Qwt User's Guide  6.1.0
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QwtScaleDraw Class Reference

A class for drawing scales. More...

#include <qwt_scale_draw.h>

Inheritance diagram for QwtScaleDraw:
Inheritance graph
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Public Types

enum  Alignment { BottomScale, TopScale, LeftScale, RightScale }
 
- Public Types inherited from QwtAbstractScaleDraw
enum  ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
 
typedef QFlags< ScaleComponentScaleComponents
 Scale components.
 

Public Member Functions

 QwtScaleDraw ()
 Constructor. More...
 
virtual ~QwtScaleDraw ()
 Destructor.
 
void getBorderDistHint (const QFont &, int &start, int &end) const
 Determine the minimum border distance. More...
 
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 &)
 Move the position of the scale. More...
 
void setLength (double length)
 
Alignment alignment () const
 
void setAlignment (Alignment)
 
Qt::Orientation orientation () const
 
QPointF pos () const
 
double length () const
 
void setLabelAlignment (Qt::Alignment)
 Change the label flags. More...
 
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
 Find the bounding rectangle for the label. More...
 
- Public Member Functions inherited from QwtAbstractScaleDraw
 QwtAbstractScaleDraw ()
 Constructor. More...
 
virtual ~QwtAbstractScaleDraw ()
 Destructor.
 
void setScaleDiv (const QwtScaleDiv &s)
 
const QwtScaleDivscaleDiv () const
 
void setTransformation (QwtTransform *)
 
const QwtScaleMapscaleMap () const
 
QwtScaleMapscaleMap ()
 
void enableComponent (ScaleComponent, bool enable=true)
 
bool hasComponent (ScaleComponent) const
 
void setTickLength (QwtScaleDiv::TickType, double length)
 
double tickLength (QwtScaleDiv::TickType) const
 
double maxTickLength () const
 
void setSpacing (double margin)
 Set the spacing between tick and labels. More...
 
double spacing () const
 Get the spacing. More...
 
void setPenWidth (int width)
 Specify the width of the scale pen. More...
 
int penWidth () const
 
virtual void draw (QPainter *, const QPalette &) const
 Draw the scale. More...
 
virtual QwtText label (double) const
 Convert a value into its representing label. More...
 
void setMinimumExtent (double)
 Set a minimum for the extent. More...
 
double minimumExtent () 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
 
- Protected Member Functions inherited from QwtAbstractScaleDraw
void invalidateCache ()
 
const QwtTexttickLabel (const QFont &, double value) const
 Convert a value into its representing label and cache it. More...
 

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.

Member Function Documentation

QwtScaleDraw::Alignment QwtScaleDraw::alignment ( ) const

Return alignment of the scale

See Also
setAlignment()
Returns
Alignment of the scale
QRect QwtScaleDraw::boundingLabelRect ( const QFont &  font,
double  value 
) const

Find the bounding rectangle for the label.

The coordinates of the rectangle are absolute ( calculated from pos() ). in direction of the tick.

Parameters
fontFont used for painting
valueValue
Returns
Bounding rectangle
See Also
labelRect()
void QwtScaleDraw::drawBackbone ( QPainter *  painter) const
protectedvirtual

Draws the baseline of the scale

Parameters
painterPainter
See Also
drawTick(), drawLabel()

Implements QwtAbstractScaleDraw.

void QwtScaleDraw::drawLabel ( QPainter *  painter,
double  value 
) const
protectedvirtual

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
protectedvirtual

Draw a tick

Parameters
painterPainter
valueValue of the tick
lenLength 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
Returns
Extent
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 that depends on the length of the ticks in direction of the alignment().

Parameters
valueValue
Returns
Position, where to paint a label
QRectF QwtScaleDraw::labelRect ( const QFont &  font,
double  value 
) const

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

Parameters
fontFont used for painting
valueValue
Returns
Bounding rectangle that is needed to draw a label
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
Returns
Size that is needed to draw a label
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
Returns
Transformation matrix
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
Returns
Minimum length that is needed to draw the scale
See Also
extent()
void QwtScaleDraw::move ( double  x,
double  y 
)
inline

Move the position of the scale

Parameters
xX coordinate
yY coordinate
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.

Returns
Orientation of the scale
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

Parameters
alignAlignment 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 tick length + 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\n
QwtScaleDraw::BottomScale: Qt::AlignHCenter | Qt::AlignBottom\n
QwtScaleDraw::LeftScale: Qt::AlignLeft | Qt::AlignVCenter\n
QwtScaleDraw::RightScale: Qt::AlignRight | Qt::AlignVCenter\n

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.

Parameters
lengthLength of the backbone
See Also
move(), minLabelDist()