Qwt User's Guide 6.0.0
Public Types | Public Member Functions | Protected Member Functions

QwtScaleDraw Class Reference

A class for drawing scales. More...

#include <qwt_scale_draw.h>

Inheritance diagram for QwtScaleDraw:
Inheritance graph
[legend]

List of all members.

Public Types

enum  Alignment {
  BottomScale,
  TopScale,
  LeftScale,
  RightScale
}

Public Member Functions

 QwtScaleDraw ()
virtual ~QwtScaleDraw ()
void getBorderDistHint (const QFont &, int &start, int &end) const
int minLabelDist (const QFont &) const
int minLength (const QFont &) const
virtual double extent (const QFont &) const
void move (double x, double y)
void move (const QPointF &)
void setLength (double length)
Alignment alignment () const
void setAlignment (Alignment)
Qt::Orientation orientation () const
QPointF pos () const
double 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
QPointF labelPosition (double val) const
QRectF labelRect (const QFont &, double val) const
QSizeF labelSize (const QFont &, double val) const
QRect boundingLabelRect (const QFont &, double val) const

Protected Member Functions

QTransform labelTransformation (const QPointF &, const QSizeF &) const
virtual void drawTick (QPainter *, double val, double len) const
virtual void drawBackbone (QPainter *) const
virtual void drawLabel (QPainter *, 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

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.


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:
fontFont used for painting
valueValue
See also:
labelRect()
void QwtScaleDraw::drawBackbone ( QPainter *  painter) const [protected, virtual]

Draws the baseline of the scale

Parameters:
painterPainter
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:
painterPainter
valueValue
See also:
drawTick(), drawBackbone(), boundingLabelRect()

Implements QwtAbstractScaleDraw.

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

Draw a tick

Parameters:
painterPainter
valueValue of the tick
lenLenght of the tick
See also:
drawBackbone(), drawLabel()

Implements QwtAbstractScaleDraw.

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:
fontFont 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:
fontFont
startStart border distance
endEnd border distance
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:
valueValue
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:
fontFont used for painting
valueValue
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:
fontLabel font
valueValue
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:
posPosition where to paint the label
sizeSize 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:
fontFont
Returns:
the maximum height of a label
int QwtScaleDraw::maxLabelWidth ( const QFont &  font) const
Parameters:
fontFont
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:
fontFont
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:
fontFont 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:
posOrigin 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()
QPointF 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:
alignmentOr'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:
rotationAngle 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()