.TH "QwtScaleEngine" 3 "Sun Jul 18 2021" "Version 6.2.0" "Qwt User's Guide" \" -*- nroff -*-
.ad l
.nh
.SH NAME
QwtScaleEngine \- Base class for scale engines\&.  

.SH SYNOPSIS
.br
.PP
.PP
\fC#include <qwt_scale_engine\&.h>\fP
.PP
Inherited by \fBQwtLinearScaleEngine\fP, and \fBQwtLogScaleEngine\fP\&.
.SS "Public Types"

.in +1c
.ti -1c
.RI "enum \fBAttribute\fP { \fBNoAttribute\fP = 0x00, \fBIncludeReference\fP = 0x01, \fBSymmetric\fP = 0x02, \fBFloating\fP = 0x04, \fBInverted\fP = 0x08 }"
.br
.ti -1c
.RI "typedef QFlags< \fBAttribute\fP > \fBAttributes\fP"
.br
.in -1c
.SS "Public Member Functions"

.in +1c
.ti -1c
.RI "\fBQwtScaleEngine\fP (uint \fBbase\fP=10)"
.br
.ti -1c
.RI "virtual \fB~QwtScaleEngine\fP ()"
.br
.RI "Destructor\&. "
.ti -1c
.RI "void \fBsetBase\fP (uint \fBbase\fP)"
.br
.ti -1c
.RI "uint \fBbase\fP () const"
.br
.ti -1c
.RI "void \fBsetAttribute\fP (\fBAttribute\fP, bool on=true)"
.br
.ti -1c
.RI "bool \fBtestAttribute\fP (\fBAttribute\fP) const"
.br
.ti -1c
.RI "void \fBsetAttributes\fP (\fBAttributes\fP)"
.br
.ti -1c
.RI "\fBAttributes\fP \fBattributes\fP () const"
.br
.ti -1c
.RI "void \fBsetReference\fP (double)"
.br
.RI "Specify a reference point\&. "
.ti -1c
.RI "double \fBreference\fP () const"
.br
.ti -1c
.RI "void \fBsetMargins\fP (double lower, double upper)"
.br
.RI "Specify margins at the scale's endpoints\&. "
.ti -1c
.RI "double \fBlowerMargin\fP () const"
.br
.ti -1c
.RI "double \fBupperMargin\fP () const"
.br
.ti -1c
.RI "virtual void \fBautoScale\fP (int maxNumSteps, double &x1, double &x2, double &stepSize) const =0"
.br
.ti -1c
.RI "virtual \fBQwtScaleDiv\fP \fBdivideScale\fP (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize=0\&.0) const =0"
.br
.RI "Calculate a scale division\&. "
.ti -1c
.RI "void \fBsetTransformation\fP (\fBQwtTransform\fP *)"
.br
.ti -1c
.RI "\fBQwtTransform\fP * \fBtransformation\fP () const"
.br
.in -1c
.SS "Protected Member Functions"

.in +1c
.ti -1c
.RI "bool \fBcontains\fP (const \fBQwtInterval\fP &, double value) const"
.br
.ti -1c
.RI "\fBQList\fP< double > \fBstrip\fP (const \fBQList\fP< double > &, const \fBQwtInterval\fP &) const"
.br
.ti -1c
.RI "double \fBdivideInterval\fP (double intervalSize, int numSteps) const"
.br
.ti -1c
.RI "\fBQwtInterval\fP \fBbuildInterval\fP (double value) const"
.br
.RI "Build an interval around a value\&. "
.in -1c
.SH "Detailed Description"
.PP 
Base class for scale engines\&. 

A scale engine tries to find 'reasonable' ranges and step sizes for scales\&.
.PP
The layout of the scale can be varied with \fBsetAttribute()\fP\&.
.PP
Qwt offers implementations for logarithmic and linear scales\&. 
.PP
Definition at line 45 of file qwt_scale_engine\&.h\&.
.SH "Member Typedef Documentation"
.PP 
.SS "typedef QFlags<\fBAttribute\fP > \fBQwtScaleEngine::Attributes\fP"
An ORed combination of \fBAttribute\fP values\&. 
.PP
Definition at line 78 of file qwt_scale_engine\&.h\&.
.SH "Member Enumeration Documentation"
.PP 
.SS "enum \fBQwtScaleEngine::Attribute\fP"
Layout attributes 
.PP
\fBSee also\fP
.RS 4
\fBsetAttribute()\fP, \fBtestAttribute()\fP, \fBreference()\fP, \fBlowerMargin()\fP, \fBupperMargin()\fP 
.RE
.PP

.PP
\fBEnumerator\fP
.in +1c
.TP
\fB\fINoAttribute \fP\fP
No attributes\&. 
.TP
\fB\fIIncludeReference \fP\fP
Build a scale which includes the \fBreference()\fP value\&. 
.TP
\fB\fISymmetric \fP\fP
Build a scale which is symmetric to the \fBreference()\fP value\&. 
.TP
\fB\fIFloating \fP\fP
The endpoints of the scale are supposed to be equal the outmost included values plus the specified margins (see \fBsetMargins()\fP)\&. If this attribute is \fInot\fP set, the endpoints of the scale will be integer multiples of the step size\&. 
.TP
\fB\fIInverted \fP\fP
Turn the scale upside down\&. 
.PP
Definition at line 54 of file qwt_scale_engine\&.h\&.
.SH "Constructor & Destructor Documentation"
.PP 
.SS "QwtScaleEngine::QwtScaleEngine (uint base = \fC10\fP)\fC [explicit]\fP"
Constructor
.PP
\fBParameters\fP
.RS 4
\fIbase\fP Base of the scale engine 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetBase()\fP 
.RE
.PP

.PP
Definition at line 222 of file qwt_scale_engine\&.cpp\&.
.SH "Member Function Documentation"
.PP 
.SS "\fBQwtScaleEngine::Attributes\fP QwtScaleEngine::attributes () const"

.PP
\fBReturns\fP
.RS 4
Scale attributes 
.RE
.PP
\fBSee also\fP
.RS 4
\fBAttribute\fP, \fBsetAttributes()\fP, \fBtestAttribute()\fP 
.RE
.PP

.PP
Definition at line 451 of file qwt_scale_engine\&.cpp\&.
.SS "virtual void QwtScaleEngine::autoScale (int maxNumSteps, double & x1, double & x2, double & stepSize) const\fC [pure virtual]\fP"
Align and divide an interval
.PP
\fBParameters\fP
.RS 4
\fImaxNumSteps\fP Max\&. number of steps 
.br
\fIx1\fP First limit of the interval (In/Out) 
.br
\fIx2\fP Second limit of the interval (In/Out) 
.br
\fIstepSize\fP Step size (Return value) 
.RE
.PP

.PP
Implemented in \fBQwtLogScaleEngine\fP, \fBQwtLinearScaleEngine\fP, and \fBQwtDateScaleEngine\fP\&.
.SS "uint QwtScaleEngine::base () const"

.PP
\fBReturns\fP
.RS 4
base Base of the scale engine 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetBase()\fP 
.RE
.PP

.PP
Definition at line 500 of file qwt_scale_engine\&.cpp\&.
.SS "\fBQwtInterval\fP QwtScaleEngine::buildInterval (double value) const\fC [protected]\fP"

.PP
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]
.PP
\fBParameters\fP
.RS 4
\fIvalue\fP Initial value 
.RE
.PP
\fBReturns\fP
.RS 4
Calculated interval 
.RE
.PP

.PP
Definition at line 395 of file qwt_scale_engine\&.cpp\&.
.SS "bool QwtScaleEngine::contains (const \fBQwtInterval\fP & interval, double value) const\fC [protected]\fP"
Check if an interval 'contains' a value
.PP
\fBParameters\fP
.RS 4
\fIinterval\fP Interval 
.br
\fIvalue\fP Value
.RE
.PP
\fBReturns\fP
.RS 4
True, when the value is inside the interval 
.RE
.PP

.PP
Definition at line 341 of file qwt_scale_engine\&.cpp\&.
.SS "double QwtScaleEngine::divideInterval (double intervalSize, int numSteps) const\fC [protected]\fP"
Calculate a step size for an interval size
.PP
\fBParameters\fP
.RS 4
\fIintervalSize\fP Interval size 
.br
\fInumSteps\fP Number of steps
.RE
.PP
\fBReturns\fP
.RS 4
Step size 
.RE
.PP

.PP
Definition at line 326 of file qwt_scale_engine\&.cpp\&.
.SS "virtual \fBQwtScaleDiv\fP QwtScaleEngine::divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize = \fC0\&.0\fP) const\fC [pure virtual]\fP"

.PP
Calculate a scale division\&. 
.PP
\fBParameters\fP
.RS 4
\fIx1\fP First interval limit 
.br
\fIx2\fP Second interval limit 
.br
\fImaxMajorSteps\fP Maximum for the number of major steps 
.br
\fImaxMinorSteps\fP Maximum number of minor steps 
.br
\fIstepSize\fP Step size\&. If stepSize == 0\&.0, the scaleEngine calculates one\&.
.RE
.PP
\fBReturns\fP
.RS 4
Calculated scale division 
.RE
.PP

.PP
Implemented in \fBQwtLogScaleEngine\fP, \fBQwtLinearScaleEngine\fP, and \fBQwtDateScaleEngine\fP\&.
.SS "double QwtScaleEngine::lowerMargin () const"

.PP
\fBReturns\fP
.RS 4
the margin at the lower end of the scale The default margin is 0\&.
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetMargins()\fP 
.RE
.PP

.PP
Definition at line 280 of file qwt_scale_engine\&.cpp\&.
.SS "double QwtScaleEngine::reference () const"

.PP
\fBReturns\fP
.RS 4
the reference value 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetReference()\fP, \fBsetAttribute()\fP 
.RE
.PP

.PP
Definition at line 474 of file qwt_scale_engine\&.cpp\&.
.SS "void QwtScaleEngine::setAttribute (\fBAttribute\fP attribute, bool on = \fCtrue\fP)"
Change a scale attribute
.PP
\fBParameters\fP
.RS 4
\fIattribute\fP Attribute to change 
.br
\fIon\fP On/Off
.RE
.PP
\fBSee also\fP
.RS 4
\fBAttribute\fP, \fBtestAttribute()\fP 
.RE
.PP

.PP
Definition at line 417 of file qwt_scale_engine\&.cpp\&.
.SS "void QwtScaleEngine::setAttributes (\fBAttributes\fP attributes)"
Change the scale attribute
.PP
\fBParameters\fP
.RS 4
\fIattributes\fP Set scale attributes 
.RE
.PP
\fBSee also\fP
.RS 4
\fBAttribute\fP, \fBattributes()\fP 
.RE
.PP

.PP
Definition at line 442 of file qwt_scale_engine\&.cpp\&.
.SS "void QwtScaleEngine::setBase (uint base)"
Set the base of the scale engine
.PP
While a base of 10 is what 99\&.9% of all applications need certain scales might need a different base: f\&.e 2
.PP
The default setting is 10
.PP
\fBParameters\fP
.RS 4
\fIbase\fP Base of the engine
.RE
.PP
\fBSee also\fP
.RS 4
\fBbase()\fP 
.RE
.PP

.PP
Definition at line 491 of file qwt_scale_engine\&.cpp\&.
.SS "void QwtScaleEngine::setMargins (double lower, double upper)"

.PP
Specify margins at the scale's endpoints\&. 
.PP
\fBParameters\fP
.RS 4
\fIlower\fP minimum distance between the scale's lower boundary and the smallest enclosed value 
.br
\fIupper\fP minimum distance between the scale's upper boundary and the greatest enclosed value
.RE
.PP
Margins can be used to leave a minimum amount of space between the enclosed intervals and the boundaries of the scale\&.
.PP
\fBWarning\fP
.RS 4
.PD 0
.IP "\(bu" 2
\fBQwtLogScaleEngine\fP measures the margins in decades\&.
.PP
.RE
.PP
\fBSee also\fP
.RS 4
\fBupperMargin()\fP, \fBlowerMargin()\fP 
.RE
.PP

.PP
Definition at line 312 of file qwt_scale_engine\&.cpp\&.
.SS "void QwtScaleEngine::setReference (double reference)"

.PP
Specify a reference point\&. 
.PP
\fBParameters\fP
.RS 4
\fIreference\fP New reference value
.RE
.PP
The reference point is needed if options IncludeReference or Symmetric are active\&. Its default value is 0\&.0\&.
.PP
\fBSee also\fP
.RS 4
\fBAttribute\fP 
.RE
.PP

.PP
Definition at line 465 of file qwt_scale_engine\&.cpp\&.
.SS "void QwtScaleEngine::setTransformation (\fBQwtTransform\fP * transform)"
Assign a transformation
.PP
\fBParameters\fP
.RS 4
\fItransform\fP Transformation
.RE
.PP
The transformation object is used as factory for clones that are returned by \fBtransformation()\fP
.PP
The scale engine takes ownership of the transformation\&.
.PP
\fBSee also\fP
.RS 4
\fBQwtTransform::copy()\fP, \fBtransformation()\fP 
.RE
.PP

.PP
Definition at line 248 of file qwt_scale_engine\&.cpp\&.
.SS "\fBQList\fP< double > QwtScaleEngine::strip (const \fBQList\fP< double > & ticks, const \fBQwtInterval\fP & interval) const\fC [protected]\fP"
Remove ticks from a list, that are not inside an interval
.PP
\fBParameters\fP
.RS 4
\fIticks\fP Tick list 
.br
\fIinterval\fP Interval
.RE
.PP
\fBReturns\fP
.RS 4
Stripped tick list 
.RE
.PP

.PP
Definition at line 364 of file qwt_scale_engine\&.cpp\&.
.SS "bool QwtScaleEngine::testAttribute (\fBAttribute\fP attribute) const"

.PP
\fBReturns\fP
.RS 4
True, if attribute is enabled\&.
.RE
.PP
\fBParameters\fP
.RS 4
\fIattribute\fP Attribute to be tested 
.RE
.PP
\fBSee also\fP
.RS 4
\fBAttribute\fP, \fBsetAttribute()\fP 
.RE
.PP

.PP
Definition at line 431 of file qwt_scale_engine\&.cpp\&.
.SS "\fBQwtTransform\fP * 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\&.
.PP
\fBReturns\fP
.RS 4
A clone of the transformation 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetTransformation()\fP 
.RE
.PP

.PP
Definition at line 265 of file qwt_scale_engine\&.cpp\&.
.SS "double QwtScaleEngine::upperMargin () const"

.PP
\fBReturns\fP
.RS 4
the margin at the upper end of the scale The default margin is 0\&.
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetMargins()\fP 
.RE
.PP

.PP
Definition at line 291 of file qwt_scale_engine\&.cpp\&.

.SH "Author"
.PP 
Generated automatically by Doxygen for Qwt User's Guide from the source code\&.