Qwt User's Guide 6.1.2

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QwtPlotScaleItem Class Reference

A class which draws a scale inside the plot canvas. More...

`#include <qwt_plot_scaleitem.h>`

Inheritance diagram for QwtPlotScaleItem:
[legend]

## Public Member Functions
| QwtPlotScaleItem (QwtScaleDraw::Alignment=QwtScaleDraw::BottomScale, const double pos=0.0)
| Constructor for scale item at the position pos. More...
virtual | ~QwtPlotScaleItem ()
| Destructor.
virtual int | rtti () const
void | setScaleDiv (const QwtScaleDiv &)
| Assign a scale division. More...
const QwtScaleDiv & | scaleDiv () const
void | setScaleDivFromAxis (bool on)
bool | isScaleDivFromAxis () const
void | setPalette (const QPalette &)
QPalette | palette () const
void | setFont (const QFont &)
QFont | font () const
void | setScaleDraw (QwtScaleDraw *)
| Set a scale draw. More...
const QwtScaleDraw * | scaleDraw () const
QwtScaleDraw * | scaleDraw ()
void | setPosition (double pos)
double | position () const
void | setBorderDistance (int numPixels)
| Align the scale to the canvas. More...
int | borderDistance () const
void | setAlignment (QwtScaleDraw::Alignment)
virtual void | draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &rect) const
| Draw the scale.
virtual void | updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
| Update the item to changes of the axes scale division. More...
Public Member Functions inherited from QwtPlotItem
| QwtPlotItem (const QwtText &title=QwtText())
virtual | ~QwtPlotItem ()
| Destroy the QwtPlotItem.
void | attach (QwtPlot *plot)
| Attach the item to a plot. More...
void | detach ()
| This method detaches a QwtPlotItem from any QwtPlot it has been associated with. More...
QwtPlot * | plot () const
| Return attached plot.
void | setTitle (const QString &title)
void | setTitle (const QwtText &title)
const QwtText & | title () const
void | setItemAttribute (ItemAttribute, bool on=true)
bool | testItemAttribute (ItemAttribute) const
void | setItemInterest (ItemInterest, bool on=true)
bool | testItemInterest (ItemInterest) const
void | setRenderHint (RenderHint, bool on=true)
bool | testRenderHint (RenderHint) const
void | setRenderThreadCount (uint numThreads)
uint | renderThreadCount () const
void | setLegendIconSize (const QSize &)
QSize | legendIconSize () const
double | z () const
void | setZ (double z)
| Set the z value. More...
void | show ()
| Show the item.
void | hide ()
| Hide the item.
virtual void | setVisible (bool)
bool | isVisible () const
void | setAxes (int xAxis, int yAxis)
void | setXAxis (int axis)
int | xAxis () const
| Return xAxis.
void | setYAxis (int axis)
int | yAxis () const
| Return yAxis.
virtual void | itemChanged ()
virtual void | legendChanged ()
virtual QRectF | boundingRect () const
virtual void | getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasSize, double &left, double &top, double &right, double &bottom) const
| Calculate a hint for the canvas margin. More...
virtual void | updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
| Update the item to changes of the legend info. More...
QRectF | scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
| Calculate the bounding scale rectangle of 2 maps. More...
QRectF | paintRect (const QwtScaleMap &, const QwtScaleMap &) const
| Calculate the bounding paint rectangle of 2 maps. More...
virtual QList< QwtLegendData > | legendData () const
| Return all information, that is needed to represent the item on the legend. More...
virtual QwtGraphic | legendIcon (int index, const QSizeF &) const

## Additional Inherited Members
Public Types inherited from QwtPlotItem
enum | RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotLegend, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG, Rtti_PlotTradingCurve, Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape, Rtti_PlotTextLabel, Rtti_PlotZone, Rtti_PlotUserItem = 1000 }
| Runtime type information. More...
enum | ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 }
| Plot Item Attributes. More...
enum | ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 }
| Plot Item Interests. More...
enum | RenderHint { RenderAntialiased = 0x1 }
| Render hints. More...
typedef QFlags< ItemAttribute > | ItemAttributes
| Plot Item Attributes.
typedef QFlags< ItemInterest > | ItemInterests
| Plot Item Interests.
typedef QFlags< RenderHint > | RenderHints
| Render hints.
Protected Member Functions inherited from QwtPlotItem
QwtGraphic | defaultIcon (const QBrush &, const QSizeF &) const
| Return a default icon from a brush. More...

## Detailed Description

A class which draws a scale inside the plot canvas.

QwtPlotScaleItem can be used to draw an axis inside the plot canvas. It might by synchronized to one of the axis of the plot, but can also display its own ticks and labels.

It is allowed to synchronize the scale item with a disabled axis. In plots with vertical and horizontal scale items, it might be necessary to remove ticks at the intersections, by overloading updateScaleDiv().

The scale might be at a specific position (f.e 0.0) or it might be aligned to a canvas border.

Example
  The following example shows how to replace the left axis, by a scale item at the x position 0.0.

      QwtPlotScaleItem *scaleItem =
          new QwtPlotScaleItem(QwtScaleDraw::RightScale, 0.0);
      scaleItem->setFont(plot->axisWidget(QwtPlot::yLeft)->font());
      scaleItem->attach(plot);

      plot->enableAxis(QwtPlot::yLeft, false);

## Constructor & Destructor Documentation

QwtPlotScaleItem::QwtPlotScaleItem | ( | QwtScaleDraw::Alignment | alignment = `QwtScaleDraw::BottomScale`,
|  | const double | pos = `0.0`
| ) |  |
| explicit

Constructor for scale item at the position pos.

Parameters

  alignment | In case of QwtScaleDraw::BottomScale or QwtScaleDraw::TopScale the scale item is corresponding to the xAxis(), otherwise it corresponds to the yAxis().
  pos | x or y position, depending on the corresponding axis.

See Also
  setPosition(), setAlignment()

## Member Function Documentation

int QwtPlotScaleItem::borderDistance | ( |  | ) | const

Returns
  Distance from a canvas border

See Also
  setBorderDistance(), setPosition()

QFont QwtPlotScaleItem::font | ( |  | ) | const

Returns
  tick label font

See Also
  setFont()

bool QwtPlotScaleItem::isScaleDivFromAxis | ( |  | ) | const

Returns
  True, if the synchronization of the scale division with the corresponding axis is enabled.

See Also
  setScaleDiv(), setScaleDivFromAxis()

QPalette QwtPlotScaleItem::palette | ( |  | ) | const

Returns
  palette

See Also
  setPalette()

double QwtPlotScaleItem::position | ( |  | ) | const

Returns
  Position of the scale

See Also
  setPosition(), setAlignment()

int QwtPlotScaleItem::rtti | ( |  | ) | const
| virtual

Returns
  QwtPlotItem::Rtti_PlotScale

Reimplemented from QwtPlotItem.

const QwtScaleDiv & QwtPlotScaleItem::scaleDiv | ( |  | ) | const

Returns
  Scale division

const QwtScaleDraw * QwtPlotScaleItem::scaleDraw | ( |  | ) | const

Returns
  Scale draw

See Also
  setScaleDraw()

QwtScaleDraw * QwtPlotScaleItem::scaleDraw | ( |  | ) |

Returns
  Scale draw

See Also
  setScaleDraw()

void QwtPlotScaleItem::setAlignment | ( | QwtScaleDraw::Alignment | alignment | ) |

Change the alignment of the scale

The alignment sets the orientation of the scale and the position of the ticks:

- QwtScaleDraw::BottomScale: horizontal, ticks below
- QwtScaleDraw::TopScale: horizontal, ticks above
- QwtScaleDraw::LeftScale: vertical, ticks left
- QwtScaleDraw::RightScale: vertical, ticks right

For horizontal scales the position corresponds to QwtPlotItem::yAxis(), otherwise to QwtPlotItem::xAxis().

See Also
  scaleDraw(), QwtScaleDraw::alignment(), setPosition()

void QwtPlotScaleItem::setBorderDistance | ( | int | distance | ) |

Align the scale to the canvas.

If distance is >= 0 the scale will be aligned to a border of the contents rectangle of the canvas. If alignment() is QwtScaleDraw::LeftScale, the scale will be aligned to the right border, if it is QwtScaleDraw::TopScale it will be aligned to the bottom (and vice versa),

If distance is < 0 the scale will be at the position().

Parameters

  distance | Number of pixels between the canvas border and the backbone of the scale.

See Also
  setPosition(), borderDistance()

void QwtPlotScaleItem::setFont | ( | const QFont & | font | ) |

Change the tick label font

See Also
  font()

void QwtPlotScaleItem::setPalette | ( | const QPalette & | palette | ) |

Set the palette

See Also
  QwtAbstractScaleDraw::draw(), palette()

void QwtPlotScaleItem::setPosition | ( | double | pos | ) |

Change the position of the scale

The position is interpreted as y value for horizontal axes and as x value for vertical axes.

The border distance is set to -1.

Parameters

  pos | New position

See Also
  position(), setAlignment()

void QwtPlotScaleItem::setScaleDiv | ( | const QwtScaleDiv & | scaleDiv | ) |

Assign a scale division.

When assigning a scaleDiv the scale division won't be synchronized with the corresponding axis anymore.

Parameters

  scaleDiv | Scale division

See Also
  scaleDiv(), setScaleDivFromAxis(), isScaleDivFromAxis()

void QwtPlotScaleItem::setScaleDivFromAxis | ( | bool | on | ) |

Enable/Disable the synchronization of the scale division with the corresponding axis.

Parameters

  on | true/false

See Also
  isScaleDivFromAxis()

void QwtPlotScaleItem::setScaleDraw | ( | QwtScaleDraw * | scaleDraw | ) |

Set a scale draw.

Parameters

  scaleDraw | object responsible for drawing scales.

The main use case for replacing the default QwtScaleDraw is to overload QwtAbstractScaleDraw::label, to replace or swallow tick labels.

See Also
  scaleDraw()

void QwtPlotScaleItem::updateScaleDiv | ( | const QwtScaleDiv & | xScaleDiv,
|  | const QwtScaleDiv & | yScaleDiv
| ) |  |
| virtual

Update the item to changes of the axes scale division.

In case of isScaleDivFromAxis(), the scale draw is synchronized to the correspond axis.

Parameters

  xScaleDiv | Scale division of the x-axis
  yScaleDiv | Scale division of the y-axis

See Also
  QwtPlot::updateAxes()

Reimplemented from QwtPlotItem.