QwtScaleDraw(3)

NAME
QwtScaleDraw - A class for drawing scales.

SYNOPSIS

#include <qwt_scale_draw.h>

Inherits QwtAbstractScaleDraw.

  Public Types
enum Alignment { BottomScale, TopScale, LeftScale, RightScale }

  Public Member Functions
QwtScaleDraw ()
QwtScaleDraw (const QwtScaleDraw &)
virtual ~QwtScaleDraw ()
QwtScaleDraw & operator= (const QwtScaleDraw &other)
void getBorderDistHint (const QFont &, int &start, int &end) const
int minLabelDist (const QFont &) const
int minLength (const QPen &, const QFont &) const
virtual int extent (const QPen &, const QFont &) const
void move (int x, int y)
void move (const QPoint &)
void setLength (int length)
Alignment alignment () const
void setAlignment (Alignment)
Qt::Orientation orientation () const
QPoint pos () const
int length () const
void setLabelAlignment (Qt::Alignment)
Qt::Alignment labelAlignment () const
void setLabelRotation (double rotation)
double labelRotation () const
int maxLabelHeight (const QFont &) const
int maxLabelWidth (const QFont &) const
QPoint labelPosition (double val) const
QRect labelRect (const QFont &, double val) const
QSize labelSize (const QFont &, double val) const
QRect boundingLabelRect (const QFont &, double val) const

  Protected Member Functions
QMatrix labelMatrix (const QPoint &, const QSize &) const
virtual void drawTick (QPainter *p, double val, int len) const
virtual void drawBackbone (QPainter *p) const
virtual void drawLabel (QPainter *p, double val) 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 Enumeration Documentation

  enum QwtScaleDraw::Alignment

Alignment of the scale draw

See also:
    setAlignment(), alignment()

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 (const QwtScaleDraw & other)

Copy constructor.

  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 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, int 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.

  int QwtScaleDraw::extent (const QPen & pen, 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:
    pen Pen that is used for painting backbone and ticks
    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

  Qt::Alignment QwtScaleDraw::labelAlignment () const

Returns:
    the label flags

See also:
    setLabelAlignment(), labelRotation()

  QMatrix QwtScaleDraw::labelMatrix (const QPoint & pos, const QSize & size) const [protected]

Calculate the matrix 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()

  QPoint 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

  QRect 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()

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

Calculate the size that is needed to draw a label

Parameters:
    font Label font
    value Value

  int 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

  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 QPen & pen, const QFont & font) const

Calculate the minimum length that is needed to draw the scale

Parameters:
    pen Pen that is used for painting backbone and ticks
    font Font used for painting the labels

See also:
    extent()

  void QwtScaleDraw::move (const QPoint & 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()

  void QwtScaleDraw::move (int x, int y) [inline]

Move the position of the scale

See also:
    move(const QPoint &)

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

Assignment operator.

  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()

  QPoint QwtScaleDraw::pos () const

Returns:
    Origin of the scale

See also:
    move(), length()

  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 (int length)

Set the length of the backbone.

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

See also:
    move(), minLabelDist()

Author

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