GaugeWidget.h

#ifndef GaugeWidget_H
#define GaugeWidget_H
 
#include <QWidget>
 
class GaugeWidget : public QWidget {
    Q_OBJECT
    Q_PROPERTY(double value
                   READ value
                       WRITE setValue
                           NOTIFY valueChanged)
 
public:
    static constexpr int DEF_MIN_VALUE { 0 };
 
    static constexpr int DEF_MAX_VALUE { 100 };
 
    static constexpr short TITLE_FONT_SZ { 12 };
 
    static constexpr short CURVAL_FOUT_SZ { 10 };
 
    static constexpr int ANIMATION_DURATION { 500 };
 
    static constexpr float WIDGET_MIN_WIDTH { 200 };
 
    static constexpr float WIDGET_MIN_HEIGHT { 200 };
 
    static constexpr QColor BOARD_COLOR = QColor(160, 160, 160);
 
    static constexpr QColor FROM_BOARD_COLOR = QColor(190, 190, 190);
 
    static constexpr QColor TO_BOARD_COLOR = QColor(110, 110, 110);
 
    static constexpr short BOARD_LEN = 1;
 
    static constexpr short START_ANGLE { 225 };
 
    static constexpr short TOTAL_ANGLE { 270 };
 
    static constexpr short COLOR_GRAD_WIDTH { 8 };
 
    static constexpr short COLOR_RADIUS { 90 };
 
    static constexpr QColor START_COLOR = QColor(255, 0, 0);
 
    static constexpr QColor END_COLOR = QColor(0, 255, 0);
 
    static constexpr int TICK_CNT { 55 };
 
    static constexpr short MAIN_TICK_WIDTH { 2 };
 
    static constexpr short SUB_TICK_WIDTH { 1 };
 
    static constexpr short MAIN_TICK_LENGTH { 8 };
 
    static constexpr short SUB_TICK_LENGTH { 5 };
 
    static constexpr short SUB_MAIN_RATE { 5 };
 
    static constexpr QColor TICK_COLOR = QColor(255, 255, 255);
 
    static constexpr short LABEL_FONT_SZ { 6 };
 
    static constexpr QColor LABEL_COLOR = QColor(255, 255, 255);
 
    explicit GaugeWidget(QWidget* parent = nullptr);
 
    void setRange(int min, int max) {
        max_value = max;
        min_value = min;
        update();
    }
 
    void setTitle(const QString& title) {
        this->title = title;
        update();
    }
 
    void setUnit(const QString& unit) {
        this->unit = unit;
        update();
    }
 
    inline double value() const { return current_value; }
 
    void update_value(const double value);
 
signals:
    void valueChanged(double value);
 
protected:
    void paintEvent(QPaintEvent* event) override;
 
private:
    double max_value { DEF_MIN_VALUE }; 
    double min_value { DEF_MAX_VALUE }; 
    double current_value { 0.0 }; 
 
    QFont title_font { "Arial", TITLE_FONT_SZ, QFont::Bold }; 
    QFont value_font { "Arial", CURVAL_FOUT_SZ, QFont::Bold }; 
    QFont label_font { "Arial", LABEL_FONT_SZ }; 
 
    QString title; 
    QString unit; 
 
    void setValue(const double val) {
        if (qFuzzyCompare(current_value, val))
            return;
        current_value = val;
        emit valueChanged(val);
        update();
    }
 
    void drawBackground(QPainter& p);
    void drawArc(QPainter& p);
    void drawTicks(QPainter& p);
    void drawLabels(QPainter& p);
    void drawNeedle(QPainter& p);
    void drawCenter(QPainter& p);
    void drawTexts(QPainter& p);
};
 
#endif