QwtPlotAbstractBarChart - Man Page
Abstract base class for bar chart items.
Synopsis
#include <qwt_plot_abstract_barchart.h>
Inherits QwtPlotSeriesItem.
Inherited by QwtPlotBarChart, and QwtPlotMultiBarChart.
Public Types
enum LayoutPolicy { AutoAdjustSamples, ScaleSamplesToAxes, ScaleSampleToCanvas, FixedSampleSize }
Mode how to calculate the bar width.
Public Member Functions
QwtPlotAbstractBarChart (const QwtText &title)
virtual ~QwtPlotAbstractBarChart ()
Destructor.
void setLayoutPolicy (LayoutPolicy)
LayoutPolicy layoutPolicy () const
void setLayoutHint (double)
double layoutHint () const
void setSpacing (int)
Set the spacing.
int spacing () const
void setMargin (int)
Set the margin.
int margin () const
void setBaseline (double)
Set the baseline.
double baseline () const
virtual void getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, double &left, double &top, double &right, double &bottom) const
Calculate a hint for the canvas margin.
Protected Member Functions
double sampleWidth (const QwtScaleMap &map, double canvasSize, double boundingSize, double value) const
Detailed Description
Abstract base class for bar chart items.
In opposite to almost all other plot items bar charts can't be displayed inside of their bounding rectangle and need a special API how to calculate the width of the bars and how they affect the layout of the attached plot.
Member Enumeration Documentation
enum QwtPlotAbstractBarChart::LayoutPolicy
Mode how to calculate the bar width. setLayoutPolicy(), setLayoutHint(), barWidthHint()
Enumerator
- AutoAdjustSamples
The sample width is calculated by dividing the bounding rectangle by the number of samples. The layoutHint() is used as a minimum width in paint device coordinates.
- See also
boundingRectangle()
- ScaleSamplesToAxes
layoutHint() defines an interval in axis coordinates
- ScaleSampleToCanvas
The bar width is calculated by multiplying layoutHint() with the height or width of the canvas.
- See also
boundingRectangle()
- FixedSampleSize
layoutHint() defines a fixed width in paint device coordinates.
Constructor & Destructor Documentation
QwtPlotAbstractBarChart::QwtPlotAbstractBarChart (const QwtText & title) [explicit]
Constructor
- Parameters
title Title of the chart
Member Function Documentation
double QwtPlotAbstractBarChart::baseline () const
- Returns
Value for the origin of the bar chart
- See also
setBaseline(), QwtPlotSeriesItem::orientation()
void QwtPlotAbstractBarChart::getCanvasMarginHint (const QwtScaleMap & xMap, const QwtScaleMap & yMap, const QRectF & canvasRect, double & left, double & top, double & right, double & bottom) const [virtual]
Calculate a hint for the canvas margin. Bar charts need to reserve some space for displaying the bars for the first and the last sample. The hint is calculated from the layoutHint() depending on the layoutPolicy().
The margins are in target device coordinates ( pixels on screen )
- Parameters
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
canvasRect Contents rectangle of the canvas in painter coordinates
left Returns the left margin
top Returns the top margin
right Returns the right margin
bottom Returns the bottom margin- Returns
Margin
- See also
layoutPolicy(), layoutHint(), QwtPlotItem::Margins QwtPlot::getCanvasMarginsHint(), QwtPlot::updateCanvasMargins()
Reimplemented from QwtPlotItem.
double QwtPlotAbstractBarChart::layoutHint () const
The combination of layoutPolicy() and layoutHint() define how the width of the bars is calculated
- Returns
Layout policy of the chart item
- See also
LayoutPolicy, setLayoutHint(), layoutPolicy()
QwtPlotAbstractBarChart::LayoutPolicy QwtPlotAbstractBarChart::layoutPolicy () const
The combination of layoutPolicy() and layoutHint() define how the width of the bars is calculated
- Returns
Layout policy of the chart item
- See also
setLayoutPolicy(), layoutHint()
int QwtPlotAbstractBarChart::margin () const
- Returns
Margin between the outmost bars and the contentsRect() of the canvas.
- See also
setMargin(), spacing()
double QwtPlotAbstractBarChart::sampleWidth (const QwtScaleMap & map, double canvasSize, double boundingSize, double value) const [protected]
Calculate the width for a sample in paint device coordinates
- Parameters
map Scale map for the corresponding scale
canvasSize Size of the canvas in paint device coordinates
boundingSize Bounding size of the chart in plot coordinates ( used in AutoAdjustSamples mode )
value Value of the sample- Returns
Sample width
- See also
layoutPolicy(), layoutHint()
void QwtPlotAbstractBarChart::setBaseline (double value)
Set the baseline. The baseline is the origin for the chart. Each bar is painted from the baseline in the direction of the sample value. In case of a horizontal orientation() the baseline is interpreted as x - otherwise as y - value.
The default value for the baseline is 0.
- Parameters
value Value for the baseline
- See also
baseline(), QwtPlotSeriesItem::orientation()
void QwtPlotAbstractBarChart::setLayoutHint (double hint)
The combination of layoutPolicy() and layoutHint() define how the width of the bars is calculated
- Parameters
hint Layout hint
- See also
LayoutPolicy, layoutPolicy(), layoutHint()
void QwtPlotAbstractBarChart::setLayoutPolicy (LayoutPolicy policy)
The combination of layoutPolicy() and layoutHint() define how the width of the bars is calculated
- Parameters
policy Layout policy
- See also
layoutPolicy(), layoutHint()
void QwtPlotAbstractBarChart::setMargin (int margin)
Set the margin. The margin is the distance between the outmost bars and the contentsRect() of the canvas. The default setting is 5 pixels.
- Parameters
margin Margin
- See also
spacing(), margin()
void QwtPlotAbstractBarChart::setSpacing (int spacing)
Set the spacing. The spacing is the distance between 2 samples ( bars for QwtPlotBarChart or a group of bars for QwtPlotMultiBarChart ) in paint device coordinates.
- See also
spacing()
int QwtPlotAbstractBarChart::spacing () const
- Returns
Spacing between 2 samples ( bars or groups of bars )
- See also
setSpacing(), margin()
Author
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