Qwt User's Guide
6.0.2
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#include <qwt_scale_engine.h>
Public Types | |
enum | Attribute { NoAttribute = 0x00, IncludeReference = 0x01, Symmetric = 0x02, Floating = 0x04, Inverted = 0x08 } |
typedef QFlags< Attribute > | Attributes |
Public Member Functions | |
QwtScaleEngine () | |
virtual | ~QwtScaleEngine () |
Attributes | 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 (Attributes) |
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 | |
QwtInterval | buildInterval (double v) const |
bool | contains (const QwtInterval &, double val) const |
double | divideInterval (double interval, int numSteps) const |
QList< double > | strip (const QList< double > &, const QwtInterval &) const |
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 (log10) and linear scales. Contributions for other types of scale engines (date/time, log2 ... ) are welcome.
Layout attributes
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. |
QwtScaleEngine::Attributes QwtScaleEngine::attributes | ( | ) | const |
Return the scale attributes
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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 QwtLog10ScaleEngine, and QwtLinearScaleEngine.
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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]
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protected |
Check if an interval "contains" a value
interval | Interval |
value | Value |
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protected |
Calculate a step size for an interval size
intervalSize | Interval size |
numSteps | Number of steps |
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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 QwtLog10ScaleEngine, and QwtLinearScaleEngine.
double QwtScaleEngine::lowerMargin | ( | ) | const |
double QwtScaleEngine::reference | ( | ) | const |
void QwtScaleEngine::setAttribute | ( | Attribute | attribute, |
bool | on = true |
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) |
Change a scale attribute
attribute | Attribute to change |
on | On/Off |
void QwtScaleEngine::setAttributes | ( | Attributes | 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.
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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 |
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pure virtual |
Implemented in QwtLog10ScaleEngine, and QwtLinearScaleEngine.
double QwtScaleEngine::upperMargin | ( | ) | const |