QwtAbstractScaleDraw - A abstract base class for drawing scales.

NAME

QwtAbstractScaleDraw − A abstract base class for drawing scales.

SYNOPSIS

#include <qwt_abstract_scale_draw.h>

Inherited by QwtRoundScaleDraw, and QwtScaleDraw.

Public Types

enum ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
typedef QFlags< ScaleComponent > ScaleComponents

Public Member Functions

QwtAbstractScaleDraw ()
Constructor.
virtual ˜QwtAbstractScaleDraw ()
Destructor.
void setScaleDiv (const QwtScaleDiv &)
const QwtScaleDiv & scaleDiv () const
void setTransformation (QwtTransform *)
const QwtScaleMap & scaleMap () const
QwtScaleMap & scaleMap ()
void enableComponent (ScaleComponent, bool enable=true)
bool hasComponent (ScaleComponent) const
void setTickLength (QwtScaleDiv::TickType, double length)
double tickLength (QwtScaleDiv::TickType) const
double maxTickLength () const
void setSpacing (double)
Set the spacing between tick and labels.
double spacing () const
Get the spacing.
void setPenWidthF (qreal width)
Specify the width of the scale pen.
qreal penWidthF () const
virtual void draw (QPainter *, const QPalette &) const
Draw the scale.
virtual QwtText label (double) const
Convert a value into its representing label.
virtual double extent (const QFont &font) const =0
void setMinimumExtent (double)
Set a minimum for the extent.
double minimumExtent () const
void invalidateCache ()

Protected Member Functions

virtual void drawTick (QPainter *painter, double value, double len) const =0
virtual void drawBackbone (QPainter *painter) const =0
virtual void drawLabel (QPainter *painter, double value) const =0
const QwtText & tickLabel (const QFont &, double value) const
Convert a value into its representing label and cache it.

Detailed Description

A abstract base class for drawing scales.

QwtAbstractScaleDraw can be used to draw linear or logarithmic scales.

After a scale division has been specified as a QwtScaleDiv object using setScaleDiv(), the scale can be drawn with the draw() member.

Definition at line 31 of file qwt_abstract_scale_draw.h.

Member Typedef Documentation

typedef QFlags<ScaleComponent > QwtAbstractScaleDraw::ScaleComponents

An ORed combination of ScaleComponent values.

Definition at line 51 of file qwt_abstract_scale_draw.h.

Member Enumeration Documentation

enum QwtAbstractScaleDraw::ScaleComponent

Components of a scale

See also

enableComponent(), hasComponent

Enumerator
Backbone

Backbone = the line where the ticks are located.

	*Ticks*		Ticks.
	*Labels*		Labels.

Definition at line 39 of file qwt_abstract_scale_draw.h.

Constructor & Destructor Documentation

QwtAbstractScaleDraw::QwtAbstractScaleDraw ()

Constructor. The range of the scale is initialized to [0, 100], The spacing (distance between ticks and labels) is set to 4, the tick lengths are set to 4,6 and 8 pixels

Definition at line 60 of file qwt_abstract_scale_draw.cpp.

QwtAbstractScaleDraw::˜QwtAbstractScaleDraw () [virtual]

Destructor.

Definition at line 66 of file qwt_abstract_scale_draw.cpp.

Member Function Documentation

The extent is the distance from the baseline to the outermost pixel of the scale draw in opposite to its orientation. It is at least minimumExtent() pixels.

Parameters

font Font used for drawing the tick labels

Returns

Number of pixels

See also

setMinimumExtent(), minimumExtent()

Implemented in QwtRoundScaleDraw, and QwtScaleDraw.

bool QwtAbstractScaleDraw::hasComponent (ScaleComponent component) const

Check if a component is enabled

Parameters

component Component type

Returns

true, when component is enabled

See also

enableComponent()

Definition at line 95 of file qwt_abstract_scale_draw.cpp.

void QwtAbstractScaleDraw::invalidateCache ()

Invalidate the cache used by tickLabel()

The cache is invalidated, when a new QwtScaleDiv is set. If the labels need to be changed. while the same QwtScaleDiv is set, invalidateCache() needs to be called manually.

Definition at line 417 of file qwt_abstract_scale_draw.cpp.

QwtText QwtAbstractScaleDraw::label (double value) const [virtual]

Convert a value into its representing label. The value is converted to a plain text using QLocale().toString(value). This method is often overloaded by applications to have individual labels.

Parameters

value Value

Returns

Label string.

Reimplemented in QwtCompassScaleDraw, and QwtDateScaleDraw.

Definition at line 375 of file qwt_abstract_scale_draw.cpp.

double QwtAbstractScaleDraw::maxTickLength () const

Returns

Length of the longest tick

Useful for layout calculations

See also

tickLength(), setTickLength()

Definition at line 355 of file qwt_abstract_scale_draw.cpp.

double QwtAbstractScaleDraw::minimumExtent () const

Get the minimum extent

Returns

Minimum extent

See also

extent(), setMinimumExtent()

Definition at line 302 of file qwt_abstract_scale_draw.cpp.

qreal QwtAbstractScaleDraw::penWidthF () const

Returns

Scale pen width

See also

setPenWidth()

Definition at line 156 of file qwt_abstract_scale_draw.cpp.

const QwtScaleDiv & QwtAbstractScaleDraw::scaleDiv () const

Returns

scale division

Definition at line 133 of file qwt_abstract_scale_draw.cpp.

QwtScaleMap & QwtAbstractScaleDraw::scaleMap ()

Returns

Map how to translate between scale and pixel values

Definition at line 127 of file qwt_abstract_scale_draw.cpp.

const QwtScaleMap & QwtAbstractScaleDraw::scaleMap () const

Returns

Map how to translate between scale and pixel values

Definition at line 121 of file qwt_abstract_scale_draw.cpp.

void QwtAbstractScaleDraw::setMinimumExtent (double minExtent)

Set a minimum for the extent. The extent is calculated from the components of the scale draw. In situations, where the labels are changing and the layout depends on the extent (f.e scrolling a scale), setting an upper limit as minimum extent will avoid jumps of the layout.

Parameters

minExtent Minimum extent

See also

extent(), minimumExtent()

Definition at line 289 of file qwt_abstract_scale_draw.cpp.

void QwtAbstractScaleDraw::setPenWidthF (qreal width)

Specify the width of the scale pen.

Parameters

width Pen width

See also

penWidth()

Definition at line 144 of file qwt_abstract_scale_draw.cpp.

void QwtAbstractScaleDraw::setScaleDiv (const QwtScaleDiv & scaleDiv)

Change the scale division

Parameters

scaleDiv New scale division

Definition at line 104 of file qwt_abstract_scale_draw.cpp.

void QwtAbstractScaleDraw::setSpacing (double spacing)

Set the spacing between tick and labels. The spacing is the distance between ticks and labels. The default spacing is 4 pixels.

Parameters

spacing Spacing

See also

spacing()

Definition at line 254 of file qwt_abstract_scale_draw.cpp.

void QwtAbstractScaleDraw::setTickLength (QwtScaleDiv::TickType tickType,double length)

Set the length of the ticks

Parameters

tickType Tick type
length New length

Warning

the length is limited to [0..1000]

Definition at line 315 of file qwt_abstract_scale_draw.cpp.

void QwtAbstractScaleDraw::setTransformation (QwtTransform *transformation)

Change the transformation of the scale

Parameters

transformation New scale transformation

Definition at line 115 of file qwt_abstract_scale_draw.cpp.

double QwtAbstractScaleDraw::spacing () const

Get the spacing. The spacing is the distance between ticks and labels. The default spacing is 4 pixels.

Returns

Spacing

See also

setSpacing()

Definition at line 271 of file qwt_abstract_scale_draw.cpp.

const QwtText & QwtAbstractScaleDraw::tickLabel (const QFont & font, doublevalue) const [protected]

Convert a value into its representing label and cache it. The conversion between value and label is called very often in the layout and painting code. Unfortunately the calculation of the label sizes might be slow (really slow for rich text in Qt4), so it’s necessary to cache the labels.

Parameters

font Font
value Value

Returns

Tick label

Definition at line 393 of file qwt_abstract_scale_draw.cpp.

double QwtAbstractScaleDraw::tickLength (QwtScaleDiv::TickType tickType)const

Returns

Length of the ticks

See also

setTickLength(), maxTickLength()

Definition at line 338 of file qwt_abstract_scale_draw.cpp.

Author

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Updated 2026-06-01 - jenkler.se | uex.se