QwtAbstractScaleDraw - Man Page

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

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 setPenWidth (int width)
Specify the width of the scale pen.
int penWidth () const
virtual void draw (QPainter *, const QPalette &) const
Draw the scale.
virtual QwtText label (double) const
Convert a value into its representing label.
virtual double extent (const QFont &font) const =0
void setMinimumExtent (double)
Set a minimum for the extent.
double minimumExtent () const

virtual void drawTick (QPainter *painter, double value, double len) const =0
virtual void drawBackbone (QPainter *painter) const =0
virtual void drawLabel (QPainter *painter, double value) const =0
void invalidateCache ()
const QwtText & tickLabel (const QFont &, double value) const
Convert a value into its representing label and cache it.

Components of a scale

See also

enableComponent(), hasComponent

Enumerator

Backbone

Backbone = the line where the ticks are located.

Ticks

Ticks.

Labels

Labels.

Constructor. The range of the scale is initialized to [0, 100], The spacing (distance between ticks and labels) is set to 4, the tick lengths are set to 4,6 and 8 pixels

Draw the scale.

Parameters

painter The painter
palette Palette, text color is used for the labels, foreground color for ticks and backbone

Draws the baseline of the scale

Parameters

painter Painter

See also

drawTick(), drawLabel()

Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

Draws the label for a major scale tick

Parameters

painter Painter
value Value

See also

drawTick(), drawBackbone()

Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

Draw a tick

Parameters

painter Painter
value Value of the tick
len Length of the tick

See also

drawBackbone(), drawLabel()

Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

En/Disable a component of the scale

Parameters

component Scale component
enable On/Off

See also

hasComponent()

Calculate the extent

The extent is the distance from the baseline to the outermost pixel of the scale draw in opposite to its orientation. It is at least minimumExtent() pixels.

Parameters

font Font used for drawing the tick labels

Returns

Number of pixels

See also

setMinimumExtent(), minimumExtent()

Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

Check if a component is enabled

Parameters

component Component type

Returns

true, when component is enabled

See also

enableComponent()

Invalidate the cache used by tickLabel()

The cache is invalidated, when a new QwtScaleDiv is set. If the labels need to be changed. while the same QwtScaleDiv is set, invalidateCache() needs to be called manually.

Convert a value into its representing label. The value is converted to a plain text using QLocale().toString(value). This method is often overloaded by applications to have individual labels.

Parameters

value Value

Returns

Label string.

Reimplemented in QwtDateScaleDraw, and QwtCompassScaleDraw.

Returns

Length of the longest tick

Useful for layout calculations

See also

tickLength(), setTickLength()

Get the minimum extent

Returns

Minimum extent

See also

extent(), setMinimumExtent()

Returns

Scale pen width

See also

setPenWidth()

Returns

scale division

Returns

Map how to translate between scale and pixel values

Returns

Map how to translate between scale and pixel values

Set a minimum for the extent. The extent is calculated from the components of the scale draw. In situations, where the labels are changing and the layout depends on the extent (f.e scrolling a scale), setting an upper limit as minimum extent will avoid jumps of the layout.

Parameters

minExtent Minimum extent

See also

extent(), minimumExtent()

Specify the width of the scale pen.

Parameters

width Pen width

See also

penWidth()

Change the scale division

Parameters

scaleDiv New scale division

Set the spacing between tick and labels. The spacing is the distance between ticks and labels. The default spacing is 4 pixels.

Parameters

spacing Spacing

See also

spacing()

Set the length of the ticks

Parameters

tickType Tick type
length New length

Warning

the length is limited to [0..1000]

Change the transformation of the scale

Parameters

transformation New scale transformation

Get the spacing. The spacing is the distance between ticks and labels. The default spacing is 4 pixels.

Returns

Spacing

See also

setSpacing()

Convert a value into its representing label and cache it. The conversion between value and label is called very often in the layout and painting code. Unfortunately the calculation of the label sizes might be slow (really slow for rich text in Qt4), so it's necessary to cache the labels.

Parameters

font Font
value Value

Returns

Tick label

Returns

Length of the ticks

See also

setTickLength(), maxTickLength()