QwtScaleDraw (3) - Linux Manuals

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 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.

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

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, doublevalue) 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, doublevalue) 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, doublevalue, doublelen) 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 (doublevalue) 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, doublevalue) 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, doublevalue) 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, const QSizeF &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 (doublex, doubley) [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 (Alignmentalign)

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::Alignmentalignment)

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::AlignTopQwtScaleDraw::BottomScale: Qt::AlignHCenter | Qt::AlignBottomQwtScaleDraw::LeftScale: Qt::AlignLeft | Qt::AlignVCenterQwtScaleDraw::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 (doublerotation)

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 (doublelength)

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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