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QCPCurve Class Reference

A plottable representing a parametric curve in a plot. More...

Inheritance diagram for QCPCurve:
Inheritance graph

Public Types

enum  LineStyle
 

Public Functions

 QCPCurve (QCPAxis *keyAxis, QCPAxis *valueAxis)
 
QSharedPointer< QCPCurveDataContainerdata () const
 
QCPScatterStyle scatterStyle () const
 
int scatterSkip () const
 
LineStyle lineStyle () const
 
void setData (QSharedPointer< QCPCurveDataContainer > data)
 
void setData (const QVector< double > &t, const QVector< double > &keys, const QVector< double > &values, bool alreadySorted=false)
 
void setData (const QVector< double > &keys, const QVector< double > &values)
 
void setScatterStyle (const QCPScatterStyle &style)
 
void setScatterSkip (int skip)
 
void setLineStyle (LineStyle style)
 
void addData (const QVector< double > &t, const QVector< double > &keys, const QVector< double > &values, bool alreadySorted=false)
 
void addData (const QVector< double > &keys, const QVector< double > &values)
 
void addData (double t, double key, double value)
 
void addData (double key, double value)
 
virtual double selectTest (const QPointF &pos, bool onlySelectable, QVariant *details=0) const
 
virtual QCPRange getKeyRange (bool &foundRange, QCP::SignDomain inSignDomain=QCP::sdBoth) const
 
virtual QCPRange getValueRange (bool &foundRange, QCP::SignDomain inSignDomain=QCP::sdBoth, const QCPRange &inKeyRange=QCPRange()) const
 
- Public Functions inherited from QCPAbstractPlottable1D< QCPCurveData >
 QCPAbstractPlottable1D (QCPAxis *keyAxis, QCPAxis *valueAxis)
 
virtual int dataCount () const
 
virtual double dataMainKey (int index) const
 
virtual double dataSortKey (int index) const
 
virtual double dataMainValue (int index) const
 
virtual QCPRange dataValueRange (int index) const
 
virtual QPointF dataPixelPosition (int index) const
 
virtual bool sortKeyIsMainKey () const
 
virtual QCPDataSelection selectTestRect (const QRectF &rect, bool onlySelectable) const
 
virtual int findBegin (double sortKey, bool expandedRange=true) const
 
virtual int findEnd (double sortKey, bool expandedRange=true) const
 
virtual QCPPlottableInterface1Dinterface1D ()
 
- Public Functions inherited from QCPAbstractPlottable
 QCPAbstractPlottable (QCPAxis *keyAxis, QCPAxis *valueAxis)
 
QString name () const
 
bool antialiasedFill () const
 
bool antialiasedScatters () const
 
QPen pen () const
 
QBrush brush () const
 
QCPAxiskeyAxis () const
 
QCPAxisvalueAxis () const
 
QCP::SelectionType selectable () const
 
bool selected () const
 
QCPDataSelection selection () const
 
QCPSelectionDecoratorselectionDecorator () const
 
void setName (const QString &name)
 
void setAntialiasedFill (bool enabled)
 
void setAntialiasedScatters (bool enabled)
 
void setPen (const QPen &pen)
 
void setBrush (const QBrush &brush)
 
void setKeyAxis (QCPAxis *axis)
 
void setValueAxis (QCPAxis *axis)
 
Q_SLOT void setSelectable (QCP::SelectionType selectable)
 
Q_SLOT void setSelection (QCPDataSelection selection)
 
void setSelectionDecorator (QCPSelectionDecorator *decorator)
 
void coordsToPixels (double key, double value, double &x, double &y) const
 
const QPointF coordsToPixels (double key, double value) const
 
void pixelsToCoords (double x, double y, double &key, double &value) const
 
void pixelsToCoords (const QPointF &pixelPos, double &key, double &value) const
 
void rescaleAxes (bool onlyEnlarge=false) const
 
void rescaleKeyAxis (bool onlyEnlarge=false) const
 
void rescaleValueAxis (bool onlyEnlarge=false, bool inKeyRange=false) const
 
bool addToLegend (QCPLegend *legend)
 
bool addToLegend ()
 
bool removeFromLegend (QCPLegend *legend) const
 
bool removeFromLegend () const
 
- Public Functions inherited from QCPLayerable
 QCPLayerable (QCustomPlot *plot, QString targetLayer=QString(), QCPLayerable *parentLayerable=0)
 
bool visible () const
 
QCustomPlotparentPlot () const
 
QCPLayerableparentLayerable () const
 
QCPLayerlayer () const
 
bool antialiased () const
 
void setVisible (bool on)
 
Q_SLOT bool setLayer (QCPLayer *layer)
 
bool setLayer (const QString &layerName)
 
void setAntialiased (bool enabled)
 
bool realVisibility () const
 

Protected Functions

virtual void draw (QCPPainter *painter)
 
virtual void drawLegendIcon (QCPPainter *painter, const QRectF &rect) const
 
virtual void drawCurveLine (QCPPainter *painter, const QVector< QPointF > &lines) const
 
virtual void drawScatterPlot (QCPPainter *painter, const QVector< QPointF > &points, const QCPScatterStyle &style) const
 
void getCurveLines (QVector< QPointF > *lines, const QCPDataRange &dataRange, double penWidth) const
 
void getScatters (QVector< QPointF > *scatters, const QCPDataRange &dataRange, double scatterWidth) const
 
int getRegion (double key, double value, double keyMin, double valueMax, double keyMax, double valueMin) const
 
QPointF getOptimizedPoint (int prevRegion, double prevKey, double prevValue, double key, double value, double keyMin, double valueMax, double keyMax, double valueMin) const
 
QVector< QPointF > getOptimizedCornerPoints (int prevRegion, int currentRegion, double prevKey, double prevValue, double key, double value, double keyMin, double valueMax, double keyMax, double valueMin) const
 
bool mayTraverse (int prevRegion, int currentRegion) const
 
bool getTraverse (double prevKey, double prevValue, double key, double value, double keyMin, double valueMax, double keyMax, double valueMin, QPointF &crossA, QPointF &crossB) const
 
void getTraverseCornerPoints (int prevRegion, int currentRegion, double keyMin, double valueMax, double keyMax, double valueMin, QVector< QPointF > &beforeTraverse, QVector< QPointF > &afterTraverse) const
 
double pointDistance (const QPointF &pixelPoint, QCPCurveDataContainer::const_iterator &closestData) const
 
- Protected Functions inherited from QCPAbstractPlottable1D< QCPCurveData >
void getDataSegments (QList< QCPDataRange > &selectedSegments, QList< QCPDataRange > &unselectedSegments) const
 
void drawPolyline (QCPPainter *painter, const QVector< QPointF > &lineData) const
 
- Protected Functions inherited from QCPAbstractPlottable
virtual QRect clipRect () const
 
virtual QCP::Interaction selectionCategory () const
 
void applyDefaultAntialiasingHint (QCPPainter *painter) const
 
virtual void selectEvent (QMouseEvent *event, bool additive, const QVariant &details, bool *selectionStateChanged)
 
virtual void deselectEvent (bool *selectionStateChanged)
 
void applyFillAntialiasingHint (QCPPainter *painter) const
 
void applyScattersAntialiasingHint (QCPPainter *painter) const
 
- Protected Functions inherited from QCPLayerable
virtual void parentPlotInitialized (QCustomPlot *parentPlot)
 
virtual void mousePressEvent (QMouseEvent *event, const QVariant &details)
 
virtual void mouseMoveEvent (QMouseEvent *event, const QPointF &startPos)
 
virtual void mouseReleaseEvent (QMouseEvent *event, const QPointF &startPos)
 
virtual void mouseDoubleClickEvent (QMouseEvent *event, const QVariant &details)
 
virtual void wheelEvent (QWheelEvent *event)
 
void initializeParentPlot (QCustomPlot *parentPlot)
 
void setParentLayerable (QCPLayerable *parentLayerable)
 
bool moveToLayer (QCPLayer *layer, bool prepend)
 
void applyAntialiasingHint (QCPPainter *painter, bool localAntialiased, QCP::AntialiasedElement overrideElement) const
 

Additional Inherited Members

- Signals inherited from QCPAbstractPlottable
void selectionChanged (bool selected)
 
void selectionChanged (const QCPDataSelection &selection)
 
void selectableChanged (QCP::SelectionType selectable)
 
- Signals inherited from QCPLayerable
void layerChanged (QCPLayer *newLayer)
 

Detailed Description

A plottable representing a parametric curve in a plot.

QCPCurve.png

Unlike QCPGraph, plottables of this type may have multiple points with the same key coordinate, so their visual representation can have loops. This is realized by introducing a third coordinate t, which defines the order of the points described by the other two coordinates x and y.

To plot data, assign it with the setData or addData functions. Alternatively, you can also access and modify the curve's data via the data method, which returns a pointer to the internal QCPCurveDataContainer.

Gaps in the curve can be created by adding data points with NaN as key and value (qQNaN() or std::numeric_limits<double>::quiet_NaN()) in between the two data points that shall be separated.

Changing the appearance

The appearance of the curve is determined by the pen and the brush (setPen, setBrush).

Usage

Like all data representing objects in QCustomPlot, the QCPCurve is a plottable (QCPAbstractPlottable). So the plottable-interface of QCustomPlot applies (QCustomPlot::plottable, QCustomPlot::removePlottable, etc.)

Usually, you first create an instance:

QCPCurve *newCurve = new QCPCurve(customPlot->xAxis, customPlot->yAxis);

which registers it with the QCustomPlot instance of the passed axes. Note that this QCustomPlot instance takes ownership of the plottable, so do not delete it manually but use QCustomPlot::removePlottable() instead. The newly created plottable can be modified, e.g.:

newCurve->setName("Fermat's Spiral");
newCurve->setData(tData, xData, yData);

Member Enumeration Documentation

§ LineStyle

Defines how the curve's line is represented visually in the plot. The line is drawn with the current pen of the curve (setPen).

See also
setLineStyle
Enumerator
lsNone 

No line is drawn between data points (e.g. only scatters)

lsLine 

Data points are connected with a straight line.

Constructor & Destructor Documentation

§ QCPCurve()

QCPCurve::QCPCurve ( QCPAxis keyAxis,
QCPAxis valueAxis 
)
explicit

Constructs a curve which uses keyAxis as its key axis ("x") and valueAxis as its value axis ("y"). keyAxis and valueAxis must reside in the same QCustomPlot instance and not have the same orientation. If either of these restrictions is violated, a corresponding message is printed to the debug output (qDebug), the construction is not aborted, though.

The created QCPCurve is automatically registered with the QCustomPlot instance inferred from keyAxis. This QCustomPlot instance takes ownership of the QCPCurve, so do not delete it manually but use QCustomPlot::removePlottable() instead.

Member Function Documentation

§ data()

QSharedPointer< QCPCurveDataContainer > QCPCurve::data ( ) const
inline

Returns a shared pointer to the internal data storage of type QCPCurveDataContainer. You may use it to directly manipulate the data, which may be more convenient and faster than using the regular setData or addData methods.

§ setData() [1/3]

void QCPCurve::setData ( QSharedPointer< QCPCurveDataContainer data)

This is an overloaded function.

Replaces the current data container with the provided data container.

Since a QSharedPointer is used, multiple QCPCurves may share the same data container safely. Modifying the data in the container will then affect all curves that share the container. Sharing can be achieved by simply exchanging the data containers wrapped in shared pointers:

curve2->setData(curve1->data()); // curve1 and curve2 now share data container

If you do not wish to share containers, but create a copy from an existing container, rather use the QCPDataContainer<DataType>::set method on the curve's data container directly:

curve2->data()->set(*curve1->data()); // curve2 now has copy of curve1's data in its container
See also
addData

§ setData() [2/3]

void QCPCurve::setData ( const QVector< double > &  t,
const QVector< double > &  keys,
const QVector< double > &  values,
bool  alreadySorted = false 
)

This is an overloaded function.

Replaces the current data with the provided points in t, keys and values. The provided vectors should have equal length. Else, the number of added points will be the size of the smallest vector.

If you can guarantee that the passed data points are sorted by t in ascending order, you can set alreadySorted to true, to improve performance by saving a sorting run.

See also
addData

§ setData() [3/3]

void QCPCurve::setData ( const QVector< double > &  keys,
const QVector< double > &  values 
)

This is an overloaded function.

Replaces the current data with the provided points in keys and values. The provided vectors should have equal length. Else, the number of added points will be the size of the smallest vector.

The t parameter of each data point will be set to the integer index of the respective key/value pair.

See also
addData

§ setScatterStyle()

void QCPCurve::setScatterStyle ( const QCPScatterStyle style)

Sets the visual appearance of single data points in the plot. If set to QCPScatterStyle::ssNone, no scatter points are drawn (e.g. for line-only plots with appropriate line style).

See also
QCPScatterStyle, setLineStyle

§ setScatterSkip()

void QCPCurve::setScatterSkip ( int  skip)

If scatters are displayed (scatter style not QCPScatterStyle::ssNone), skip number of scatter points are skipped/not drawn after every drawn scatter point.

This can be used to make the data appear sparser while for example still having a smooth line, and to improve performance for very high density plots.

If skip is set to 0 (default), all scatter points are drawn.

See also
setScatterStyle

§ setLineStyle()

void QCPCurve::setLineStyle ( QCPCurve::LineStyle  style)

Sets how the single data points are connected in the plot or how they are represented visually apart from the scatter symbol. For scatter-only plots, set style to lsNone and setScatterStyle to the desired scatter style.

See also
setScatterStyle

§ addData() [1/4]

void QCPCurve::addData ( const QVector< double > &  t,
const QVector< double > &  keys,
const QVector< double > &  values,
bool  alreadySorted = false 
)

This is an overloaded function.

Adds the provided points in t, keys and values to the current data. The provided vectors should have equal length. Else, the number of added points will be the size of the smallest vector.

If you can guarantee that the passed data points are sorted by keys in ascending order, you can set alreadySorted to true, to improve performance by saving a sorting run.

Alternatively, you can also access and modify the data directly via the data method, which returns a pointer to the internal data container.

§ addData() [2/4]

void QCPCurve::addData ( const QVector< double > &  keys,
const QVector< double > &  values 
)

This is an overloaded function.

Adds the provided points in keys and values to the current data. The provided vectors should have equal length. Else, the number of added points will be the size of the smallest vector.

The t parameter of each data point will be set to the integer index of the respective key/value pair.

Alternatively, you can also access and modify the data directly via the data method, which returns a pointer to the internal data container.

§ addData() [3/4]

void QCPCurve::addData ( double  t,
double  key,
double  value 
)

This is an overloaded function. Adds the provided data point as t, key and value to the current data.

Alternatively, you can also access and modify the data directly via the data method, which returns a pointer to the internal data container.

§ addData() [4/4]

void QCPCurve::addData ( double  key,
double  value 
)

This is an overloaded function.

Adds the provided data point as key and value to the current data.

The t parameter is generated automatically by increments of 1 for each point, starting at the highest t of previously existing data or 0, if the curve data is empty.

Alternatively, you can also access and modify the data directly via the data method, which returns a pointer to the internal data container.

§ selectTest()

double QCPCurve::selectTest ( const QPointF &  pos,
bool  onlySelectable,
QVariant *  details = 0 
) const
virtual

Implements a point-selection algorithm assuming the data (accessed via the 1D data interface) is point-like. Most subclasses will want to reimplement this method again, to provide a more accurate hit test based on the true data visualization geometry.

For general information about this virtual method, see the base class implementation.

Reimplemented from QCPAbstractPlottable1D< QCPCurveData >.

§ getKeyRange()

QCPRange QCPCurve::getKeyRange ( bool &  foundRange,
QCP::SignDomain  inSignDomain = QCP::sdBoth 
) const
virtual

Returns the coordinate range that all data in this plottable span in the key axis dimension. For logarithmic plots, one can set inSignDomain to either QCP::sdNegative or QCP::sdPositive in order to restrict the returned range to that sign domain. E.g. when only negative range is wanted, set inSignDomain to QCP::sdNegative and all positive points will be ignored for range calculation. For no restriction, just set inSignDomain to QCP::sdBoth (default). foundRange is an output parameter that indicates whether a range could be found or not. If this is false, you shouldn't use the returned range (e.g. no points in data).

Note that foundRange is not the same as QCPRange::validRange, since the range returned by this function may have size zero (e.g. when there is only one data point). In this case foundRange would return true, but the returned range is not a valid range in terms of QCPRange::validRange.

See also
rescaleAxes, getValueRange

Implements QCPAbstractPlottable.

§ getValueRange()

QCPRange QCPCurve::getValueRange ( bool &  foundRange,
QCP::SignDomain  inSignDomain = QCP::sdBoth,
const QCPRange inKeyRange = QCPRange() 
) const
virtual

Returns the coordinate range that the data points in the specified key range (inKeyRange) span in the value axis dimension. For logarithmic plots, one can set inSignDomain to either QCP::sdNegative or QCP::sdPositive in order to restrict the returned range to that sign domain. E.g. when only negative range is wanted, set inSignDomain to QCP::sdNegative and all positive points will be ignored for range calculation. For no restriction, just set inSignDomain to QCP::sdBoth (default). foundRange is an output parameter that indicates whether a range could be found or not. If this is false, you shouldn't use the returned range (e.g. no points in data).

If inKeyRange has both lower and upper bound set to zero (is equal to QCPRange()), all data points are considered, without any restriction on the keys.

Note that foundRange is not the same as QCPRange::validRange, since the range returned by this function may have size zero (e.g. when there is only one data point). In this case foundRange would return true, but the returned range is not a valid range in terms of QCPRange::validRange.

See also
rescaleAxes, getKeyRange

Implements QCPAbstractPlottable.

§ draw()

void QCPCurve::draw ( QCPPainter painter)
protectedvirtual

This function draws the layerable with the specified painter. It is only called by QCustomPlot, if the layerable is visible (setVisible).

Before this function is called, the painter's antialiasing state is set via applyDefaultAntialiasingHint, see the documentation there. Further, the clipping rectangle was set to clipRect.

Implements QCPAbstractPlottable.

§ drawLegendIcon()

void QCPCurve::drawLegendIcon ( QCPPainter painter,
const QRectF &  rect 
) const
protectedvirtual

called by QCPLegend::draw (via QCPPlottableLegendItem::draw) to create a graphical representation of this plottable inside rect, next to the plottable name.

The passed painter has its cliprect set to rect, so painting outside of rect won't appear outside the legend icon border.

Implements QCPAbstractPlottable.

§ drawCurveLine()

void QCPCurve::drawCurveLine ( QCPPainter painter,
const QVector< QPointF > &  lines 
) const
protectedvirtual

Draws lines between the points in lines, given in pixel coordinates.

See also
drawScatterPlot, getCurveLines

§ drawScatterPlot()

void QCPCurve::drawScatterPlot ( QCPPainter painter,
const QVector< QPointF > &  points,
const QCPScatterStyle style 
) const
protectedvirtual

Draws scatter symbols at every point passed in points, given in pixel coordinates. The scatters will be drawn with painter and have the appearance as specified in style.

See also
drawCurveLine, getCurveLines

§ getCurveLines()

void QCPCurve::getCurveLines ( QVector< QPointF > *  lines,
const QCPDataRange dataRange,
double  penWidth 
) const
protected

Called by draw to generate points in pixel coordinates which represent the line of the curve.

Line segments that aren't visible in the current axis rect are handled in an optimized way. They are projected onto a rectangle slightly larger than the visible axis rect and simplified regarding point count. The algorithm makes sure to preserve appearance of lines and fills inside the visible axis rect by generating new temporary points on the outer rect if necessary.

lines will be filled with points in pixel coordinates, that can be drawn with drawCurveLine.

dataRange specifies the beginning and ending data indices that will be taken into account for conversion. In this function, the specified range may exceed the total data bounds without harm: a correspondingly trimmed data range will be used. This takes the burden off the user of this function to check for valid indices in dataRange, e.g. when extending ranges coming from getDataSegments.

penWidth specifies the pen width that will be used to later draw the lines generated by this function. This is needed here to calculate an accordingly wider margin around the axis rect when performing the line optimization.

Methods that are also involved in the algorithm are: getRegion, getOptimizedPoint, getOptimizedCornerPoints mayTraverse, getTraverse, getTraverseCornerPoints.

See also
drawCurveLine, drawScatterPlot

§ getScatters()

void QCPCurve::getScatters ( QVector< QPointF > *  scatters,
const QCPDataRange dataRange,
double  scatterWidth 
) const
protected

Called by draw to generate points in pixel coordinates which represent the scatters of the curve. If a scatter skip is configured (setScatterSkip), the returned points are accordingly sparser.

Scatters that aren't visible in the current axis rect are optimized away.

scatters will be filled with points in pixel coordinates, that can be drawn with drawScatterPlot.

dataRange specifies the beginning and ending data indices that will be taken into account for conversion.

scatterWidth specifies the scatter width that will be used to later draw the scatters at pixel coordinates generated by this function. This is needed here to calculate an accordingly wider margin around the axis rect when performing the data point reduction.

See also
draw, drawScatterPlot

§ getRegion()

int QCPCurve::getRegion ( double  key,
double  value,
double  keyMin,
double  valueMax,
double  keyMax,
double  valueMin 
) const
protected

This function is part of the curve optimization algorithm of getCurveLines.

It returns the region of the given point (key, value) with respect to a rectangle defined by keyMin, keyMax, valueMin, and valueMax.

The regions are enumerated from top to bottom (valueMin to valueMax) and left to right (keyMin to keyMax):

147
258
369

With the rectangle being region 5, and the outer regions extending infinitely outwards. In the curve optimization algorithm, region 5 is considered to be the visible portion of the plot.

§ getOptimizedPoint()

QPointF QCPCurve::getOptimizedPoint ( int  otherRegion,
double  otherKey,
double  otherValue,
double  key,
double  value,
double  keyMin,
double  valueMax,
double  keyMax,
double  valueMin 
) const
protected

This function is part of the curve optimization algorithm of getCurveLines.

This method is used in case the current segment passes from inside the visible rect (region 5, see getRegion) to any of the outer regions (otherRegion). The current segment is given by the line connecting (key, value) with (otherKey, otherValue).

It returns the intersection point of the segment with the border of region 5.

For this function it doesn't matter whether (key, value) is the point inside region 5 or whether it's (otherKey, otherValue), i.e. whether the segment is coming from region 5 or leaving it. It is important though that otherRegion correctly identifies the other region not equal to 5.

§ getOptimizedCornerPoints()

QVector< QPointF > QCPCurve::getOptimizedCornerPoints ( int  prevRegion,
int  currentRegion,
double  prevKey,
double  prevValue,
double  key,
double  value,
double  keyMin,
double  valueMax,
double  keyMax,
double  valueMin 
) const
protected

This function is part of the curve optimization algorithm of getCurveLines.

In situations where a single segment skips over multiple regions it might become necessary to add extra points at the corners of region 5 (see getRegion) such that the optimized segment doesn't unintentionally cut through the visible area of the axis rect and create plot artifacts. This method provides these points that must be added, assuming the original segment doesn't start, end, or traverse region 5. (Corner points where region 5 is traversed are calculated by getTraverseCornerPoints.)

For example, consider a segment which directly goes from region 4 to 2 but originally is far out to the top left such that it doesn't cross region 5. Naively optimizing these points by projecting them on the top and left borders of region 5 will create a segment that surely crosses 5, creating a visual artifact in the plot. This method prevents this by providing extra points at the top left corner, making the optimized curve correctly pass from region 4 to 1 to 2 without traversing 5.

§ mayTraverse()

bool QCPCurve::mayTraverse ( int  prevRegion,
int  currentRegion 
) const
protected

This function is part of the curve optimization algorithm of getCurveLines.

This method returns whether a segment going from prevRegion to currentRegion (see getRegion) may traverse the visible region 5. This function assumes that neither prevRegion nor currentRegion is 5 itself.

If this method returns false, the segment for sure doesn't pass region 5. If it returns true, the segment may or may not pass region 5 and a more fine-grained calculation must be used (getTraverse).

§ getTraverse()

bool QCPCurve::getTraverse ( double  prevKey,
double  prevValue,
double  key,
double  value,
double  keyMin,
double  valueMax,
double  keyMax,
double  valueMin,
QPointF &  crossA,
QPointF &  crossB 
) const
protected

This function is part of the curve optimization algorithm of getCurveLines.

This method assumes that the mayTraverse test has returned true, so there is a chance the segment defined by (prevKey, prevValue) and (key, value) goes through the visible region 5.

The return value of this method indicates whether the segment actually traverses region 5 or not.

If the segment traverses 5, the output parameters crossA and crossB indicate the entry and exit points of region 5. They will become the optimized points for that segment.

§ getTraverseCornerPoints()

void QCPCurve::getTraverseCornerPoints ( int  prevRegion,
int  currentRegion,
double  keyMin,
double  valueMax,
double  keyMax,
double  valueMin,
QVector< QPointF > &  beforeTraverse,
QVector< QPointF > &  afterTraverse 
) const
protected

This function is part of the curve optimization algorithm of getCurveLines.

This method assumes that the getTraverse test has returned true, so the segment definitely traverses the visible region 5 when going from prevRegion to currentRegion.

In certain situations it is not sufficient to merely generate the entry and exit points of the segment into/out of region 5, as getTraverse provides. It may happen that a single segment, in addition to traversing region 5, skips another region outside of region 5, which makes it necessary to add an optimized corner point there (very similar to the job getOptimizedCornerPoints does for segments that are completely in outside regions and don't traverse 5).

As an example, consider a segment going from region 1 to region 6, traversing the lower left corner of region 5. In this configuration, the segment additionally crosses the border between region 1 and 2 before entering region 5. This makes it necessary to add an additional point in the top left corner, before adding the optimized traverse points. So in this case, the output parameter beforeTraverse will contain the top left corner point, and afterTraverse will be empty.

In some cases, such as when going from region 1 to 9, it may even be necessary to add additional corner points before and after the traverse. Then both beforeTraverse and afterTraverse return the respective corner points.

§ pointDistance()

double QCPCurve::pointDistance ( const QPointF &  pixelPoint,
QCPCurveDataContainer::const_iterator &  closestData 
) const
protected

Calculates the (minimum) distance (in pixels) the curve's representation has from the given pixelPoint in pixels. This is used to determine whether the curve was clicked or not, e.g. in selectTest. The closest data point to pixelPoint is returned in closestData. Note that if the curve has a line representation, the returned distance may be smaller than the distance to the closestData point, since the distance to the curve line is also taken into account.

If either the curve has no data or if the line style is lsNone and the scatter style's shape is QCPScatterStyle::ssNone (i.e. there is no visual representation of the curve), returns -1.0.


The documentation for this class was generated from the following files: