QwtAbstractScaleDraw - Man Page
A abstract base class for drawing scales.
Synopsis
#include <qwt_abstract_scale_draw.h>
Inherited by QwtRoundScaleDraw, and QwtScaleDraw.
Public Types
enum ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
typedef QFlags< ScaleComponent > ScaleComponents
Scale components.
Public Member Functions
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
Protected Member Functions
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.
Detailed Description
A abstract base class for drawing scales.
QwtAbstractScaleDraw can be used to draw linear or logarithmic scales.
After a scale division has been specified as a QwtScaleDiv object using setScaleDiv(), the scale can be drawn with the draw() member.
Member Enumeration Documentation
enum QwtAbstractScaleDraw::ScaleComponent
Components of a scale
- See also
enableComponent(), hasComponent
Enumerator
- Backbone
Backbone = the line where the ticks are located.
- Ticks
Ticks.
- Labels
Labels.
Constructor & Destructor Documentation
QwtAbstractScaleDraw::QwtAbstractScaleDraw ()
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
Member Function Documentation
void QwtAbstractScaleDraw::draw (QPainter * painter, const QPalette & palette) const [virtual]
Draw the scale.
- Parameters
painter The painter
palette Palette, text color is used for the labels, foreground color for ticks and backbone
virtual void QwtAbstractScaleDraw::drawBackbone (QPainter * painter) const [protected], [pure virtual]
Draws the baseline of the scale
- Parameters
painter Painter
- See also
drawTick(), drawLabel()
Implemented in QwtScaleDraw, and QwtRoundScaleDraw.
virtual void QwtAbstractScaleDraw::drawLabel (QPainter * painter, double value) const [protected], [pure virtual]
Draws the label for a major scale tick
- Parameters
painter Painter
value Value- See also
drawTick(), drawBackbone()
Implemented in QwtScaleDraw, and QwtRoundScaleDraw.
virtual void QwtAbstractScaleDraw::drawTick (QPainter * painter, double value, double len) const [protected], [pure virtual]
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.
void QwtAbstractScaleDraw::enableComponent (ScaleComponent component, bool enable = true)
En/Disable a component of the scale
- Parameters
component Scale component
enable On/Off- See also
hasComponent()
virtual double QwtAbstractScaleDraw::extent (const QFont & font) const [pure virtual]
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.
bool QwtAbstractScaleDraw::hasComponent (ScaleComponent component) const
Check if a component is enabled
- Parameters
component Component type
- Returns
true, when component is enabled
- See also
enableComponent()
void QwtAbstractScaleDraw::invalidateCache () [protected]
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.
QwtText QwtAbstractScaleDraw::label (double value) const [virtual]
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.
double QwtAbstractScaleDraw::maxTickLength () const
- Returns
Length of the longest tick
Useful for layout calculations
- See also
tickLength(), setTickLength()
double QwtAbstractScaleDraw::minimumExtent () const
Get the minimum extent
- Returns
Minimum extent
- See also
extent(), setMinimumExtent()
int QwtAbstractScaleDraw::penWidth () const
- Returns
Scale pen width
- See also
setPenWidth()
const QwtScaleDiv & QwtAbstractScaleDraw::scaleDiv () const
- Returns
scale division
QwtScaleMap & QwtAbstractScaleDraw::scaleMap ()
- Returns
Map how to translate between scale and pixel values
const QwtScaleMap & QwtAbstractScaleDraw::scaleMap () const
- Returns
Map how to translate between scale and pixel values
void QwtAbstractScaleDraw::setMinimumExtent (double minExtent)
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()
void QwtAbstractScaleDraw::setPenWidth (int width)
Specify the width of the scale pen.
- Parameters
width Pen width
- See also
penWidth()
void QwtAbstractScaleDraw::setScaleDiv (const QwtScaleDiv & scaleDiv)
Change the scale division
- Parameters
scaleDiv New scale division
void QwtAbstractScaleDraw::setSpacing (double spacing)
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()
void QwtAbstractScaleDraw::setTickLength (QwtScaleDiv::TickType tickType, double length)
Set the length of the ticks
- Parameters
tickType Tick type
length New length- Warning
the length is limited to [0..1000]
void QwtAbstractScaleDraw::setTransformation (QwtTransform * transformation)
Change the transformation of the scale
- Parameters
transformation New scale transformation
double QwtAbstractScaleDraw::spacing () const
Get the spacing. The spacing is the distance between ticks and labels. The default spacing is 4 pixels.
- Returns
Spacing
- See also
setSpacing()
const QwtText & QwtAbstractScaleDraw::tickLabel (const QFont & font, double value) const [protected]
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
double QwtAbstractScaleDraw::tickLength (QwtScaleDiv::TickType tickType) const
- Returns
Length of the ticks
- See also
setTickLength(), maxTickLength()
Author
Generated automatically by Doxygen for Qwt User's Guide from the source code.