Man page - qwtscaledraw(3)

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Manual

QwtScaleDraw

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 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
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.

Protected Member Functions

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

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:

font Font used for painting
value Value

Returns:

Bounding rectangle

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, double len)const [protected], [virtual]

Draw a tick

Parameters:

painter Painter
value Value of the tick
len Length 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:

font Font 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:

font Font
start Start border distance
end End 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:

value Value

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:

font Font used for painting
value Value

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:

font Label font
value Value

Returns:

Size that is needed to draw a label

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()

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

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

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:

x X coordinate
y Y 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:

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.

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:

align 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 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() .

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.

Parameters:

length Length of the backbone

See also:

move() , minLabelDist()

Author

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