😃 第二季来啦 😃
简约的加载动画,用于网络查询等耗时操作时给用户的提示.
这是最终效果:

一共只有三个文件,可以直接编译运行

//main.cpp
#include "LoadingAnimWidget.h"
#include <QApplication>
#include <QVBoxLayout>
#include <QGridLayout>
int main(int argc, char *argv[])
{QApplication a(argc, argv);QWidget w;w.setWindowTitle("加载动画 第二季");QGridLayout * mainLayout = new QGridLayout;auto* anim1= new BouncingBalls;mainLayout->addWidget(anim1,0,0);auto* anim2 = new SlinkyCircle;mainLayout->addWidget(anim2,0,1);w.setLayout(mainLayout);w.show();anim1->start();anim2->start();return a.exec();
}

//LoadingAnimWidget.h
#ifndef LOADINGANIMWIDGET_H
#define LOADINGANIMWIDGET_H
#include <QPropertyAnimation>
#include <QWidget>
class LoadingAnimBase:public QWidget
{Q_OBJECT
public:LoadingAnimBase(QWidget* parent=nullptr);virtual ~LoadingAnimBase();
public slots:virtual void exec();virtual void start();virtual void stop();
protected:QPropertyAnimation mAnim;qreal mAngle;
};class BouncingBalls:public LoadingAnimBase//一蹦一蹦的小球
{Q_OBJECTQ_PROPERTY(qreal angle READ angle WRITE setAngle)
public:explicit BouncingBalls(QWidget* parent = nullptr);qreal angle()const;void setAngle(qreal an);
protected:void paintEvent(QPaintEvent *event);
};
class SlinkyCircle:public LoadingAnimBase{//可以伸缩的管子,绕着中心转动,就像弹簧圈,英语叫做slinky,查了好久才查到这个单词,有点强迫症😂Q_OBJECTQ_PROPERTY(qreal angle READ angle WRITE setAngle)
public:explicit SlinkyCircle(QWidget* parent = nullptr);qreal angle()const;void setAngle(qreal an);
protected:void paintEvent(QPaintEvent *event);
};#endif // LOADINGANIMWIDGET_H

//LoadingAnimWidget.cpp
#include "LoadingAnimWidget.h"
#include <QDebug>
#include <QPaintEvent>
#include <QPainter>
LoadingAnimBase::LoadingAnimBase(QWidget* parent):QWidget(parent){mAnim.setPropertyName("angle");mAnim.setTargetObject(this);mAnim.setDuration(2000);mAnim.setLoopCount(-1);//run forevermAnim.setEasingCurve(QEasingCurve::Linear);setFixedSize(200,200);mAngle = 0;
}
LoadingAnimBase::~LoadingAnimBase(){}
void LoadingAnimBase::exec(){if(mAnim.state() == QAbstractAnimation::Stopped){start();}else{stop();}
}
void LoadingAnimBase::start(){mAnim.setStartValue(0);mAnim.setEndValue(360);mAnim.start();
}
void LoadingAnimBase::stop(){mAnim.stop();
}BouncingBalls::BouncingBalls(QWidget* parent):LoadingAnimBase (parent){
}
qreal BouncingBalls::angle()const{return mAngle;}
void BouncingBalls::setAngle(qreal an){mAngle = an;update();
}
void BouncingBalls::paintEvent(QPaintEvent *event){//这个动画和角度无关,但还是保留了之前的360度,因为360这个数字很好,除以谁都除的清QPainter painter(this);painter.setRenderHint(QPainter::Antialiasing);painter.setPen(Qt::NoPen);static const QStringList colorList{"yellow","orangered","lime","coral","steelblue"};const int x = width();const int y = height();const int d = 0.1*x;    //小球的直径static const int startAngle[5] = {0,45,90,135,180};//五个小球启动时间点static const qreal maxHeight = 0.25*y;//小球蹦起来的最大高度painter.translate(1.0/6 * x - d/2, 0.5 * y);//最左边的小球的静止坐标是 (1/6*x , 0.6*y),画圆的起点是左上角,所以x坐标还要减去半径for(int i = 0;i < 5;++i){const auto start = startAngle[i];qreal delta = mAngle - start;painter.setBrush(QBrush(QColor(colorList[i])));if(delta > 0 && delta < 180){//每个小球蹦起来的持续时间是4个单位,每个单位是45if(delta > 90) delta = 180 - delta;painter.drawEllipse(QRectF(0,-maxHeight * delta / 90.0,d,d));}else{//原地不动painter.drawEllipse(QRectF(0,0,d,d));}painter.translate(x/6.0,0);}
}
SlinkyCircle::SlinkyCircle(QWidget* parent):LoadingAnimBase (parent){mAnim.setEasingCurve(QEasingCurve::InOutCubic);
}
qreal SlinkyCircle::angle()const{ return mAngle;}
void SlinkyCircle::setAngle(qreal an){mAngle = an;update();
}void SlinkyCircle::paintEvent(QPaintEvent *event){QPainter painter(this);painter.setRenderHint(QPainter::Antialiasing);painter.setPen(Qt::NoPen);//画一个番茄色的背景painter.setBrush(QBrush(QColor("tomato")));painter.drawRoundedRect(this->rect(),8,8);//画圆弧painter.setBrush(Qt::NoBrush);const int x = this->width();const int y = this->height();QPen pen("white");pen.setCapStyle(Qt::RoundCap);pen.setWidth(x/20);painter.setPen(pen);painter.translate(x/2,y/2);static const qreal spanAngle = 45;//mAngle<=45,要把弧线拉伸出来static const qreal shrinkAngle = 360-spanAngle;//mAngle==315时,要把弧线收缩起来auto arcRect = this->rect().adjusted(x/5,y/5,-x/5,-y/5);arcRect.translate(-x/2,-y/2);static const int direction = -1;//顺时针if(mAngle < spanAngle){painter.drawArc(arcRect,90 * 16,mAngle * 16 * direction);}else{//弧长是固定的//40 - 320 --> 320 , 280 --> 320if(mAngle > shrinkAngle){painter.drawArc(arcRect,90 * 16,-(360-mAngle)*16 * direction);}else{//我转动的角度是当前角度 - 拉伸门槛,因为有收尾的不动的时间段,占据了一段角度,所以要把转动的角度拉伸一些,//这个比例就是 (360-spanAngle) / (shrinkAngle - spanAngle)const auto delta = (mAngle - spanAngle) * (360-spanAngle) / (shrinkAngle - spanAngle);painter.rotate(-delta * direction);painter.drawArc(arcRect,90 * 16,spanAngle * 16 * direction);}}}