QwtAbstractScaleDraw(3)

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 = 1, Ticks = 2, Labels = 4 }

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

  Protected Member Functions
virtual void drawTick (QPainter *painter, double value, int 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

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

Member Enumeration Documentation

  enum QwtAbstractScaleDraw::ScaleComponent

Components of a scale

•   Backbone

•   Ticks

•   Labels

See also:
    enableComponent(), hasComponent

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

  QwtAbstractScaleDraw::QwtAbstractScaleDraw (const QwtAbstractScaleDraw & other)

Copy constructor.

  QwtAbstractScaleDraw::~QwtAbstractScaleDraw () [virtual]

Destructor.

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 [protected, pure virtual]

Draws the baseline of the scale

Parameters:
    painter Painter

See also:
    drawTick(), drawLabel()

Implemented in QwtRoundScaleDraw, and QwtScaleDraw.

  virtual void QwtAbstractScaleDraw::drawLabel (QPainter * painter, double value) const [protected, pure virtual]

Draws the label for a major scale tick

Parameters:
    painter Painter
    value Value

See also:
    drawTick, drawBackbone

Implemented in QwtRoundScaleDraw, and QwtScaleDraw.

  virtual void QwtAbstractScaleDraw::drawTick (QPainter * painter, double value, int len) const [protected, pure virtual]

Draw a tick

Parameters:
    painter Painter
    value Value of the tick
    len Lenght of the tick

See also:
    drawBackbone(), drawLabel()

Implemented in QwtRoundScaleDraw, and QwtScaleDraw.

  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 int QwtAbstractScaleDraw::extent (const QPen &, const QFont &) const [pure virtual]

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.

  bool QwtAbstractScaleDraw::hasComponent (ScaleComponent component) const

Check if a component is enabled

See also:
    enableComponent()

  void QwtAbstractScaleDraw::invalidateCache () [protected]

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.

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

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.

  int QwtAbstractScaleDraw::majTickLength () const

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

  const QwtScaleMap & QwtAbstractScaleDraw::map () const

Returns:
    Map how to translate between scale and pixel values

  int QwtAbstractScaleDraw::minimumExtent () const

Get the minimum extent

See also:
    extent(), setMinimumExtent()

  QwtAbstractScaleDraw & QwtAbstractScaleDraw::operator= (const QwtAbstractScaleDraw & other)

Assignment operator.

  const QwtScaleDiv & QwtAbstractScaleDraw::scaleDiv () const

Returns:
    scale division

  QwtScaleMap & QwtAbstractScaleDraw::scaleMap ()

Returns:
    Map how to translate between scale and pixel values

  void QwtAbstractScaleDraw::setMinimumExtent (int minExtent)

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()

  void QwtAbstractScaleDraw::setScaleDiv (const QwtScaleDiv & sd)

Change the scale division

Parameters:
    sd New scale division

  void QwtAbstractScaleDraw::setSpacing (int 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, int 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 (QwtScaleTransformation * transformation)

Change the transformation of the scale

Parameters:
    transformation New scale transformation

  int QwtAbstractScaleDraw::spacing () const

Get the spacing.

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

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

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

Return the length of the ticks

See also:
    setTickLength(), majTickLength()

Author

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