| QwtPlotHistogram(3) | Qwt User's Guide | QwtPlotHistogram(3) |
NAME¶
QwtPlotHistogram - QwtPlotHistogram represents a series of samples, where an interval is associated with a value ( $y = f([x1,x2])$ ).SYNOPSIS¶
#include <qwt_plot_histogram.h> Inherits QwtPlotSeriesItem< QwtIntervalSample >.Public Types¶
enum HistogramStyle { Outline, Columns, Lines, UserStyle = 100 }
Public Member Functions¶
QwtPlotHistogram (const QString &title=QString::null)
Protected Member Functions¶
virtual QwtColumnRect columnRect (const QwtIntervalSample &, const QwtScaleMap &, const QwtScaleMap &) const
Detailed Description¶
QwtPlotHistogram represents a series of samples, where an interval is associated with a value ( $y = f([x1,x2])$ ). The representation depends on the style() and an optional symbol() that is displayed for each interval. Note:The term 'histogram' is used in a different way in the
areas of digital image processing and statistics. Wikipedia introduces the
terms 'image histogram' and 'color histogram' to avoid confusions. While
'image histograms' can be displayed by a QwtPlotCurve there is no
applicable plot item for a 'color histogram' yet.
Member Enumeration Documentation¶
enum QwtPlotHistogram::HistogramStyle Histogram styles. The default style is QwtPlotHistogram::Columns.¶
See also:setStyle(), style(), setSymbol(),
symbol(), setBaseline()
Enumerator:
- Outline
- Draw an outline around the area, that is build by all intervals using the pen() and fill it with the brush(). The outline style requires, that the intervals are in increasing order and not overlapping.
- Columns
- Draw a column for each interval. When a symbol() has been set the symbol is used otherwise the column is displayed as plain rectangle using pen() and brush().
- Lines
- Draw a simple line using the pen() for each interval.
- UserStyle
- Styles >= UserStyle are reserved for derived classes that overload drawSeries() with additional application specific ways to display a histogram.
Constructor & Destructor Documentation¶
QwtPlotHistogram::QwtPlotHistogram (const QString &title = QString::null) [explicit] Constructor¶
Parameters:title Title of the histogram.
QwtPlotHistogram::QwtPlotHistogram (const QwtText &title) [explicit] Constructor¶
Parameters:title Title of the histogram.
QwtPlotHistogram::~QwtPlotHistogram () [virtual]¶
Destructor.Member Function Documentation¶
double QwtPlotHistogram::baseline () const Returns:¶
Value of the baseline
See also:
setBaseline()
QRectF QwtPlotHistogram::boundingRect () const [virtual] Returns:¶
Bounding rectangle of all samples. For an empty series
the rectangle is invalid.
Reimplemented from QwtPlotSeriesItem< QwtIntervalSample >.
const QBrush & QwtPlotHistogram::brush () const Returns:¶
Brush used in a style() depending way.
See also:
setPen(), brush()
QwtColumnRect QwtPlotHistogram::columnRect (const QwtIntervalSample &sample, const QwtScaleMap &xMap, const QwtScaleMap &yMap) const [protected, virtual] Calculate the area that is covered by a sample¶
Parameters:sample Sample
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
Returns:
Rectangle, that is covered by a sample
void QwtPlotHistogram::drawColumn (QPainter *painter, const QwtColumnRect &rect, const QwtIntervalSample &sample) const [protected, virtual] Draw a column for a sample in Columns style().¶
When a symbol() has been set the symbol is used otherwise the column is displayed as plain rectangle using pen() and brush(). Parameters:painter Painter
rect Rectangle where to paint the column in paint device coordinates
sample Sample to be displayed
Note:
In applications, where different intervals need to be
displayed in a different way ( f.e different colors or even using differnt
symbols) it is recommended to overload drawColumn().
void QwtPlotHistogram::drawColumns (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, intfrom, intto) const [protected] Draw a histogram in Columns style()¶
Parameters:painter Painter
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
from Index of the first sample to be painted
to Index of the last sample to be painted. If to < 0 the histogram
will be painted to its last point.
See also:
setStyle(), style(), setSymbol(),
drawColumn()
void QwtPlotHistogram::drawLegendIdentifier (QPainter *painter, const QRectF &rect) const [virtual] Draw a plain rectangle without pen using the brush() as identifier¶
Parameters:painter Painter
rect Bounding rectangle for the identifier
Reimplemented from QwtLegendItemManager.
void QwtPlotHistogram::drawLines (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, intfrom, intto) const [protected] Draw a histogram in Lines style()¶
Parameters:painter Painter
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
from Index of the first sample to be painted
to Index of the last sample to be painted. If to < 0 the histogram
will be painted to its last point.
See also:
setStyle(), style(), setPen()
void QwtPlotHistogram::drawOutline (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, intfrom, intto) const [protected] Draw a histogram in Outline style()¶
Parameters:painter Painter
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
from Index of the first sample to be painted
to Index of the last sample to be painted. If to < 0 the histogram
will be painted to its last point.
See also:
setStyle(), style()
Warning:
The outline style requires, that the intervals are in
increasing order and not overlapping.
void QwtPlotHistogram::drawSeries (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, intfrom, intto) const [virtual] Draw a subset of the histogram samples¶
Parameters:painter Painter
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
canvasRect Contents rect of the canvas
from Index of the first sample to be painted
to Index of the last sample to be painted. If to < 0 the series will
be painted to its last sample.
See also:
drawOutline(), drawLines(),
drawColumns
Implements QwtPlotAbstractSeriesItem.
const QPen & QwtPlotHistogram::pen () const Returns:¶
Pen used in a style() depending way.
See also:
setPen(), brush()
int QwtPlotHistogram::rtti () const [virtual] Returns:¶
QwtPlotItem::Rtti_PlotHistogram
Reimplemented from QwtPlotItem.
void QwtPlotHistogram::setBaseline (doublevalue)¶
Set the value of the baseline. Each column representing an QwtIntervalSample is defined by its interval and the interval between baseline and the value of the sample. The default value of the baseline is 0.0. Parameters:value Value of the baseline
See also:
baseline()
void QwtPlotHistogram::setBrush (const QBrush &brush) Assign a brush, that is used in a style() depending way.¶
Parameters:brush New brush
See also:
pen(), brush()
void QwtPlotHistogram::setPen (const QPen &pen) Assign a pen, that is used in a style() depending way.¶
Parameters:pen New pen
See also:
pen(), brush()
void QwtPlotHistogram::setSamples (const QVector< QwtIntervalSample > &samples) Initialize data with an array of samples.¶
Parameters:samples Vector of points
void QwtPlotHistogram::setStyle ( HistogramStylestyle) Set the histogram's drawing style¶
Parameters:style Histogram style
See also:
HistogramStyle, style()
void QwtPlotHistogram::setSymbol (const QwtColumnSymbol *symbol)¶
Assign a symbol. In Column style an optional symbol can be assigned, that is responsible for displaying the rectangle that is defined by the interval and the distance between baseline() and value. When no symbol has been defined the area is displayed as plain rectangle using pen() and brush(). See also:style(), symbol(), drawColumn(),
pen(), brush()
Note:
In applications, where different intervals need to be
displayed in a different way ( f.e different colors or even using differnt
symbols) it is recommended to overload drawColumn().
QwtPlotHistogram::HistogramStyle QwtPlotHistogram::style () const Return the current style¶
See also:HistogramStyle, setStyle()
const QwtColumnSymbol * QwtPlotHistogram::symbol () const Returns:¶
Current symbol or NULL, when no symbol has been
assigned
See also:
setSymbol()
Author¶
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