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基于QT实现自定义温度计的示例代码

作者：疯狂的挖掘机

QT原生控件没有实现如仪表盘或者温度计的控件,只好自己实现,所以本文为大家介绍了如何利用qt实现自定义温度/湿度控件,感兴趣的小伙伴可以了解下

0 引入

QT原生控件没有实现如仪表盘或者温度计的控件，只好自己实现，文章代码部分参考引用的文章。直接上图

图一 带有标尺的温度计、湿度

图二 温度计、湿度

控件最核心的部分：在函数paintEvent绘制部分，如果需要动画效果还需要加一个QPropertyAnimation ，这是最主要的，剩下的细节根据需求增加减少即可。

1、带有标尺的温度/湿度计控件

因为只做数据显示用，所以只需要向控件传数据即可。

主要功能：

1、可设置显示范围；

2、显示过程中加了动画效果；

3、背景色和前景色以及刻度尺颜色可变；

4、刻度尺间距可变，控件大小随着QWidget适应；

1.头文件

代码如下（示例）：

protected:
    void paintEvent(QPaintEvent *);
    void drawBg(QPainter *painter);
    void drawProgress(QPainter *painter);
    void drawRulerTop(QPainter *painter);
    void drawRulerBottom(QPainter *painter);

private:
    QPropertyAnimation *m_valueAnimation;
    double minValue;                //最小值
    double maxValue;                //最大值
    qreal value;                    //当前值
    int longStep;                   //长线条等分步长
    int shortStep;                  //短线条等分步长
    bool rulerTop;                  //刻度线在上面
    bool isAdd;                     //是否为增加，默认为的增加

    QColor bgColor;                 //背景颜色
    QColor lineColor;               //线条颜色
    QColor progressColor;           //进度颜色

public:
    qreal getValue()               const;
    void setrulerTop(bool istop);   //设定刻度线再上还是在下，默认是在上
    void setValue(qreal v);
    void setRange(int minValue, int maxValue);
    void startAnimation();
    void updateValue(double value);
    void setBgColor(const QColor &bgColor);               //设置背景颜色
    void setLineColor(const QColor &lineColor);           //设置线条颜色
    void setProgressColor(const QColor &progressColor);   //设置进度颜色

2.核心代码

绘制部分参考引用2代码，感谢刘典武老师的无私开源，有需要的可去做定制。

代码如下：

void HumidityProgress::startAnimation()
{
    qreal startValue =  value;
    if(isAdd)
    {
        m_valueAnimation->setKeyValueAt(0.5, value+0.5);
        m_valueAnimation->setKeyValueAt(1, value);
        m_valueAnimation->setStartValue(startValue-0.5);
        m_valueAnimation->start();
    }
    else{
        m_valueAnimation->setKeyValueAt(0.5, value-0.5);
        m_valueAnimation->setKeyValueAt(1, value);
        m_valueAnimation->setStartValue(startValue+0.5);
        m_valueAnimation->start();
    }

}

void HumidityProgress::paintEvent(QPaintEvent *)
{
    //绘制准备工作,启用反锯齿
    QPainter painter(this);
    painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);

    //按照绘制顺序
    drawBg(&painter);
    drawProgress(&painter);
    if (rulerTop) {
        drawRulerTop(&painter);
    } else {
        drawRulerBottom(&painter);
    }
}

void HumidityProgress::drawBg(QPainter *painter)
{
    painter->save();
    painter->setPen(lineColor);
    painter->setBrush(bgColor);
    painter->drawRect(rect());
    painter->restore();
}

void HumidityProgress::drawProgress(QPainter *painter)
{
    painter->save();
    painter->setPen(Qt::NoPen);
    painter->setBrush(progressColor);

    double length = width();
    double increment = length / (maxValue - minValue);
    double initX = (value - minValue) * increment;

    QRect rect(0, 0, initX, height());
    painter->drawRect(rect);
    painter->restore();
}

void HumidityProgress::drawRulerTop(QPainter *painter)
{
    painter->save();
    painter->setPen(lineColor);

    double initX = 0;

    //绘制横向标尺上部分底部线
    double initTopY = 0;
    QPointF lineTopLeftPot = QPointF(initX, initTopY);
    QPointF lineTopRightPot = QPointF(width() - initX, initTopY);
    painter->drawLine(lineTopLeftPot, lineTopRightPot);

    //绘制上部分及下部分横向标尺刻度
    double length = width();
    //计算每一格移动多少
    double increment = length / (maxValue - minValue);
    //长线条短线条长度
    int longLineLen = 15;
    int shortLineLen = 10;

    //根据范围值绘制刻度值及刻度值 长线条需要移动10像素 短线条需要移动5像素
    for (int i = minValue; i <= maxValue; i = i + shortStep) {
        if (i % longStep == 0) {
            QPointF topPot = QPointF(initX, initTopY);
            QPointF bottomPot = QPointF(initX, initTopY + longLineLen);
            painter->drawLine(topPot, bottomPot);

            //第一个值和最后一个值不要绘制
            if (i == minValue || i == maxValue) {
                initX += increment * shortStep;
                continue;
            }

            QString strValue = QString("%1").arg((double)i, 0, 'f', 0);
            double textWidth = fontMetrics().width(strValue);
            double textHeight = fontMetrics().height();

            QPointF textPot = QPointF(initX - textWidth / 2, initTopY + textHeight + longLineLen);
            painter->drawText(textPot, strValue);
        } else {
            if (i % (longStep / 2) == 0) {
                shortLineLen = 10;
            } else {
                shortLineLen = 6;
            }

            QPointF topPot = QPointF(initX, initTopY);
            QPointF bottomPot = QPointF(initX, initTopY + shortLineLen);
            painter->drawLine(topPot, bottomPot);
        }

        initX += increment * shortStep;
    }

    painter->restore();
}

该处使用的url网络请求的数据。

2、竖起来的温度/湿度计控件

因为只做数据显示用，所以只需要向控件传数据即可。

控件是好看，但是大小不能改变，所以这里需要自己实现了，源码作者已经放上。

1.头文件

代码如下（示例）：

#ifndef THERMOMETREDLG_H
#define THERMOMETREDLG_H
#include <QWidget>
#include <QPropertyAnimation>
#include <QPainter>
#include <QTimer>
class thermometreDlg : public QWidget
{
    Q_OBJECT
    Q_PROPERTY(qreal value READ getValue WRITE setValue)  //声明属性
public:
    explicit thermometreDlg(QWidget *parent = nullptr);
    qreal getValue();
    void setValue(qreal value);
    void changeValue(qreal value);
protected:
    void paintEvent(QPaintEvent *e);
public slots:
    void startAnimation();
signals:
private:
    qreal m_value;
    qreal curValue;
    int m_width;
    QRectF m_rect;
    int maxValue, minValue;
    qreal m_radius;
    QPropertyAnimation *m_valueAnimation;
    void updateRect();
};
#endif // THERMOMETREDLG_H

2.实现

代码如下（示例）：

#include "thermometredlg.h"
#include <QDebug>
thermometreDlg::thermometreDlg(QWidget *parent) : QWidget(parent)
{
    m_width = 20;
    maxValue = 100;
    minValue = 0;
    m_radius = 1.05;
    m_value = 0;
    curValue = m_value;
    QTimer *at = new QTimer(this);
    at->start(1000);
    m_valueAnimation = new QPropertyAnimation(this, "value");
    m_valueAnimation->setDuration(1000);
    m_valueAnimation->setEasingCurve(QEasingCurve::OutCubic);
    m_valueAnimation->setLoopCount(1);
    connect(at, SIGNAL(timeout()), this, SLOT(startAnimation()));
}
void thermometreDlg::updateRect()
{
    m_rect.setX(0);
    m_rect.setY(20 - height()/2);
    m_rect.setWidth(m_width);
    m_rect.setHeight(height() - 40 - m_width* m_radius);
}
void thermometreDlg::setValue(qreal value)
{
    m_value = value;
    update();
}
void thermometreDlg::changeValue(qreal value)
{
    if(value > maxValue)
        value = maxValue;
    if(value < minValue)
        value = minValue;
    curValue = value;
}
qreal thermometreDlg::getValue()
{
    return m_value;
}
void thermometreDlg::paintEvent(QPaintEvent *e)
{
    updateRect();
    QPainter painter(this);
    QPen pen(Qt::black);
    painter.translate(this->width()/2, this->height()/2);  //坐标轴移动到中心点
    painter.setRenderHints(QPainter::TextAntialiasing | QPainter::Antialiasing);  // 启用反锯齿
    painter.save();
    //绘制上方的柱状
    painter.fillRect(m_rect, QColor(168,200, 225));
    //绘制底部的圆
    QRectF tmpRect = QRectF(m_rect.bottomLeft(), QPointF(m_width, height()/2- m_width*m_radius));
    painter.fillRect(tmpRect, QColor(255, 0, 0));
    painter.setPen(Qt::NoPen);
    painter.setBrush(QColor(255, 0, 0));
    painter.drawEllipse(tmpRect.bottomLeft()+QPointF(tmpRect.width()/2, 0),m_width*m_radius, m_width*m_radius);
    painter.restore();
    //绘制刻度以及刻度值
    painter.save();
    painter.setPen(QColor(Qt::black));
    int nYCount = (maxValue - minValue)/10+1;
    qreal perHeight = (m_rect.height())/nYCount;
    for (int i=0; i<nYCount; ++i) {
        QPointF basePoint = m_rect.bottomLeft() - QPointF(0, perHeight/2) - QPointF(0, perHeight*i);
        //左侧大刻度
        painter.drawLine(basePoint, basePoint+QPointF(-10, 0));
        for (int j=1; j<10; ++j) {
            if(i == nYCount -1)
                continue;
            painter.drawLine(basePoint-QPointF(0, perHeight/10*j),basePoint-QPointF(5, perHeight/10*j));
        }
        painter.drawText(basePoint+QPointF(-28, 4), QString("%1").arg(minValue+i*10));
        //右侧大刻度
        basePoint = m_rect.bottomRight() - QPointF(0, perHeight/2) - QPointF(0, perHeight*i);
        painter.drawLine(basePoint, basePoint+QPointF(10, 0));
        for (int j=1; j<10; ++j) {
            if(i == nYCount -1)
                continue;
            painter.drawLine(basePoint-QPointF(0, perHeight/10*j),basePoint-QPointF(-5, perHeight/10*j));
        }
    }
    painter.restore();
    //根据值填充m_rect
    qreal h = (m_value-minValue)/(maxValue-minValue)*(m_rect.height()-perHeight);
    if(h<0)
        h = 0;
    if(h > m_rect.height())
        h = m_rect.height();
    painter.fillRect(m_rect.adjusted(0, m_rect.height()-h-perHeight/2-1 , 0, 0), QColor(255, 0, 0));
    QWidget::paintEvent(e);
}
void thermometreDlg::startAnimation()
{
    qreal startValue = getValue();
    m_valueAnimation->setKeyValueAt(0, startValue-1);
    m_valueAnimation->setKeyValueAt(0.5, curValue+1);
    m_valueAnimation->setKeyValueAt(1, curValue);
    m_valueAnimation->setStartValue(startValue-2);
    m_valueAnimation->start();
}

以上就是基于QT实现自定义温度计的示例代码的详细内容，更多关于QT温度计的资料请关注脚本之家其它相关文章！

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