QwtPlotScaleItem - Man Page

A class which draws a scale inside the plot canvas.

Synopsis

#include <qwt_plot_scaleitem.h>

Inherits QwtPlotItem.

Public Member Functions

QwtPlotScaleItem (QwtScaleDraw::Alignment=QwtScaleDraw::BottomScale, const double pos=0.0)
Constructor for scale item at the position pos.
virtual ~QwtPlotScaleItem ()
Destructor.
virtual int rtti () const
void setScaleDiv (const QwtScaleDiv &)
Assign a scale division.
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.
const QwtScaleDraw * scaleDraw () const
QwtScaleDraw * scaleDraw ()
void setPosition (double pos)
double position () const
void setBorderDistance (int)
Align the scale to the canvas.
int borderDistance () const
void setAlignment (QwtScaleDraw::Alignment)
virtual void draw (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const
Draw the scale.
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
Update the item to changes of the axes scale division.

Additional Inherited Members

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 );

\endpar

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

QwtScaleDraw * QwtPlotScaleItem::scaleDraw ()

Returns

Scale draw

See also

setScaleDraw()

const QwtScaleDraw * QwtPlotScaleItem::scaleDraw () const

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.

Author

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Info

Mon Jun 1 2020 Version 6.1.5 Qwt User's Guide