Qt writes custom controls: one of the text spotlight effects

#ifndef WIDGET_H#define WIDGET_H#include #include class Widget : public QWidget{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();protected:void paintEvent(QPaintEvent *event)override;private:void onTimer();QString text;QTimer timer;QRect textRect;int changeValue{0};bool runDirectionIsRight{true};};#endif // WIDGET_H

#include "widget.h"#include #include #include Widget::Widget(QWidget *parent): QWidget(parent){text = "The water of the Yellow River comes from the sky and flows to the sea without returning";auto font = this->font();font.setPixelSize(40);font.setBold(true);setFont(font);connect(&timer,&QTimer::timeout,this,&Widget::onTimer);timer.start(40);}Widget::~Widget(){}void Widget::paintEvent(QPaintEvent *event){QPainter painter(this);painter.setRenderHint(QPainter::Antialiasing,true);painter.setFont(this->font());auto rect = event->rect();painter.save();painter.setPen(QColor("#574E54"));painter.drawText(rect, Qt::AlignCenter | Qt::TextWordWrap, text);painter.restore();textRect = painter.boundingRect(rect,Qt::AlignCenter | Qt::TextWordWrap,text);auto pos = textRect.topLeft() + QPoint(changeValue,0);QPolygon polygon;polygon << pos << pos + QPoint(50,0);pos = textRect.bottomLeft() + QPoint(changeValue,0);polygon << pos + QPoint(25,0) << pos - QPoint(25,0);;QPainterPath path;path.addPolygon(polygon);painter.setClipPath(path);auto tempRect = polygon.boundingRect();QLinearGradient linearGradient(tempRect.topRight(),tempRect.bottomLeft());linearGradient.setColorAt(0.0,Qt::magenta);linearGradient.setColorAt(0.2,Qt::darkYellow);linearGradient.setColorAt(0.4,Qt::green);linearGradient.setColorAt(0.6,Qt::red);linearGradient.setColorAt(0.8,Qt::darkRed);linearGradient.setColorAt(1.0,Qt::blue);painter.setBrush(Qt::transparent);painter.setPen(QPen(QBrush(linearGradient),3));painter.drawText(rect, Qt::AlignCenter | Qt::TextWordWrap, text);}void Widget::onTimer(){if(runDirectionIsRight){changeValue += 15;if(changeValue >= textRect.width()){runDirectionIsRight = false;}}else{changeValue -= 15;if(changeValue <= 0){runDirectionIsRight = true;}}update();}