# QwtScaleDraw Class Reference

A class for drawing scales. More...

`#include <qwt_scale_draw.h>`

Inheritance diagram for QwtScaleDraw:
[legend]

List of all members.

## Public Types

enum | Alignment { BottomScale, TopScale, LeftScale, RightScale }
enum | ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
typedef QFlags< ScaleComponent > | ScaleComponents

## Public Member Functions

Alignment | alignment () const
QRect | boundingLabelRect (const QFont &, double val) const
virtual void | draw (QPainter *, const QPalette &) const
void | enableComponent (ScaleComponent, bool enable=true)
virtual double | extent (const QFont &) const
void | getBorderDistHint (const QFont &, int &start, int &end) const
bool | hasComponent (ScaleComponent) const
virtual QwtText | label (double) const
Qt::Alignment | labelAlignment () const
QPointF | labelPosition (double val) const
QRectF | labelRect (const QFont &, double val) const
double | labelRotation () const
QSizeF | labelSize (const QFont &, double val) const
double | length () const
int | maxLabelHeight (const QFont &) const
int | maxLabelWidth (const QFont &) const
double | maxTickLength () const
double | minimumExtent () const
int | minLabelDist (const QFont &) const
int | minLength (const QFont &) const
void | move (const QPointF &)
void | move (double x, double y)
Qt::Orientation | orientation () const
int | penWidth () const
QPointF | pos () const
| QwtScaleDraw ()
const QwtScaleDiv & | scaleDiv () const
QwtScaleMap & | scaleMap ()
const QwtScaleMap & | scaleMap () const
void | setAlignment (Alignment)
void | setLabelAlignment (Qt::Alignment)
void | setLabelRotation (double rotation)
void | setLength (double length)
void | setMinimumExtent (double)
void | setPenWidth (int width)
void | setScaleDiv (const QwtScaleDiv &s)
void | setSpacing (double margin)
void | setTickLength (QwtScaleDiv::TickType, double length)
void | setTransformation (QwtScaleTransformation *)
double | spacing () const
double | tickLength (QwtScaleDiv::TickType) const
virtual | ~QwtScaleDraw ()

## Protected Member Functions

virtual void | drawBackbone (QPainter *) const
virtual void | drawLabel (QPainter *, double val) const
virtual void | drawTick (QPainter *, double val, double len) const
void | invalidateCache ()
QTransform | labelTransformation (const QPointF &, const QSizeF &) const
const QwtText & | tickLabel (const QFont &, double value) const

## Detailed Description

A class for drawing scales.

QwtScaleDraw can be used to draw linear or logarithmic scales. A scale has a position, an alignment and a length, which can be specified . The labels can be rotated and aligned to the ticks using setLabelRotation() and setLabelAlignment().

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 Typedef Documentation

typedef QFlags<ScaleComponent> QwtAbstractScaleDraw::ScaleComponents `[inherited]`

Scale components.

## Member Enumeration Documentation

enum QwtScaleDraw::Alignment

Alignment of the scale draw

See also:
  setAlignment(), alignment()

Enumerator:

  BottomScale | The scale is below.
  TopScale | The scale is above.
  LeftScale | The scale is left.
  RightScale | The scale is right.

enum QwtAbstractScaleDraw::ScaleComponent `[inherited]`

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

QwtScaleDraw::QwtScaleDraw | ( |  | ) |

Constructor.

The range of the scale is initialized to [0, 100], The position is at (0, 0) with a length of 100. The orientation is QwtAbstractScaleDraw::Bottom.

QwtScaleDraw::~QwtScaleDraw | ( |  | ) | `[virtual]`

Destructor.

## Member Function Documentation

QwtScaleDraw::Alignment QwtScaleDraw::alignment | ( |  | ) | const

Return alignment of the scale

See also:
  setAlignment()

QRect QwtScaleDraw::boundingLabelRect | ( | const QFont & | font,
|  | double | value
| ) |  | const

Find the bounding rect for the label. The coordinates of the rect are absolute coordinates ( calculated from pos() ). in direction of the tick.

Parameters:

  font | Font used for painting
  value | Value

See also:
  labelRect()

void QwtAbstractScaleDraw::draw | ( | QPainter * | painter,
|  | const QPalette & | palette
| ) |  | const`[virtual, inherited]`

Draw the scale.

Parameters:

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

void QwtScaleDraw::drawBackbone | ( | QPainter * | painter | ) | const`[protected, virtual]`

Draws the baseline of the scale

Parameters:

  painter | Painter

See also:
  drawTick(), drawLabel()

Implements QwtAbstractScaleDraw.

void QwtScaleDraw::drawLabel | ( | QPainter * | painter,
|  | double | value
| ) |  | const`[protected, virtual]`

Draws the label for a major scale tick

Parameters:

  painter | Painter
  value | Value

See also:
  drawTick(), drawBackbone(), boundingLabelRect()

Implements QwtAbstractScaleDraw.

void QwtScaleDraw::drawTick | ( | QPainter * | painter,
|  | double | value,
|  | double | len
| ) |  | const`[protected, virtual]`

Draw a tick

Parameters:

  painter | Painter
  value | Value of the tick
  len | Lenght of the tick

See also:
  drawBackbone(), drawLabel()

Implements QwtAbstractScaleDraw.

void QwtAbstractScaleDraw::enableComponent | ( | ScaleComponent | component,
|  | bool | enable = `true`
| ) |  | `[inherited]`

En/Disable a component of the scale

Parameters:

  component | Scale component
  enable | On/Off

See also:
  hasComponent()

double QwtScaleDraw::extent | ( | const QFont & | font | ) | const`[virtual]`

Calculate the width/height that is needed for a vertical/horizontal scale.

The extent is calculated from the pen width of the backbone, the major tick length, the spacing and the maximum width/height of the labels.

Parameters:

  font | Font used for painting the labels

See also:
  minLength()

Implements QwtAbstractScaleDraw.

void QwtScaleDraw::getBorderDistHint | ( | const QFont & | font,
|  | int & | start,
|  | int & | end
| ) |  | const

Determine the minimum border distance.

This member function returns the minimum space needed to draw the mark labels at the scale's endpoints.

Parameters:

  font | Font
  start | Start border distance
  end | End border distance

bool QwtAbstractScaleDraw::hasComponent | ( | ScaleComponent | component | ) | const`[inherited]`

Check if a component is enabled

See also:
  enableComponent()

void QwtAbstractScaleDraw::invalidateCache | ( |  | ) | `[protected, inherited]`

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, invalidateCache() needs to be called manually.

QwtText QwtAbstractScaleDraw::label | ( | double | value | ) | const`[virtual, inherited]`

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.

Qt::Alignment QwtScaleDraw::labelAlignment | ( |  | ) | const

Returns:
  the label flags

See also:
  setLabelAlignment(), labelRotation()

QPointF QwtScaleDraw::labelPosition | ( | double | value | ) | const

Find the position, where to paint a label

The position has a distance of majTickLength() + spacing() + 1 from the backbone. The direction depends on the alignment()

Parameters:

  value | Value

QRectF QwtScaleDraw::labelRect | ( | const QFont & | font,
|  | double | value
| ) |  | const

Find the bounding rect for the label. The coordinates of the rect are relative to spacing + ticklength from the backbone in direction of the tick.

Parameters:

  font | Font used for painting
  value | Value

double QwtScaleDraw::labelRotation | ( |  | ) | const

Returns:
  the label rotation

See also:
  setLabelRotation(), labelAlignment()

QSizeF QwtScaleDraw::labelSize | ( | const QFont & | font,
|  | double | value
| ) |  | const

Calculate the size that is needed to draw a label

Parameters:

  font | Label font
  value | Value

QTransform QwtScaleDraw::labelTransformation | ( | const QPointF & | pos,
|  | const QSizeF & | size
| ) |  | const`[protected]`

Calculate the transformation that is needed to paint a label depending on its alignment and rotation.

Parameters:

  pos | Position where to paint the label
  size | Size of the label

See also:
  setLabelAlignment(), setLabelRotation()

double QwtScaleDraw::length | ( |  | ) | const

Returns:
  the length of the backbone

See also:
  setLength(), pos()

int QwtScaleDraw::maxLabelHeight | ( | const QFont & | font | ) | const

Parameters:

  font | Font

Returns:
  the maximum height of a label

int QwtScaleDraw::maxLabelWidth | ( | const QFont & | font | ) | const

Parameters:

  font | Font

Returns:
  the maximum width of a label

double QwtAbstractScaleDraw::maxTickLength | ( |  | ) | const`[inherited]`

Returns:
  Length of the longest tick

Useful for layout calculations

See also:
  tickLength(), setTickLength()

double QwtAbstractScaleDraw::minimumExtent | ( |  | ) | const`[inherited]`

Get the minimum extent

See also:
  extent(), setMinimumExtent()

int QwtScaleDraw::minLabelDist | ( | const QFont & | font | ) | const

Determine the minimum distance between two labels, that is necessary that the texts don't overlap.

Parameters:

  font | Font

Returns:
  The maximum width of a label

See also:
  getBorderDistHint()

int QwtScaleDraw::minLength | ( | const QFont & | font | ) | const

Calculate the minimum length that is needed to draw the scale

Parameters:

  font | Font used for painting the labels

See also:
  extent()

void QwtScaleDraw::move | ( | double | x,
|  | double | y
| ) |  | `[inline]`

Move the position of the scale

See also:
  move(const QPointF &)

void QwtScaleDraw::move | ( | const QPointF & | pos | ) |

Move the position of the scale.

The meaning of the parameter pos depends on the alignment:

QwtScaleDraw::LeftScale
  The origin is the topmost point of the backbone. The backbone is a vertical line. Scale marks and labels are drawn at the left of the backbone.
QwtScaleDraw::RightScale
  The origin is the topmost point of the backbone. The backbone is a vertical line. Scale marks and labels are drawn at the right of the backbone.
QwtScaleDraw::TopScale
  The origin is the leftmost point of the backbone. The backbone is a horizontal line. Scale marks and labels are drawn above the backbone.
QwtScaleDraw::BottomScale
  The origin is the leftmost point of the backbone. The backbone is a horizontal line Scale marks and labels are drawn below the backbone.

Parameters:

  pos | Origin of the scale

See also:
  pos(), setLength()

Qt::Orientation QwtScaleDraw::orientation | ( |  | ) | const

Return the orientation

TopScale, BottomScale are horizontal (Qt::Horizontal) scales, LeftScale, RightScale are vertical (Qt::Vertical) scales.

See also:
  alignment()

int QwtAbstractScaleDraw::penWidth | ( |  | ) | const`[inherited]`

Returns:
  Scale pen width

See also:
  setPenWidth()

Reimplemented in QwtDialScaleDraw.

QPointF QwtScaleDraw::pos | ( |  | ) | const

Returns:
  Origin of the scale

See also:
  move(), length()

const QwtScaleDiv & QwtAbstractScaleDraw::scaleDiv | ( |  | ) | const`[inherited]`

Returns:
  scale division

QwtScaleMap & QwtAbstractScaleDraw::scaleMap | ( |  | ) | `[inherited]`

Returns:
  Map how to translate between scale and pixel values

const QwtScaleMap & QwtAbstractScaleDraw::scaleMap | ( |  | ) | const`[inherited]`

Returns:
  Map how to translate between scale and pixel values

void QwtScaleDraw::setAlignment | ( | Alignment | align | ) |

Set the alignment of the scale

The default alignment is QwtScaleDraw::BottomScale

See also:
  alignment()

void QwtScaleDraw::setLabelAlignment | ( | Qt::Alignment | alignment | ) |

Change the label flags.

Labels are aligned to the point ticklength + spacing away from the backbone.

The alignment is relative to the orientation of the label text. In case of an flags of 0 the label will be aligned depending on the orientation of the scale:

QwtScaleDraw::TopScale: Qt::AlignHCenter | Qt::AlignTop
QwtScaleDraw::BottomScale: Qt::AlignHCenter | Qt::AlignBottom
QwtScaleDraw::LeftScale: Qt::AlignLeft | Qt::AlignVCenter
QwtScaleDraw::RightScale: Qt::AlignRight | Qt::AlignVCenter

Changing the alignment is often necessary for rotated labels.

Parameters:

  alignment | Or'd Qt::AlignmentFlags see <qnamespace.h>

See also:
  setLabelRotation(), labelRotation(), labelAlignment()

Warning:
  The various alignments might be confusing. The alignment of the label is not the alignment of the scale and is not the alignment of the flags (QwtText::flags()) returned from QwtAbstractScaleDraw::label().

void QwtScaleDraw::setLabelRotation | ( | double | rotation | ) |

Rotate all labels.

When changing the rotation, it might be necessary to adjust the label flags too. Finding a useful combination is often the result of try and error.

Parameters:

  rotation | Angle in degrees. When changing the label rotation, the label flags often needs to be adjusted too.

See also:
  setLabelAlignment(), labelRotation(), labelAlignment().

void QwtScaleDraw::setLength | ( | double | length | ) |

Set the length of the backbone.

The length doesn't include the space needed for overlapping labels.

See also:
  move(), minLabelDist()

void QwtAbstractScaleDraw::setMinimumExtent | ( | double | minExtent | ) | `[inherited]`

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::setPenWidth | ( | int | width | ) | `[inherited]`

Specify the width of the scale pen.

Parameters:

  width | Pen width

See also:
  penWidth()

void QwtAbstractScaleDraw::setScaleDiv | ( | const QwtScaleDiv & | sd | ) | `[inherited]`

Change the scale division

Parameters:

  sd | New scale division

void QwtAbstractScaleDraw::setSpacing | ( | double | spacing | ) | `[inherited]`

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
| ) |  | `[inherited]`

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 | ) | `[inherited]`

Change the transformation of the scale

Parameters:

  transformation | New scale transformation

double QwtAbstractScaleDraw::spacing | ( |  | ) | const`[inherited]`

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, inherited]`

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`[inherited]`

Return the length of the ticks

See also:
  setTickLength(), maxTickLength()