guide QwtScaleEngine(3) NAME QwtScaleEngine - Base class for scale engines. SYNOPSIS #include Inherited by QwtLinearScaleEngine, and QwtLogScaleEngine. Public Types enum Attribute { NoAttribute = 0x00, IncludeReference = 0x01, Symmetric = 0x02, Floating = 0x04, Inverted = 0x08 } typedef QFlags< Attribute > Attributes Public Member Functions QwtScaleEngine (uint base=10) virtual ~QwtScaleEngine () Destructor. void setBase (uint base) uint base () const void setAttribute (Attribute, bool on=true) bool testAttribute (Attribute) const void setAttributes (Attributes) Attributes attributes () const void setReference (double) Specify a reference point. double reference () const void setMargins (double lower, double upper) Specify margins at the scale's endpoints. 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 maxMajorSteps, int maxMinorSteps, double stepSize=0.0) const =0 Calculate a scale division. void setTransformation (QwtTransform *) QwtTransform * transformation () const Protected Member Functions bool contains (const QwtInterval &, double value) const QList< double > strip (const QList< double > &, const QwtInterval &) const double divideInterval (double intervalSize, int numSteps) const QwtInterval buildInterval (double value) const Build an interval around a value. 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 and linear scales. Definition at line 45 of file qwt_scale_engine.h. Member Typedef Documentation typedef QFlags QwtScaleEngine::Attributes An ORed combination of Attribute values. Definition at line 78 of file qwt_scale_engine.h. 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. Definition at line 54 of file qwt_scale_engine.h. Constructor & Destructor Documentation QwtScaleEngine::QwtScaleEngine (uint base = 10) [explicit] Constructor Parameters base Base of the scale engine See also setBase() Definition at line 222 of file qwt_scale_engine.cpp. Member Function Documentation QwtScaleEngine::Attributes QwtScaleEngine::attributes () const Returns Scale attributes See also Attribute, setAttributes(), testAttribute() Definition at line 451 of file qwt_scale_engine.cpp. 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 QwtLogScaleEngine, QwtLinearScaleEngine, and QwtDateScaleEngine. uint QwtScaleEngine::base () const Returns base Base of the scale engine See also setBase() Definition at line 500 of file qwt_scale_engine.cpp. QwtInterval QwtScaleEngine::buildInterval (double value) const [protected] Build an interval around a value. In case of v == 0.0 the interval is [-0.5, 0.5], otherwise it is [0.5 * v, 1.5 * v] Parameters value Initial value Returns Calculated interval Definition at line 395 of file qwt_scale_engine.cpp. bool QwtScaleEngine::contains (const QwtInterval & interval, double value) const [protected] Check if an interval 'contains' a value Parameters interval Interval value Value Returns True, when the value is inside the interval Definition at line 341 of file qwt_scale_engine.cpp. 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 Definition at line 326 of file qwt_scale_engine.cpp. virtual QwtScaleDiv QwtScaleEngine::divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize = 0.0) const [pure virtual] Calculate a scale division. Parameters x1 First interval limit x2 Second interval limit maxMajorSteps Maximum for the number of major steps maxMinorSteps Maximum number of minor steps stepSize Step size. If stepSize == 0.0, the scaleEngine calculates one. Returns Calculated scale division Implemented in QwtLogScaleEngine, QwtLinearScaleEngine, and QwtDateScaleEngine. double QwtScaleEngine::lowerMargin () const Returns the margin at the lower end of the scale The default margin is 0. See also setMargins() Definition at line 280 of file qwt_scale_engine.cpp. double QwtScaleEngine::reference () const Returns the reference value See also setReference(), setAttribute() Definition at line 474 of file qwt_scale_engine.cpp. void QwtScaleEngine::setAttribute (Attribute attribute, bool on = true) Change a scale attribute Parameters attribute Attribute to change on On/Off See also Attribute, testAttribute() Definition at line 417 of file qwt_scale_engine.cpp. void QwtScaleEngine::setAttributes (Attributes attributes) Change the scale attribute Parameters attributes Set scale attributes See also Attribute, attributes() Definition at line 442 of file qwt_scale_engine.cpp. void QwtScaleEngine::setBase (uint base) Set the base of the scale engine While a base of 10 is what 99.9% of all applications need certain scales might need a different base: f.e 2 The default setting is 10 Parameters base Base of the engine See also base() Definition at line 491 of file qwt_scale_engine.cpp. 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 o QwtLogScaleEngine measures the margins in decades. See also upperMargin(), lowerMargin() Definition at line 312 of file qwt_scale_engine.cpp. void QwtScaleEngine::setReference (double reference) Specify a reference point. Parameters reference New reference value The reference point is needed if options IncludeReference or Symmetric are active. Its default value is 0.0. See also Attribute Definition at line 465 of file qwt_scale_engine.cpp. void QwtScaleEngine::setTransformation (QwtTransform * transform) Assign a transformation Parameters transform Transformation The transformation object is used as factory for clones that are returned by transformation() The scale engine takes ownership of the transformation. See also QwtTransform::copy(), transformation() Definition at line 248 of file qwt_scale_engine.cpp. 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 Definition at line 364 of file qwt_scale_engine.cpp. bool QwtScaleEngine::testAttribute (Attribute attribute) const Returns True, if attribute is enabled. Parameters attribute Attribute to be tested See also Attribute, setAttribute() Definition at line 431 of file qwt_scale_engine.cpp. QwtTransform * QwtScaleEngine::transformation () const Create and return a clone of the transformation of the engine. When the engine has no special transformation NULL is returned, indicating no transformation. Returns A clone of the transformation See also setTransformation() Definition at line 265 of file qwt_scale_engine.cpp. double QwtScaleEngine::upperMargin () const Returns the margin at the upper end of the scale The default margin is 0. See also setMargins() Definition at line 291 of file qwt_scale_engine.cpp. Author Generated automatically by Doxygen for Qwt User's Guide from the source code. Version 6.2.0 Sun Jul 18 2021 QwtScaleEngine(3)