QwtPlotScaleItem(3) Qwt User's Guide QwtPlotScaleItem(3)

QwtPlotScaleItem - A class which draws a scale inside the plot canvas.

#include <qwt_plot_scaleitem.h>

Inherits QwtPlotItem.


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.

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 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()

Returns:

Distance from a canvas border

See also:

setBorderDistance(), setPosition()

Returns:

tick label font

See also:

setFont()

Returns:

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

See also:

setScaleDiv(), setScaleDivFromAxis()

Returns:

palette

See also:

setPalette()

Returns:

Position of the scale

See also:

setPosition(), setAlignment()

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()

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()

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()

Change the tick label font

See also:

font()

Set the palette

See also:

QwtAbstractScaleDraw::draw(), palette()

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()

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()

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

Parameters:

on true/false

See also:

isScaleDivFromAxis()

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()

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.

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Wed Jan 2 2019 Version 6.1.4