在平时浏览网站，或者使用软件的时候，经常可以见到：在点击了某个按钮之后，按钮上会显示动图以及提示文字。在QT中，比较常见且简单的做法就是：给按钮设置一个layout，然后在这个layout里面添加QLabel（作为QMovie的载体），以及用于显示文字的QLabel。该方案可参考：https://blog.csdn.net/hellokandy/article/details/120043562

但本文将采取另外一种方式（编写一个用于播放Gif 的QPushButton类）来实现，原生的按钮只要提升为该类即可。

1、效果图

2、GifPushButton

1、GifPushButton.h

#ifndef GIFPUSHBUTTON_H
#define GIFPUSHBUTTON_H
#include <QWidget>
#include <QPushButton>

class QMovie;
class GifPushButton : public QPushButton
{
    Q_OBJECT
public:
    explicit GifPushButton(QWidget *parent = nullptr);
    ~GifPushButton(){}
    //
    void SetMovie(const QString &fileName);
    void SetMovie(QMovie *movie);
    QMovie *GetMovie() const;
    //
    void Start();
    void Stop();
    //
signals:
    void movieChanged();

protected:
    void showEvent(QShowEvent *event) override;
    void hideEvent(QHideEvent *event) override;

private slots:
    void OnFrameChanged(int frameNumber);
private:
    QMovie *m_movie = nullptr;
    bool m_movieResized = false;
};

#endif // GIFPUSHBUTTON_H

2、GifPushButton.cpp

#include "gifpushbutton.h"
#include <QMovie>
#include <QDebug>

GifPushButton::GifPushButton(QWidget *parent)
    : QPushButton(parent)
    , m_movie(nullptr)
{

}

void GifPushButton::SetMovie(const QString &fileName)
{
    auto movie = new QMovie(this);
    movie->setFileName(fileName);
    SetMovie(movie);
}

void GifPushButton::SetMovie(QMovie *movie)
{
    if(!movie){
        return;
    }

    if(movie == m_movie){
        return;
    }

    if(m_movie)
    {
        m_movie->stop();
        disconnect(movie, &QMovie::frameChanged, this, &GifPushButton::OnFrameChanged);
    }

    if(movie->parent() != this){
        movie->setParent(this);
    }
    movie->jumpToFrame(0);
    m_movie = movie;
    connect(movie, &QMovie::frameChanged, this, &GifPushButton::OnFrameChanged);
    connect(movie, &QMovie::destroyed, this, [](QObject *object){
        Q_UNUSED(object);
        qDebug() << "movie destroyed";
    });
    //
    emit movieChanged();
}

QMovie *GifPushButton::GetMovie() const
{
    return m_movie;
}

void GifPushButton::Start()
{
    if(m_movie){
        m_movie->start();
    }
}

void GifPushButton::Stop()
{
    if(m_movie){
        m_movie->stop();
        setIcon(QIcon());
    }
}

void GifPushButton::showEvent(QShowEvent *event)
{
    if(m_movie){
       m_movie->start();
    }
    //GifPushButton::showEvent(event);
}

void GifPushButton::hideEvent(QHideEvent *event)
{
    if(m_movie){
        m_movie->stop();
    }
    //GifPushButton::hideEvent(event);
}

void GifPushButton::OnFrameChanged(int frameNumber)
{
    if(!m_movie){
        return;
    }

    if(!m_movieResized)
    {
        int len = qMin(width(), height());
        QSize sz = QSize(len, len);
        m_movie->setScaledSize(sz);
        QRect rect = m_movie->frameRect();
        //
        m_movieResized = true;
        qDebug() << sz << rect.size();
    }

    QPixmap pix = m_movie->currentPixmap();
    setIcon(QIcon(pix));
}

3、如何使用

#include "maindialog.h"
#include "ui_maindialog.h"

MainDialog::MainDialog(QWidget *parent)
    : QDialog(parent)
    , ui(new Ui::MainDialog)
{
    ui->setupUi(this);
    //
    ui->button_loading->setFixedSize(150, 36);
    ui->button_downloading->setFixedSize(150, 36);
    ui->button_dancing->setFixedSize(150, 36);
    //
    ui->button_loading->SetMovie(":/image/loading.gif");
    ui->button_downloading->SetMovie(":/image/downloading.gif");
    ui->button_dancing->SetMovie(":/image/dancing.gif");
    //from qss style
    ui->button_loading->setProperty("button_type", "120x48");
}

MainDialog::~MainDialog()
{
    delete ui;
}

void MainDialog::on_button_start_clicked()
{
    ui->button_loading->Start();
}

void MainDialog::on_button_stop_clicked()
{
    ui->button_loading->Stop();
}