《QT实用小工具·五十》动态增删数据与平滑缩放移动的折线图
1、概述
源码放在文章末尾
该项目实现了带动画、带交互的折线图，包含如下特点：
动态增删数值
自适应显示坐标轴数值
鼠标悬浮显示十字对准线
鼠标靠近点自动贴附
支持直线与平滑曲线效果
自定义点的显示类型与大小
自适应点的数值显示位置
根据指定锚点缩放
平滑的横向移动
选中的纵向渐变效果
项目demo演示如下所示：
项目部分代码如下所示：
#ifndef LINECHART_H
#define LINECHART_H#include <QObject>
#include <QWidget>
#include <QList>
#include <QPainter>
#include <QPainterPath>
#include <QPropertyAnimation>
#include <QtMath>struct ChartData
{QString title;QColor color = Qt::black;int xMin = 0;int xMax = 0;int yMin = 0;int yMax = 0;QList<QPoint> points;QList<QString> xLabels; // X显示的名字，可空，比如日期
};struct Vector2D : public QPointF
{Vector2D(double x, double y) : QPointF(x, y){}Vector2D(QPointF p) : QPointF(p){}/// 向量长度double length(){return sqrt(x() * x() + y() * y());}/// 转单位向量Vector2D normalize(){double len = length();double inv;if (len < 1e-4)inv = 0;elseinv = 1 / length();return Vector2D(x() * inv, y() * inv);}/// 向量相加Vector2D operator+ (Vector2D v){return Vector2D(x() + v.x(), y() + v.y());}/// 向量翻倍Vector2D operator* (double f){return Vector2D(x() * f, y() * f);}/// 内积double dot(Vector2D v){return x() * v.x() + y() * v.y();}/// 两个向量夹角double angle(Vector2D v){return acos(dot(v) / (length() * v.length())) * 180 / M_PI;}
};class LineChart : public QWidget
{Q_OBJECTQ_PROPERTY(int display_x_min READ getDisplayXMin WRITE setDisplayXMin)Q_PROPERTY(int display_x_max READ getDisplayXMax WRITE setDisplayXMax)Q_PROPERTY(int display_y_min READ getDisplayYMin WRITE setDisplayYMin)Q_PROPERTY(int display_y_max READ getDisplayYMax WRITE setDisplayYMax)public:LineChart(QWidget *parent = nullptr);int lineCount() const;void setPointLineType(int t);void setPointValueType(int t);void setPointDotType(int t);void setPointDotRadius(int r);void setLabelSpacing(int s);void addLine(ChartData data);void removeLine(int index);void addPoint(int index, int x, int y);void addPoint(int index, int x, int y, const QString& label);void removeFirst(int index);void updateAnchors();void zoom(double prop);void moveHorizontal(int x);signals:void signalSelectRangeChanged(int start, int end);public slots:void zoomIn();void zoomOut();protected:void paintEvent(QPaintEvent *event) override;void enterEvent(QEvent *event) override;void leaveEvent(QEvent *event) override;void mouseMoveEvent(QMouseEvent *event) override;void mousePressEvent(QMouseEvent *event) override;void mouseReleaseEvent(QMouseEvent *event) override;void wheelEvent(QWheelEvent *event) override;private:void setDisplayXMin(int v);int getDisplayXMin() const;void setDisplayXMax(int v);int getDisplayXMax() const;void setDisplayYMin(int v);int getDisplayYMin() const;void setDisplayYMax(int v);int getDisplayYMax() const;void saveRange();void startRangeAnimation();QPropertyAnimation* startAnimation(const QByteArray &property, int start, int end, bool* flag, int duration = 300, QEasingCurve curve = QEasingCurve::OutQuad);int getValueByCursorPos(QPoint pos);private:// 数据QList<ChartData> datas; // 所有折线的数据// 界面QRect contentRect; // 显示的范围，实时刷新QRect paddings = QRect(32, 32, 32, 32); // 四周留白(width=right,height=bottom)QColor borderColor = Qt::gray; // 边界线颜色int labelSpacing = 2; // 标签间距// 信息显示bool autoResize = true; // 自动调整大小int displayXMin = 0, displayXMax = 0; // 显示的X轴范围int displayYMin = 0, displayYMax = 0; // 显示的Y轴范围bool usePointXLabels = true; // 优先使用点对应的label，还是相同间距的数值QList<QString> xLabels; // 显示的文字（可能少于值数量）QList<int> xLabelPoss;int pointLineType = 3; // 连线类型：1直线，2二次贝塞尔曲线，3三次贝塞尔曲线（更精确但吃性能）int pointValueType = 2; // 数值显示位置：0无，1强制上方，2自动附近int pointDotType = 1; // 圆点类型：0无，1空心圆，2实心圆，3小方块int pointDotRadius = 2; // 圆点半径// 动画效果bool enableAnimation = true;int _savedXMin, _savedXMax; // 修改前的数值int _savedYMin, _savedYMax;bool animatingXMin = false, animatingXMax = false; // 是否正在动画中bool animatingYMin = false, animatingYMax = false;int _animatedXMin, _animatedXMax; // 动画中的数值（仅影响显示）int _animatedYMin, _animatedYMax;// 交互数据bool pressing = false;QPoint pressPos, releasePos;bool hovering = false;QPoint hoverPos;int nearDis = 8; // 四周这些距离内算是“附近”// 悬浮提示bool showCrossOnPressing = true; // 按下显示十字对准线QColor hightlightColor = QColor("#FF7300"); // 高亮颜色// 鼠标选择bool enableSelect = true;bool selecting = false;int selectPos = 0; // 最后一次鼠标点击的X像素（相对显示矩形）int selectXStart = 0, selectXEnd = 0; // 鼠标按下/松开的对应X值位置QColor selectColor = QColor("#F08080"); // 选择区域颜色// 缩放(仅针对X轴)bool enableScale = true;int displayXStart = 0, displayXEnd = 0;
};#endif // LINECHART_H