DiagramScene Class Reference

Detailed Description

A scene graph for a 2D Diagram including coordinate axes with labels and ticks for one or more plotted graphs.

Definition at line 17 of file DiagramScene.h.

#include <DiagramScene.h>

Inheritance diagram for DiagramScene:

Collaboration diagram for DiagramScene:

Public Member Functions
	DiagramScene (QObject *parent=nullptr)
	DiagramScene (DiagramList *list, QObject *parent=nullptr)
	~DiagramScene () override
QArrow *	addArrow (qreal length, qreal angle, QPen &pen)
void	addGraph (DiagramList *list)
	Adds a graph to the scene, including all data points and meta-information.
QGraphicsGrid *	addGrid (const QRectF &rect, int xTicks, int yTicks, const QPen &pen)
	Adds a grid-object to the scene.

Static Public Attributes
static const int	MARGIN = 30

Private Member Functions
void	addCaption (const QString &name, QPen &pen)
	The margin between the boundary of the scene and the bounding box of all items within the scene.
QNonScalableGraphicsTextItem *	addNonScalableText (const QString &text, const QFont &font=QFont())
	Adds a non-scalable text object to the scene.
void	adjustAxis (qreal &min, qreal &max, int &numberOfTicks)
void	adjustScaling ()
void	clearGrid ()
	Destroys the grid object (coordinate system) when a new graph is added.
void	constructGrid ()
void	drawGraph (DiagramList *list)
	Plots the graph.
int	getXAxisOffset ()
int	getYAxisOffset ()
void	initialize ()
void	setDiagramBoundaries (DiagramList *list)
void	setXAxis (QArrow *arrow)
	Sets an arrow as x-axis.
void	setYAxis (QArrow *arrow)
	Sets an arrow as y-axis.
void	update ()

Private Attributes
QRectF	_bounds
QRectF	_unscaledBounds
QVector< DiagramList * >	_lists
QVector< QGraphicsItemGroup * >	_graphCaptions
QVector< QGraphicsPathItem * >	_graphs
QGraphicsGrid *	_grid
QDateTime	_startDate
float	_scaleX
float	_scaleY
QArrow *	_xAxis
QArrow *	_yAxis
QNonScalableGraphicsTextItem *	_xLabel
QNonScalableGraphicsTextItem *	_yLabel
QNonScalableGraphicsTextItem *	_xUnit
QNonScalableGraphicsTextItem *	_yUnit
QVector< QNonScalableGraphicsTextItem * >	_xTicksText
QVector< QNonScalableGraphicsTextItem * >	_yTicksText

Constructor & Destructor Documentation

DiagramScene() [1/2]

DiagramScene::DiagramScene ( QObject * parent = nullptr )

explicit

Creates a new scene. Since no data points are given some default values are used for constructing all the necessary objects.

Definition at line 17 of file DiagramScene.cpp.

                                          : QGraphicsScene(parent)
{
    _bounds.setRect(0, 0, 1, 1);
    initialize();
}

References _bounds, and initialize().

DiagramScene() [2/2]

DiagramScene::DiagramScene ( DiagramList * list, QObject * parent = nullptr )

explicit

Creates a new scene.

Parameters

list	includes all necessary information of the graph to display.
parent	The parent QObject.

Definition at line 28 of file DiagramScene.cpp.

    : QGraphicsScene(parent)
{
    setDiagramBoundaries(list);
    initialize();
}

References initialize(), and setDiagramBoundaries().

~DiagramScene()

DiagramScene::~DiagramScene ( )

override

Definition at line 35 of file DiagramScene.cpp.

{
    delete _grid;
    delete _xAxis;
    delete _yAxis;
    delete _xLabel;
    delete _yLabel;
    delete _xUnit;
    delete _yUnit;
    for (auto& graphCaption : _graphCaptions)
    {
        delete graphCaption;
    }
    _graphCaptions.clear();
    for (auto& graph : _graphs)
    {
        delete graph;
    }
    _graphs.clear();
    for (auto& text : _xTicksText)
    {
        delete text;
    }
    _xTicksText.clear();
    for (auto& text : _yTicksText)
    {
        delete text;
    }
    _yTicksText.clear();
    for (auto& list : _lists)
    {
        delete list;
    }
    _lists.clear();
}

References _graphCaptions, _graphs, _grid, _lists, _xAxis, _xLabel, _xTicksText, _xUnit, _yAxis, _yLabel, _yTicksText, and _yUnit.

Member Function Documentation

addArrow()

QArrow * DiagramScene::addArrow	(	qreal	length,
		qreal	angle,
		QPen &	pen )

Adds an arrow object to the diagram which might be used as a coordinate axis, etc.

Definition at line 73 of file DiagramScene.cpp.

{
    auto* arrow = new QArrow(length, angle, 8, 5, pen);
    addItem(arrow);
    return arrow;
}

Referenced by initialize().

addCaption()

void DiagramScene::addCaption ( const QString & name, QPen & pen )

private

The margin between the boundary of the scene and the bounding box of all items within the scene.

Adds a caption for a graph beneath the actual diagram.

Definition at line 81 of file DiagramScene.cpp.

{
    auto* caption = new QGraphicsItemGroup(nullptr);
    QGraphicsLineItem* l = addLine(0, 0, 100, 0, pen);
    QGraphicsTextItem* t = addText(name);
    l->setPos(0, 0);
    t->setPos(110, -(t->boundingRect()).height() / 2);
    caption->addToGroup(l);
    caption->addToGroup(t);
    caption->setFlag(QGraphicsItem::ItemIgnoresTransformations, true);
 
    _graphCaptions.push_back(caption);
    addItem(_graphCaptions[_graphCaptions.size() - 1]);
}

References _graphCaptions.

Referenced by drawGraph().

addGraph()

void DiagramScene::addGraph

(

DiagramList *

list

)

Adds a graph to the scene, including all data points and meta-information.

Definition at line 97 of file DiagramScene.cpp.

{
    setDiagramBoundaries(list);
    adjustScaling();
    _xLabel->setPlainText(list->getXLabel());
    _yLabel->setPlainText(list->getYLabel());
    _xUnit->setPlainText(list->getXUnit());
    _yUnit->setPlainText(list->getYUnit());
 
    clearGrid();
    constructGrid();
 
    _lists.push_back(list);
    for (auto& list : _lists)
    {
        drawGraph(list);
    }
 
    update();
}

References _lists, _xLabel, _xUnit, _yLabel, _yUnit, adjustScaling(), clearGrid(), constructGrid(), drawGraph(), DiagramList::getXLabel(), DiagramList::getXUnit(), DiagramList::getYLabel(), DiagramList::getYUnit(), setDiagramBoundaries(), and update().

addGrid()

QGraphicsGrid * DiagramScene::addGrid	(	const QRectF &	rect,
		int	xTicks,
		int	yTicks,
		const QPen &	pen )

Adds a grid-object to the scene.

Definition at line 119 of file DiagramScene.cpp.

{
    QGraphicsGrid* g = new QGraphicsGrid(rect, xTicks, yTicks, true, pen);
    addItem(g);
    return g;
}

Referenced by constructGrid().

addNonScalableText()

QNonScalableGraphicsTextItem * DiagramScene::addNonScalableText ( const QString & text, const QFont & font = QFont() )

private

Adds a non-scalable text object to the scene.

Definition at line 128 of file DiagramScene.cpp.

{
    auto* item = new QNonScalableGraphicsTextItem(text);
    item->setFont(font);
    addItem(item);
    return item;
}

Referenced by constructGrid(), and initialize().

adjustAxis()

void DiagramScene::adjustAxis ( qreal & min, qreal & max, int & numberOfTicks )

private

Resizes a given axis to "nice" dimensions and calculates an adequate number of ticks to be placed on it

Definition at line 139 of file DiagramScene.cpp.

{
    const int MinTicks = 4;
    double grossStep = (max - min) / MinTicks;
    double step = pow(10.0, std::floor(log10(grossStep)));
    if (5 * step < grossStep)
    {
        step *= 5;
    }
    else if (2 * step < grossStep)
    {
        step *= 2;
    }
    numberOfTicks = int(ceil(max / step) - std::floor(min / step));
    if (numberOfTicks < MinTicks)
    {
        numberOfTicks = MinTicks;
    }
    min = std::floor(min / step) * step;
    max = ceil(max / step) * step;
}

Referenced by constructGrid().

adjustScaling()

void DiagramScene::adjustScaling ( )

private

Calculates scaling factors to set coordinate system and graphs to default window size

Definition at line 163 of file DiagramScene.cpp.

{
    if ((_unscaledBounds.width() > 0) && (_unscaledBounds.height() > 0))
    {
        _scaleX = kDefaultX / static_cast<float>(_unscaledBounds.width());
        _scaleY = kDefaultY / static_cast<float>(_unscaledBounds.height());
    }
}

References _scaleX, _scaleY, _unscaledBounds, kDefaultX, and kDefaultY.

Referenced by addGraph().

clearGrid()

void DiagramScene::clearGrid ( )

private

Destroys the grid object (coordinate system) when a new graph is added.

Definition at line 173 of file DiagramScene.cpp.

{
    if (!_lists.isEmpty())
    {
        removeItem(_grid);
 
        for (auto& text : _xTicksText)
        {
            removeItem(text);
        }
        for (auto& text : _yTicksText)
        {
            removeItem(text);
        }
        for (auto& graph : _graphs)
        {
            removeItem(graph);
        }
        for (auto& graphCaption : _graphCaptions)
        {
            removeItem(graphCaption);
        }
 
        _xTicksText.clear();
        _yTicksText.clear();
        _graphs.clear();
        _graphCaptions.clear();
    }
}

References _graphCaptions, _graphs, _grid, _lists, _xTicksText, and _yTicksText.

Referenced by addGraph().

constructGrid()

void DiagramScene::constructGrid ( )

private

Adjusts the underlying grid based on the graphs that are displayed in the diagram

Definition at line 205 of file DiagramScene.cpp.

{
    // be very careful with scaling parameters here!
    int numXTicks;
    int numYTicks;
    qreal xMin = _unscaledBounds.left();
    qreal yMin = _unscaledBounds.top();
    qreal xMax = _unscaledBounds.right();
    qreal yMax = _unscaledBounds.bottom();
 
    adjustAxis(xMin, xMax, numXTicks);
    adjustAxis(yMin, yMax, numYTicks);
 
    // adjust boundaries of coordinate system according to scaling
    _bounds.setRect(xMin * _scaleX,
                    yMin * _scaleY,
                    (xMax - xMin) * _scaleX,
                    (yMax - yMin) * _scaleY);
 
    QPen pen(Qt::black, 1, Qt::SolidLine, Qt::SquareCap, Qt::RoundJoin);
    _grid = addGrid(_bounds, numXTicks, numYTicks, pen);
 
    if (_startDate == QDateTime())
    {
        for (int i = 0; i <= numXTicks; ++i)
        {
            auto x =
                static_cast<int>(_bounds.left() / _scaleX +
                                 (i * (_bounds.width() / _scaleX) / numXTicks));
            _xTicksText.push_back(addNonScalableText(QString::number(x)));
            _xTicksText.last()->setPos(x * _scaleX, _bounds.bottom() + 15);
        }
    }
    else
    {
        for (int i = 0; i <= numXTicks; ++i)
        {
            auto x =
                static_cast<int>(_bounds.left() / _scaleX +
                                 (i * (_bounds.width() / _scaleX) / numXTicks));
            QDateTime currentDate = _startDate.addSecs(x);
            _xTicksText.push_back(
                addNonScalableText(currentDate.toString("dd.MM.yyyy")));
            _xTicksText.last()->setPos(x * _scaleX, _bounds.bottom() + 15);
        }
    }
 
    for (int j = 0; j <= numYTicks; ++j)
    {
        qreal y = _bounds.bottom() / _scaleY -
                  (j * (_bounds.height() / _scaleY) / numYTicks);
        qreal label = _bounds.top() / _scaleY +
                      (j * (_bounds.height() / _scaleY) / numYTicks);
        _yTicksText.push_back(addNonScalableText(QString::number(label)));
        _yTicksText.last()->setPos(_bounds.left() - MARGIN / 2, y * _scaleY);
    }
}

References _bounds, _grid, _scaleX, _scaleY, _startDate, _unscaledBounds, _xTicksText, _yTicksText, addGrid(), addNonScalableText(), adjustAxis(), and MARGIN.

Referenced by addGraph().

drawGraph()

void DiagramScene::drawGraph ( DiagramList * list )

private

Plots the graph.

For correct display the graph needs to be flipped vertically and then translated back to its original position

Definition at line 264 of file DiagramScene.cpp.

{
    QPainterPath path;
 
    if (list->getPath(path, _scaleX, _scaleY))
    {
        QPen pen(list->getColor(), 2, Qt::SolidLine, Qt::SquareCap,
                 Qt::RoundJoin);
        pen.setCosmetic(true);
        _graphs.push_back(addPath(path, pen));
        addCaption(list->getName(), pen);
 
        int last = _graphs.size() - 1;

        int verticalShift =
            static_cast<int>(2 * (list->minYValue() * _scaleY) +
                             (_graphs[last]->boundingRect()).height());
        _graphs[last]->setTransform(
            QTransform(QMatrix(1, 0, 0, -1, 0, verticalShift)));
    }
}

References _graphs, _scaleX, _scaleY, addCaption(), DiagramList::getColor(), DiagramList::getName(), DiagramList::getPath(), and DiagramList::minYValue().

Referenced by addGraph().

getXAxisOffset()

int DiagramScene::getXAxisOffset ( )

private

Returns the y-value at which the x-axis should cross the y-axis. This value is zero if minYValue<0<maxYValue and minYValue otherwise.

Definition at line 292 of file DiagramScene.cpp.

{
    return (_bounds.top() <= 0 && _bounds.bottom() > 0)
               ? static_cast<int>(_bounds.bottom() + _bounds.top())
               : static_cast<int>(_bounds.bottom());
}

References _bounds.

Referenced by update().

getYAxisOffset()

int DiagramScene::getYAxisOffset ( )

private

Returns the x-value at which the y-axis should cross the x-axis. This value is zero if minXValue<0<maxXValue and minXValue otherwise.

Definition at line 301 of file DiagramScene.cpp.

{
    return (_bounds.left() <= 0 && _bounds.right() > 0)
               ? 0
               : static_cast<int>(_bounds.left());
}

References _bounds.

Referenced by update().

initialize()

void DiagramScene::initialize ( )

private

Initialises the coordinate axes, adds labels and/or units to the axes, calculates axes-lengths, offsets, etc.

Definition at line 310 of file DiagramScene.cpp.

{
    QPen pen(Qt::black, 1, Qt::SolidLine, Qt::SquareCap, Qt::RoundJoin);
    pen.setCosmetic(true);
 
    setXAxis(addArrow(_bounds.width(), 0, pen));
    setYAxis(addArrow(_bounds.height(), -90, pen));
    _xLabel = addNonScalableText(" ");
    _yLabel = addNonScalableText(" ");
    _yLabel->setRotation(-90);
 
    _xUnit = addNonScalableText(" ");
    _yUnit = addNonScalableText(" ");
 
    update();
}

References _bounds, _xLabel, _xUnit, _yLabel, _yUnit, addArrow(), addNonScalableText(), setXAxis(), setYAxis(), and update().

Referenced by DiagramScene(), and DiagramScene().

setDiagramBoundaries()

void DiagramScene::setDiagramBoundaries ( DiagramList * list )

private

Updates the (unscaled) boundaries of the visible coordinate system when a new list is added (boundaries are rescaled in the constructGrid-method

Definition at line 329 of file DiagramScene.cpp.

{
    if (!_lists.isEmpty())
    {
        if (list->minXValue() < _unscaledBounds.left())
        {
            _unscaledBounds.setLeft(list->minXValue());
        }
        if (list->minYValue() < _unscaledBounds.top())
        {
            _unscaledBounds.setTop(list->minYValue());
        }
        if (list->maxXValue() > _unscaledBounds.right())
        {
            _unscaledBounds.setRight(list->maxXValue());
        }
        if (list->maxYValue() > _unscaledBounds.bottom())
        {
            _unscaledBounds.setBottom(list->maxYValue());
        }
        if (_startDate > list->getStartDate())
        {
            _startDate = list->getStartDate();
        }
    }
    else
    {
        _unscaledBounds.setRect(list->minXValue(), list->minYValue(),
                                list->maxXValue() - list->minXValue(),
                                list->maxYValue() - list->minYValue());
        _startDate = list->getStartDate();
    }
}

References _lists, _startDate, _unscaledBounds, DiagramList::getStartDate(), DiagramList::maxXValue(), DiagramList::maxYValue(), DiagramList::minXValue(), and DiagramList::minYValue().

Referenced by DiagramScene(), and addGraph().

setXAxis()

void DiagramScene::setXAxis ( QArrow * arrow )

inlineprivate

Sets an arrow as x-axis.

Definition at line 45 of file DiagramScene.h.

{ _xAxis = arrow; }

References _xAxis.

Referenced by initialize().

setYAxis()

void DiagramScene::setYAxis ( QArrow * arrow )

inlineprivate

Sets an arrow as y-axis.

Definition at line 48 of file DiagramScene.h.

{ _yAxis = arrow; }

References _yAxis.

Referenced by initialize().

update()

void DiagramScene::update ( )

private

Updates the scene at the start and every time new data points are added. Specifically, objects on the scene are assigned their position in the new coordinate system and are resized if necessary.

Definition at line 369 of file DiagramScene.cpp.

{
    _xAxis->setPos(_bounds.left(), getXAxisOffset());
    _yAxis->setPos(getYAxisOffset(), _bounds.bottom());
    _xAxis->setLength(_bounds.width());
    _yAxis->setLength(_bounds.height());
 
    _xLabel->setPos(_bounds.left() + _bounds.width() / 2,
                    _bounds.bottom() + 1.5 * MARGIN);
    _yLabel->setPos(_bounds.left() - 1.5 * MARGIN,
                    _bounds.top() + _bounds.height() / 2);
 
    _xUnit->setPos(_bounds.right(), _bounds.bottom() + 1.2 * MARGIN);
    _yUnit->setPos(_bounds.left(), _bounds.top() - 0.5 * MARGIN);
 
    /* update graphs and their captions */
    QRectF rect;
    for (int i = 0; i < _graphs.size(); i++)
    {
        rect = _graphs[i]->boundingRect();
        auto offset = static_cast<int>(fabs(rect.bottom() - _bounds.bottom()) -
                                       fabs(rect.top() - _bounds.top()));
        _graphs[i]->setPos(0, offset);
 
        rect = itemsBoundingRect();
        _graphCaptions[i]->setPos(_bounds.left(), rect.bottom() + 10);
    }
}

References _bounds, _graphCaptions, _graphs, _xAxis, _xLabel, _xUnit, _yAxis, _yLabel, _yUnit, getXAxisOffset(), getYAxisOffset(), and MARGIN.

Referenced by addGraph(), and initialize().

Member Data Documentation

_bounds

QRectF DiagramScene::_bounds

private

Definition at line 52 of file DiagramScene.h.

Referenced by DiagramScene(), constructGrid(), getXAxisOffset(), getYAxisOffset(), initialize(), and update().

_graphCaptions

QVector<QGraphicsItemGroup*> DiagramScene::_graphCaptions

private

Definition at line 55 of file DiagramScene.h.

Referenced by ~DiagramScene(), addCaption(), clearGrid(), and update().

_graphs

QVector<QGraphicsPathItem*> DiagramScene::_graphs

private

Definition at line 56 of file DiagramScene.h.

Referenced by ~DiagramScene(), clearGrid(), drawGraph(), and update().

_grid

QGraphicsGrid* DiagramScene::_grid

private

Definition at line 57 of file DiagramScene.h.

Referenced by ~DiagramScene(), clearGrid(), and constructGrid().

_lists

QVector<DiagramList*> DiagramScene::_lists

private

Definition at line 54 of file DiagramScene.h.

Referenced by ~DiagramScene(), addGraph(), clearGrid(), and setDiagramBoundaries().

_scaleX

float DiagramScene::_scaleX

private

Definition at line 59 of file DiagramScene.h.

Referenced by adjustScaling(), constructGrid(), and drawGraph().

_scaleY

float DiagramScene::_scaleY

private

Definition at line 60 of file DiagramScene.h.

Referenced by adjustScaling(), constructGrid(), and drawGraph().

_startDate

QDateTime DiagramScene::_startDate

private

Definition at line 58 of file DiagramScene.h.

Referenced by constructGrid(), and setDiagramBoundaries().

_unscaledBounds

QRectF DiagramScene::_unscaledBounds

private

Definition at line 53 of file DiagramScene.h.

Referenced by adjustScaling(), constructGrid(), and setDiagramBoundaries().

_xAxis

QArrow* DiagramScene::_xAxis

private

Definition at line 61 of file DiagramScene.h.

Referenced by ~DiagramScene(), setXAxis(), and update().

_xLabel

QNonScalableGraphicsTextItem* DiagramScene::_xLabel

private

Definition at line 63 of file DiagramScene.h.

Referenced by ~DiagramScene(), addGraph(), initialize(), and update().

_xTicksText

QVector<QNonScalableGraphicsTextItem*> DiagramScene::_xTicksText

private

Definition at line 67 of file DiagramScene.h.

Referenced by ~DiagramScene(), clearGrid(), and constructGrid().

_xUnit

QNonScalableGraphicsTextItem* DiagramScene::_xUnit

private

Definition at line 65 of file DiagramScene.h.

Referenced by ~DiagramScene(), addGraph(), initialize(), and update().

_yAxis

QArrow* DiagramScene::_yAxis

private

Definition at line 62 of file DiagramScene.h.

Referenced by ~DiagramScene(), setYAxis(), and update().

_yLabel

QNonScalableGraphicsTextItem* DiagramScene::_yLabel

private

Definition at line 64 of file DiagramScene.h.

Referenced by ~DiagramScene(), addGraph(), initialize(), and update().

_yTicksText

QVector<QNonScalableGraphicsTextItem*> DiagramScene::_yTicksText

private

Definition at line 68 of file DiagramScene.h.

Referenced by ~DiagramScene(), clearGrid(), and constructGrid().

_yUnit

QNonScalableGraphicsTextItem* DiagramScene::_yUnit

private

Definition at line 66 of file DiagramScene.h.

Referenced by ~DiagramScene(), addGraph(), initialize(), and update().

MARGIN

const int DiagramScene::MARGIN = 30

static

Definition at line 28 of file DiagramScene.h.

Referenced by constructGrid(), DiagramView::minimumSizeHint(), DiagramView::sizeHint(), update(), and DiagramView::update().

---

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

• DiagramScene.h
• DiagramScene.cpp