# QwtPlotScaleItem Class Reference

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

`#include <qwt_plot_scaleitem.h>`

Inheritance diagram for QwtPlotScaleItem:
[legend]

List of all members.

## Public Types

enum | ItemAttribute { Legend = 1, AutoScale = 2 }
enum | RenderHint { RenderAntialiased = 1 }
enum | RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG, Rtti_PlotUserItem = 1000 }

## Public Member Functions

void | attach (QwtPlot *plot)
int | borderDistance () const
virtual QwtDoubleRect | boundingRect () const
void | detach ()
virtual void | draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &rect) const
QFont | font () const
void | hide ()
QwtDoubleRect | invTransform (const QwtScaleMap &, const QwtScaleMap &, const QRect &) const
bool | isScaleDivFromAxis () const
bool | isVisible () const
virtual void | itemChanged ()
virtual QWidget * | legendItem () const
QRect | paintRect (const QwtScaleMap &, const QwtScaleMap &) const
QPalette | palette () const
QwtPlot * | plot () const
double | position () const
| QwtPlotScaleItem (QwtScaleDraw::Alignment=QwtScaleDraw::BottomScale, const double pos=0.0)
virtual int | rtti () const
const QwtScaleDiv & | scaleDiv () const
const QwtScaleDraw * | scaleDraw () const
QwtScaleDraw * | scaleDraw ()
QwtDoubleRect | scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
void | setAlignment (QwtScaleDraw::Alignment)
void | setAxis (int xAxis, int yAxis)
void | setBorderDistance (int numPixels)
void | setFont (const QFont &)
void | setItemAttribute (ItemAttribute, bool on=true)
void | setPalette (const QPalette &)
void | setPosition (double pos)
void | setRenderHint (RenderHint, bool on=true)
void | setScaleDiv (const QwtScaleDiv &)
void | setScaleDivFromAxis (bool on)
void | setScaleDraw (QwtScaleDraw *)
void | setTitle (const QString &title)
void | setTitle (const QwtText &title)
virtual void | setVisible (bool)
void | setXAxis (int axis)
void | setYAxis (int axis)
void | setZ (double z)
void | show ()
bool | testItemAttribute (ItemAttribute) const
bool | testRenderHint (RenderHint) const
const QwtText & | title () const
QRect | transform (const QwtScaleMap &, const QwtScaleMap &, const QwtDoubleRect &) const
virtual void | updateLegend (QwtLegend *) const
virtual void | updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
int | xAxis () const
int | yAxis () const
double | z () const
virtual | ~QwtPlotScaleItem ()

## 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);

## Member Enumeration Documentation

enum QwtPlotItem::ItemAttribute `[inherited]`

Plot Item Attributes

- Legend
  The item is represented on the legend.
- AutoScale
  The boundingRect() of the item is included in the autoscaling calculation.

See also:
  setItemAttribute(), testItemAttribute()

enum QwtPlotItem::RenderHint `[inherited]`

Render hints.

enum QwtPlotItem::RttiValues `[inherited]`

Runtime type information.

RttiValues is used to cast plot items, without having to enable runtime type information of the compiler.

## 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/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()

QwtPlotScaleItem::~QwtPlotScaleItem | ( |  | ) | `[virtual]`

Destructor.

## Member Function Documentation

void QwtPlotItem::attach | ( | QwtPlot * | plot | ) | `[inherited]`

Attach the item to a plot.

This method will attach a QwtPlotItem to the QwtPlot argument. It will first detach the QwtPlotItem from any plot from a previous call to attach (if necessary). If a NULL argument is passed, it will detach from any QwtPlot it was attached to.

Parameters:

  plot | Plot widget

See also:
  QwtPlotItem::detach()

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

Returns:
  Distance from a canvas border

See also:
  setBorderDistance(), setPosition()

QwtDoubleRect QwtPlotItem::boundingRect | ( |  | ) | const`[virtual, inherited]`

Returns:
  An invalid bounding rect: QwtDoubleRect(1.0, 1.0, -2.0, -2.0)

Reimplemented in QwtPlotCurve, QwtPlotMarker, QwtPlotSpectrogram, and QwtPlotSvgItem.

void QwtPlotItem::detach | ( |  | ) | `[inline, inherited]`

This method detaches a QwtPlotItem from any QwtPlot it has been associated with.

detach() is equivalent to calling attach( NULL )

See also:
  attach( QwtPlot* plot )

void QwtPlotScaleItem::draw | ( | QPainter * | p,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRect & | rect
| ) |  | const`[virtual]`

Draw the scale.

Implements QwtPlotItem.

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

Returns:
  tick label font

See also:
  setFont()

void QwtPlotItem::hide | ( |  | ) | `[inherited]`

Hide the item.

QwtDoubleRect QwtPlotItem::invTransform | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRect & | rect
| ) |  | const`[inherited]`

Transform a rectangle from paint to scale coordinates

Parameters:

  xMap | X map
  yMap | Y map
  rect | Rectangle in paint coordinates

Returns:
  Rectangle in scale coordinates

See also:
  transform()

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

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

See also:
  setScaleDiv(), setScaleDivFromAxis()

bool QwtPlotItem::isVisible | ( |  | ) | const`[inherited]`

Returns:
  true if visible

See also:
  setVisible(), show(), hide()

void QwtPlotItem::itemChanged | ( |  | ) | `[virtual, inherited]`

Update the legend and call QwtPlot::autoRefresh for the parent plot.

See also:
  updateLegend()

QWidget * QwtPlotItem::legendItem | ( |  | ) | const`[virtual, inherited]`

Allocate the widget that represents the item on the legend.

The default implementation is made for QwtPlotCurve and returns a QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and updateLegend().

Returns:
  QwtLegendItem()

See also:
  updateLegend() QwtLegend()

Implements QwtLegendItemManager.

QRect QwtPlotItem::paintRect | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap
| ) |  | const`[inherited]`

Calculate the bounding paint rect of 2 maps.

Parameters:

  xMap | X map
  yMap | X map

Returns:
  Bounding rect of the scale maps

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

Returns:
  palette

See also:
  setPalette()

QwtPlot * QwtPlotItem::plot | ( |  | ) | const`[inherited]`

Return attached plot.

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()

QwtDoubleRect QwtPlotItem::scaleRect | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap
| ) |  | const`[inherited]`

Calculate the bounding scale rect of 2 maps.

Parameters:

  xMap | X map
  yMap | X map

Returns:
  Bounding rect of the scale maps

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 QwtPlotItem::setAxis | ( | int | xAxis,
|  | int | yAxis
| ) |  | `[inherited]`

Set X and Y axis

The item will painted according to the coordinates its Axes.

Parameters:

  xAxis | X Axis
  yAxis | Y Axis

See also:
  setXAxis(), setYAxis(), xAxis(), yAxis()

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 rect 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 QwtPlotItem::setItemAttribute | ( | ItemAttribute | attribute,
|  | bool | on = `true`
| ) |  | `[inherited]`

Toggle an item attribute

Parameters:

  attribute | Attribute type
  on | true/false

See also:
  testItemAttribute(), ItemAttribute

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 QwtPlotItem::setRenderHint | ( | RenderHint | hint,
|  | bool | on = `true`
| ) |  | `[inherited]`

Toggle an render hint

Parameters:

  hint | Render hint
  on | true/false

See also:
  testRenderHint(), RenderHint

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 QwtPlotItem::setTitle | ( | const QString & | title | ) | `[inherited]`

Set a new title

Parameters:

  title | Title

See also:
  title()

void QwtPlotItem::setTitle | ( | const QwtText & | title | ) | `[inherited]`

Set a new title

Parameters:

  title | Title

See also:
  title()

void QwtPlotItem::setVisible | ( | bool | on | ) | `[virtual, inherited]`

Show/Hide the item

Parameters:

  on | Show if true, otherwise hide

See also:
  isVisible(), show(), hide()

void QwtPlotItem::setXAxis | ( | int | axis | ) | `[inherited]`

Set the X axis

The item will painted according to the coordinates its Axes.

Parameters:

  axis | X Axis

See also:
  setAxis(), setYAxis(), xAxis()

void QwtPlotItem::setYAxis | ( | int | axis | ) | `[inherited]`

Set the Y axis

The item will painted according to the coordinates its Axes.

Parameters:

  axis | Y Axis

See also:
  setAxis(), setXAxis(), yAxis()

void QwtPlotItem::setZ | ( | double | z | ) | `[inherited]`

Set the z value.

Plot items are painted in increasing z-order.

Parameters:

  z | Z-value

See also:
  z(), QwtPlotDict::itemList()

void QwtPlotItem::show | ( |  | ) | `[inherited]`

Show the item.

bool QwtPlotItem::testItemAttribute | ( | ItemAttribute | attribute | ) | const`[inherited]`

Test an item attribute

Parameters:

  attribute | Attribute type

Returns:
  true/false

See also:
  setItemAttribute(), ItemAttribute

bool QwtPlotItem::testRenderHint | ( | RenderHint | hint | ) | const`[inherited]`

Test a render hint

Parameters:

  hint | Render hint

Returns:
  true/false

See also:
  setRenderHint(), RenderHint

const QwtText & QwtPlotItem::title | ( |  | ) | const`[inherited]`

Returns:
  Title of the item

See also:
  setTitle()

QRect QwtPlotItem::transform | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QwtDoubleRect & | rect
| ) |  | const`[inherited]`

Transform a rectangle

Parameters:

  xMap | X map
  yMap | Y map
  rect | Rectangle in scale coordinates

Returns:
  Rectangle in paint coordinates

See also:
  invTransform()

void QwtPlotItem::updateLegend | ( | QwtLegend * | legend | ) | const`[virtual, inherited]`

Update the widget that represents the item on the legend.

updateLegend() is called from itemChanged() to adopt the widget representing the item on the legend to its new configuration.

The default implementation is made for QwtPlotCurve and updates a QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and updateLegend().

Parameters:

  legend | Legend

See also:
  legendItem(), itemChanged(), QwtLegend()

Implements QwtLegendItemManager.

Reimplemented in QwtPlotCurve.

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.

int QwtPlotItem::xAxis | ( |  | ) | const`[inherited]`

Return xAxis.

int QwtPlotItem::yAxis | ( |  | ) | const`[inherited]`

Return yAxis.

double QwtPlotItem::z | ( |  | ) | const`[inherited]`

Plot items are painted in increasing z-order.

Returns:
  setZ(), QwtPlotDict::itemList()