| @@ -11,3 +11,90 QSplineSeries& QSplineSeries::operator << (const QPointF &value) | |||
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11 | 11 | emit changed(); |
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12 | 12 | return *this; |
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13 | 13 | } |
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14 | ||
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15 | void QSplineSeries::GetCurveControlPoints() | |
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16 | { | |
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17 | int n = m_data.size() - 1; | |
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18 | if (n < 1) | |
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19 | throw new ArgumentException | |
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20 | ("At least two knot points required", "knots"); | |
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21 | if (n == 1) | |
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22 | { // Special case: Bezier curve should be a straight line. | |
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23 | firstControlPoints = new Point[1]; | |
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24 | // 3P1 = 2P0 + P3 | |
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25 | firstControlPoints[0].X = (2 * knots[0].X + knots[1].X) / 3; | |
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26 | firstControlPoints[0].Y = (2 * knots[0].Y + knots[1].Y) / 3; | |
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27 | ||
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28 | secondControlPoints = new Point[1]; | |
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29 | // P2 = 2P1 P0 | |
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30 | secondControlPoints[0].X = 2 * | |
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31 | firstControlPoints[0].X - knots[0].X; | |
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32 | secondControlPoints[0].Y = 2 * | |
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33 | firstControlPoints[0].Y - knots[0].Y; | |
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34 | return; | |
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35 | } | |
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36 | ||
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37 | // Calculate first Bezier control points | |
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38 | // Right hand side vector | |
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39 | double[] rhs = new double[n]; | |
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40 | ||
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41 | // Set right hand side X values | |
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42 | for (int i = 1; i < n - 1; ++i) | |
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43 | rhs[i] = 4 * knots[i].X + 2 * knots[i + 1].X; | |
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44 | rhs[0] = knots[0].X + 2 * knots[1].X; | |
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45 | rhs[n - 1] = (8 * knots[n - 1].X + knots[n].X) / 2.0; | |
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46 | // Get first control points X-values | |
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47 | double[] x = GetFirstControlPoints(rhs); | |
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48 | ||
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49 | // Set right hand side Y values | |
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50 | for (int i = 1; i < n - 1; ++i) | |
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51 | rhs[i] = 4 * knots[i].Y + 2 * knots[i + 1].Y; | |
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52 | rhs[0] = knots[0].Y + 2 * knots[1].Y; | |
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53 | rhs[n - 1] = (8 * knots[n - 1].Y + knots[n].Y) / 2.0; | |
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54 | // Get first control points Y-values | |
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55 | double[] y = GetFirstControlPoints(rhs); | |
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56 | ||
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57 | // Fill output arrays. | |
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58 | firstControlPoints = new Point[n]; | |
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59 | secondControlPoints = new Point[n]; | |
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60 | for (int i = 0; i < n; ++i) | |
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61 | { | |
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62 | // First control point | |
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63 | firstControlPoints[i] = new Point(x[i], y[i]); | |
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64 | // Second control point | |
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65 | if (i < n - 1) | |
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66 | secondControlPoints[i] = new Point(2 * knots | |
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67 | [i + 1].X - x[i + 1], 2 * | |
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68 | knots[i + 1].Y - y[i + 1]); | |
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69 | else | |
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70 | secondControlPoints[i] = new Point((knots | |
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71 | [n].X + x[n - 1]) / 2, | |
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72 | (knots[n].Y + y[n - 1]) / 2); | |
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73 | } | |
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74 | } | |
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75 | ||
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76 | /// <summary> | |
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77 | /// Solves a tridiagonal system for one of coordinates (x or y) | |
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78 | /// of first Bezier control points. | |
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79 | /// </summary> | |
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80 | /// <param name="rhs">Right hand side vector.</param> | |
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81 | /// <returns>Solution vector.</returns> | |
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82 | void GetFirstControlPoints(qreal[] rhs) | |
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83 | { | |
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84 | int n = rhs.Length; | |
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85 | double[] x = new double[n]; // Solution vector. | |
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86 | double[] tmp = new double[n]; // Temp workspace. | |
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87 | ||
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88 | double b = 2.0; | |
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89 | x[0] = rhs[0] / b; | |
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90 | for (int i = 1; i < n; i++) // Decomposition and forward substitution. | |
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91 | { | |
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92 | tmp[i] = 1 / b; | |
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93 | b = (i < n - 1 ? 4.0 : 3.5) - tmp[i]; | |
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94 | x[i] = (rhs[i] - x[i - 1]) / b; | |
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95 | } | |
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96 | for (int i = 1; i < n; i++) | |
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97 | x[n - i - 1] -= tmp[n - i] * x[n - i]; // Backsubstitution. | |
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98 | ||
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99 | return x; | |
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100 | } | |
| @@ -14,6 +14,7 class QSplineSeries : public QChartSeries | |||
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14 | 14 | QChartSeriesType type() const { return QChartSeries::SeriesTypeSpline; } |
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15 | 15 | void addData(QPointF value); |
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16 | 16 | QSplineSeries& operator << (const QPointF &value); |
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17 | void calculateControlPoints(); | |
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17 | 18 | |
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18 | 19 | signals: |
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19 | 20 | |
| @@ -21,6 +22,7 class QSplineSeries : public QChartSeries | |||
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21 | 22 | |
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22 | 23 | private: |
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23 | 24 | QList<QPointF> m_data; |
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25 | QList<QPointF> m_controlPoints; | |
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24 | 26 | |
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25 | 27 | }; |
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26 | 28 | |
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