更新文档

third/3rd_qcustomplot/3rd_qcustomplot.pri

@@ -2,6 +2,10 @@ greaterThan(QT_MAJOR_VERSION, 4): QT += printsupport
 greaterThan(QT_MAJOR_VERSION, 4): CONFIG += c++11
 #lessThan(QT_MAJOR_VERSION, 5): QMAKE_CXXFLAGS += -std=c++11
 
+#引入平滑曲线类
+HEADERS += $$PWD/smoothcurve.h
+SOURCES += $$PWD/smoothcurve.cpp
+
 #没有定义任何版本则默认采用2.0
 !contains(DEFINES, qcustomplot_v1_3) {
 !contains(DEFINES, qcustomplot_v2_0) {

third/3rd_qcustomplot/smoothcurve.cpp

@@ -0,0 +1,120 @@
+#include "smoothcurve.h"
+#include "qdebug.h"
+
+QPainterPath SmoothCurve::createSmoothCurve(const QVector<QPointF> &points)
+{
+    QPainterPath path;
+    int len = points.size();
+    if (len < 2) {
+        return path;
+    }
+
+    QVector<QPointF> firstControlPoints;
+    QVector<QPointF> secondControlPoints;
+    calculateControlPoints(points, &firstControlPoints, &secondControlPoints);
+    path.moveTo(points[0].x(), points[0].y());
+
+    for (int i = 0; i < len - 1; ++i) {
+        path.cubicTo(firstControlPoints[i], secondControlPoints[i], points[i + 1]);
+    }
+
+    return path;
+}
+
+QPainterPath SmoothCurve::createSmoothCurve2(const QVector<QPointF> &points)
+{
+    //采用Qt原生方法不做任何处理
+    int count = points.count();
+    if (count == 0) {
+        return QPainterPath();
+    }
+
+    QPainterPath path(points.at(0));
+    for (int i = 0; i < count - 1; ++i) {
+        //控制点的 x 坐标为 sp 与 ep 的 x 坐标和的一半
+        //第一个控制点 c1 的 y 坐标为起始点 sp 的 y 坐标
+        //第二个控制点 c2 的 y 坐标为结束点 ep 的 y 坐标
+        QPointF sp = points.at(i);
+        QPointF ep = points.at(i + 1);
+        QPointF c1 = QPointF((sp.x() + ep.x()) / 2, sp.y());
+        QPointF c2 = QPointF((sp.x() + ep.x()) / 2, ep.y());
+        path.cubicTo(c1, c2, ep);
+    }
+
+    return path;
+}
+
+void SmoothCurve::calculateFirstControlPoints(double *&result, const double *rhs, int n)
+{
+    result = new double[n];
+    double *tmp = new double[n];
+    double b = 2.0;
+    result[0] = rhs[0] / b;
+
+    for (int i = 1; i < n; ++i) {
+        tmp[i] = 1 / b;
+        b = (i < n - 1 ? 4.0 : 3.5) - tmp[i];
+        result[i] = (rhs[i] - result[i - 1]) / b;
+    }
+
+    for (int i = 1; i < n; ++i) {
+        result[n - i - 1] -= tmp[n - i] * result[n - i];
+    }
+
+    delete tmp;
+}
+
+void SmoothCurve::calculateControlPoints(const QVector<QPointF> &datas,
+                                         QVector<QPointF> *firstControlPoints,
+                                         QVector<QPointF> *secondControlPoints)
+{
+    int n = datas.size() - 1;
+    for (int i = 0; i < n; ++i) {
+        firstControlPoints->append(QPointF());
+        secondControlPoints->append(QPointF());
+    }
+
+    if (n == 1) {
+        (*firstControlPoints)[0].rx() = (2 * datas[0].x() + datas[1].x()) / 3;
+        (*firstControlPoints)[0].ry() = (2 * datas[0].y() + datas[1].y()) / 3;
+        (*secondControlPoints)[0].rx() = 2 * (*firstControlPoints)[0].x() - datas[0].x();
+        (*secondControlPoints)[0].ry() = 2 * (*firstControlPoints)[0].y() - datas[0].y();
+        return;
+    }
+
+    double *xs = 0;
+    double *ys = 0;
+    double *rhsx = new double[n];
+    double *rhsy = new double[n];
+
+    for (int i = 1; i < n - 1; ++i) {
+        rhsx[i] = 4 * datas[i].x() + 2 * datas[i + 1].x();
+        rhsy[i] = 4 * datas[i].y() + 2 * datas[i + 1].y();
+    }
+
+    rhsx[0] = datas[0].x() + 2 * datas[1].x();
+    rhsx[n - 1] = (8 * datas[n - 1].x() + datas[n].x()) / 2.0;
+    rhsy[0] = datas[0].y() + 2 * datas[1].y();
+    rhsy[n - 1] = (8 * datas[n - 1].y() + datas[n].y()) / 2.0;
+
+    calculateFirstControlPoints(xs, rhsx, n);
+    calculateFirstControlPoints(ys, rhsy, n);
+
+    for (int i = 0; i < n; ++i) {
+        (*firstControlPoints)[i].rx() = xs[i];
+        (*firstControlPoints)[i].ry() = ys[i];
+
+        if (i < n - 1) {
+            (*secondControlPoints)[i].rx() = 2 * datas[i + 1].x() - xs[i + 1];
+            (*secondControlPoints)[i].ry() = 2 * datas[i + 1].y() - ys[i + 1];
+        } else {
+            (*secondControlPoints)[i].rx() = (datas[n].x() + xs[n - 1]) / 2;
+            (*secondControlPoints)[i].ry() = (datas[n].y() + ys[n - 1]) / 2;
+        }
+    }
+
+    delete xs;
+    delete ys;
+    delete rhsx;
+    delete rhsy;
+}

third/3rd_qcustomplot/smoothcurve.h

@@ -0,0 +1,28 @@
+#ifndef SMOOTHCURVE_H
+#define SMOOTHCURVE_H
+
+#include <QObject>
+#include <QVector>
+#include <QPointF>
+#include <QPainterPath>
+
+#ifdef quc
+class Q_DECL_EXPORT SmoothCurve
+#else
+class SmoothCurve
+#endif
+
+{
+public:
+    //创建平滑曲线路径
+    static QPainterPath createSmoothCurve(const QVector<QPointF> &points);
+    static QPainterPath createSmoothCurve2(const QVector<QPointF> &points);
+
+private:
+    static void calculateFirstControlPoints(double *&result, const double *rhs, int n);
+    static void calculateControlPoints(const QVector<QPointF> &datas,
+                                       QVector<QPointF> *firstControlPoints,
+                                       QVector<QPointF> *secondControlPoints);
+};
+
+#endif // SMOOTHCURVE_H