Qwt User's Guide
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A abstract base class for drawing scales. More...
#include <qwt_abstract_scale_draw.h>
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 &s) |
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 margin) |
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. |
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.
Components of a scale
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
void QwtAbstractScaleDraw::draw | ( | QPainter * | painter, |
const QPalette & | palette | ||
) | const [virtual] |
Draw the scale.
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
painter | Painter |
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
painter | Painter |
value | Value |
Implemented in QwtScaleDraw, and QwtRoundScaleDraw.
virtual void QwtAbstractScaleDraw::drawTick | ( | QPainter * | painter, |
double | value, | ||
double | len | ||
) | const [protected, pure virtual] |
Draw a tick
painter | Painter |
value | Value of the tick |
len | Length of the tick |
Implemented in QwtScaleDraw, and QwtRoundScaleDraw.
void QwtAbstractScaleDraw::enableComponent | ( | ScaleComponent | component, |
bool | enable = true |
||
) |
En/Disable a component of the scale
component | Scale component |
enable | On/Off |
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.
font | Font used for drawing the tick labels |
Implemented in QwtScaleDraw, and QwtRoundScaleDraw.
bool QwtAbstractScaleDraw::hasComponent | ( | ScaleComponent | component | ) | const |
Check if a component is enabled
component | Component type |
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.
value | Value |
Reimplemented in QwtDateScaleDraw, and QwtCompassScaleDraw.
double QwtAbstractScaleDraw::maxTickLength | ( | ) | const |
Useful for layout calculations
double QwtAbstractScaleDraw::minimumExtent | ( | ) | const |
int QwtAbstractScaleDraw::penWidth | ( | ) | const |
const QwtScaleDiv & QwtAbstractScaleDraw::scaleDiv | ( | ) | const |
const QwtScaleMap & QwtAbstractScaleDraw::scaleMap | ( | ) | const |
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.
minExtent | Minimum extent |
void QwtAbstractScaleDraw::setPenWidth | ( | int | width | ) |
void QwtAbstractScaleDraw::setScaleDiv | ( | const QwtScaleDiv & | scaleDiv | ) |
Change the scale division
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.
spacing | Spacing |
void QwtAbstractScaleDraw::setTickLength | ( | QwtScaleDiv::TickType | tickType, |
double | length | ||
) |
Set the length of the ticks
tickType | Tick type |
length | New length |
void QwtAbstractScaleDraw::setTransformation | ( | QwtTransform * | transformation | ) |
Change the transformation of the scale
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.
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.
font | Font |
value | Value |
double QwtAbstractScaleDraw::tickLength | ( | QwtScaleDiv::TickType | tickType | ) | const |