Base class for scale engines. More...
#include <qwt_scale_engine.h>
Public Types | |
enum | Attribute { NoAttribute = 0, IncludeReference = 1, Symmetric = 2, Floating = 4, Inverted = 8 } |
Public Member Functions | |
QwtScaleEngine () | |
virtual | ~QwtScaleEngine () |
void | setAttribute (Attribute, bool on=true) |
bool | testAttribute (Attribute) const |
void | setAttributes (int) |
int | attributes () const |
void | setReference (double reference) |
double | reference () const |
void | setMargins (double lower, double upper) |
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 maxMajSteps, int maxMinSteps, double stepSize=0.0) const =0 |
virtual QwtScaleTransformation * | transformation () const =0 |
Protected Member Functions | |
bool | contains (const QwtDoubleInterval &, double val) const |
QwtValueList | strip (const QwtValueList &, const QwtDoubleInterval &) const |
double | divideInterval (double interval, int numSteps) const |
QwtDoubleInterval | buildInterval (double v) const |
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.
QwtScaleEngine::QwtScaleEngine | ( | ) | [explicit] |
Constructor.
QwtScaleEngine::~QwtScaleEngine | ( | ) | [virtual] |
Destructor.
int QwtScaleEngine::attributes | ( | ) | const |
Return the scale attributes
virtual void QwtScaleEngine::autoScale | ( | int | maxNumSteps, | |
double & | x1, | |||
double & | x2, | |||
double & | stepSize | |||
) | const [pure virtual] |
Align and divide an interval
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.
QwtDoubleInterval 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 QwtDoubleInterval & | interval, | |
double | value | |||
) | const [protected] |
Check if an interval "contains" a value
interval | Interval | |
value | Value |
double QwtScaleEngine::divideInterval | ( | double | intervalSize, | |
int | numSteps | |||
) | const [protected] |
Calculate a step size for an interval size
intervalSize | Interval size | |
numSteps | Number of steps |
virtual QwtScaleDiv QwtScaleEngine::divideScale | ( | double | x1, | |
double | x2, | |||
int | maxMajSteps, | |||
int | maxMinSteps, | |||
double | stepSize = 0.0 | |||
) | const [pure virtual] |
Calculate a scale division.
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 |
double QwtScaleEngine::reference | ( | ) | const |
void QwtScaleEngine::setAttribute | ( | Attribute | attribute, | |
bool | on = true | |||
) |
Change a scale attribute
attribute | Attribute to change | |
on | On/Off |
void QwtScaleEngine::setAttributes | ( | int | attributes | ) |
Change the scale attribute
attributes | Set scale attributes |
void QwtScaleEngine::setMargins | ( | double | lower, | |
double | upper | |||
) |
Specify margins at the scale's endpoints.
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.
void QwtScaleEngine::setReference | ( | double | r | ) |
Specify a reference point.
r | new reference value |
The reference point is needed if options IncludeReference or Symmetric are active. Its default value is 0.0.
QwtValueList QwtScaleEngine::strip | ( | const QwtValueList & | ticks, | |
const QwtDoubleInterval & | interval | |||
) | const [protected] |
Remove ticks from a list, that are not inside an interval
ticks | Tick list | |
interval | Interval |
bool QwtScaleEngine::testAttribute | ( | Attribute | attribute | ) | const |
Check if a attribute is set.
attribute | Attribute to be tested |
virtual QwtScaleTransformation* QwtScaleEngine::transformation | ( | ) | const [pure virtual] |
Implemented in QwtLinearScaleEngine, and QwtLog10ScaleEngine.
double QwtScaleEngine::upperMargin | ( | ) | const |