QwtPlotRasterItem - Man Page

enum CachePolicy { NoCache, PaintCache, ScreenCache }
enum ItemAttribute { Legend =  1, AutoScale =  2 }
enum RenderHint { RenderAntialiased =  1 }
enum RttiValues { Rtti_PlotItem =  0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG, Rtti_PlotUserItem =  1000 }

int alpha () const
void attach (QwtPlot *plot)
virtual QwtDoubleRect boundingRect () const
CachePolicy cachePolicy () const
void detach ()
virtual void draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &rect) const
void hide ()
void invalidateCache ()
QwtDoubleRect invTransform (const QwtScaleMap &, const QwtScaleMap &, const QRect &) const
bool isVisible () const
virtual void itemChanged ()
virtual QWidget * legendItem () const
QRect paintRect (const QwtScaleMap &, const QwtScaleMap &) const
QwtPlot * plot () const
QwtPlotRasterItem (const QString &title=QString::null)
QwtPlotRasterItem (const QwtText &title)
virtual QSize rasterHint (const QwtDoubleRect &) const
virtual int rtti () const
QwtDoubleRect scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
void setAlpha (int alpha)
void setAxis (int xAxis, int yAxis)
void setCachePolicy (CachePolicy)
void setItemAttribute (ItemAttribute, bool on=true)
void setRenderHint (RenderHint, bool on=true)
void setTitle (const QString &title)
void setTitle (const QwtText &title)
virtual void setVisible (bool)
void setXAxis (int axis)
void setYAxis (int axis)
void setZ (double z)
void show ()
bool testItemAttribute (ItemAttribute) const
bool testRenderHint (RenderHint) const
const QwtText & title () const
QRect transform (const QwtScaleMap &, const QwtScaleMap &, const QwtDoubleRect &) const
virtual void updateLegend (QwtLegend *) const
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
int xAxis () const
int yAxis () const
double z () const
virtual ~QwtPlotRasterItem ()

virtual QImage renderImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtDoubleRect &area) const =0

NoCache
renderImage() is called, whenever the item has to be repainted

• PaintCache
  renderImage() is called, whenever the image cache is not valid, or the scales, or the size of the canvas has changed. This type of cache is only useful for improving the performance of hide/show operations. All other situations are already handled by the plot canvas cache.
• ScreenCache
  The screen cache is an image in size of the screen. As long as the scales don't change the target image is scaled from the cache. This might improve the performance when resizing the plot widget, but suffers from scaling effects.

The default policy is NoCache

• Legend
  The item is represented on the legend.
• AutoScale
  The boundingRect() of the item is included in the autoscaling calculation.

See also:

Render hints.

Runtime type information. RttiValues is used to cast plot items, without having to enable runtime type information of the compiler.

Constructor.

Constructor.

Destructor.

See also:

Attach the item to a plot. This method will attach a QwtPlotItem to the QwtPlot argument. It will first detach the QwtPlotItem from any plot from a previous call to attach (if necessary). If a NULL argument is passed, it will detach from any QwtPlot it was attached to.

Parameters:

plot Plot widget

See also:

QwtPlotItem::detach()

Reimplemented in QwtPlotCurve, QwtPlotMarker, QwtPlotSpectrogram, and QwtPlotSvgItem.

See also:

This method detaches a QwtPlotItem from any QwtPlot it has been associated with. detach() is equivalent to calling attach( NULL )

See also:

Draw the raster data. Parameters:

Implements QwtPlotItem.

Reimplemented in QwtPlotSpectrogram.

Hide the item.

See also:

Parameters:

xMap X map
yMap Y map
rect Rectangle in paint coordinates

Returns:

Rectangle in scale coordinates

See also:

transform()

See also:

See also:

Allocate the widget that represents the item on the legend. The default implementation is made for QwtPlotCurve and returns a QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and updateLegend().

Returns:

QwtLegendItem()

See also:

updateLegend() QwtLegend()

Implements QwtLegendItemManager.

Calculate the bounding paint rect of 2 maps. Parameters:

Returns:

Bounding rect of the scale maps

Return attached plot.

Returns the recommended raster for a given rect. F.e the raster hint can be used to limit the resolution of the image that is rendered.

The default implementation returns an invalid size (QSize()), what means: no hint.

Reimplemented in QwtPlotSpectrogram.

The format of the image must be QImage::Format_Indexed8, QImage::Format_RGB32 or QImage::Format_ARGB32

Parameters:

xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
area Requested area for the image in scale coordinates

Implemented in QwtPlotSpectrogram.

The rtti value is useful for environments, where the runtime type information is disabled and it is not possible to do a dynamic_cast<...>.

Returns:

rtti value

See also:

RttiValues

Reimplemented in QwtPlotCurve, QwtPlotGrid, QwtPlotMarker, QwtPlotScaleItem, QwtPlotSpectrogram, and QwtPlotSvgItem.

Calculate the bounding scale rect of 2 maps. Parameters:

Returns:

Bounding rect of the scale maps

Set an alpha value for the raster data. Often a plot has several types of raster data organized in layers. ( f.e a geographical map, with weather statistics ). Using setAlpha() raster items can be stacked easily.

The alpha value is a value [0, 255] to control the transparency of the image. 0 represents a fully transparent color, while 255 represents a fully opaque color.

Parameters:

alpha Alpha value

• alpha >= 0
  All alpha values of the pixels returned by renderImage() will be set to alpha, beside those with an alpha value of 0 (invalid pixels).
• alpha < 0 The alpha values returned by renderImage() are not changed.

The default alpha value is -1.

See also:

The item will painted according to the coordinates its Axes.

Parameters:

xAxis X Axis
yAxis Y Axis

See also:

setXAxis(), setYAxis(), xAxis(), yAxis()

The default policy is NoCache

Parameters:

policy Cache policy

See also:

CachePolicy, cachePolicy()

Parameters:

attribute Attribute type
on true/false

See also:

testItemAttribute(), ItemAttribute

Parameters:

hint Render hint
on true/false

See also:

testRenderHint(), RenderHint

Parameters:

title Title

See also:

title()

Parameters:

title Title

See also:

title()

Parameters:

on Show if true, otherwise hide

See also:

isVisible(), show(), hide()

The item will painted according to the coordinates its Axes.

Parameters:

axis X Axis

See also:

setAxis(), setYAxis(), xAxis()

The item will painted according to the coordinates its Axes.

Parameters:

axis Y Axis

See also:

setAxis(), setXAxis(), yAxis()

Set the z value. Plot items are painted in increasing z-order.

Parameters:

z Z-value

See also:

z(), QwtPlotDict::itemList()

Show the item.

Parameters:

attribute Attribute type

Returns:

true/false

See also:

setItemAttribute(), ItemAttribute

Parameters:

hint Render hint

Returns:

true/false

See also:

setRenderHint(), RenderHint

See also:

Parameters:

xMap X map
yMap Y map
rect Rectangle in scale coordinates

Returns:

Rectangle in paint coordinates

See also:

invTransform()

Update the widget that represents the item on the legend. updateLegend() is called from itemChanged() to adopt the widget representing the item on the legend to its new configuration.

The default implementation is made for QwtPlotCurve and updates a QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and updateLegend().

Parameters:

legend Legend

See also:

legendItem(), itemChanged(), QwtLegend()

Implements QwtLegendItemManager.

Reimplemented in QwtPlotCurve.

Update the item to changes of the axes scale division. Update the item, when the axes of plot have changed. The default implementation does nothing, but items that depend on the scale division (like QwtPlotGrid()) have to reimplement updateScaleDiv()

Parameters:

xScaleDiv Scale division of the x-axis
yScaleDiv Scale division of the y-axis

See also:

QwtPlot::updateAxes()

Reimplemented in QwtPlotGrid, and QwtPlotScaleItem.

Return xAxis.

Return yAxis.

Returns:

setZ(), QwtPlotDict::itemList()