如何在Qt中多次显示一组动画

Question

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>
#include <QPushButton>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    m_animation = new QPropertyAnimation(ui->label, "geometry");
    startAnimation();
}
MainWindow::~MainWindow()
{
    delete ui;
    delete m_animation;
}
void MainWindow::startAnimation()
{
    m_animation->setDuration(3000);
    m_animation->setKeyValueAt(0, QRect(50, 50, 128, 128));
    m_animation->setKeyValueAt(0.25, QRect(200, 50, 128, 128));
    m_animation->setKeyValueAt(0.5, QRect(50, 50, 128, 128));
    m_animation->setKeyValueAt(0.75, QRect(200, 50, 128, 128));
    m_animation->setKeyValueAt(1, QRect(50, 50, 128, 128));
    m_animation->start();
}

我想多次显示startAnimation函数中完成的动画，现在它只显示两次。我尝试使用QSequential但这也不起作用。我也尝试将此函数与线程连接，但是当我创建线程类的对象时，它显示未解决的符号错误。

Answer 1

您应该设置 loopCount 属性。

void MainWindow::startAnimation()
{
    m_animation->setLoopCount(10);
    m_animation->setDuration(3000);
    m_animation->setKeyValueAt(0, QRect(50, 50, 128, 128));
    m_animation->setKeyValueAt(0.25, QRect(200, 50, 128, 128));
    m_animation->setKeyValueAt(0.5, QRect(50, 50, 128, 128));
    m_animation->setKeyValueAt(0.75, QRect(200, 50, 128, 128));
    m_animation->setKeyValueAt(1, QRect(50, 50, 128, 128));
    m_animation->start();
}

Answer 2

不，这里不需要线程。您所需要的只是QSequentialAnimationGroup(正如我之前所说(。例如：

int numberOfLoops = 3;
QSequentialAnimationGroup *group = new QSequentialAnimationGroup(this);
for(int i = 0; i < numberOfLoops; ++i)
{
    QPropertyAnimation *m_animation = new QPropertyAnimation(this, "geometry");
    m_animation->setDuration(3000);
    m_animation->setKeyValueAt(0, QRect(50, 50, 128, 128));
    m_animation->setKeyValueAt(0.25, QRect(200, 50, 128, 128));
    m_animation->setKeyValueAt(0.5, QRect(50, 50, 128, 128));
    m_animation->setKeyValueAt(0.75, QRect(200, 50, 128, 128));
    m_animation->setKeyValueAt(1, QRect(50, 50, 128, 128));
    group->addAnimation(m_animation);
}
group->start(QAbstractAnimation::DeleteWhenStopped);

但我仍然认为你现在的代码对我的方法有点错误，所以最终的代码是：

//type 3 and animation will repeat 3 time, type 10 and it will repeat 10 and so on
int numberOfLoops = 5;
QSequentialAnimationGroup *group = new QSequentialAnimationGroup(this);
for(int i = 0; i < numberOfLoops; ++i)
{
    QPropertyAnimation *m_animation = new QPropertyAnimation(this, "geometry");
    m_animation->setDuration(1500);
    m_animation->setKeyValueAt(0, QRect(50, 50, 128, 128));
    m_animation->setKeyValueAt(0.5, QRect(200, 50, 128, 128));
    m_animation->setKeyValueAt(1, QRect(50, 50, 128, 128));
    group->addAnimation(m_animation);
}
group->start(QAbstractAnimation::DeleteWhenStopped);

也不要认为这段代码会产生内存泄漏，不！如您所见，我添加了QAbstractAnimation::DeleteWhenStopped标志，这意味着您创建的所有QPropertyAnimation对象也将被删除(当动画停止时(！为了证明您可以添加一行并运行应用程序，您将看到所有对象都将被删除(但这只是一个证明，例如release应用程序中不需要这样做(：

//...
    group->addAnimation(m_animation);
    connect(m_animation,&QPropertyAnimation::destroyed,[](){qDebug()<< "m_animation destroyed";});
//...

但是我在这里使用了C++11(CONFIG += c++11 .pro文件(以及信号和插槽的新语法，但当然，如果需要，您可以使用旧语法。