使用QCutomPlot做的读取txt文件显示频谱图的demo,帮助大家了解QCustomPlot的基本使用

1.运行结果

        demo比较简单,用于文件读取,鼠标放大缩小,右键截图等基础功能.

2.绘图详解

        绘图核心是将类提升为QCustomPlot之后进行重绘,重绘之前设计图表曲线,图标标题,坐标轴,坐标轴范围,背景颜色,网格线样式,刻度样式等.

        初始化绘图代码如下:

void MainWindow::setupSpectrumPlot()
{
    // 设置图表曲线
    ui->widget->addGraph();
    ui->widget->graph(0)->setPen(QPen(Qt::blue));
    ui->widget->graph(0)->setBrush(QBrush(QColor(0, 0, 255, 20)));

    ui->widget->plotLayout()->insertRow(0);
    QCPTextElement *title = new QCPTextElement(ui->widget, "频谱示例", QFont("微软雅黑", 12, QFont::Bold));
    ui->widget->plotLayout()->addElement(0, 0, title);

    // 设置坐标轴标签
    ui->widget->xAxis->setLabel("频率");
    ui->widget->yAxis->setLabel("幅度");

    // 设置坐标轴范围
    ui->widget->xAxis->setRange(0, 100);
    ui->widget->yAxis->setRange(0, 1);

    // 设置背景颜色
    ui->widget->setBackground(QBrush(Qt::white));

    // 设置网格线样式
    ui->widget->xAxis->grid()->setPen(QPen(Qt::gray, 0.5, Qt::DotLine));
    ui->widget->yAxis->grid()->setPen(QPen(Qt::gray, 0.5, Qt::DotLine));
    ui->widget->xAxis->grid()->setSubGridPen(QPen(Qt::lightGray, 0.2, Qt::DotLine));
    ui->widget->yAxis->grid()->setSubGridPen(QPen(Qt::lightGray, 0.2, Qt::DotLine));
    ui->widget->xAxis->grid()->setSubGridVisible(true);
    ui->widget->yAxis->grid()->setSubGridVisible(true);

    // 设置坐标轴刻度样式
    ui->widget->xAxis->setTickPen(QPen(Qt::black, 1));
    ui->widget->yAxis->setTickPen(QPen(Qt::black, 1));
    ui->widget->xAxis->setSubTickPen(QPen(Qt::black, 0.5));
    ui->widget->yAxis->setSubTickPen(QPen(Qt::black, 0.5));

    // 启用抗锯齿
    ui->widget->setAntialiasedElements(QCP::aeAll);

    // ============ 十字线初始化 ============
    // 水平线
    crosshairH = new QCPItemStraightLine(ui->widget);
    crosshairH->setPen(QPen(QColor(150, 150, 150), 1, Qt::DashLine));
    crosshairH->setVisible(false);

    // 垂直线
    crosshairV = new QCPItemStraightLine(ui->widget);
    crosshairV->setPen(QPen(QColor(150, 150, 150), 1, Qt::DashLine));
    crosshairV->setVisible(false);

    // 坐标标签
    coordText = new QCPItemText(ui->widget);
    coordText->setPositionAlignment(Qt::AlignLeft|Qt::AlignTop);
    coordText->position->setType(QCPItemPosition::ptAxisRectRatio);
    coordText->position->setCoords(0.02, 0.02); // 左上角
    coordText->setText("X: -, Y: -");
    coordText->setTextAlignment(Qt::AlignLeft);
    coordText->setFont(QFont(font().family(), 9));
    coordText->setPadding(QMargins(5, 5, 5, 5));
    coordText->setBrush(QBrush(QColor(255, 255, 255, 200)));
    coordText->setPen(QPen(QColor(100, 100, 100)));

    ui->widget->replot();
}