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Inheritance diagram for QCPLayer:

Public Types

enum  LayerMode { lmLogical , lmBuffered }

Public Member Functions

 QCPLayer (QCustomPlot *parentPlot, const QString &layerName)
QList< QCPLayerable * > children () const
int index () const
LayerMode mode () const
QString name () const
QCustomPlotparentPlot () const
void replot ()
void setMode (LayerMode mode)
void setVisible (bool visible)
bool visible () const
- Public Member Functions inherited from QObject
 QObject (QObject *parent)
QBindable< QStringbindableObjectName ()
bool blockSignals (bool block)
const QObjectListchildren () const const
QMetaObject::Connection connect (const QObject *sender, const char *signal, const char *method, Qt::ConnectionType type) const const
void deleteLater ()
void destroyed (QObject *obj)
bool disconnect (const char *signal, const QObject *receiver, const char *method) const const
bool disconnect (const QObject *receiver, const char *method) const const
void dumpObjectInfo () const const
void dumpObjectTree () const const
QList< QByteArraydynamicPropertyNames () const const
virtual bool event (QEvent *e)
virtual bool eventFilter (QObject *watched, QEvent *event)
findChild (const QString &name, Qt::FindChildOptions options) const const
QList< T > findChildren (const QRegularExpression &re, Qt::FindChildOptions options) const const
QList< T > findChildren (const QString &name, Qt::FindChildOptions options) const const
QList< T > findChildren (Qt::FindChildOptions options) const const
bool inherits (const char *className) const const
void installEventFilter (QObject *filterObj)
bool isQuickItemType () const const
bool isWidgetType () const const
bool isWindowType () const const
void killTimer (int id)
virtual const QMetaObjectmetaObject () const const
void moveToThread (QThread *targetThread)
QString objectName () const const
void objectNameChanged (const QString &objectName)
QObjectparent () const const
QVariant property (const char *name) const const
 Q_CLASSINFO (Name, Value)
 Q_ENUM (...)
 Q_ENUM_NS (...)
 Q_ENUMS (...)
 Q_FLAG (...)
 Q_FLAG_NS (...)
 Q_FLAGS (...)
qobject_cast (const QObject *object)
qobject_cast (QObject *object)
void removeEventFilter (QObject *obj)
void setObjectName (const QString &name)
void setObjectName (QAnyStringView name)
void setParent (QObject *parent)
bool setProperty (const char *name, const QVariant &value)
bool setProperty (const char *name, QVariant &&value)
bool signalsBlocked () const const
int startTimer (int interval, Qt::TimerType timerType)
int startTimer (std::chrono::milliseconds interval, Qt::TimerType timerType)
QThreadthread () const const

Protected Member Functions

void addChild (QCPLayerable *layerable, bool prepend)
void draw (QCPPainter *painter)
void drawToPaintBuffer ()
void removeChild (QCPLayerable *layerable)
- Protected Member Functions inherited from QObject
virtual void childEvent (QChildEvent *event)
virtual void connectNotify (const QMetaMethod &signal)
virtual void customEvent (QEvent *event)
virtual void disconnectNotify (const QMetaMethod &signal)
bool isSignalConnected (const QMetaMethod &signal) const const
int receivers (const char *signal) const const
QObjectsender () const const
int senderSignalIndex () const const
virtual void timerEvent (QTimerEvent *event)

Protected Attributes

QList< QCPLayerable * > mChildren
int mIndex
LayerMode mMode
QString mName
QWeakPointer< QCPAbstractPaintBuffermPaintBuffer
bool mVisible

Additional Inherited Members

- Properties inherited from QObject
- Static Public Member Functions inherited from QObject
QMetaObject::Connection connect (const QObject *sender, const char *signal, const QObject *receiver, const char *method, Qt::ConnectionType type)
QMetaObject::Connection connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type)
QMetaObject::Connection connect (const QObject *sender, PointerToMemberFunction signal, const QObject *context, Functor functor, Qt::ConnectionType type)
QMetaObject::Connection connect (const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method, Qt::ConnectionType type)
QMetaObject::Connection connect (const QObject *sender, PointerToMemberFunction signal, Functor functor)
bool disconnect (const QMetaObject::Connection &connection)
bool disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *method)
bool disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method)
bool disconnect (const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method)
QString tr (const char *sourceText, const char *disambiguation, int n)
- Public Attributes inherited from QObject
typedef QObjectList

Detailed Description

A layer that may contain objects, to control the rendering order.

The Layering system of QCustomPlot is the mechanism to control the rendering order of the elements inside the plot.

It is based on the two classes QCPLayer and QCPLayerable. QCustomPlot holds an ordered list of one or more instances of QCPLayer (see QCustomPlot::addLayer, QCustomPlot::layer, QCustomPlot::moveLayer, etc.). When replotting, QCustomPlot goes through the list of layers bottom to top and successively draws the layerables of the layers into the paint buffer(s).

A QCPLayer contains an ordered list of QCPLayerable instances. QCPLayerable is an abstract base class from which almost all visible objects derive, like axes, grids, graphs, items, etc.

Default layers

Initially, QCustomPlot has six layers: "background", "grid", "main", "axes", "legend" and "overlay" (in that order). On top is the "overlay" layer, which only contains the QCustomPlot's selection rect (QCustomPlot::selectionRect). The next two layers "axes" and "legend" contain the default axes and legend, so they will be drawn above plottables. In the middle, there is the "main" layer. It is initially empty and set as the current layer (see QCustomPlot::setCurrentLayer). This means, all new plottables, items etc. are created on this layer by default. Then comes the "grid" layer which contains the QCPGrid instances (which belong tightly to QCPAxis, see QCPAxis::grid). The Axis rect background shall be drawn behind everything else, thus the default QCPAxisRect instance is placed on the "background" layer. Of course, the layer affiliation of the individual objects can be changed as required (QCPLayerable::setLayer).

Controlling the rendering order via layers

Controlling the ordering of layerables in the plot is easy: Create a new layer in the position you want the layerable to be in, e.g. above "main", with QCustomPlot::addLayer. Then set the current layer with QCustomPlot::setCurrentLayer to that new layer and finally create the objects normally. They will be placed on the new layer automatically, due to the current layer setting. Alternatively you could have also ignored the current layer setting and just moved the objects with QCPLayerable::setLayer to the desired layer after creating them.

It is also possible to move whole layers. For example, If you want the grid to be shown in front of all plottables/items on the "main" layer, just move it above "main" with QCustomPlot::moveLayer.

The rendering order within one layer is simply by order of creation or insertion. The item created last (or added last to the layer), is drawn on top of all other objects on that layer.

When a layer is deleted, the objects on it are not deleted with it, but fall on the layer below the deleted layer, see QCustomPlot::removeLayer.

Replotting only a specific layer

If the layer mode (setMode) is set to lmBuffered, you can replot only this specific layer by calling replot. In certain situations this can provide better replot performance, compared with a full replot of all layers. Upon creation of a new layer, the layer mode is initialized to lmLogical. The only layer that is set to lmBuffered in a new QCustomPlot instance is the "overlay" layer, containing the selection rect.

Definition at line 625 of file qcustomplot.h.

Member Enumeration Documentation

◆ LayerMode

Defines the different rendering modes of a layer. Depending on the mode, certain layers can be replotted individually, without the need to replot (possibly complex) layerables on other layers.

See also

Layer is used only for rendering order, and shares paint buffer with all other adjacent logical layers.


Layer has its own paint buffer and may be replotted individually (see replot).

Definition at line 645 of file qcustomplot.h.

Constructor & Destructor Documentation

◆ QCPLayer()

QCPLayer::QCPLayer ( QCustomPlot * parentPlot,
const QString & layerName )

Creates a new QCPLayer instance.

Normally you shouldn't directly instantiate layers, use QCustomPlot::addLayer instead.

It is not checked that layerName is actually a unique layer name in parentPlot. This check is only performed by QCustomPlot::addLayer.

Definition at line 1049 of file qcustomplot.cpp.

◆ ~QCPLayer()

QCPLayer::~QCPLayer ( )

Definition at line 1061 of file qcustomplot.cpp.

Member Function Documentation

◆ addChild()

void QCPLayer::addChild ( QCPLayerable * layerable,
bool prepend )

Adds the layerable to the list of this layer. If prepend is set to true, the layerable will be prepended to the list, i.e. be drawn beneath the other layerables already in the list.

This function does not change the mLayer member of layerable to this layer. (Use QCPLayerable::setLayer to change the layer of an object, not this function.)

See also

Definition at line 1206 of file qcustomplot.cpp.

◆ children()

QList< QCPLayerable * > QCPLayer::children ( ) const

Returns a list of all layerables on this layer. The order corresponds to the rendering order: layerables with higher indices are drawn above layerables with lower indices.

Definition at line 657 of file qcustomplot.h.

◆ draw()

void QCPLayer::draw ( QCPPainter * painter)

Draws the contents of this layer with the provided painter.

See also
replot, drawToPaintBuffer

Definition at line 1125 of file qcustomplot.cpp.

◆ drawToPaintBuffer()

void QCPLayer::drawToPaintBuffer ( )

Draws the contents of this layer into the paint buffer which is associated with this layer. The association is established by the parent QCustomPlot, which manages all paint buffers (see QCustomPlot::setupPaintBuffers).

See also

Definition at line 1148 of file qcustomplot.cpp.

◆ index()

int QCPLayer::index ( ) const

Returns the index this layer has in the QCustomPlot. The index is the integer number by which this layer can be accessed via QCustomPlot::layer.

Layers with higher indices will be drawn above layers with lower indices.

Definition at line 656 of file qcustomplot.h.

◆ mode()

LayerMode QCPLayer::mode ( ) const

Definition at line 659 of file qcustomplot.h.

◆ name()

QString QCPLayer::name ( ) const

Definition at line 655 of file qcustomplot.h.

◆ parentPlot()

QCustomPlot * QCPLayer::parentPlot ( ) const

Definition at line 654 of file qcustomplot.h.

◆ removeChild()

void QCPLayer::removeChild ( QCPLayerable * layerable)

Removes the layerable from the list of this layer.

This function does not change the mLayer member of layerable. (Use QCPLayerable::setLayer to change the layer of an object, not this function.)

See also

Definition at line 1229 of file qcustomplot.cpp.

◆ replot()

void QCPLayer::replot ( )

If the layer mode (setMode) is set to lmBuffered, this method allows replotting only the layerables on this specific layer, without the need to replot all other layers (as a call to QCustomPlot::replot would do).

QCustomPlot also makes sure to replot all layers instead of only this one, if the layer ordering or any layerable-layer-association has changed since the last full replot and any other paint buffers were thus invalidated.

If the layer mode is lmLogical however, this method simply calls QCustomPlot::replot on the parent QCustomPlot instance.

See also

Definition at line 1180 of file qcustomplot.cpp.

◆ setMode()

void QCPLayer::setMode ( QCPLayer::LayerMode mode)

Sets the rendering mode of this layer.

If mode is set to lmBuffered for a layer, it will be given a dedicated paint buffer by the parent QCustomPlot instance. This means it may be replotted individually by calling QCPLayer::replot, without needing to replot all other layers.

Layers which are set to lmLogical (the default) are used only to define the rendering order and can't be replotted individually.

Note that each layer which is set to lmBuffered requires additional paint buffers for the layers below, above and for the layer itself. This increases the memory consumption and (slightly) decreases the repainting speed because multiple paint buffers need to be joined. So you should carefully choose which layers benefit from having their own paint buffer. A typical example would be a layer which contains certain layerables (e.g. items) that need to be changed and thus replotted regularly, while all other layerables on other layers stay static. By default, only the topmost layer called "overlay" is in mode lmBuffered, and contains the selection rect.

See also

Definition at line 1109 of file qcustomplot.cpp.

◆ setVisible()

void QCPLayer::setVisible ( bool visible)

Sets whether this layer is visible or not. If visible is set to false, all layerables on this layer will be invisible.

This function doesn't change the visibility property of the layerables (QCPLayerable::setVisible), but the QCPLayerable::realVisibility of each layerable takes the visibility of the parent layer into account.

Definition at line 1083 of file qcustomplot.cpp.

◆ visible()

bool QCPLayer::visible ( ) const

Definition at line 658 of file qcustomplot.h.

Member Data Documentation

◆ mChildren

QList<QCPLayerable*> QCPLayer::mChildren

Definition at line 673 of file qcustomplot.h.

◆ mIndex

int QCPLayer::mIndex

Definition at line 672 of file qcustomplot.h.

◆ mMode

LayerMode QCPLayer::mMode

Definition at line 675 of file qcustomplot.h.

◆ mName

QString QCPLayer::mName

Definition at line 671 of file qcustomplot.h.

◆ mPaintBuffer

QWeakPointer<QCPAbstractPaintBuffer> QCPLayer::mPaintBuffer

Definition at line 678 of file qcustomplot.h.

◆ mParentPlot

QCustomPlot* QCPLayer::mParentPlot

Definition at line 670 of file qcustomplot.h.

◆ mVisible

bool QCPLayer::mVisible

Definition at line 674 of file qcustomplot.h.

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