QwtScaleDraw - A class for drawing scales.

NAME SYNOPSIS Public Types Public Member Functions Protected Member Functions Detailed Description Member Enumeration Documentation enum QwtScaleDraw::Alignment Constructor & Destructor Documentation QwtScaleDraw::QwtScaleDraw () QwtScaleDraw::˜QwtScaleDraw () [virtual] Member Function Documentation QwtScaleDraw::Alignment QwtScaleDraw::alignment () const QRect QwtScaleDraw::boundingLabelRect (const QFont & font, double value)const void QwtScaleDraw::drawBackbone (QPainter * painter) const [override],[protected], [virtual] void QwtScaleDraw::drawLabel (QPainter * painter, double value) const[override], [protected], [virtual] void QwtScaleDraw::drawTick (QPainter * painter, double value, double len)const [override], [protected], [virtual] double QwtScaleDraw::extent (const QFont & font) const [override],[virtual] void QwtScaleDraw::getBorderDistHint (const QFont & font, int & start, int& end) const Qt::Alignment QwtScaleDraw::labelAlignment () const QPointF QwtScaleDraw::labelPosition (double value) const QRectF QwtScaleDraw::labelRect (const QFont & font, double value) const double QwtScaleDraw::labelRotation () const QSizeF QwtScaleDraw::labelSize (const QFont & font, double value) const QTransform QwtScaleDraw::labelTransformation (const QPointF & pos, constQSizeF & size) const [protected] double QwtScaleDraw::length () const int QwtScaleDraw::maxLabelHeight (const QFont & font) const int QwtScaleDraw::maxLabelWidth (const QFont & font) const int QwtScaleDraw::minLabelDist (const QFont & font) const int QwtScaleDraw::minLength (const QFont & font) const void QwtScaleDraw::move (const QPointF & pos) void QwtScaleDraw::move (double x, double y) [inline] Qt::Orientation QwtScaleDraw::orientation () const QPointF QwtScaleDraw::pos () const void QwtScaleDraw::setAlignment (Alignment align) void QwtScaleDraw::setLabelAlignment (Qt::Alignment alignment) void QwtScaleDraw::setLabelRotation (double rotation) void QwtScaleDraw::setLength (double length) Author

NAME

QwtScaleDraw − A class for drawing scales.

SYNOPSIS

#include <qwt_scale_draw.h>

Inherits QwtAbstractScaleDraw.

Inherited by QwtDateScaleDraw.

Public Types

enum Alignment { BottomScale, TopScale, LeftScale, RightScale }

Public Types inherited from QwtAbstractScaleDraw

enum ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
typedef QFlags< ScaleComponent > ScaleComponents

Public Member Functions

QwtScaleDraw ()
Constructor.
virtual ˜QwtScaleDraw ()
Destructor.
void getBorderDistHint (const QFont &, int &start, int &end) const
Determine the minimum border distance.
int minLabelDist (const QFont &) const
int minLength (const QFont &) const
virtual double extent (const QFont &) const override
void move (double x, double y)
void move (const QPointF &)
Move the position of the scale.
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.
Qt::Alignment labelAlignment () const
void setLabelRotation (double rotation)
double labelRotation () const
int maxLabelHeight (const QFont &) const
int maxLabelWidth (const QFont &) const
QPointF labelPosition (double value) const
QRectF labelRect (const QFont &, double value) const
QSizeF labelSize (const QFont &, double value) const
QRect boundingLabelRect (const QFont &, double value) const
Find the bounding rectangle for the label.

Public Member Functions inherited from QwtAbstractScaleDraw

QwtAbstractScaleDraw ()
Constructor.
virtual ˜QwtAbstractScaleDraw ()
Destructor.
void setScaleDiv (const QwtScaleDiv &)
const QwtScaleDiv & scaleDiv () const
void setTransformation (QwtTransform *)
const QwtScaleMap & scaleMap () const
QwtScaleMap & scaleMap ()
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)
Set the spacing between tick and labels.
double spacing () const
Get the spacing.
void setPenWidthF (qreal width)
Specify the width of the scale pen.
qreal penWidthF () const
virtual void draw (QPainter *, const QPalette &) const
Draw the scale.
virtual QwtText label (double) const
Convert a value into its representing label.
void setMinimumExtent (double)
Set a minimum for the extent.
double minimumExtent () const
void invalidateCache ()

Protected Member Functions

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

Protected Member Functions inherited from QwtAbstractScaleDraw

const QwtText & tickLabel (const QFont &, double value) const
Convert a value into its representing label and cache it.

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.

Definition at line 35 of file qwt_scale_draw.h.

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.

Definition at line 42 of file qwt_scale_draw.h.

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.

Definition at line 292 of file qwt_scale_draw.cpp.

QwtScaleDraw::˜QwtScaleDraw () [virtual]

Returns

Extent

See also

minLength()

Implements QwtAbstractScaleDraw.

Definition at line 523 of file qwt_scale_draw.cpp.

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

Definition at line 361 of file qwt_scale_draw.cpp.

Qt::Alignment QwtScaleDraw::labelAlignment () const

Returns

the label flags

See also

setLabelAlignment(), labelRotation()

Definition at line 978 of file qwt_scale_draw.cpp.

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

value Value

Returns

Position, where to paint a label

Definition at line 596 of file qwt_scale_draw.cpp.

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

font Font used for painting
value Value

Returns

Bounding rectangle that is needed to draw a label

Definition at line 887 of file qwt_scale_draw.cpp.

double QwtScaleDraw::labelRotation () const

Returns

the label rotation

See also

setLabelRotation(), labelAlignment()

Definition at line 939 of file qwt_scale_draw.cpp.

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

Returns

Size that is needed to draw a label

Definition at line 912 of file qwt_scale_draw.cpp.

QTransform QwtScaleDraw::labelTransformation (const QPointF & pos, constQSizeF & 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

Returns

Transformation matrix

See also

setLabelAlignment(), setLabelRotation()

Definition at line 817 of file qwt_scale_draw.cpp.

double QwtScaleDraw::length () const

Returns

the length of the backbone

See also

setLength(), pos()

Definition at line 749 of file qwt_scale_draw.cpp.

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

Parameters

font Font

Returns

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()

Definition at line 707 of file qwt_scale_draw.cpp.

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

Move the position of the scale

Parameters

x X coordinate
y Y coordinate

See also

move(const QPointF &)

Definition at line 118 of file qwt_scale_draw.h.

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()

Definition at line 337 of file qwt_scale_draw.cpp.

QPointF QwtScaleDraw::pos () const

Returns

Origin of the scale

See also

move(), length()

Definition at line 717 of file qwt_scale_draw.cpp.

void QwtScaleDraw::setAlignment (Alignment align)

Set the alignment of the scale

Parameters

align Alignment of the scale

The default alignment is QwtScaleDraw::BottomScale

See also

alignment()

Definition at line 322 of file qwt_scale_draw.cpp.

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
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().

Definition at line 969 of file qwt_scale_draw.cpp.

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().

Definition at line 930 of file qwt_scale_draw.cpp.

void QwtScaleDraw::setLength (double length)

Set the length of the backbone.

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

Parameters

length Length of the backbone

See also

move(), minLabelDist()

Definition at line 732 of file qwt_scale_draw.cpp.

Author

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Updated 2026-06-01 - jenkler.se | uex.se