QwtAbstractScaleDraw Class Reference

A abstract base class for drawing scales. More...

#include <qwt_abstract_scale_draw.h>

Inheritance diagram for QwtAbstractScaleDraw:

Public Types
enum	ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
typedef QFlags< ScaleComponent >	ScaleComponents
	Scale components.

Public Member Functions
	QwtAbstractScaleDraw ()
	Constructor. More...
virtual	~QwtAbstractScaleDraw ()
	Destructor.
void	setScaleDiv (const QwtScaleDiv &s)
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 margin)
	Set the spacing between tick and labels. More...
double	spacing () const
	Get the spacing. More...
void	setPenWidth (int width)
	Specify the width of the scale pen. More...
int	penWidth () const
virtual void	draw (QPainter *, const QPalette &) const
	Draw the scale. More...
virtual QwtText	label (double) const
	Convert a value into its representing label. More...
virtual double	extent (const QFont &font) const =0
void	setMinimumExtent (double)
	Set a minimum for the extent. More...
double	minimumExtent () const

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
void	invalidateCache ()
const QwtText &	tickLabel (const QFont &, double value) const
	Convert a value into its representing label and cache it. More...

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.

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.

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

Member Function Documentation

void QwtAbstractScaleDraw::draw ( QPainter *  painter, const QPalette &  palette  ) const

virtual

Draw the scale.

Parameters

painter	The painter
palette	Palette, text color is used for the labels, foreground color for ticks and backbone

virtual void QwtAbstractScaleDraw::drawBackbone ( QPainter *  painter ) const

protectedpure virtual

Draws the baseline of the scale

Parameters

painter

Painter

See Also

drawTick(), drawLabel()

Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

virtual void QwtAbstractScaleDraw::drawLabel ( QPainter *  painter, double  value  ) const

protectedpure virtual

Draws the label for a major scale tick

Parameters

painter	Painter
value	Value

See Also

drawTick(), drawBackbone()

Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

virtual void QwtAbstractScaleDraw::drawTick ( QPainter *  painter, double  value, double  len  ) const

protectedpure virtual

Draw a tick

Parameters

painter	Painter
value	Value of the tick
len	Length of the tick

See Also

drawBackbone(), drawLabel()

Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

void QwtAbstractScaleDraw::enableComponent	(	ScaleComponent	component,
		bool	enable = true
	)

En/Disable a component of the scale

Parameters

component	Scale component
enable	On/Off

See Also

hasComponent()

virtual double QwtAbstractScaleDraw::extent ( const QFont &  font ) const

pure virtual

Calculate the extent

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 QwtScaleDraw, and QwtRoundScaleDraw.

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()

void QwtAbstractScaleDraw::invalidateCache ( )

protected

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.

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 QwtDateScaleDraw, and QwtCompassScaleDraw.

double QwtAbstractScaleDraw::maxTickLength

(

)

const

Returns

Length of the longest tick

Useful for layout calculations

See Also

tickLength(), setTickLength()

double QwtAbstractScaleDraw::minimumExtent

(

)

const

Get the minimum extent

Returns

Minimum extent

See Also

extent(), setMinimumExtent()

int QwtAbstractScaleDraw::penWidth

(

)

const

Returns

Scale pen width

See Also

setPenWidth()

const QwtScaleDiv & QwtAbstractScaleDraw::scaleDiv

(

)

const

Returns

scale division

const QwtScaleMap & QwtAbstractScaleDraw::scaleMap

(

)

const

Returns

Map how to translate between scale and pixel values

QwtScaleMap & QwtAbstractScaleDraw::scaleMap

(

)

Returns

Map how to translate between scale and pixel values

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()

void QwtAbstractScaleDraw::setPenWidth

(

int

width

)

Specify the width of the scale pen.

Parameters

width

Pen width

See Also

penWidth()

void QwtAbstractScaleDraw::setScaleDiv

(

const QwtScaleDiv &

scaleDiv

)

Change the scale division

Parameters

scaleDiv

New scale division

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()

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]

void QwtAbstractScaleDraw::setTransformation

(

QwtTransform *

transformation

)

Change the transformation of the scale

Parameters

transformation

New scale transformation

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()

const QwtText & QwtAbstractScaleDraw::tickLabel ( const QFont &  font, double  value  ) 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

double QwtAbstractScaleDraw::tickLength

(

QwtScaleDiv::TickType

tickType

)

const

Returns

Length of the ticks

See Also

setTickLength(), maxTickLength()