Qt使用QGraphicsView实现滑动窗体效果

http://blog.csdn.net/huihui1988/article/details/5725955

QGraphicsView用来显示一个滚动视图区的QGraphicsScene内容。QGraphicsScene提供了QGraphicsItem的容器功能。通常与QGraphicsView一起使用来描述可视化图形项目。

 

QGraphicsScene提供了一个视图的场景，通过在这样一个场景之上加入不同的QGraphicsItem来构建视图。而QGraphicsView则提供了一个widget来显示QGraphicsScene的内容。所以要想成功构建一个视图，这三个元素缺一不可。

 

以下是一个QGraphicsView的例子，实现滑动的窗体效果，工具栏和图片均为场景中的Item。

 

 

 

 #include <QtCore>
 #include <QtGui>
 #include <QtSvg>
 /*程序中用到了svg格式的图片，所以需包含QtSvg*/
 #define PAGE_COUNT 5
 /*定义滑动窗体的窗体数*/

 

 

定义工具栏，NviBar继承自QGraphicsRectItem，用法与QGraphicsItem类似。

 class NaviBar : public QObject, public QGraphicsRectItem
 {
     Q_OBJECT
 public:
     NaviBar();
     void setPageOffset(qreal ofs);
 signals:
     void pageSelected(int page);
 protected:
     void mousePressEvent(QGraphicsSceneMouseEvent *event);
     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0);
 private:
     QList<QGraphicsSvgItem*> m_icons;
     QGraphicsRectItem *m_cursor;
 };

 

 

函数实现

 #define ICON_SIZE 50
 #define ICON_PAD 4
 NaviBar::NaviBar()
         : QGraphicsRectItem()
 {
     setRect(0, 0, 5 * ICON_SIZE, ICON_SIZE);
     setPen(Qt::NoPen);
     QStringList names;
     names << "map" << "web" << "home" << "weather" << "contacts";
     for (int i = 0; i < names.count(); ++i) {
         QString fname = names[i];
         fname.prepend(":/icons/");
         fname.append("-page.svg");
         QGraphicsSvgItem *icon = new QGraphicsSvgItem(fname);
         icon->setParentItem(this);
         const int dim = ICON_SIZE - ICON_PAD * 2;
         qreal sw = dim / icon->boundingRect().width();
         qreal sh = dim / icon->boundingRect().height();
         icon->setTransform(QTransform().scale(sw, sh));
         icon->setZValue(2);
         m_icons << icon;
     }
     m_cursor = new QGraphicsRectItem;
     m_cursor->setParentItem(this);
     m_cursor->setRect(0, 0, ICON_SIZE, ICON_SIZE);
     m_cursor->setZValue(1);
     m_cursor->setPen(Qt::NoPen);
     m_cursor->setBrush(QColor(Qt::white));
     m_cursor->setOpacity(0.6);
 }
 void NaviBar::setPageOffset(qreal ofs)
 {
     m_cursor->setPos(ofs * ICON_SIZE, 0);
     for (int i = 0; i < m_icons.count(); ++i) {
         int y = (i == static_cast<int>(ofs + 0.5)) ? ICON_PAD : ICON_PAD * 2;
         m_icons[i]->setPos(i * ICON_SIZE + ICON_PAD, y);
         m_icons[i]->setOpacity(1);
     }
 }
 void NaviBar::mousePressEvent(QGraphicsSceneMouseEvent *event)
 {
     emit pageSelected(static_cast<int>(event->pos().x() / ICON_SIZE));
 }
 void NaviBar::paint(QPainter * painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
 {
     painter->setBrush(Qt::white);
     painter->setOpacity(0.2);
     painter->drawRect(option->rect.adjusted(-20, ICON_PAD, 20, 0));
 }

 

 

 

定义视图

 class ParallaxHome: public QGraphicsView
 {
     Q_OBJECT
 public:
     QGraphicsScene m_scene;
     NaviBar *m_naviBar;
     QGraphicsPixmapItem *m_wallpaper;
     QTimeLine m_pageAnimator;
     qreal m_pageOffset;
     QList<QGraphicsPixmapItem*> m_items;
     QList<QPointF> m_positions;
 public:
     ParallaxHome(QWidget *parent = 0)
             : QGraphicsView(parent)
             , m_pageOffset(-2) {
         setupScene();
         setScene(&m_scene);
         setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
         setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
         setFrameShape(QFrame::NoFrame);
         setWindowTitle("Parallax Home");
         connect(&m_pageAnimator, SIGNAL(frameChanged(int)), SLOT(shiftPage(int)));
         m_pageAnimator.setDuration(500);
         m_pageAnimator.setFrameRange(0, 100);
         m_pageAnimator.setCurveShape(QTimeLine::EaseInCurve);
         pageChanged(static_cast<int>(m_pageOffset));
     }
 signals:
     void pageChanged(int page);
 public slots:
     void slideRight() {
         if (m_pageAnimator.state() != QTimeLine::NotRunning)
             return;
         int edge = -(m_pageOffset - 1);
         if (edge < PAGE_COUNT)
             slideBy(-1);
     }
     void slideLeft() {
         if (m_pageAnimator.state() != QTimeLine::NotRunning)
             return;
         if (m_pageOffset < 0)
             slideBy(1);
     }
     void slideBy(int dx) {
         int start = m_pageOffset * 1000;
         int end = (m_pageOffset + dx) * 1000;
         m_pageAnimator.setFrameRange(start, end);
         m_pageAnimator.start();
     }
     void choosePage(int page) {
         if (m_pageAnimator.state() != QTimeLine::NotRunning)
             return;
         if (static_cast<int>(-m_pageOffset) == page)
             return;
         slideBy(-page - m_pageOffset);
     }
 private slots:
     void shiftPage(int frame) {
         int ww = width();
         int hh = height() - m_naviBar->rect().height();
         int oldPage = static_cast<int>(-m_pageOffset);
         m_pageOffset = static_cast<qreal>(frame) / qreal(1000);
         int newPage = static_cast<int>(-m_pageOffset);
         m_naviBar->setPageOffset(-m_pageOffset);
         if (oldPage != newPage)
             emit pageChanged(newPage);
         int ofs = m_pageOffset * ww;
         for (int i = 0; i < m_items.count(); ++i) {
             QPointF pos = m_positions[i];
             QPointF xy(pos.x() * ww, pos.y() * hh);
             m_items[i]->setPos(xy + QPointF(ofs, 0));
         }
         int center = m_wallpaper->pixmap().width() / 2;
         const int parallax = 3;
         int base = center - (ww / 2) - (PAGE_COUNT >> 1) * (ww / parallax);
         int wofs = base - m_pageOffset * ww / parallax;
         m_wallpaper->setPos(-wofs, 0);
     }
 protected:
     void resizeEvent(QResizeEvent *event) {
         Q_UNUSED(event);
         layoutScene();
     }
     void keyPressEvent(QKeyEvent *event) {
         if (event->key() == Qt::Key_Right)
             slideRight();
         if (event->key() == Qt::Key_Left)
             slideLeft();
         event->accept();
     }
 private:
     void layoutScene() {
         int ww = width();
         int hh = height();
         m_scene.setSceneRect(0, 0, PAGE_COUNT * ww - 1, hh - 1);
         centerOn(ww / 2, hh / 2);
         int nw = m_naviBar->rect().width();
         int nh = m_naviBar->rect().height();
         m_naviBar->setPos((ww - nw) / 2, hh - nh);
         shiftPage(m_pageOffset * 1000);
     }
     void setupScene() {
         qsrand(QTime::currentTime().second());
         QStringList names;
         names << "brownies" << "cookies" << "mussels" << "pizza" << "sushi";
         names << "chocolate" << "fish" << "pasta" << "puding" << "trouts";
         for (int i = 0; i < PAGE_COUNT * 2; ++i) {
             QString fname = names[i];
             fname.prepend(":/images/");
             fname.append(".jpg");
             QPixmap pixmap(fname);
             pixmap = pixmap.scaledToWidth(200);
             QGraphicsPixmapItem *item = m_scene.addPixmap(pixmap);
             m_items << item;
             qreal x = (i >> 1) + (qrand() % 30) / 100.0;
             qreal y = (i & 1) / 2.0  + (qrand() % 20) / 100.0;
             m_positions << QPointF(x, y);
             item->setZValue(1);
         }
         m_naviBar = new NaviBar;
         m_scene.addItem(m_naviBar);
         m_naviBar->setZValue(2);
         connect(m_naviBar, SIGNAL(pageSelected(int)), SLOT(choosePage(int)));
         m_wallpaper = m_scene.addPixmap(QPixmap(":/icons/surfacing.png"));
         m_wallpaper->setZValue(0);
         m_scene.setItemIndexMethod(QGraphicsScene::NoIndex);
     }
 };

 

 

main函数

 #include "parallaxhome.moc"
 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     ParallaxHome w;
     w.resize(360, 640);
     w.show();
     return app.exec();
 }

 

 

效果图