Vespucci  1.0.0
QCPColorMap Class Reference

A plottable representing a two-dimensional color map in a plot. More...

#include <qcustomplot.h>

Inheritance diagram for QCPColorMap:
QCPAbstractPlottable QCPLayerable


void dataRangeChanged (QCPRange newRange)
void dataScaleTypeChanged (QCPAxis::ScaleType scaleType)
void gradientChanged (QCPColorGradient newGradient)
- Signals inherited from QCPAbstractPlottable
void selectionChanged (bool selected)
void selectableChanged (bool selectable)
- Signals inherited from QCPLayerable
void layerChanged (QCPLayer *newLayer)

Public Member Functions

 QCPColorMap (QCPAxis *keyAxis, QCPAxis *valueAxis)
virtual ~QCPColorMap ()
QCPColorMapDatadata () const
QCPRange dataRange () const
QCPAxis::ScaleType dataScaleType () const
bool interpolate () const
bool tightBoundary () const
QCPColorGradient gradient () const
QCPColorScalecolorScale () const
void setData (QCPColorMapData *data, bool copy=false)
Q_SLOT void setDataRange (const QCPRange &dataRange)
Q_SLOT void setDataScaleType (QCPAxis::ScaleType scaleType)
Q_SLOT void setGradient (const QCPColorGradient &gradient)
void setInterpolate (bool enabled)
void setTightBoundary (bool enabled)
void setColorScale (QCPColorScale *colorScale)
void rescaleDataRange (bool recalculateDataBounds=false)
Q_SLOT void updateLegendIcon (Qt::TransformationMode transformMode=Qt::SmoothTransformation, const QSize &thumbSize=QSize(32, 18))
virtual void clearData ()
virtual double selectTest (const QPointF &pos, bool onlySelectable, QVariant *details=0) const
- Public Member Functions inherited from QCPAbstractPlottable
 QCPAbstractPlottable (QCPAxis *keyAxis, QCPAxis *valueAxis)
QString name () const
bool antialiasedFill () const
bool antialiasedScatters () const
bool antialiasedErrorBars () const
QPen pen () const
QPen selectedPen () const
QBrush brush () const
QBrush selectedBrush () const
QCPAxiskeyAxis () const
QCPAxisvalueAxis () const
bool selectable () const
bool selected () const
void setName (const QString &name)
void setAntialiasedFill (bool enabled)
void setAntialiasedScatters (bool enabled)
void setAntialiasedErrorBars (bool enabled)
void setPen (const QPen &pen)
void setSelectedPen (const QPen &pen)
void setBrush (const QBrush &brush)
void setSelectedBrush (const QBrush &brush)
void setKeyAxis (QCPAxis *axis)
void setValueAxis (QCPAxis *axis)
Q_SLOT void setSelectable (bool selectable)
Q_SLOT void setSelected (bool selected)
virtual bool addToLegend ()
virtual bool removeFromLegend () const
void rescaleAxes (bool onlyEnlarge=false) const
void rescaleKeyAxis (bool onlyEnlarge=false) const
void rescaleValueAxis (bool onlyEnlarge=false) const
- Public Member Functions inherited from QCPLayerable
 QCPLayerable (QCustomPlot *plot, QString targetLayer=QString(), QCPLayerable *parentLayerable=0)
 ~QCPLayerable ()
bool visible () const
QCustomPlotparentPlot () const
QCPLayerableparentLayerable () const
QCPLayerlayer () const
bool antialiased () const
void setVisible (bool on)
Q_SLOT bool setLayer (QCPLayer *layer)
bool setLayer (const QString &layerName)
void setAntialiased (bool enabled)
bool realVisibility () const

Protected Member Functions

virtual void updateMapImage ()
virtual void draw (QCPPainter *painter)
virtual void drawLegendIcon (QCPPainter *painter, const QRectF &rect) const
virtual QCPRange getKeyRange (bool &foundRange, SignDomain inSignDomain=sdBoth) const
virtual QCPRange getValueRange (bool &foundRange, SignDomain inSignDomain=sdBoth) const
- Protected Member Functions inherited from QCPAbstractPlottable
virtual QRect clipRect () const
virtual QCP::Interaction selectionCategory () const
void applyDefaultAntialiasingHint (QCPPainter *painter) const
virtual void selectEvent (QMouseEvent *event, bool additive, const QVariant &details, bool *selectionStateChanged)
virtual void deselectEvent (bool *selectionStateChanged)
void coordsToPixels (double key, double value, double &x, double &y) const
const QPointF coordsToPixels (double key, double value) const
void pixelsToCoords (double x, double y, double &key, double &value) const
void pixelsToCoords (const QPointF &pixelPos, double &key, double &value) const
QPen mainPen () const
QBrush mainBrush () const
void applyFillAntialiasingHint (QCPPainter *painter) const
void applyScattersAntialiasingHint (QCPPainter *painter) const
void applyErrorBarsAntialiasingHint (QCPPainter *painter) const
double distSqrToLine (const QPointF &start, const QPointF &end, const QPointF &point) const
- Protected Member Functions inherited from QCPLayerable
virtual void parentPlotInitialized (QCustomPlot *parentPlot)
void initializeParentPlot (QCustomPlot *parentPlot)
void setParentLayerable (QCPLayerable *parentLayerable)
bool moveToLayer (QCPLayer *layer, bool prepend)
void applyAntialiasingHint (QCPPainter *painter, bool localAntialiased, QCP::AntialiasedElement overrideElement) const

Protected Attributes

QCPRange mDataRange
QCPAxis::ScaleType mDataScaleType
QCPColorGradient mGradient
bool mInterpolate
bool mTightBoundary
QPointer< QCPColorScalemColorScale
QImage mMapImage
QPixmap mLegendIcon
bool mMapImageInvalidated
- Protected Attributes inherited from QCPAbstractPlottable
QString mName
bool mAntialiasedFill
bool mAntialiasedScatters
bool mAntialiasedErrorBars
QPen mPen
QPen mSelectedPen
QBrush mBrush
QBrush mSelectedBrush
QPointer< QCPAxismKeyAxis
QPointer< QCPAxismValueAxis
bool mSelectable
bool mSelected
- Protected Attributes inherited from QCPLayerable
bool mVisible
QPointer< QCPLayerablemParentLayerable
bool mAntialiased


class QCustomPlot
class QCPLegend

Additional Inherited Members

- Protected Types inherited from QCPAbstractPlottable
enum  SignDomain { sdNegative, sdBoth, sdPositive }

Detailed Description

A plottable representing a two-dimensional color map in a plot.


The data is stored in the class QCPColorMapData, which can be accessed via the data() method.

A color map has three dimensions to represent a data point: The key dimension, the value dimension and the data dimension. As with other plottables such as graphs, key and value correspond to two orthogonal axes on the QCustomPlot surface that you specify in the QColorMap constructor. The data dimension however is encoded as the color of the point at (key, value).

Set the number of points (or cells) in the key/value dimension via QCPColorMapData::setSize. The plot coordinate range over which these points will be displayed is specified via QCPColorMapData::setRange. The first cell will be centered on the lower range boundary and the last cell will be centered on the upper range boundary. The data can be set by either accessing the cells directly with QCPColorMapData::setCell or by addressing the cells via their plot coordinates with QCPColorMapData::setData. If possible, you should prefer setCell, since it doesn't need to do any coordinate transformation and thus performs a bit better.

The cell with index (0, 0) is at the bottom left, if the color map uses normal (i.e. not reversed) key and value axes.

To show the user which colors correspond to which data values, a QCPColorScale is typically placed to the right of the axis rect. See the documentation there for details on how to add and use a color scale.

Changing the appearance

The central part of the appearance is the color gradient, which can be specified via setGradient. See the documentation of QCPColorGradient for details on configuring a color gradient.

The data range that is mapped to the colors of the gradient can be specified with setDataRange. To make the data range encompass the whole data set minimum to maximum, call rescaleDataRange.


Like all data representing objects in QCustomPlot, the QCPColorMap is a plottable (QCPAbstractPlottable). So the plottable-interface of QCustomPlot applies (QCustomPlot::plottable, QCustomPlot::addPlottable, QCustomPlot::removePlottable, etc.)

Usually, you first create an instance:

QCPColorMap *colorMap = new QCPColorMap(customPlot->xAxis, customPlot->yAxis);

add it to the customPlot with QCustomPlot::addPlottable:


and then modify the properties of the newly created color map, e.g.:

colorMap->data()->setSize(50, 50);
colorMap->data()->setRange(QCPRange(0, 2), QCPRange(0, 2));
for (int x=0; x<50; ++x)
for (int y=0; y<50; ++y)
colorMap->data()->setCell(x, y, qCos(x/10.0)+qSin(y/10.0));
The QCPColorMap always displays the data at equal key/value intervals, even if the key or value axis is set to a logarithmic scaling. If you want to use QCPColorMap with logarithmic axes, you shouldn't use the QCPColorMapData::setData method as it uses a linear transformation to determine the cell index. Rather directly access the cell index with QCPColorMapData::setCell.

Definition at line 3096 of file qcustomplot.h.

Constructor & Destructor Documentation

QCPColorMap::QCPColorMap ( QCPAxis keyAxis,
QCPAxis valueAxis 

Constructs a color map with the specified keyAxis and valueAxis.

The constructed QCPColorMap can be added to the plot with QCustomPlot::addPlottable, QCustomPlot then takes ownership of the color map.

Definition at line 20560 of file qcustomplot.cpp.

QCPColorMap::~QCPColorMap ( )

Definition at line 20570 of file qcustomplot.cpp.

Member Function Documentation

void QCPColorMap::clearData ( )

Clears the colormap data by calling QCPColorMapData::clear() on the internal data. This also resizes the map to 0x0 cells.

Implements QCPAbstractPlottable.

Definition at line 20785 of file qcustomplot.cpp.

QCPColorScale* QCPColorMap::colorScale ( ) const

Definition at line 3118 of file qcustomplot.h.

QCPColorMapData * QCPColorMap::data ( ) const

Returns a pointer to the internal data storage of type QCPColorMapData. Access this to modify data points (cells) and the color map key/value range.

See also

Definition at line 3112 of file qcustomplot.h.

QCPRange QCPColorMap::dataRange ( ) const

Definition at line 3113 of file qcustomplot.h.

void QCPColorMap::dataRangeChanged ( QCPRange  newRange)

This signal is emitted when the data range changes.

See also
QCPAxis::ScaleType QCPColorMap::dataScaleType ( ) const

Definition at line 3114 of file qcustomplot.h.

void QCPColorMap::dataScaleTypeChanged ( QCPAxis::ScaleType  scaleType)

This signal is emitted when the data scale type changes.

See also
void QCPColorMap::draw ( QCPPainter painter)

Implements QCPAbstractPlottable.

Definition at line 20857 of file qcustomplot.cpp.

void QCPColorMap::drawLegendIcon ( QCPPainter painter,
const QRectF &  rect 
) const

Implements QCPAbstractPlottable.

Definition at line 20893 of file qcustomplot.cpp.

QCPRange QCPColorMap::getKeyRange ( bool &  foundRange,
SignDomain  inSignDomain = sdBoth 
) const

Implements QCPAbstractPlottable.

Definition at line 20913 of file qcustomplot.cpp.

QCPRange QCPColorMap::getValueRange ( bool &  foundRange,
SignDomain  inSignDomain = sdBoth 
) const

Implements QCPAbstractPlottable.

Definition at line 20935 of file qcustomplot.cpp.

QCPColorGradient QCPColorMap::gradient ( ) const

Definition at line 3117 of file qcustomplot.h.

void QCPColorMap::gradientChanged ( QCPColorGradient  newGradient)

This signal is emitted when the gradient changes.

See also
bool QCPColorMap::interpolate ( ) const

Definition at line 3115 of file qcustomplot.h.

void QCPColorMap::rescaleDataRange ( bool  recalculateDataBounds = false)

Sets the data range (setDataRange) to span the minimum and maximum values that occur in the current data set. This corresponds to the rescaleKeyAxis or rescaleValueAxis methods, only for the third data dimension of the color map.

The minimum and maximum values of the data set are buffered in the internal QCPColorMapData instance (data). As data is updated via its QCPColorMapData::setCell or QCPColorMapData::setData, the buffered minimum and maximum values are updated, too. For performance reasons, however, they are only updated in an expanding fashion. So the buffered maximum can only increase and the buffered minimum can only decrease. In consequence, changes to the data that actually lower the maximum of the data set (by overwriting the cell holding the current maximum with a smaller value), aren't recognized and the buffered maximum overestimates the true maximum of the data set. The same happens for the buffered minimum. To recalculate the true minimum and maximum by explicitly looking at each cell, the method QCPColorMapData::recalculateDataBounds can be used. For convenience, setting the parameter recalculateDataBounds calls this method before setting the data range to the buffered minimum and maximum.

See also

Definition at line 20747 of file qcustomplot.cpp.

double QCPColorMap::selectTest ( const QPointF &  pos,
bool  onlySelectable,
QVariant *  details = 0 
) const

This function is used to decide whether a click hits a layerable object or not.

pos is a point in pixel coordinates on the QCustomPlot surface. This function returns the shortest pixel distance of this point to the object. If the object is either invisible or the distance couldn't be determined, -1.0 is returned. Further, if onlySelectable is true and the object is not selectable, -1.0 is returned, too.

If the item is represented not by single lines but by an area like QCPItemRect or QCPItemText, a click inside the area returns a constant value greater zero (typically the selectionTolerance of the parent QCustomPlot multiplied by 0.99). If the click lies outside the area, this function returns -1.0.

Providing a constant value for area objects allows selecting line objects even when they are obscured by such area objects, by clicking close to the lines (i.e. closer than 0.99*selectionTolerance).

The actual setting of the selection state is not done by this function. This is handled by the parent QCustomPlot when the mouseReleaseEvent occurs, and the finally selected object is notified via the selectEvent/deselectEvent methods.

details is an optional output parameter. Every layerable subclass may place any information in details. This information will be passed to selectEvent when the parent QCustomPlot decides on the basis of this selectTest call, that the object was successfully selected. The subsequent call to selectEvent will carry the details. This is useful for multi-part objects (like QCPAxis). This way, a possibly complex calculation to decide which part was clicked is only done once in selectTest. The result (i.e. the actually clicked part) can then be placed in details. So in the subsequent selectEvent, the decision which part was selected doesn't have to be done a second time for a single selection operation.

You may pass 0 as details to indicate that you are not interested in those selection details.

See also
selectEvent, deselectEvent, QCustomPlot::setInteractions

Implements QCPAbstractPlottable.

Definition at line 20791 of file qcustomplot.cpp.

void QCPColorMap::setColorScale ( QCPColorScale colorScale)

Associates the color scale colorScale with this color map.

This means that both the color scale and the color map synchronize their gradient, data range and data scale type (setGradient, setDataRange, setDataScaleType). Multiple color maps can be associated with one single color scale. This causes the color maps to also synchronize those properties, via the mutual color scale.

This function causes the color map to adopt the current color gradient, data range and data scale type of colorScale. After this call, you may change these properties at either the color map or the color scale, and the setting will be applied to both.

Pass 0 as colorScale to disconnect the color scale from this color map again.

Definition at line 20701 of file qcustomplot.cpp.

void QCPColorMap::setData ( QCPColorMapData data,
bool  copy = false 

Replaces the current data with the provided data.

If copy is set to true, the data object will only be copied. if false, the color map takes ownership of the passed data and replaces the internal data pointer with it. This is significantly faster than copying for large datasets.

Definition at line 20582 of file qcustomplot.cpp.

void QCPColorMap::setDataRange ( const QCPRange dataRange)

Sets the data range of this color map to dataRange. The data range defines which data values are mapped to the color gradient.

To make the data range span the full range of the data set, use rescaleDataRange.

See also

Definition at line 20608 of file qcustomplot.cpp.

void QCPColorMap::setDataScaleType ( QCPAxis::ScaleType  scaleType)

Sets whether the data is correlated with the color gradient linearly or logarithmically.

See also

Definition at line 20627 of file qcustomplot.cpp.

void QCPColorMap::setGradient ( const QCPColorGradient gradient)

Sets the color gradient that is used to represent the data. For more details on how to create an own gradient or use one of the preset gradients, see QCPColorGradient.

The colors defined by the gradient will be used to represent data values in the currently set data range, see setDataRange. Data points that are outside this data range will either be colored uniformly with the respective gradient boundary color, or the gradient will repeat, depending on QCPColorGradient::setPeriodic.

See also

Definition at line 20650 of file qcustomplot.cpp.

void QCPColorMap::setInterpolate ( bool  enabled)

Sets whether the color map image shall use bicubic interpolation when displaying the color map shrinked or expanded, and not at a 1:1 pixel-to-data scale.

A 10*10 color map, with interpolation and without interpolation enabled

Definition at line 20666 of file qcustomplot.cpp.

void QCPColorMap::setTightBoundary ( bool  enabled)

Sets whether the outer most data rows and columns are clipped to the specified key and value range (see QCPColorMapData::setKeyRange, QCPColorMapData::setValueRange).

if enabled is set to false, the data points at the border of the color map are drawn with the same width and height as all other data points. Since the data points are represented by rectangles of one color centered on the data coordinate, this means that the shown color map extends by half a data point over the specified key/value range in each direction.

A color map, with tight boundary enabled and disabled

Definition at line 20682 of file qcustomplot.cpp.

bool QCPColorMap::tightBoundary ( ) const

Definition at line 3116 of file qcustomplot.h.

void QCPColorMap::updateLegendIcon ( Qt::TransformationMode  transformMode = Qt::SmoothTransformation,
const QSize &  thumbSize = QSize(32, 18) 

Takes the current appearance of the color map and updates the legend icon, which is used to represent this color map in the legend (see QCPLegend).

The transformMode specifies whether the rescaling is done by a faster, low quality image scaling algorithm (Qt::FastTransformation) or by a slower, higher quality algorithm (Qt::SmoothTransformation).

The current color map appearance is scaled down to thumbSize. Ideally, this should be equal to the size of the legend icon (see QCPLegend::setIconSize). If it isn't exactly the configured legend icon size, the thumb will be rescaled during drawing of the legend item.

See also

Definition at line 20768 of file qcustomplot.cpp.

void QCPColorMap::updateMapImage ( )

Definition at line 20817 of file qcustomplot.cpp.

Friends And Related Function Documentation

friend class QCPLegend

Definition at line 3166 of file qcustomplot.h.

friend class QCustomPlot

Definition at line 3165 of file qcustomplot.h.

Member Data Documentation

QPointer<QCPColorScale> QCPColorMap::mColorScale

Definition at line 3150 of file qcustomplot.h.

QCPRange QCPColorMap::mDataRange

Definition at line 3144 of file qcustomplot.h.

QCPAxis::ScaleType QCPColorMap::mDataScaleType

Definition at line 3145 of file qcustomplot.h.

QCPColorGradient QCPColorMap::mGradient

Definition at line 3147 of file qcustomplot.h.

bool QCPColorMap::mInterpolate

Definition at line 3148 of file qcustomplot.h.

QPixmap QCPColorMap::mLegendIcon

Definition at line 3153 of file qcustomplot.h.

QCPColorMapData* QCPColorMap::mMapData

Definition at line 3146 of file qcustomplot.h.

QImage QCPColorMap::mMapImage

Definition at line 3152 of file qcustomplot.h.

bool QCPColorMap::mMapImageInvalidated

Definition at line 3154 of file qcustomplot.h.

bool QCPColorMap::mTightBoundary

Definition at line 3149 of file qcustomplot.h.

The documentation for this class was generated from the following files: