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QCPLayoutElement Class Reference

The abstract base class for all objects that form the layout system. More...

Inheritance diagram for QCPLayoutElement:
Inheritance graph

Public Types

enum  UpdatePhase
 
enum  SizeConstraintRect
 

Public Functions

 QCPLayoutElement (QCustomPlot *parentPlot=nullptr)
 
QCPLayoutlayout () const
 
QRect rect () const
 
QRect outerRect () const
 
QMargins margins () const
 
QMargins minimumMargins () const
 
QCP::MarginSides autoMargins () const
 
QSize minimumSize () const
 
QSize maximumSize () const
 
SizeConstraintRect sizeConstraintRect () const
 
QCPMarginGroupmarginGroup (QCP::MarginSide side) const
 
QHash< QCP::MarginSide, QCPMarginGroup * > marginGroups () const
 
void setOuterRect (const QRect &rect)
 
void setMargins (const QMargins &margins)
 
void setMinimumMargins (const QMargins &margins)
 
void setAutoMargins (QCP::MarginSides sides)
 
void setMinimumSize (const QSize &size)
 
void setMinimumSize (int width, int height)
 
void setMaximumSize (const QSize &size)
 
void setMaximumSize (int width, int height)
 
void setSizeConstraintRect (SizeConstraintRect constraintRect)
 
void setMarginGroup (QCP::MarginSides sides, QCPMarginGroup *group)
 
virtual void update (UpdatePhase phase)
 
virtual QSize minimumOuterSizeHint () const
 
virtual QSize maximumOuterSizeHint () const
 
virtual QList< QCPLayoutElement * > elements (bool recursive) const
 
virtual double selectTest (const QPointF &pos, bool onlySelectable, QVariant *details=nullptr) const
 
- Public Functions inherited from QCPLayerable
 QCPLayerable (QCustomPlot *plot, QString targetLayer=QString(), QCPLayerable *parentLayerable=nullptr)
 
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 Functions

virtual int calculateAutoMargin (QCP::MarginSide side)
 
virtual void layoutChanged ()
 
virtual void applyDefaultAntialiasingHint (QCPPainter *painter) const
 
virtual void draw (QCPPainter *painter)
 
virtual void parentPlotInitialized (QCustomPlot *parentPlot)
 
- Protected Functions inherited from QCPLayerable
virtual QCP::Interaction selectionCategory () const
 
virtual QRect clipRect () const
 
virtual void selectEvent (QMouseEvent *event, bool additive, const QVariant &details, bool *selectionStateChanged)
 
virtual void deselectEvent (bool *selectionStateChanged)
 
virtual void mousePressEvent (QMouseEvent *event, const QVariant &details)
 
virtual void mouseMoveEvent (QMouseEvent *event, const QPointF &startPos)
 
virtual void mouseReleaseEvent (QMouseEvent *event, const QPointF &startPos)
 
virtual void mouseDoubleClickEvent (QMouseEvent *event, const QVariant &details)
 
virtual void wheelEvent (QWheelEvent *event)
 
void initializeParentPlot (QCustomPlot *parentPlot)
 
void setParentLayerable (QCPLayerable *parentLayerable)
 
bool moveToLayer (QCPLayer *layer, bool prepend)
 
void applyAntialiasingHint (QCPPainter *painter, bool localAntialiased, QCP::AntialiasedElement overrideElement) const
 

Additional Inherited Members

- Signals inherited from QCPLayerable
void layerChanged (QCPLayer *newLayer)
 

Detailed Description

The abstract base class for all objects that form the layout system.

This is an abstract base class. As such, it can't be instantiated directly, rather use one of its subclasses.

A Layout element is a rectangular object which can be placed in layouts. It has an outer rect (QCPLayoutElement::outerRect) and an inner rect (QCPLayoutElement::rect). The difference between outer and inner rect is called its margin. The margin can either be set to automatic or manual (setAutoMargins) on a per-side basis. If a side is set to manual, that margin can be set explicitly with setMargins and will stay fixed at that value. If it's set to automatic, the layout element subclass will control the value itself (via calculateAutoMargin).

Layout elements can be placed in layouts (base class QCPLayout) like QCPLayoutGrid. The top level layout is reachable via QCustomPlot::plotLayout, and is a QCPLayoutGrid. Since QCPLayout itself derives from QCPLayoutElement, layouts can be nested.

Thus in QCustomPlot one can divide layout elements into two categories: The ones that are invisible by themselves, because they don't draw anything. Their only purpose is to manage the position and size of other layout elements. This category of layout elements usually use QCPLayout as base class. Then there is the category of layout elements which actually draw something. For example, QCPAxisRect, QCPLegend and QCPTextElement are of this category. This does not necessarily mean that the latter category can't have child layout elements. QCPLegend for instance, actually derives from QCPLayoutGrid and the individual legend items are child layout elements in the grid layout.

Member Enumeration Documentation

§ UpdatePhase

Defines the phases of the update process, that happens just before a replot. At each phase, update is called with the according UpdatePhase value.

Enumerator
upPreparation 

Phase used for any type of preparation that needs to be done before margin calculation and layout.

upMargins 

Phase in which the margins are calculated and set.

upLayout 

Final phase in which the layout system places the rects of the elements.

§ SizeConstraintRect

Defines to which rect of a layout element the size constraints that can be set via setMinimumSize and setMaximumSize apply. The outer rect (outerRect) includes the margins (e.g. in the case of a QCPAxisRect the axis labels), whereas the inner rect (rect) does not.

See also
setSizeConstraintRect
Enumerator
scrInnerRect 

Minimum/Maximum size constraints apply to inner rect.

scrOuterRect 

Minimum/Maximum size constraints apply to outer rect, thus include layout element margins.

Constructor & Destructor Documentation

§ QCPLayoutElement()

QCPLayoutElement::QCPLayoutElement ( QCustomPlot parentPlot = nullptr)
explicit

Creates an instance of QCPLayoutElement and sets default values.

Member Function Documentation

§ layout()

QCPLayout * QCPLayoutElement::layout ( ) const
inline

Returns the parent layout of this layout element.

§ rect()

QRect QCPLayoutElement::rect ( ) const
inline

Returns the inner rect of this layout element. The inner rect is the outer rect (outerRect, setOuterRect) shrinked by the margins (setMargins, setAutoMargins).

In some cases, the area between outer and inner rect is left blank. In other cases the margin area is used to display peripheral graphics while the main content is in the inner rect. This is where automatic margin calculation becomes interesting because it allows the layout element to adapt the margins to the peripheral graphics it wants to draw. For example, QCPAxisRect draws the axis labels and tick labels in the margin area, thus needs to adjust the margins (if setAutoMargins is enabled) according to the space required by the labels of the axes.

See also
outerRect

§ outerRect()

QRect QCPLayoutElement::outerRect ( ) const
inline

Returns the outer rect of this layout element. The outer rect is the inner rect expanded by the margins (setMargins, setAutoMargins). The outer rect is used (and set via setOuterRect) by the parent QCPLayout to control the size of this layout element.

See also
rect

§ setOuterRect()

void QCPLayoutElement::setOuterRect ( const QRect &  rect)

Sets the outer rect of this layout element. If the layout element is inside a layout, the layout sets the position and size of this layout element using this function.

Calling this function externally has no effect, since the layout will overwrite any changes to the outer rect upon the next replot.

The layout element will adapt its inner rect by applying the margins inward to the outer rect.

See also
rect

§ setMargins()

void QCPLayoutElement::setMargins ( const QMargins &  margins)

Sets the margins of this layout element. If setAutoMargins is disabled for some or all sides, this function is used to manually set the margin on those sides. Sides that are still set to be handled automatically are ignored and may have any value in margins.

The margin is the distance between the outer rect (controlled by the parent layout via setOuterRect) and the inner rect (which usually contains the main content of this layout element).

See also
setAutoMargins

§ setMinimumMargins()

void QCPLayoutElement::setMinimumMargins ( const QMargins &  margins)

If setAutoMargins is enabled on some or all margins, this function is used to provide minimum values for those margins.

The minimum values are not enforced on margin sides that were set to be under manual control via setAutoMargins.

See also
setAutoMargins

§ setAutoMargins()

void QCPLayoutElement::setAutoMargins ( QCP::MarginSides  sides)

Sets on which sides the margin shall be calculated automatically. If a side is calculated automatically, a minimum margin value may be provided with setMinimumMargins. If a side is set to be controlled manually, the value may be specified with setMargins.

Margin sides that are under automatic control may participate in a QCPMarginGroup (see setMarginGroup), to synchronize (align) it with other layout elements in the plot.

See also
setMinimumMargins, setMargins, QCP::MarginSide

§ setMinimumSize() [1/2]

void QCPLayoutElement::setMinimumSize ( const QSize &  size)

Sets the minimum size of this layout element. A parent layout tries to respect the size here by changing row/column sizes in the layout accordingly.

If the parent layout size is not sufficient to satisfy all minimum size constraints of its child layout elements, the layout may set a size that is actually smaller than size. QCustomPlot propagates the layout's size constraints to the outside by setting its own minimum QWidget size accordingly, so violations of size should be exceptions.

Whether this constraint applies to the inner or the outer rect can be specified with setSizeConstraintRect (see rect and outerRect).

§ setMinimumSize() [2/2]

void QCPLayoutElement::setMinimumSize ( int  width,
int  height 
)

This is an overloaded function.

Sets the minimum size of this layout element.

Whether this constraint applies to the inner or the outer rect can be specified with setSizeConstraintRect (see rect and outerRect).

§ setMaximumSize() [1/2]

void QCPLayoutElement::setMaximumSize ( const QSize &  size)

Sets the maximum size of this layout element. A parent layout tries to respect the size here by changing row/column sizes in the layout accordingly.

Whether this constraint applies to the inner or the outer rect can be specified with setSizeConstraintRect (see rect and outerRect).

§ setMaximumSize() [2/2]

void QCPLayoutElement::setMaximumSize ( int  width,
int  height 
)

This is an overloaded function.

Sets the maximum size of this layout element.

Whether this constraint applies to the inner or the outer rect can be specified with setSizeConstraintRect (see rect and outerRect).

§ setSizeConstraintRect()

void QCPLayoutElement::setSizeConstraintRect ( SizeConstraintRect  constraintRect)

Sets to which rect of a layout element the size constraints apply. Size constraints can be set via setMinimumSize and setMaximumSize.

The outer rect (outerRect) includes the margins (e.g. in the case of a QCPAxisRect the axis labels), whereas the inner rect (rect) does not.

See also
setMinimumSize, setMaximumSize

§ setMarginGroup()

void QCPLayoutElement::setMarginGroup ( QCP::MarginSides  sides,
QCPMarginGroup group 
)

Sets the margin group of the specified margin sides.

Margin groups allow synchronizing specified margins across layout elements, see the documentation of QCPMarginGroup.

To unset the margin group of sides, set group to nullptr.

Note that margin groups only work for margin sides that are set to automatic (setAutoMargins).

See also
QCP::MarginSide

§ update()

void QCPLayoutElement::update ( UpdatePhase  phase)
virtual

Updates the layout element and sub-elements. This function is automatically called before every replot by the parent layout element. It is called multiple times, once for every UpdatePhase. The phases are run through in the order of the enum values. For details about what happens at the different phases, see the documentation of UpdatePhase.

Layout elements that have child elements should call the update method of their child elements, and pass the current phase unchanged.

The default implementation executes the automatic margin mechanism in the upMargins phase. Subclasses should make sure to call the base class implementation.

Reimplemented in QCPLayout, QCPPolarAxisAngular, QCPAxisRect, and QCPColorScale.

§ minimumOuterSizeHint()

QSize QCPLayoutElement::minimumOuterSizeHint ( ) const
virtual

Returns the suggested minimum size this layout element (the outerRect) may be compressed to, if no manual minimum size is set.

if a minimum size (setMinimumSize) was not set manually, parent layouts use the returned size (usually indirectly through QCPLayout::getFinalMinimumOuterSize) to determine the minimum allowed size of this layout element.

A manual minimum size is considered set if it is non-zero.

The default implementation simply returns the sum of the horizontal margins for the width and the sum of the vertical margins for the height. Reimplementations may use their detailed knowledge about the layout element's content to provide size hints.

Reimplemented in QCPLayoutGrid, QCPPlottableLegendItem, QCPTextElement, and QCPPolarLegendItem.

§ maximumOuterSizeHint()

QSize QCPLayoutElement::maximumOuterSizeHint ( ) const
virtual

Returns the suggested maximum size this layout element (the outerRect) may be expanded to, if no manual maximum size is set.

if a maximum size (setMaximumSize) was not set manually, parent layouts use the returned size (usually indirectly through QCPLayout::getFinalMaximumOuterSize) to determine the maximum allowed size of this layout element.

A manual maximum size is considered set if it is smaller than Qt's QWIDGETSIZE_MAX.

The default implementation simply returns QWIDGETSIZE_MAX for both width and height, implying no suggested maximum size. Reimplementations may use their detailed knowledge about the layout element's content to provide size hints.

Reimplemented in QCPLayoutGrid, and QCPTextElement.

§ elements()

QList< QCPLayoutElement * > QCPLayoutElement::elements ( bool  recursive) const
virtual

Returns a list of all child elements in this layout element. If recursive is true, all sub-child elements are included in the list, too.

Warning
There may be nullptr entries in the returned list. For example, QCPLayoutGrid may have empty cells which yield nullptr at the respective index.

Reimplemented in QCPLayoutGrid, QCPLayout, QCPPolarAxisAngular, and QCPAxisRect.

§ selectTest()

double QCPLayoutElement::selectTest ( const QPointF &  pos,
bool  onlySelectable,
QVariant *  details = nullptr 
) const
virtual

Layout elements are sensitive to events inside their outer rect. If pos is within the outer rect, this method returns a value corresponding to 0.99 times the parent plot's selection tolerance. However, layout elements are not selectable by default. So if onlySelectable is true, -1.0 is returned.

See QCPLayerable::selectTest for a general explanation of this virtual method.

QCPLayoutElement subclasses may reimplement this method to provide more specific selection test behaviour.

Reimplemented from QCPLayerable.

Reimplemented in QCPLayoutInset, QCPLegend, QCPPolarAxisAngular, QCPTextElement, and QCPAbstractLegendItem.

§ calculateAutoMargin()

int QCPLayoutElement::calculateAutoMargin ( QCP::MarginSide  side)
protectedvirtual

Returns the margin size for this side. It is used if automatic margins is enabled for this side (see setAutoMargins). If a minimum margin was set with setMinimumMargins, the returned value will not be smaller than the specified minimum margin.

The default implementation just returns the respective manual margin (setMargins) or the minimum margin, whichever is larger.

Reimplemented in QCPAxisRect.

§ layoutChanged()

void QCPLayoutElement::layoutChanged ( )
protectedvirtual

This virtual method is called when this layout element was moved to a different QCPLayout, or when this layout element has changed its logical position (e.g. row and/or column) within the same QCPLayout. Subclasses may use this to react accordingly.

Since this method is called after the completion of the move, you can access the new parent layout via layout().

The default implementation does nothing.

Reimplemented in QCPAxisRect.

§ applyDefaultAntialiasingHint()

virtual void QCPLayoutElement::applyDefaultAntialiasingHint ( QCPPainter painter) const
inlineprotectedvirtual

This function applies the default antialiasing setting to the specified painter, using the function applyAntialiasingHint. It is the antialiasing state the painter is put in, when draw is called on the layerable. If the layerable has multiple entities whose antialiasing setting may be specified individually, this function should set the antialiasing state of the most prominent entity. In this case however, the draw function usually calls the specialized versions of this function before drawing each entity, effectively overriding the setting of the default antialiasing hint.

First example: QCPGraph has multiple entities that have an antialiasing setting: The graph line, fills and scatters. Those can be configured via QCPGraph::setAntialiased, QCPGraph::setAntialiasedFill and QCPGraph::setAntialiasedScatters. Consequently, there isn't only the QCPGraph::applyDefaultAntialiasingHint function (which corresponds to the graph line's antialiasing), but specialized ones like QCPGraph::applyFillAntialiasingHint and QCPGraph::applyScattersAntialiasingHint. So before drawing one of those entities, QCPGraph::draw calls the respective specialized applyAntialiasingHint function.

Second example: QCPItemLine consists only of a line so there is only one antialiasing setting which can be controlled with QCPItemLine::setAntialiased. (This function is inherited by all layerables. The specialized functions, as seen on QCPGraph, must be added explicitly to the respective layerable subclass.) Consequently it only has the normal QCPItemLine::applyDefaultAntialiasingHint. The QCPItemLine::draw function doesn't need to care about setting any antialiasing states, because the default antialiasing hint is already set on the painter when the draw function is called, and that's the state it wants to draw the line with.

Implements QCPLayerable.

Reimplemented in QCPPolarAxisAngular, QCPLegend, QCPAxisRect, QCPColorScale, QCPTextElement, and QCPAbstractLegendItem.

§ draw()

virtual void QCPLayoutElement::draw ( QCPPainter painter)
inlineprotectedvirtual

This function draws the layerable with the specified painter. It is only called by QCustomPlot, if the layerable is visible (setVisible).

Before this function is called, the painter's antialiasing state is set via applyDefaultAntialiasingHint, see the documentation there. Further, the clipping rectangle was set to clipRect.

Implements QCPLayerable.

Reimplemented in QCPPolarAxisAngular, QCPLegend, QCPAxisRect, QCPPlottableLegendItem, QCPTextElement, QCPAbstractLegendItem, and QCPPolarLegendItem.

§ parentPlotInitialized()

void QCPLayoutElement::parentPlotInitialized ( QCustomPlot parentPlot)
protectedvirtual

propagates the parent plot initialization to all child elements, by calling QCPLayerable::initializeParentPlot on them.

Reimplemented from QCPLayerable.

Reimplemented in QCPLegend.


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