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Axis refactoring to support better barcharts
Axis refactoring to support better barcharts

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qsplineseries.cpp
142 lines | 4.8 KiB | text/x-c | CppLexer
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r295 #include "qsplineseries.h"
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r433 /*!
\class QSplineSeries
\brief Series type used to store data needed to draw a spline.
QSplineSeries stores the data points along with the segment control points needed by QPainterPath to draw spline
Control points are automatically calculated when data changes. The algorithm computes the points so that the normal spline can be drawn.
*/
/*!
\fn QSeriesType QSplineSeries::type() const
Returns the type of the series
*/
/*!
\fn QSeriesType QSplineSeries::controlPoint(int index) const
Returns the control point specified by \a index
*/
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r401 QTCOMMERCIALCHART_BEGIN_NAMESPACE
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r433 /*!
Constructs empty series object which is a child of \a parent.
When series object is added to QChartView or QChart instance then the ownerships is transfered.
*/
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r295 QSplineSeries::QSplineSeries(QObject *parent) :
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r470 QLineSeries(parent)
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r295 {
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r431 connect(this,SIGNAL(pointAdded(int)), this, SLOT(updateControlPoints()));
connect(this,SIGNAL(pointRemoved(int)), this, SLOT(updateControlPoints()));
connect(this,SIGNAL(pointReplaced(int)), this, SLOT(updateControlPoints()));
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r295 }
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r305
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r433 /*!
\internal
Calculates control points which are needed by QPainterPath.cubicTo function to draw the cubic Bezier cureve between two points.
*/
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r401 void QSplineSeries::calculateControlPoints()
{
// Based on http://www.codeproject.com/Articles/31859/Draw-a-Smooth-Curve-through-a-Set-of-2D-Points-wit
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r433 // CPOL License
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r401
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r419 int n = m_x.size() - 1;
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r401 if (n == 1)
{ // Special case: Bezier curve should be a straight line.
// firstControlPoints = new Point[1];
// 3P1 = 2P0 + P3
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r419 m_controlPoints.append(QPointF((2 * m_x[0] + m_x[1]) / 3, (2 * m_y[0] + m_y[1]) / 3));
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r401
// P2 = 2P1 P0
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r419 m_controlPoints.append(QPointF(2 * m_controlPoints[0].x() - m_x[0], 2 * m_controlPoints[0].y() - m_y[0]));
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r401 return;
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r318 }
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r401 // Calculate first Bezier control points
// Right hand side vector
// Set of equations for P0 to Pn points.
//
// | 2 1 0 0 ... 0 0 0 ... 0 0 0 | | P1_1 | | P0 + 2 * P1 |
// | 1 4 1 0 ... 0 0 0 ... 0 0 0 | | P1_2 | | 4 * P1 + 2 * P2 |
// | 0 1 4 1 ... 0 0 0 ... 0 0 0 | | P1_3 | | 4 * P2 + 2 * P3 |
// | . . . . . . . . . . . . | | ... | | ... |
// | 0 0 0 0 ... 1 4 1 ... 0 0 0 | * | P1_i | = | 4 * P(i-1) + 2 * Pi |
// | . . . . . . . . . . . . | | ... | | ... |
// | 0 0 0 0 0 0 0 0 ... 1 4 1 | | P1_(n-1)| | 4 * P(n-2) + 2 * P(n-1) |
// | 0 0 0 0 0 0 0 0 ... 0 2 7 | | P1_n | | 8 * P(n-1) + Pn |
//
QList<qreal> rhs;
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r419 rhs.append(m_x[0] + 2 * m_x[1]);
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r401
// Set right hand side X values
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r429 for (int i = 1; i < n - 1; ++i)
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r419 rhs.append(4 * m_x[i] + 2 * m_x[i + 1]);
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r401
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r419 rhs.append((8 * m_x[n - 1] + m_x[n]) / 2.0);
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r401 // Get first control points X-values
QList<qreal> x = getFirstControlPoints(rhs);
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r419 rhs[0] = m_y[0] + 2 * m_y[1];
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r401
// Set right hand side Y values
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r429 for (int i = 1; i < n - 1; ++i)
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r419 rhs[i] = 4 * m_y[i] + 2 * m_y[i + 1];
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r401
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r419 rhs[n - 1] = (8 * m_y[n - 1] + m_y[n]) / 2.0;
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r401 // Get first control points Y-values
QList<qreal> y = getFirstControlPoints(rhs);
// Fill output arrays.
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r429 for (int i = 0; i < n; ++i)
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r318 {
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r401 // First control point
m_controlPoints.append(QPointF(x[i], y[i]));
// Second control point
if (i < n - 1)
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r419 m_controlPoints.append(QPointF(2 * m_x[i + 1] - x[i + 1], 2 * m_y[i + 1] - y[i + 1]));
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r401 else
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r419 m_controlPoints.append(QPointF((m_x[n] + x[n - 1]) / 2, (m_y[n] + y[n - 1]) / 2));
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r318 }
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r401 }
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r433 /*!
\internal
*/
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r401 QList<qreal> QSplineSeries::getFirstControlPoints(QList<qreal> rhs)
{
QList<qreal> x; // Solution vector.
QList<qreal> tmp; // Temp workspace.
qreal b = 2.0;
x.append(rhs[0] / b);
tmp.append(0);
for (int i = 1; i < rhs.size(); i++) // Decomposition and forward substitution.
{
tmp.append(1 / b);
b = (i < rhs.size() - 1 ? 4.0 : 3.5) - tmp[i];
x.append((rhs[i] - x[i - 1]) / b);
}
for (int i = 1; i < rhs.size(); i++)
x[rhs.size() - i - 1] -= tmp[rhs.size() - i] * x[rhs.size() - i]; // Backsubstitution.
return x;
}
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r431
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r433 /*!
\internal
Updates the control points, besed on currently avaiable knots.
*/
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r431 void QSplineSeries::updateControlPoints()
{
if(m_x.size() > 1)
{
m_controlPoints.clear();
calculateControlPoints();
}
}
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r401 #include "moc_qsplineseries.cpp"
QTCOMMERCIALCHART_END_NAMESPACE