一、前言

项目中在下发指令时，结果异步返回，可能需要一段时间，因此需要用到加载动画。
用的比较简单，就是新建Widget子窗口，放一个Label，使用QMovie在Label中播放GIF。
当下发指令时，就打开子窗口显示加载过程，同时开启一个定时器，如果在定时器触发超时信号或超时之前收到结果，则隐藏加载过程子窗口，并关闭定时器。

二、使用

1.FormLoading.h

#ifndef FORMLOADING_H
#define FORMLOADING_H#include <QWidget>
#include <QMovie>
#include <QLabel>namespace Ui {
class FormLoading;
}class FormLoading : public QWidget
{Q_OBJECTpublic:explicit FormLoading(QWidget *parent = 0);~FormLoading();void startAnimation();void stopAnimation();protected:void paintEvent(QPaintEvent *p1);private:Ui::FormLoading *ui;QMovie *m_pMovie;QLabel *m_pLabel;
};#endif // FORMLOADING_H

2.FormLoading.cpp

#include "formloading.h"
#include "ui_formloading.h"
#include <QVBoxLayout>
#include <QPainter>
#include <QBitmap>
FormLoading::FormLoading(QWidget *parent) :QWidget(parent),ui(new Ui::FormLoading)
{ui->setupUi(this);// 设置窗口置顶和无边框this->setWindowFlags(Qt::WindowStaysOnTopHint | Qt::FramelessWindowHint);// 设置窗口透明用来支持圆角样式属性this->setAttribute(Qt::WA_TranslucentBackground);// 设置模态对话框this->setWindowModality(Qt::ApplicationModal);setFixedSize(350, 280);m_pMovie = new QMovie(":/images/loading.gif");m_pLabel = new QLabel(this);m_pLabel->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter);// 设置背景透明m_pLabel->setAutoFillBackground(true);//m_pLabel->setStyleSheet("width:150px;border-radius:10px; background-color: rgb(255, 255, 255);");m_pLabel->setStyleSheet("background-color: rgba(255, 255, 255, 0);");m_pLabel->setMovie(m_pMovie);QVBoxLayout *pLayout = new QVBoxLayout(this);pLayout->addWidget(m_pLabel);setLayout(pLayout);
}FormLoading::~FormLoading()
{delete ui;if(m_pMovie != nullptr){delete m_pMovie;}if(m_pLabel != nullptr){delete m_pLabel;}
}// 绘图事件
void FormLoading::paintEvent(QPaintEvent *p1)
{//绘制样式QStyleOption opt;opt.init(this);QPainter p(this);style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);//绘制样式QBitmap bmp(this->size());bmp.fill();QPainter painter(&bmp);painter.setPen(Qt::NoPen);painter.setBrush(Qt::black);painter.setRenderHint(QPainter::Antialiasing);painter.drawRoundedRect(bmp.rect(), 15, 15);setMask(bmp);
}void FormLoading::startAnimation()
{m_pMovie->start();
}void FormLoading::stopAnimation()
{m_pMovie->stop();
}