Qwt User's Guide  6.1.1
 All Classes Functions Variables Typedefs Enumerations Enumerator Pages
Public Types | Public Member Functions | Protected Member Functions | List of all members
QwtAbstractScaleDraw Class Referenceabstract

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

#include <qwt_abstract_scale_draw.h>

Inheritance diagram for QwtAbstractScaleDraw:
Inheritance graph
[legend]

Public Types

enum  ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
 
typedef QFlags< ScaleComponentScaleComponents
 Scale components.
 

Public Member Functions

 QwtAbstractScaleDraw ()
 Constructor. More...
 
virtual ~QwtAbstractScaleDraw ()
 Destructor.
 
void setScaleDiv (const QwtScaleDiv &s)
 
const QwtScaleDivscaleDiv () const
 
void setTransformation (QwtTransform *)
 
const QwtScaleMapscaleMap () const
 
QwtScaleMapscaleMap ()
 
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 QwtTexttickLabel (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

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
painterThe painter
palettePalette, 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
painterPainter
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
painterPainter
valueValue
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
painterPainter
valueValue of the tick
lenLength 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
componentScale component
enableOn/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
fontFont 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
componentComponent 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
valueValue
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
minExtentMinimum extent
See Also
extent(), minimumExtent()
void QwtAbstractScaleDraw::setPenWidth ( int  width)

Specify the width of the scale pen.

Parameters
widthPen width
See Also
penWidth()
void QwtAbstractScaleDraw::setScaleDiv ( const QwtScaleDiv scaleDiv)

Change the scale division

Parameters
scaleDivNew 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
spacingSpacing
See Also
spacing()
void QwtAbstractScaleDraw::setTickLength ( QwtScaleDiv::TickType  tickType,
double  length 
)

Set the length of the ticks

Parameters
tickTypeTick type
lengthNew length
Warning
the length is limited to [0..1000]
void QwtAbstractScaleDraw::setTransformation ( QwtTransform transformation)

Change the transformation of the scale

Parameters
transformationNew 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
fontFont
valueValue
Returns
Tick label
double QwtAbstractScaleDraw::tickLength ( QwtScaleDiv::TickType  tickType) const
Returns
Length of the ticks
See Also
setTickLength(), maxTickLength()