Qt项目实战：红绿灯小程序

目录

一.初始化对象

二.捕获并处理特定的事件

三.自定义绘制方法

四.绘制外部边框

五.绘制内部边框

六.绘制按钮的背景色

七.绘制覆盖层（高光效果）

八.效果

九.代码

1.h

2.cpp

---

一.初始化对象

1.设置文本、颜色、边框和背景色等默认值。

2.安装事件过滤器以捕获鼠标事件。

3.创建定时器 timerAlarm 用于处理报警状态，并连接到槽函数 alarm()。

二.捕获并处理特定的事件

1.当检测到鼠标按下事件时，如果点击在按钮范围内，则记录当前点并设置 pressed = true。

2.如果正在拖动按钮且允许移动，则更新按钮的位置。

3.当鼠标释放时，重置 pressed 状态并发出点击信号 (clicked())。

三.自定义绘制方法

1.根据 showRect 的值决定绘制矩形或其他图形元素（如边框、背景、文字等）。

2.使用抗锯齿技术提高绘制质量。

四.绘制外部边框

使用线性渐变填充颜色绘制圆形边框，分别为外层和内层

五.绘制内部边框

六.绘制按钮的背景色

绘制一个圆形作为背景，使用设置好的背景颜色填充

七.绘制覆盖层（高光效果）

如果启用遮罩层，则根据指定半径绘制小圆圈和大圆圈形成高光效果，并应用渐变色填充。

八.效果

九.代码

1.h

#ifndef LIGHTBUTTON_H
#define LIGHTBUTTON_H
#include <QWidget>

#ifdef quc
class Q_DECL_EXPORT LightButton : public QWidget
#else
class LightButton : public QWidget
#endif

{
    Q_OBJECT

    Q_PROPERTY(QString text READ getText WRITE setText)
    Q_PROPERTY(QColor textColor READ getTextColor WRITE setTextColor)
    Q_PROPERTY(QColor alarmColor READ getAlarmColor WRITE setAlarmColor)
    Q_PROPERTY(QColor normalColor READ getNormalColor WRITE setNormalColor)

    Q_PROPERTY(QColor borderOutColorStart READ getBorderOutColorStart WRITE setBorderOutColorStart)
    Q_PROPERTY(QColor borderOutColorEnd READ getBorderOutColorEnd WRITE setBorderOutColorEnd)
    Q_PROPERTY(QColor borderInColorStart READ getBorderInColorStart WRITE setBorderInColorStart)
    Q_PROPERTY(QColor borderInColorEnd READ getBorderInColorEnd WRITE setBorderInColorEnd)
    Q_PROPERTY(QColor bgColor READ getBgColor WRITE setBgColor)

    Q_PROPERTY(bool canMove READ getCanMove WRITE setCanMove)
    Q_PROPERTY(bool showRect READ getShowRect WRITE setShowRect)
    Q_PROPERTY(bool showOverlay READ getShowOverlay WRITE setShowOverlay)
    Q_PROPERTY(QColor overlayColor READ getOverlayColor WRITE setOverlayColor)

public:
    explicit LightButton(QWidget *parent = 0);

protected:
    bool eventFilter(QObject *watched, QEvent *event);
    void paintEvent(QPaintEvent *);
    void drawBorderOut(QPainter *painter);
    void drawBorderIn(QPainter *painter);
    void drawBg(QPainter *painter);
    void drawText(QPainter *painter);
    void drawOverlay(QPainter *painter);

private:
    QString text;               //文本
    QColor textColor;           //文字颜色
    QColor alarmColor;          //报警颜色
    QColor normalColor;         //正常颜色

    QColor borderOutColorStart; //外边框渐变开始颜色
    QColor borderOutColorEnd;   //外边框渐变结束颜色
    QColor borderInColorStart;  //里边框渐变开始颜色
    QColor borderInColorEnd;    //里边框渐变结束颜色
    QColor bgColor;             //背景颜色

    bool showRect;              //显示成矩形
    bool canMove;               //是否能够移动
    bool showOverlay;           //是否显示遮罩层
    QColor overlayColor;        //遮罩层颜色

    bool pressed;               //鼠标是否按下
    QPoint lastPoint;           //鼠标最后按下坐标

    bool isAlarm;               //是否报警
    QTimer *timerAlarm;         //定时器切换颜色

public:
    //默认尺寸和最小尺寸
    QSize sizeHint() const;
    QSize minimumSizeHint() const;

    //获取和设置文本
    QString getText() const;
    void setText(const QString &text);

    //获取和设置文本颜色
    QColor getTextColor() const;
    void setTextColor(const QColor &textColor);

    //获取和设置报警颜色
    QColor getAlarmColor() const;
    void setAlarmColor(const QColor &alarmColor);

    //获取和设置正常颜色
    QColor getNormalColor() const;
    void setNormalColor(const QColor &normalColor);

    //获取和设置外边框渐变颜色
    QColor getBorderOutColorStart() const;
    void setBorderOutColorStart(const QColor &borderOutColorStart);

    QColor getBorderOutColorEnd() const;
    void setBorderOutColorEnd(const QColor &borderOutColorEnd);

    //获取和设置里边框渐变颜色
    QColor getBorderInColorStart() const;
    void setBorderInColorStart(const QColor &borderInColorStart);

    QColor getBorderInColorEnd() const;
    void setBorderInColorEnd(const QColor &borderInColorEnd);

    //获取和设置背景色
    QColor getBgColor() const;
    void setBgColor(const QColor &bgColor);

    //获取和设置是否可移动
    bool getCanMove() const;
    void setCanMove(bool canMove);

    //获取和设置是否显示矩形
    bool getShowRect() const;
    void setShowRect(bool showRect);

    //获取和设置是否显示遮罩层
    bool getShowOverlay() const;
    void setShowOverlay(bool showOverlay);

    //获取和设置遮罩层颜色
    QColor getOverlayColor() const;
    void setOverlayColor(const QColor &overlayColor);

public Q_SLOTS:
    //设置为绿色
    void setGreen();
    //设置为红色
    void setRed();
    //设置为黄色
    void setYellow();
    //设置为黑色
    void setBlack();
    //设置为灰色
    void setGray();
    //设置为蓝色
    void setBlue();

    //设置为淡蓝色
    void setLightBlue();
    //设置为淡红色
    void setLightRed();
    //设置为淡绿色
    void setLightGreen();

    //设置报警闪烁
    void startAlarm();
    void stopAlarm();
    void alarm();

Q_SIGNALS:
    //单击信号
    void clicked();
};

#endif // LIGHTBUTTON_H

2.cpp

#pragma execution_character_set("utf-8")

#include "lightbutton.h"
#include "qpainter.h"
#include "qpainterpath.h"
#include "qevent.h"
#include "qtimer.h"

LightButton::LightButton(QWidget *parent) : QWidget(parent)
{
    text = "";
    textColor = QColor(255, 255, 255);
    alarmColor = QColor(255, 107, 107);
    normalColor = QColor(10, 10, 10);

    borderOutColorStart = QColor(255, 255, 255);
    borderOutColorEnd = QColor(166, 166, 166);

    borderInColorStart = QColor(166, 166, 166);
    borderInColorEnd = QColor(255, 255, 255);

    bgColor = QColor(100, 184, 255);

    showRect = false;
    showOverlay = true;
    overlayColor = QColor(255, 255, 255);

    canMove = false;
    pressed = false;
    this->installEventFilter(this);

    isAlarm = false;
    timerAlarm = new QTimer(this);
    connect(timerAlarm, SIGNAL(timeout()), this, SLOT(alarm()));
    timerAlarm->setInterval(500);
}

bool LightButton::eventFilter(QObject *watched, QEvent *event)
{
    int type = event->type();
    QMouseEvent *mouseEvent = (QMouseEvent *)event;
    if (type == QEvent::MouseButtonPress) {
        if (this->rect().contains(mouseEvent->pos()) && (mouseEvent->button() == Qt::LeftButton)) {
            lastPoint = mouseEvent->pos();
            pressed = true;
        }
    } else if (type == QEvent::MouseMove && pressed) {
        if (canMove) {
            int dx = mouseEvent->pos().x() - lastPoint.x();
            int dy = mouseEvent->pos().y() - lastPoint.y();
            this->move(this->x() + dx, this->y() + dy);
        }
    } else if (type == QEvent::MouseButtonRelease && pressed) {
        pressed = false;
        Q_EMIT clicked();
    }

    return QWidget::eventFilter(watched, event);
}

void LightButton::paintEvent(QPaintEvent *)
{
    int width = this->width();
    int height = this->height();
    int side = qMin(width, height);

    //绘制准备工作,启用反锯齿,平移坐标轴中心,等比例缩放
    QPainter painter(this);
    painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);

    if (showRect) {
        //绘制矩形区域
        painter.setPen(Qt::NoPen);
        painter.setBrush(bgColor);
        painter.drawRoundedRect(this->rect(), 5, 5);

        //绘制文字
        if (!text.isEmpty()) {
            QFont font;
            font.setPixelSize(side - 20);
            painter.setFont(font);
            painter.setPen(textColor);
            painter.drawText(this->rect(), Qt::AlignCenter, text);
        }
    } else {
        painter.translate(width / 2, height / 2);
        painter.scale(side / 200.0, side / 200.0);

        //绘制外边框
        drawBorderOut(&painter);
        //绘制内边框
        drawBorderIn(&painter);
        //绘制内部指示颜色
        drawBg(&painter);
        //绘制居中文字
        drawText(&painter);
        //绘制遮罩层
        drawOverlay(&painter);
    }
}

void LightButton::drawBorderOut(QPainter *painter)
{
    int radius = 99;
    painter->save();
    painter->setPen(Qt::NoPen);
    QLinearGradient borderGradient(0, -radius, 0, radius);
    borderGradient.setColorAt(0, borderOutColorStart);
    borderGradient.setColorAt(1, borderOutColorEnd);
    painter->setBrush(borderGradient);
    painter->drawEllipse(-radius, -radius, radius * 2, radius * 2);
    painter->restore();
}

void LightButton::drawBorderIn(QPainter *painter)
{
    int radius = 90;
    painter->save();
    painter->setPen(Qt::NoPen);
    QLinearGradient borderGradient(0, -radius, 0, radius);
    borderGradient.setColorAt(0, borderInColorStart);
    borderGradient.setColorAt(1, borderInColorEnd);
    painter->setBrush(borderGradient);
    painter->drawEllipse(-radius, -radius, radius * 2, radius * 2);
    painter->restore();
}

void LightButton::drawBg(QPainter *painter)
{
    int radius = 80;
    painter->save();
    painter->setPen(Qt::NoPen);
    painter->setBrush(bgColor);
    painter->drawEllipse(-radius, -radius, radius * 2, radius * 2);
    painter->restore();
}

void LightButton::drawText(QPainter *painter)
{
    if (text.isEmpty()) {
        return;
    }

    int radius = 100;
    painter->save();

    QFont font;
    font.setPixelSize(85);
    painter->setFont(font);
    painter->setPen(textColor);
    QRect rect(-radius, -radius, radius * 2, radius * 2);
    painter->drawText(rect, Qt::AlignCenter, text);
    painter->restore();
}

void LightButton::drawOverlay(QPainter *painter)
{
    if (!showOverlay) {
        return;
    }

    int radius = 80;
    painter->save();
    painter->setPen(Qt::NoPen);

    QPainterPath smallCircle;
    QPainterPath bigCircle;
    radius -= 1;
    smallCircle.addEllipse(-radius, -radius, radius * 2, radius * 2);
    radius *= 2;
    bigCircle.addEllipse(-radius, -radius + 140, radius * 2, radius * 2);

    //高光的形状为小圆扣掉大圆的部分
    QPainterPath highlight = smallCircle - bigCircle;

    QLinearGradient linearGradient(0, -radius / 2, 0, 0);
    overlayColor.setAlpha(100);
    linearGradient.setColorAt(0.0, overlayColor);
    overlayColor.setAlpha(30);
    linearGradient.setColorAt(1.0, overlayColor);
    painter->setBrush(linearGradient);
    painter->rotate(-20);
    painter->drawPath(highlight);

    painter->restore();
}

QSize LightButton::sizeHint() const
{
    return QSize(100, 100);
}

QSize LightButton::minimumSizeHint() const
{
    return QSize(10, 10);
}

QString LightButton::getText() const
{
    return this->text;
}

void LightButton::setText(const QString &text)
{
    if (this->text != text) {
        this->text = text;
        this->update();
    }
}

QColor LightButton::getTextColor() const
{
    return this->textColor;
}

void LightButton::setTextColor(const QColor &textColor)
{
    if (this->textColor != textColor) {
        this->textColor = textColor;
        this->update();
    }
}

QColor LightButton::getAlarmColor() const
{
    return this->alarmColor;
}

void LightButton::setAlarmColor(const QColor &alarmColor)
{
    if (this->alarmColor != alarmColor) {
        this->alarmColor = alarmColor;
        this->update();
    }
}

QColor LightButton::getNormalColor() const
{
    return this->normalColor;
}

void LightButton::setNormalColor(const QColor &normalColor)
{
    if (this->normalColor != normalColor) {
        this->normalColor = normalColor;
        this->update();
    }
}

QColor LightButton::getBorderOutColorStart() const
{
    return this->borderOutColorStart;
}

void LightButton::setBorderOutColorStart(const QColor &borderOutColorStart)
{
    if (this->borderOutColorStart != borderOutColorStart) {
        this->borderOutColorStart = borderOutColorStart;
        this->update();
    }
}

QColor LightButton::getBorderOutColorEnd() const
{
    return this->borderOutColorEnd;
}

void LightButton::setBorderOutColorEnd(const QColor &borderOutColorEnd)
{
    if (this->borderOutColorEnd != borderOutColorEnd) {
        this->borderOutColorEnd = borderOutColorEnd;
        this->update();
    }
}

QColor LightButton::getBorderInColorStart() const
{
    return this->borderInColorStart;
}

void LightButton::setBorderInColorStart(const QColor &borderInColorStart)
{
    if (this->borderInColorStart != borderInColorStart) {
        this->borderInColorStart = borderInColorStart;
        this->update();
    }
}

QColor LightButton::getBorderInColorEnd() const
{
    return this->borderInColorEnd;
}

void LightButton::setBorderInColorEnd(const QColor &borderInColorEnd)
{
    if (this->borderInColorEnd != borderInColorEnd) {
        this->borderInColorEnd = borderInColorEnd;
        this->update();
    }
}

QColor LightButton::getBgColor() const
{
    return this->bgColor;
}

void LightButton::setBgColor(const QColor &bgColor)
{
    if (this->bgColor != bgColor) {
        this->bgColor = bgColor;
        this->update();
    }
}

bool LightButton::getCanMove() const
{
    return this->canMove;
}

void LightButton::setCanMove(bool canMove)
{
    if (this->canMove != canMove) {
        this->canMove = canMove;
        this->update();
    }
}

bool LightButton::getShowRect() const
{
    return this->showRect;
}

void LightButton::setShowRect(bool showRect)
{
    if (this->showRect != showRect) {
        this->showRect = showRect;
        this->update();
    }
}

bool LightButton::getShowOverlay() const
{
    return this->showOverlay;
}

void LightButton::setShowOverlay(bool showOverlay)
{
    if (this->showOverlay != showOverlay) {
        this->showOverlay = showOverlay;
        this->update();
    }
}

QColor LightButton::getOverlayColor() const
{
    return this->overlayColor;
}

void LightButton::setOverlayColor(const QColor &overlayColor)
{
    if (this->overlayColor != overlayColor) {
        this->overlayColor = overlayColor;
        this->update();
    }
}

void LightButton::setGreen()
{
    textColor = QColor(255, 255, 255);
    setBgColor(QColor(0, 166, 0));
}

void LightButton::setRed()
{
    textColor = QColor(255, 255, 255);
    setBgColor(QColor(255, 0, 0));
}

void LightButton::setYellow()
{
    textColor = QColor(25, 50, 7);
    setBgColor(QColor(238, 238, 0));
}

void LightButton::setBlack()
{
    textColor = QColor(255, 255, 255);
    setBgColor(QColor(10, 10, 10));
}

void LightButton::setGray()
{
    textColor = QColor(255, 255, 255);
    setBgColor(QColor(129, 129, 129));
}

void LightButton::setBlue()
{
    textColor = QColor(255, 255, 255);
    setBgColor(QColor(0, 0, 166));
}

void LightButton::setLightBlue()
{
    textColor = QColor(255, 255, 255);
    setBgColor(QColor(100, 184, 255));
}

void LightButton::setLightRed()
{
    textColor = QColor(255, 255, 255);
    setBgColor(QColor(255, 107, 107));
}

void LightButton::setLightGreen()
{
    textColor = QColor(255, 255, 255);
    setBgColor(QColor(24, 189, 155));
}

void LightButton::startAlarm()
{
    if (!timerAlarm->isActive()) {
        timerAlarm->start();
    }
}

void LightButton::stopAlarm()
{
    if (timerAlarm->isActive()) {
        timerAlarm->stop();
    }
}

void LightButton::alarm()
{
    if (isAlarm) {
        textColor = QColor(255, 255, 255);
        bgColor = normalColor;
    } else {
        textColor = QColor(255, 255, 255);
        bgColor = alarmColor;
    }

    this->update();
    isAlarm = !isAlarm;
}