QwtPlotTradingCurve(3)

NAME
QwtPlotTradingCurve -

QwtPlotTradingCurve illustrates movements in the price of a financial instrument over time.

SYNOPSIS

#include <qwt_plot_tradingcurve.h>

Inherits QwtPlotSeriesItem, and QwtSeriesStore< QwtOHLCSample >.

  Public Types
enum SymbolStyle { NoSymbol = -1, Bar, CandleStick, UserSymbol = 100 }
Symbol styles.
enum Direction { Increasing, Decreasing }
Direction of a price movement.
enum PaintAttribute { ClipSymbols = 0x01 }
typedef QFlags< PaintAttribute > PaintAttributes
Paint attributes.

  Public Member Functions
QwtPlotTradingCurve (const QString &title=QString::null)
QwtPlotTradingCurve (const QwtText &title)
virtual ~QwtPlotTradingCurve ()
Destructor.
virtual int rtti () const
void setPaintAttribute (PaintAttribute, bool on=true)
bool testPaintAttribute (PaintAttribute) const
void setSamples (const QVector< QwtOHLCSample > &)
void setSamples (QwtSeriesData< QwtOHLCSample > *)
void setSymbolStyle (SymbolStyle style)
SymbolStyle symbolStyle () const
void setSymbolPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
void setSymbolPen (const QPen &)
Set the symbol pen.
QPen symbolPen () const
void setSymbolBrush (Direction, const QBrush &)
QBrush symbolBrush (Direction) const
void setSymbolExtent (double width)
Set the extent of the symbol.
double symbolExtent () const
void setMinSymbolWidth (double)
double minSymbolWidth () const
void setMaxSymbolWidth (double)
double maxSymbolWidth () const
virtual void drawSeries (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual QRectF boundingRect () const
virtual QwtGraphic legendIcon (int index, const QSizeF &) const

  Protected Member Functions
void init ()
Initialize internal members.
virtual void drawSymbols (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual void drawUserSymbol (QPainter *, SymbolStyle, const QwtOHLCSample &, Qt::Orientation, bool inverted, double width) const
Draw a symbol for a symbol style >= UserSymbol.
void drawBar (QPainter *painter, const QwtOHLCSample &, Qt::Orientation, bool inverted, double width) const
Draw a bar.
void drawCandleStick (QPainter *, const QwtOHLCSample &, Qt::Orientation, double width) const
Draw a candle stick.
virtual double scaledSymbolWidth (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const

Detailed Description

QwtPlotTradingCurve illustrates movements in the price of a financial instrument over time. QwtPlotTradingCurve supports candlestick or bar ( OHLC ) charts that are used in the domain of technical analysis.

While the length ( height or width depending on orientation() ) of each symbol depends on the corresponding OHLC sample the size of the other dimension can be controlled using:

•   setSymbolExtent()

•   setSymbolMinWidth()

•   setSymbolMaxWidth()

The extent is a size in scale coordinates, so that the symbol width is increasing when the plot is zoomed in. Minimum/Maximum width is in widget coordinates independent from the zoom level. When setting the minimum and maximum to the same value, the width of the symbol is fixed.

Member Enumeration Documentation

  enum QwtPlotTradingCurve::Direction

Direction of a price movement.

Enumerator

Increasing
    The closing price is higher than the opening price.

Decreasing
    The closing price is lower than the opening price.

  enum QwtPlotTradingCurve::PaintAttribute
Attributes to modify the drawing algorithm.

See Also:
    setPaintAttribute(), testPaintAttribute()

Enumerator

ClipSymbols
    Check if a symbol is on the plot canvas before painting it.

  enum QwtPlotTradingCurve::SymbolStyle

Symbol styles. The default setting is QwtPlotSeriesItem::CandleStick.

See Also:
    setSymbolStyle(), symbolStyle()

Enumerator

NoSymbol
    Nothing is displayed.

Bar A line on the chart shows the price range (the highest and lowest prices) over one unit of time, e.g. one day or one hour. Tick marks project from each side of the line indicating the opening and closing price.

CandleStick
    The range between opening/closing price are displayed as a filled box. The fill brush depends on the direction of the price movement. The box is connected to the highest/lowest values by lines.

UserSymbol
    SymbolTypes >= UserSymbol are displayed by drawUserSymbol(), that needs to be overloaded and implemented in derived curve classes.

See Also:
    drawUserSymbol()

Constructor & Destructor Documentation

  QwtPlotTradingCurve::QwtPlotTradingCurve (const QString &title = QString::null) [explicit]
Constructor

Parameters:
    title Title of the curve

  QwtPlotTradingCurve::QwtPlotTradingCurve (const QwtText &title) [explicit]
Constructor

Parameters:
    title Title of the curve

Member Function Documentation

  QRectF QwtPlotTradingCurve::boundingRect () const [virtual]

Returns:
    Bounding rectangle of all samples. For an empty series the rectangle is invalid.

Reimplemented from QwtPlotSeriesItem.

  void QwtPlotTradingCurve::drawBar (QPainter *painter, const QwtOHLCSample &sample, Qt::Orientationorientation, boolinverted, doublewidth) const [protected]

Draw a bar.

Parameters:
    painter Qt painter, initialized with pen/brush
    sample Sample, already translated into paint device coordinates
    orientation Vertical or horizontal
    inverted When inverted is false the open tick is painted to the left/top, otherwise it is painted right/bottom. The close tick is painted in the opposite direction of the open tick. painted in the opposite d opposite direction.
    width Width or height of the candle, depending on the orientation

See Also:
    Bar

  void QwtPlotTradingCurve::drawCandleStick (QPainter *painter, const QwtOHLCSample &sample, Qt::Orientationorientation, doublewidth) const [protected]

Draw a candle stick.

Parameters:
    painter Qt painter, initialized with pen/brush
    sample Samples already translated into paint device coordinates
    orientation Vertical or horizontal
    width Width or height of the candle, depending on the orientation

See Also:
    CandleStick

  void QwtPlotTradingCurve::drawSeries (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, intfrom, intto) const [virtual]
Draw an interval of the curve

Parameters:
    painter Painter
    xMap Maps x-values into pixel coordinates.
    yMap Maps y-values into pixel coordinates.
    canvasRect Contents rectangle of the canvas
    from Index of the first point to be painted
    to Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

See Also:
    drawSymbols()

Implements QwtPlotSeriesItem.

  void QwtPlotTradingCurve::drawSymbols (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, intfrom, intto) const [protected], [virtual]
Draw symbols

Parameters:
    painter Painter
    xMap x map
    yMap y map
    canvasRect Contents rectangle of the canvas
    from Index of the first point to be painted
    to Index of the last point to be painted

See Also:
    drawSeries()

  void QwtPlotTradingCurve::drawUserSymbol (QPainter *painter, SymbolStylesymbolStyle, const QwtOHLCSample &sample, Qt::Orientationorientation, boolinverted, doublesymbolWidth) const [protected], [virtual]

Draw a symbol for a symbol style >= UserSymbol. The implementation does nothing and is intended to be overloaded

Parameters:
    painter Qt painter, initialized with pen/brush
    symbolStyle Symbol style
    sample Samples already translated into paint device coordinates
    orientation Vertical or horizontal
    inverted True, when the opposite scale ( Qt::Vertical: x, Qt::Horizontal: y ) is increasing in the opposite direction as QPainter coordinates.
    symbolWidth Width of the symbol in paint device coordinates

  QwtGraphic QwtPlotTradingCurve::legendIcon (intindex, const QSizeF &size) const [virtual]

Returns:
    A rectangle filled with the color of the symbol pen

Parameters:
    index Index of the legend entry ( usually there is only one )
    size Icon size

See Also:
    setLegendIconSize(), legendData()

Reimplemented from QwtPlotItem.

  double QwtPlotTradingCurve::maxSymbolWidth () const

Returns:
    Maximum for the symbol width

See Also:
    setMaxSymbolWidth(), minSymbolWidth(), symbolExtent()

  double QwtPlotTradingCurve::minSymbolWidth () const

Returns:
    Minmum for the symbol width

See Also:
    setMinSymbolWidth(), maxSymbolWidth(), symbolExtent()

  int QwtPlotTradingCurve::rtti () const [virtual]

Returns:
    QwtPlotItem::Rtti_PlotTradingCurve

Reimplemented from QwtPlotItem.

  double QwtPlotTradingCurve::scaledSymbolWidth (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const [protected], [virtual]
Calculate the symbol width in paint coordinates

The width is calculated by scaling the symbol extent into paint device coordinates bounded by the minimum/maximum symbol width.

Parameters:
    xMap Maps x-values into pixel coordinates.
    yMap Maps y-values into pixel coordinates.
    canvasRect Contents rectangle of the canvas

Returns:
    Symbol width in paint coordinates

See Also:
    symbolExtent(), minSymbolWidth(), maxSymbolWidth()

  void QwtPlotTradingCurve::setMaxSymbolWidth (doublewidth)
Set a maximum for the symbol width

A value <= 0.0 means an unlimited width

Parameters:
    width Width in paint device coordinates

See Also:
    maxSymbolWidth(), setMinSymbolWidth(), setSymbolExtent()

  void QwtPlotTradingCurve::setMinSymbolWidth (doublewidth)
Set a minimum for the symbol width

Parameters:
    width Width in paint device coordinates

See Also:
    minSymbolWidth(), setMaxSymbolWidth(), setSymbolExtent()

  void QwtPlotTradingCurve::setPaintAttribute (PaintAttributeattribute, boolon = true)
Specify an attribute how to draw the curve

Parameters:
    attribute Paint attribute
    on On/Off

See Also:
    testPaintAttribute()

  void QwtPlotTradingCurve::setSamples (const QVector< QwtOHLCSample > &samples)
Initialize data with an array of samples.

Parameters:
    samples Vector of samples

See Also:
    QwtPlotSeriesItem::setData()

  void QwtPlotTradingCurve::setSamples (QwtSeriesData< QwtOHLCSample > *data)
Assign a series of samples

setSamples() is just a wrapper for setData() without any additional value - beside that it is easier to find for the developer.

Parameters:
    data Data

Warning:
    The item takes ownership of the data object, deleting it when its not used anymore.

  void QwtPlotTradingCurve::setSymbolBrush (Directiondirection, const QBrush &brush)
Set the symbol brush

Parameters:
    direction Direction type
    brush Brush used to fill the body of all candlestick symbols with the direction

See Also:
    symbolBrush(), setSymbolPen()

  void QwtPlotTradingCurve::setSymbolExtent (doubleextent)

Set the extent of the symbol. The width of the symbol is given in scale coordinates. When painting a symbol the width is scaled into paint device coordinates by scaledSymbolWidth(). The scaled width is bounded by minSymbolWidth(), maxSymbolWidth()

Parameters:
    extent Symbol width in scale coordinates

See Also:
    symbolExtent(), scaledSymbolWidth(), setMinSymbolWidth(), setMaxSymbolWidth()

  void QwtPlotTradingCurve::setSymbolPen (const QColor &color, qrealwidth = 0.0, Qt::PenStylestyle = Qt::SolidLine)
Build and assign the symbol pen

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic ( see QPen::isCosmetic() ). This method has been introduced to hide this incompatibility.

Parameters:
    color Pen color
    width Pen width
    style Pen style

See Also:
    pen(), brush()

  void QwtPlotTradingCurve::setSymbolPen (const QPen &pen)

Set the symbol pen. The symbol pen is used for rendering the lines of the bar or candlestick symbols

See Also:
    symbolPen(), setSymbolBrush()

  void QwtPlotTradingCurve::setSymbolStyle (SymbolStylestyle)
Set the symbol style

Parameters:
    style Symbol style

See Also:
    symbolStyle(), setSymbolExtent(), setSymbolPen(), setSymbolBrush()

  QBrush QwtPlotTradingCurve::symbolBrush (Directiondirection) const

Parameters:
    direction

Returns:
    Brush used to fill the body of all candlestick symbols with the direction

See Also:
    setSymbolPen(), symbolBrush()

  double QwtPlotTradingCurve::symbolExtent () const

Returns:
    Extent of a symbol in scale coordinates

See Also:
    setSymbolExtent(), scaledSymbolWidth(), minSymbolWidth(), maxSymbolWidth()

  QPen QwtPlotTradingCurve::symbolPen () const

Returns:
    Symbol pen

See Also:
    setSymbolPen(), symbolBrush()

  QwtPlotTradingCurve::SymbolStyle QwtPlotTradingCurve::symbolStyle () const

Returns:
    Symbol style

See Also:
    setSymbolStyle(), symbolExtent(), symbolPen(), symbolBrush()

  bool QwtPlotTradingCurve::testPaintAttribute (PaintAttributeattribute) const

Returns:
    True, when attribute is enabled

See Also:
    PaintAttribute, setPaintAttribute()

Author

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