今天文章讲述的是如何用Qt实现图片轮播的效果，其实我们经常在网页中看到各种广告就是使用了图片轮播，实现小区域内嵌入多个广告的效果。
其实实现起来也不难，只要使用Qt的动画类即可实现类似的效果。之前做了一个，效果不佳，今天重新写了一遍，实现了类似上面第一种的效果，通过Qt的动画类修改透明度来实现上下两张图片的切换效果，下面上效果图。
二、代码之路
CarouselImageWindow.h
#include <QWidget>
#include <QScrollArea>
#include <QTimer>
#include <QPropertyAnimation>
#include <QPushButton>
class CarouselImageWindow : public QWidget
{
Q_OBJECT
public:
CarouselImageWindow(QWidget *parent = NULL);
~CarouselImageWindow();
// 设置图片列表;
void setImageList(QStringList imageFileNameList);
// 添加图片;
void addImage(QString imageFileName);
// 开始播放;
void startPlay();
private:
// 初始化图片切换按钮;
void initChangeImageButton();
// 绘图事件;
void paintEvent(QPaintEvent *event);
// 鼠标点击事件;
void mousePressEvent(QMouseEvent* event);
public slots:
// 图片切换时钟;
void onImageChangeTimeout();
// 图片切换按钮点击;
void onImageSwitchButtonClicked(int buttonId);
private:
// 用来做图片切换滑动效果，目前以透明度作为切换效果;
QScrollArea* m_imagePlayWidget;
// 图片列表;
QList<QString> m_imageFileNameList;
// 图片切换时钟;
QTimer m_imageChangeTimer;
// 当前显示图片index;
int m_currentDrawImageIndx;
// 切换图片;
QPixmap m_currentPixmap;
QPixmap m_nextPixmap;
// 图片切换动画类;
QPropertyAnimation* m_opacityAnimation;
// 按钮列表;
QList<QPushButton*> m_pButtonChangeImageList;
};CarouselImageWindow.cpp
#include "CarouselImageWindow.h"
#include <QHBoxLayout>
#include <QPainter>
#include <QDebug>
#include <QButtonGroup>
CarouselImageWindow::CarouselImageWindow(QWidget *parent)
: QWidget(parent)
, m_currentDrawImageIndx(0)
{
// 添加ImageOpacity属性;
this->setProperty("ImageOpacity", 1.0);
// 动画切换类;
m_opacityAnimation = new QPropertyAnimation(this, "ImageOpacity");
// 这里要设置的动画时间小于图片切换时间;
m_opacityAnimation->setDuration(1500);
// 设置ImageOpacity属性值的变化范围;
m_opacityAnimation->setStartValue(1.0);
m_opacityAnimation->setEndValue(0.0);
// 透明度变化及时更新绘图;
connect(m_opacityAnimation, SIGNAL(valueChanged(const QVariant&)), this, SLOT(update()));
// 设置图片切换时钟槽函数;
connect(&m_imageChangeTimer, SIGNAL(timeout()), this, SLOT(onImageChangeTimeout()));
this->setFixedSize(QSize(400, 250));
this->setWindowFlags(Qt::FramelessWindowHint);
}
CarouselImageWindow::~CarouselImageWindow()
{
}
void CarouselImageWindow::initChangeImageButton()
{
// 注意图片过多按钮可能放置不下;
QButtonGroup* changeButtonGroup = new QButtonGroup;
QHBoxLayout* hLayout = new QHBoxLayout();
hLayout->addStretch();
for (int i = 0; i < m_imageFileNameList.count(); i++)
{
QPushButton* pButton = new QPushButton;
pButton->setFixedSize(QSize(16, 16));
pButton->setCheckable(true);
pButton->setStyleSheet("QPushButton{border-image:url(:/Resources/select1.png);}\
QPushButton:checked{border-image:url(:/Resources/select2.png);}");
changeButtonGroup->addButton(pButton, i);
m_pButtonChangeImageList.append(pButton);
hLayout->addWidget(pButton);
}
hLayout->addStretch();
hLayout->setSpacing(10);
hLayout->setMargin(0);
connect(changeButtonGroup, SIGNAL(buttonClicked(int)), this, SLOT(onImageSwitchButtonClicked(int)));
QVBoxLayout* mainLayout = new QVBoxLayout(this);
mainLayout->addStretch();
mainLayout->addLayout(hLayout);
mainLayout->setContentsMargins(0, 0, 0, 20);
}
void CarouselImageWindow::setImageList(QStringList imageFileNameList)
{
m_imageFileNameList = imageFileNameList;
}
void CarouselImageWindow::addImage(QString imageFileName)
{
m_imageFileNameList.append(imageFileName);
}
void CarouselImageWindow::startPlay()
{
// 添加完图片之后，根据图片多少设置图片切换按钮;
initChangeImageButton();
if (m_imageFileNameList.count() == 1)
{
m_pButtonChangeImageList[m_currentDrawImageIndx]->setChecked(true);
}
else if (m_imageFileNameList.count() > 1)
{
m_pButtonChangeImageList[m_currentDrawImageIndx]->setChecked(true);
m_currentPixmap = QPixmap(m_imageFileNameList.at(m_currentDrawImageIndx));
m_imageChangeTimer.start(2000);
update();
}
}
void CarouselImageWindow::onImageChangeTimeout()
{
// 设置前后的图片;
m_currentPixmap = QPixmap(m_imageFileNameList.at(m_currentDrawImageIndx));
m_currentDrawImageIndx++;
if (m_currentDrawImageIndx >= m_imageFileNameList.count())
{
m_currentDrawImageIndx = 0;
}
m_nextPixmap = QPixmap(m_imageFileNameList.at(m_currentDrawImageIndx));
m_pButtonChangeImageList[m_currentDrawImageIndx]->setChecked(true);
// 动画类重新开始;
m_opacityAnimation->start();
}
void CarouselImageWindow::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
QRect imageRect = this->rect();
// 如果图片列表为空，显示默认图片;
if (m_imageFileNameList.isEmpty())
{
QPixmap backPixmap = QPixmap(":/Resources/CarouselImageBack.png");
painter.drawPixmap(imageRect, backPixmap.scaled(imageRect.size()));
}
// 如果只有一张图片;
else if (m_imageFileNameList.count() == 1)
{
QPixmap backPixmap = QPixmap(m_imageFileNameList.first());
painter.drawPixmap(imageRect, backPixmap.scaled(imageRect.size()));
}
// 多张图片;
else if (m_imageFileNameList.count() > 1)
{
float imageOpacity = this->property("ImageOpacity").toFloat();
painter.setOpacity(1);
painter.drawPixmap(imageRect, m_nextPixmap.scaled(imageRect.size()));
painter.setOpacity(imageOpacity);
painter.drawPixmap(imageRect, m_currentPixmap.scaled(imageRect.size()));
}
}
void CarouselImageWindow::onImageSwitchButtonClicked(int buttonId)
{
m_currentDrawImageIndx = buttonId - 1;
if (m_currentDrawImageIndx == -1)
{
m_currentDrawImageIndx = m_imageFileNameList.count() - 1;
}
onImageChangeTimeout();
m_imageChangeTimer.start(2000);
update();
}
void CarouselImageWindow::mousePressEvent(QMouseEvent* event)
{
// 这里可以对当前图片进行点击然后触发每个图片对应的效果;
// 比如web上好多类似的弹出对应的广告页面等功能;
qDebug() << m_currentDrawImageIndx;
return __super::mousePressEvent(event);
}测试代码
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
CarouselImageWindow w;
w.addImage(":/Resources/image1.jpg");
w.addImage(":/Resources/image2.jpg");
w.addImage(":/Resources/image3.jpg");
w.addImage(":/Resources/image4.jpg");
w.startPlay();
w.show();
return a.exec();
}