QwtPolarGrid Class Reference

An item which draws scales and grid lines on a polar plot. More...

#include <qwt_polar_grid.h>

Inheritance diagram for QwtPolarGrid:
Inheritance graph
[legend]

List of all members.

Public Types

enum  DisplayFlag {
  SmartOriginLabel = 1,
  HideMaxRadiusLabel = 2,
  ClipAxisBackground = 4,
  SmartScaleDraw = 8,
  ClipGridLines = 16
}
enum  GridAttribute { AutoScaling = 1 }

Public Member Functions

 QwtPolarGrid ()
virtual ~QwtPolarGrid ()
virtual int rtti () const
void setDisplayFlag (DisplayFlag, bool on=true)
bool testDisplayFlag (DisplayFlag) const
void setGridAttribute (GridAttribute, bool on=true)
bool testGridAttribute (GridAttribute) const
void showGrid (int scaleId, bool show=true)
bool isGridVisible (int scaleId) const
void showMinorGrid (int scaleId, bool show=true)
bool isMinorGridVisible (int scaleId) const
void showAxis (int axisId, bool show=true)
bool isAxisVisible (int axisId) const
void setPen (const QPen &p)
void setFont (const QFont &)
void setMajorGridPen (const QPen &p)
void setMajorGridPen (int scaleId, const QPen &p)
QPen majorGridPen (int scaleId) const
void setMinorGridPen (const QPen &p)
void setMinorGridPen (int scaleId, const QPen &p)
QPen minorGridPen (int scaleId) const
void setAxisPen (int axisId, const QPen &p)
QPen axisPen (int axisId) const
void setAxisFont (int axisId, const QFont &p)
QFont axisFont (int axisId) const
virtual void draw (QPainter *p, const QwtScaleMap &azimuthMap, const QwtScaleMap &radialMap, const QwtDoublePoint &pole, double radius, const QwtDoubleRect &rect) const
virtual void updateScaleDiv (const QwtScaleDiv &azimuthMap, const QwtScaleDiv &radialMap, const QwtDoubleInterval &)
virtual int marginHint () const

Protected Member Functions

void drawRays (QPainter *, const QwtDoubleRect &, const QwtDoublePoint &pole, double radius, const QwtScaleMap &azimuthMap, const QwtValueList &) const
void drawCircles (QPainter *, const QwtDoubleRect &, const QwtDoublePoint &pole, const QwtScaleMap &radialMap, const QwtValueList &) const
void drawAxis (QPainter *, int axisId) const

Detailed Description

An item which draws scales and grid lines on a polar plot.

The QwtPolarGrid class can be used to draw a coordinate grid. A coordinate grid consists of major and minor gridlines. The locations of the gridlines are determined by the azimuth and radial scale divisions.

QwtPolarGrid is also responsible for drawing the axis representing the scales. It is possible to display 4 radial and one azimuth axis.

Whenever the scale divisions of the plot widget changes the grid is synchronized by updateScaleDiv().

See also:
QwtPolarPlot, QwtPolar::Axis

Member Enumeration Documentation

Mysterious flags trying to avoid conflicts, when painting the scales and grid lines.

  • SmartOriginLabel
    Try to avoid situations, where the label of the origin is painted over another axis.
  • HideMaxRadiusLabel
    Often the outermost tick of the radial scale is close to the canvas border. With HideMaxRadiusLabel enabled it is not painted.
  • ClipAxisBackground
    The tick labels of the radial scales might be hard to read, when they are painted on top of the radial grid lines ( or on top of a curve/spectrogram ). When ClipAxisBackground the bounding rect of each label is added to the clip region.
  • SmartScaleDraw
    Don't paint the backbone of the radial axes, when they are very close to a line of the azimuth grid.
  • ClipGridLines
    All grid lines are clipped against the plot area before being painted. When the plot is zoomed in this will have an significant impact on the performance of the painting cde.

The default setting enables all flags.

Grid attributes.

  • AutoScaling
    When AutoScaling is enabled, the radial axes will be adjusted to the interval, that is currently visible on the canvas plot.

Constructor & Destructor Documentation

QwtPolarGrid::QwtPolarGrid (  )  [explicit]

Constructor.

Enables major and disables minor grid lines. The azimuth and right radial axis are visible. all other axes are hidden. Autoscaling is enabled.

QwtPolarGrid::~QwtPolarGrid (  )  [virtual]

Destructor.


Member Function Documentation

QFont QwtPolarGrid::axisFont ( int  axisId  )  const
Returns:
Font for the tick labels of a specific axis
Parameters:
axisId Axis id (QwtPolar::Axis)
QPen QwtPolarGrid::axisPen ( int  axisId  )  const
Returns:
Pen for painting a specific axis
Parameters:
axisId Axis id (QwtPolar::Axis)
See also:
setAxisPen()
void QwtPolarGrid::draw ( QPainter *  painter,
const QwtScaleMap &  azimuthMap,
const QwtScaleMap &  radialMap,
const QwtDoublePoint &  pole,
double  radius,
const QwtDoubleRect &  canvasRect 
) const [virtual]

Draw the grid and axes

Parameters:
painter Painter
azimuthMap Maps azimuth values to values related to 0.0, M_2PI
radialMap Maps radius values into painter coordinates.
pole Position of the pole in painter coordinates
radius Radius of the complete plot area in painter coordinates
canvasRect Contents rect of the canvas in painter coordinates

Implements QwtPolarItem.

void QwtPolarGrid::drawAxis ( QPainter *  painter,
int  axisId 
) const [protected]

Paint an axis

Parameters:
painter Painter
axisId Axis id (QwtPolar::Axis)
void QwtPolarGrid::drawCircles ( QPainter *  painter,
const QwtDoubleRect &  canvasRect,
const QwtDoublePoint &  pole,
const QwtScaleMap &  radialMap,
const QwtValueList &  values 
) const [protected]

Draw circles

Parameters:
painter Painter
canvasRect Contents rect of the canvas in painter coordinates
pole Position of the pole in painter coordinates
radialMap Maps radius values into painter coordinates.
values Radial values, indicating the distances from the pole
void QwtPolarGrid::drawRays ( QPainter *  painter,
const QwtDoubleRect &  canvasRect,
const QwtDoublePoint &  pole,
double  radius,
const QwtScaleMap &  azimuthMap,
const QwtValueList &  values 
) const [protected]

Draw lines from the pole

Parameters:
painter Painter
canvasRect Contents rect of the canvas in painter coordinates
pole Position of the pole in painter coordinates
radius Length of the lines in painter coordinates
azimuthMap Maps azimuth values to values related to 0.0, M_2PI
values Azimuth values, indicating the direction of the lines
bool QwtPolarGrid::isAxisVisible ( int  axisId  )  const
Returns:
true if the axis is visible
Parameters:
axisId Axis id (QwtPolar::Axis)
See also:
showAxis()
bool QwtPolarGrid::isGridVisible ( int  scaleId  )  const
Returns:
true if grid lines are enabled
Parameters:
scaleId Scale id ( QwtPolar::Scale )
See also:
QwtPolar::Scale, showGrid()
bool QwtPolarGrid::isMinorGridVisible ( int  scaleId  )  const
Returns:
true if minor grid lines are enabled
Parameters:
scaleId Scale id ( QwtPolar::Scale )
See also:
showMinorGrid()
QPen QwtPolarGrid::majorGridPen ( int  scaleId  )  const
Returns:
Pen for painting the major grid lines of a specific scale
Parameters:
scaleId Scale id ( QwtPolar::Scale )
See also:
setMajorGridPen(), minorGridPen()
int QwtPolarGrid::marginHint (  )  const [virtual]
Returns:
Number of pixels, that are necessary to paint the azimuth scale
See also:
QwtRoundScaleDraw::extent()

Reimplemented from QwtPolarItem.

QPen QwtPolarGrid::minorGridPen ( int  scaleId  )  const
Returns:
Pen for painting the minor grid lines of a specific scale
Parameters:
scaleId Scale id ( QwtPolar::Scale )
int QwtPolarGrid::rtti (  )  const [virtual]
Returns:
QwtPlotItem::Rtti_PolarGrid

Reimplemented from QwtPolarItem.

void QwtPolarGrid::setAxisFont ( int  axisId,
const QFont &  font 
)

Assign a font for the tick labels of a specific axis

Parameters:
axisId Axis id (QwtPolar::Axis)
font new Font
void QwtPolarGrid::setAxisPen ( int  axisId,
const QPen &  pen 
)

Assign a pen for painting an axis

Parameters:
axisId Axis id (QwtPolar::Axis)
pen Pen
See also:
axisPen()
void QwtPolarGrid::setDisplayFlag ( DisplayFlag  flag,
bool  on = true 
)

Change the display flags

Parameters:
flag See DisplayFlag
on true/false
void QwtPolarGrid::setFont ( const QFont &  font  ) 

Assign a font for all scale tick labels

Parameters:
font Font
See also:
setAxisFont()
void QwtPolarGrid::setGridAttribute ( GridAttribute  attribute,
bool  on = true 
)

Specify an attribute for the grid.

Parameters:
attribute Grid attribute
on On/Off

/sa GridAttribute, testGridAttribute(), updateScaleDiv(), QwtPolarPlot::zoom(), QwtPolarPlot::scaleDiv()

void QwtPolarGrid::setMajorGridPen ( int  scaleId,
const QPen &  pen 
)

Assign a pen for the major grid lines of a specific scale

Parameters:
scaleId Scale id ( QwtPolar::Scale )
pen Pen
See also:
setPen(), setMinorGridPen(), majorGridPen
void QwtPolarGrid::setMajorGridPen ( const QPen &  pen  ) 

Assign a pen for the major grid lines

Parameters:
pen Pen
See also:
setPen(), setMinorGridPen(), majorGridPen
void QwtPolarGrid::setMinorGridPen ( int  scaleId,
const QPen &  pen 
)

Assign a pen for the minor grid lines of a specific scale

Parameters:
scaleId Scale id ( QwtPolar::Scale )
pen Pen
See also:
setPen(), setMajorGridPen(), minorGridPen
void QwtPolarGrid::setMinorGridPen ( const QPen &  pen  ) 

Assign a pen for the minor grid lines

Parameters:
pen Pen
See also:
setPen(), setMajorGridPen(), minorGridPen()
void QwtPolarGrid::setPen ( const QPen &  pen  ) 

Assign a pen for all axes and grid lines

Parameters:
pen Pen
See also:
setMajorGridPen(), setMinorGridPen(), setAxisPen()
void QwtPolarGrid::showAxis ( int  axisId,
bool  show = true 
)

Show/Hide an axis

Parameters:
axisId Axis id (QwtPolar::Axis)
show true/false
See also:
isAxisVisible()
void QwtPolarGrid::showGrid ( int  scaleId,
bool  show = true 
)

Show/Hide grid lines for a scale

Parameters:
scaleId Scale id ( QwtPolar::Scale )
show true/false
void QwtPolarGrid::showMinorGrid ( int  scaleId,
bool  show = true 
)

Show/Hide minor grid lines for a scale

To display minor grid lines. showGrid() needs to be enabled too.

Parameters:
scaleId Scale id ( QwtPolar::Scale )
show true/false
See also:
showGrid
bool QwtPolarGrid::testDisplayFlag ( DisplayFlag  flag  )  const
Returns:
true, if flag is enabled
Parameters:
flag See DisplayFlag
bool QwtPolarGrid::testGridAttribute ( GridAttribute  attribute  )  const
Returns:
true, if attribute is enabled
See also:
GridAttribute, setGridAttribute()
void QwtPolarGrid::updateScaleDiv ( const QwtScaleDiv &  azimuthScaleDiv,
const QwtScaleDiv &  radialScaleDiv,
const QwtDoubleInterval &  interval 
) [virtual]

Update the item to changes of the axes scale division.

If AutoScaling is enabled the radial scale is calculated from the interval, otherwise the scales are adopted to the plot scales.

Parameters:
azimuthScaleDiv Scale division of the azimuth-scale
radialScaleDiv Scale division of the radius-axis
interval The interval of the radius-axis, that is visible on the canvas
See also:
QwtPolarPlot::setGridAttributes()

Reimplemented from QwtPolarItem.


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