ts-qt/components/charts/line_chart.cc

//
// Created by Codex on 2025/12/10.
//

#include "line_chart.hh"
#include <QLinearGradient>
#include <algorithm>
#include <cmath>
#include <limits>

using creeper::line_widget::internal::LinePlot;

LinePlot::LinePlot() {
    setBackground(Qt::transparent);
}

LinePlot::~LinePlot() = default;

void LinePlot::load_theme_manager(creeper::ThemeManager& mgr) {
    mgr.append_handler(this, [this](const creeper::ThemeManager& manager) {
        scheme_ = manager.color_scheme();
        apply_theme();
        if (initialized_) {
            replot();
        }
    });
}

void LinePlot::set_data(const QVector<QPointF>& points) {
    points_ = points;
    trim_points();
    if (initialized_) {
        update_graph();
    }
}

void LinePlot::set_max_points(int count) {
    const int clamped = std::max(1, count);
    if (clamped == max_points_) {
        return;
    }
    max_points_ = clamped;
    trim_points();
    if (initialized_) {
        update_graph();
    }
}

void LinePlot::paintEvent(QPaintEvent* event) {
    if (!initialized_) {
        initialize_plot();
    }
    QCustomPlot::paintEvent(event);
}

void LinePlot::initialize_plot() {
    if (initialized_) {
        return;
    }

    axisRect()->setAutoMargins(QCP::msNone);
    axisRect()->setMargins(QMargins(40, 12, 12, 18));
    axisRect()->setBackground(QBrush(QColor(246, 249, 255)));

    legend->setVisible(false);
    xAxis->setVisible(true);
    yAxis->setVisible(true);
    xAxis->setRange(0.0, std::max(10, max_points_));
    yAxis->setRange(0.0, default_y_range_);

    xAxis->grid()->setVisible(false);
    yAxis->grid()->setVisible(false);
    xAxis->setTicks(false);
    yAxis->setTicks(true);
    xAxis->setSubTicks(false);
    yAxis->setSubTicks(false);
    xAxis->setTickLength(0);
    yAxis->setTickLength(0);
    yAxis->setTickLabelPadding(6);
    yAxis->setLabelPadding(8);

    graph_ = addGraph();
    graph_->setLineStyle(QCPGraph::lsLine);
    graph_->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssCircle, QPen(Qt::NoPen), QBrush(Qt::white), 6));
    graph_->setBrush(QColor(16, 54, 128, 42));
    graph_->setAntialiased(true);
    graph_->setAdaptiveSampling(true);

    initialized_ = true;
    apply_theme();
    update_graph();
}

void LinePlot::reset_graph_range() {
    xAxis->setRange(0.0, std::max(10, max_points_));
    yAxis->setRange(0.0, default_y_range_);
}

void LinePlot::apply_theme() {
    QColor line_color{ 16, 54, 128 };
    QColor text_color{ 30, 30, 30 };
    QColor bg_color{ 232, 238, 248 };
    if (scheme_.has_value()) {
        if (scheme_->primary.isValid()) {
            line_color = scheme_->primary;
        }
        if (scheme_->on_surface.isValid()) {
            text_color = scheme_->on_surface;
        }
        if (scheme_->surface_container_high.isValid()) {
            bg_color = scheme_->surface_container_high;
        }
        else if (scheme_->surface_container.isValid()) {
            bg_color = scheme_->surface_container;
        }
        else if (scheme_->surface.isValid()) {
            bg_color = scheme_->surface;
        }
    }

    QColor grid_color = bg_color;

    QPen axis_pen(bg_color);
    axis_pen.setWidthF(1.0);
    xAxis->setBasePen(axis_pen);
    yAxis->setBasePen(axis_pen);
    xAxis->setTickPen(axis_pen);
    yAxis->setTickPen(axis_pen);
    xAxis->setTickLabelColor(Qt::transparent);
    yAxis->setTickLabelColor(text_color);
    xAxis->setLabelColor(Qt::transparent);
    yAxis->setLabelColor(text_color);
    axisRect()->setBackground(bg_color);

    if (graph_) {
        QPen pen(line_color);
        pen.setWidthF(3.0);
        pen.setCapStyle(Qt::RoundCap);
        graph_->setPen(pen);

        QLinearGradient fill_grad(0, 0, 0, 1);
        fill_grad.setCoordinateMode(QGradient::CoordinateMode::ObjectBoundingMode);
        fill_grad.setColorAt(0.0, QColor(line_color.red(), line_color.green(), line_color.blue(), 70));
        fill_grad.setColorAt(1.0, QColor(line_color.red(), line_color.green(), line_color.blue(), 18));
        graph_->setBrush(QBrush(fill_grad));

        auto scatter = graph_->scatterStyle();
        scatter.setPen(QPen(line_color, 1.5));
        scatter.setBrush(QBrush(QColor(bg_color).lighter(104)));
        scatter.setSize(7);
        graph_->setScatterStyle(scatter);
    }
}

void LinePlot::update_graph() {
    if (!initialized_) {
        return;
    }
    if (!graph_) {
        graph_ = addGraph();
        apply_theme();
    }

    if (points_.isEmpty()) {
        graph_->data()->clear();
        reset_graph_range();
        replot();
        return;
    }

    QVector<double> keys(points_.size());
    QVector<double> values(points_.size());
    double          min_key = std::numeric_limits<double>::max();
    double          max_key = std::numeric_limits<double>::lowest();
    double          min_val = std::numeric_limits<double>::max();
    double          max_val = std::numeric_limits<double>::lowest();

    for (int i = 0; i < points_.size(); ++i) {
        const auto& pt = points_[i];
        keys[i]        = pt.x();
        values[i]      = pt.y();
        min_key        = std::min(min_key, pt.x());
        max_key        = std::max(max_key, pt.x());
        min_val        = std::min(min_val, pt.y());
        max_val        = std::max(max_val, pt.y());
    }

    graph_->setData(keys, values, true);

    if (min_key == std::numeric_limits<double>::max()) {
        reset_graph_range();
    }
    else {
        const double key_span = std::max(1e-3, max_key - min_key);
        xAxis->setRange(min_key, max_key + key_span * 0.02);

        double value_span = max_val - min_val;
        if (value_span < 1e-3) {
            value_span = std::max(std::abs(max_val), 1.0);
            min_val    = max_val - value_span * 0.5;
        }
        const double padding = std::max(value_span * 0.25, 1.0);
        yAxis->setRange(min_val - padding, max_val + padding);
    }

    replot();
}

void LinePlot::trim_points() {
    if (max_points_ <= 0 || points_.size() <= max_points_) {
        return;
    }
    const int start = points_.size() - max_points_;
    points_         = points_.mid(start);
}

using namespace creeper;

void SumLinePlot::paintEvent(QPaintEvent* event) {
    line_widget::internal::LinePlot::paintEvent(event);
}