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

QwtAbstractScaleDraw -

#include <qwt_abstract_scale_draw.h>
Inherited by QwtRoundScaleDraw, and QwtScaleDraw.


enum ScaleComponent { Backbone = 1, Ticks = 2, Labels = 4 }
 


QwtAbstractScaleDraw ()
 
QwtAbstractScaleDraw (const QwtAbstractScaleDraw &)
 
virtual ~QwtAbstractScaleDraw ()
 
virtual void draw (QPainter *, const QPalette &) const
 
void enableComponent (ScaleComponent, bool enable=true)
 
virtual int extent (const QPen &, const QFont &) const =0
 
bool hasComponent (ScaleComponent) const
 
virtual QwtText label (double) const
 
int majTickLength () const
 
const QwtScaleMap & map () const
 
int minimumExtent () const
 
QwtAbstractScaleDraw & operator= (const QwtAbstractScaleDraw &)
 
const QwtScaleDiv & scaleDiv () const
 
QwtScaleMap & scaleMap ()
 
void setMinimumExtent (int)
 
void setScaleDiv (const QwtScaleDiv &s)
 
void setSpacing (int margin)
 
void setTickLength (QwtScaleDiv::TickType, int length)
 
void setTransformation (QwtScaleTransformation *)
 
int spacing () const
 
int tickLength (QwtScaleDiv::TickType) const
 


virtual void drawBackbone (QPainter *painter) const =0
 
virtual void drawLabel (QPainter *painter, double value) const =0
 
virtual void drawTick (QPainter *painter, double value, int len) const =0
 
void invalidateCache ()
 
const QwtText & tickLabel (const QFont &, double value) const
 

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 QwtAbstractScaleDraw::setScaleDiv(const QwtScaleDiv &s), the scale can be drawn with the QwtAbstractScaleDraw::draw() member.

Components of a scale
Backbone
Ticks
Labels
See also:
enableComponent(), hasComponent

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

Draw the scale. Parameters:
painter The painter
 
palette Palette, text color is used for the labels, foreground color for ticks and backbone

Draws the baseline of the scale
Parameters:
painter Painter
See also:
drawTick(), drawLabel()
Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

Draws the label for a major scale tick
Parameters:
painter Painter
 
value Value
See also:
drawTick, drawBackbone
Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

Draw a tick
Parameters:
painter Painter
 
value Value of the tick
 
len Lenght of the tick
See also:
drawBackbone(), drawLabel()
Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

En/Disable a component of the scale
Parameters:
component Scale component
 
enable On/Off
See also:
hasComponent()

Calculate the extent
The extent is the distcance from the baseline to the outermost pixel of the scale draw in opposite to its orientation. It is at least minimumExtent() pixels.
See also:
setMinimumExtent(), minimumExtent()
Implemented in QwtRoundScaleDraw, and QwtScaleDraw.

Check if a component is enabled
See also:
enableComponent()

Invalidate the cache used by QwtAbstractScaleDraw::tickLabel
The cache is invalidated, when a new QwtScaleDiv is set. If the labels need to be changed. while the same QwtScaleDiv is set, QwtAbstractScaleDraw::invalidateCache needs to be called manually.

Convert a value into its representing label. The value is converted to a plain text using QLocale::system().toString(value). This method is often overloaded by applications to have individual labels.
Parameters:
value Value
Returns:
Label string.
Reimplemented in QwtDialScaleDraw.

The same as QwtAbstractScaleDraw::tickLength(QwtScaleDiv::MajorTick).

Returns:
Map how to translate between scale and pixel values

Get the minimum extent
See also:
extent(), setMinimumExtent()

Returns:
scale division

Returns:
Map how to translate between scale and pixel values

Set a minimum for the extent. The extent is calculated from the coomponents 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()

Change the scale division
Parameters:
sd New scale division

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()

Set the length of the ticks
Parameters:
tickType Tick type
 
length New length
Warning:
the length is limited to [0..1000]

Change the transformation of the scale
Parameters:
transformation New scale transformation

Get the spacing. The spacing is the distance between ticks and labels. The default spacing is 4 pixels.
See also:
setSpacing()

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

Return the length of the ticks
See also:
setTickLength(), majTickLength()

Generated automatically by Doxygen for Qwt User's Guide from the source code.
Tue Nov 20 2012 Version 5.2.3

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