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Qt转动轮播图的实现方法

发布时间：2020-07-18 09:47:28 作者：小猪
来源：亿速云 阅读：548

这篇文章主要讲解了Qt转动轮播图的实现方法，内容清晰明了，对此有兴趣的小伙伴可以学习一下，相信大家阅读完之后会有帮助。

Qt轮播图的实现代码，供大家参考，具体内容如下

qt轮播图简单的实现，功能会在后面完善

效果图：

Qt转动轮播图的实现方法

这里我是用了QGraphicsScene+QGraphicsView+QGraphicsObject，其中对QGraphicsView和QGraphicsObject进行继承派生类功能进行了添加。时间有限，直接贴上关键代码部分供大家参考。

//pictrueitem.h
#ifndef PICTRUEITEM_H
#define PICTRUEITEM_H
#include <QGraphicsPixmapItem>
#include <QGraphicsItem>
#include <QGraphicsObject>
#include <QPixmap>
class PictrueItem : public QGraphicsObject
{
  Q_OBJECT

public:
  explicit PictrueItem(QGraphicsItem *parent = Q_NULLPTR);
  explicit PictrueItem(const QPixmap &pixmap, QGraphicsItem *parent = Q_NULLPTR);
  virtual ~PictrueItem();
  void setPixmap(const QPixmap &pixmap);
  QPixmap pixmap() const;
  virtual QRectF boundingRect() const;
  void setTransformationMode(Qt::TransformationMode mode);
  QPointF offset() const;
  void setOffset(const QPointF &offset);
  virtual int type()const;
  void setType(int type);
  int itemId()const;
  void setItemId(int id);

protected:
  void mousePressEvent(QGraphicsSceneMouseEvent *event);

  void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);

  virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);

Q_SIGNALS:

  void clicked();
  void clickedId(int);

private:

  QPointF pressedScenePoint;
  QPointF m_offset;
  QPointF m_pos;
  Qt::TransformationMode mode;
  QPixmap m_pixmap;
  bool isPressed;
  int m_type;
  int m_id;
  qreal m_pointPercent;
};

#endif // PICTRUEITEM_H
//pictrueitem.cpp
#include "pictrueitem.h"
#include <QGraphicsSceneMouseEvent>
#include <QPainter>
#include <QDebug>
PictrueItem::PictrueItem(QGraphicsItem *parent)
  :QGraphicsObject(parent),
   isPressed(false),
   mode(Qt::SmoothTransformation),
   m_type(0),
   m_id(0),
   m_pointPercent((qreal)0.0)
{

}

PictrueItem::PictrueItem(const QPixmap &pixmap, QGraphicsItem *parent)
  :QGraphicsObject(parent),
   isPressed(false),
   mode(Qt::SmoothTransformation),
   m_type(0)
{
  m_pixmap = pixmap;
}

PictrueItem::~PictrueItem()
{

}

void PictrueItem::setPixmap(const QPixmap &pixmap)
{
  prepareGeometryChange();
  m_pixmap = pixmap;
  update();
}

QPixmap PictrueItem::pixmap() const
{
  return m_pixmap;
}

QRectF PictrueItem::boundingRect() const
{
  if(m_pixmap.isNull())
    return QRectF();
  return QRectF(m_offset, m_pixmap.size() / m_pixmap.devicePixelRatio());
}

void PictrueItem::setTransformationMode(Qt::TransformationMode mode)
{
  if (mode != this->mode)
  {
    this->mode = mode;
    update();
  }
}

QPointF PictrueItem::offset() const
{
  return m_offset;
}

void PictrueItem::setOffset(const QPointF &offset)
{
  m_offset = offset;
  if (m_offset == offset)
    return;
  prepareGeometryChange();
  m_offset = offset;
  update();
}

int PictrueItem::type() const
{
  return m_type;
}

void PictrueItem::setType(int type)
{
  m_type = type;
}

int PictrueItem::itemId() const
{
  return m_id;
}

void PictrueItem::setItemId(int id)
{
  m_id = id;
}


void PictrueItem::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
  //只响应鼠标左键
  if(event->button() == Qt::LeftButton)
  {
    pressedScenePoint = event->pos();
    isPressed = true;

  }
}

void PictrueItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
  if(event->button() == Qt::LeftButton){
    if(isPressed &&
        boundingRect().contains(event->pos()) &&
        boundingRect().contains(pressedScenePoint))
    {
      isPressed = false;
      emit clicked();
      emit clickedId(type());
    }
  }
}

void PictrueItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
  Q_UNUSED(widget);
  Q_UNUSED(option);
  painter->setRenderHint(QPainter::SmoothPixmapTransform,
              (this->mode == Qt::SmoothTransformation));

  painter->drawPixmap(m_offset, m_pixmap);

}
//pictrueview.h
#ifndef PICTRUEVIEW_H
#define PICTRUEVIEW_H
#include <QGraphicsView>

class PictrueView : public QGraphicsView
{
  Q_OBJECT

public:
  PictrueView(QWidget *parent = Q_NULLPTR);
  virtual ~PictrueView();
protected:
  void resizeEvent(QResizeEvent *event);
public:
Q_SIGNALS:
  void sizeChanged(const QSize &);
};

#endif // PICTRUEVIEW_H
//pictrueview.cpp
#include "pictrueview.h"
#include <QResizeEvent>
PictrueView::PictrueView(QWidget *parent)
  :QGraphicsView(parent)
{

}

PictrueView::~PictrueView()
{
  //none
}

void PictrueView::resizeEvent(QResizeEvent *event)
{
  emit sizeChanged(event->size());
  return QGraphicsView::resizeEvent(event);
}

下面那行按钮实现

//pictruebutton.h
#ifndef PICTRUERADIOBUTTON_H
#define PICTRUERADIOBUTTON_H
#include <QAbstractButton>

class PictrueButton : public QAbstractButton
{
  Q_OBJECT

public:
   explicit PictrueButton(QWidget *parent = Q_NULLPTR);
  ~PictrueButton();
  int id()const;
  void setId(int id);
Q_SIGNALS:
  void entered();
  void entered(int);
protected:
  virtual void paintEvent(QPaintEvent *);
  virtual void enterEvent(QEvent *event);
  virtual void leaveEvent(QEvent *event);
private:
  bool m_isSelected;
  int m_id;
};

#endif // PICTRUERADIOBUTTON_H
//pictruebutton.cpp
#include "pictruebutton.h"
#include <QPen>
#include <QPainter>
#include <QDebug>
#include <QPainterPath>
PictrueButton::PictrueButton(QWidget *parent)
  :QAbstractButton(parent),
   m_isSelected(false),
   m_id(0)
{
  setCheckable(true);
  setFixedSize(50,10);
}

PictrueButton::~PictrueButton()
{

}

int PictrueButton::id() const
{
  return m_id;
}

void PictrueButton::setId(int id)
{
  m_id = id;
}

void PictrueButton::paintEvent(QPaintEvent *)
{
  QPainter painter(this);
  QRectF drawRect = this->rect();
  QPainterPath drawPath;
  qDebug()<<drawRect;
  QPen drawPen;
  drawPen.setWidth(3);
  //选中为蓝,未选中为灰
  drawPen.setColor(Qt::gray);
  painter.setPen(drawPen);
  //抗锯齿
  painter.setRenderHint(QPainter::Antialiasing);
  drawPath.addRoundedRect(drawRect,10,10);
  painter.setClipPath(drawPath);
  if(isChecked())
    painter.fillRect(drawRect,QColor(0,0,255,128));
  else
    painter.fillRect(drawRect,QColor(128,128,128,128));
}

void PictrueButton::enterEvent(QEvent *event)
{
  if(!isChecked())
    setChecked(true);
  emit entered(m_id);
  return QAbstractButton::enterEvent(event);
}

void PictrueButton::leaveEvent(QEvent *event)
{
  return QAbstractButton::leaveEvent(event);
}
//qmainWindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#define RAW_VIEW_SIZE QSize(476,414)
#define SCALE_VIEW_PIXMAP (qreal)2/1 //View与图片比例
#define SCALE_BIG_SMALL (qreal)2/1 //图片大小比例
//P1-P8，8个位置，根据需要改动
#define P1 (qreal)0.00
#define P2 (qreal)0.25
#define P3 (qreal)0.50
#define P4 (qreal)0.75
#define P5 (qreal)1.00
#define P6 P4
#define P7 P3
#define P8 P2
#define MID_TYPE 2
#define FPS 60//帧数，每秒
#define DURATION_MS 500//移动一次图元经过时间,毫秒，不得低于帧数

namespace Ui {
class MainWindow;
}
class QGraphicsScene;
class QButtonGroup;
class MainWindow : public QMainWindow
{
  Q_OBJECT

public:
  enum Rules:int{
    RuleA = 1,
    RuleB = -1,
    RuleC = 2,
    RuleD = -2
  };

  explicit MainWindow(QWidget *parent = 0);
  ~MainWindow();
  int getIndexByRules(int oldIndex,int rule);
  template<typename T>
  void rollList(QList<T> &oldList, int dir, int count);
  void rollItem(int rollDir,unsigned rollCount);
public Q_SLOTS:
  void timerOutFunc(); 
  void nextItem();
  void previousItem();
  void clickedItemRoll(int type);
protected:

private:
  Ui::MainWindow *ui;
  QTimer *m_timer;
  QGraphicsScene *m_scene;
  QLineF midLine;
  QList<qreal> pointList;
  QList<QPixmap> pixmapList;
  QList<qreal> zValueList;
  QList<qreal> pixmapScaleList;
  int m_index;
  Rules currentRule;
  unsigned m_rollCount;
  QButtonGroup *btnGroup;
  bool btnMoveEnable;
};

#endif // MAINWINDOW_H

下面是滚动的关键代码

void MainWindow::timerOutFunc()
{
  for(int i = 0; i<8; i++)
  {
    if(qAbs(midLine.pointAt(pointList[getIndexByRules(i,dir)]).x()-itemList[i]->pos().x())<qAbs(unitList[i]))
    {
      if(finishList.contains(i))
        continue;
      itemList[i]->setPos(midLine.pointAt(pointList[getIndexByRules(i,dir)]));
      //设置新的显示优先级
      itemList[i]->setScale(pixmapScaleList[getIndexByRules(i,dir)]);
      //设置新的类型
      itemList[i]->setType(getIndexByRules(i,dir));
      //i==7-->最后一个图元移动完成
      finishList.append(i);
      if(finishList.size() == 8)
      {
        //循环旋转图元表和图片表
        rollList(itemList,dir,1);
        rollList(pixmapList,dir,1);
        for(int i = 0; i<8; i++)
          itemList[i]->setZValue(zValueList[i]);
        m_timer->stop();
        finishList.clear();
        if(btnGroup->checkedId()!=itemList[MID_TYPE]->itemId())
          btnGroup->button(getIndexByRules(btnGroup->checkedId(),dir))->setChecked(true);
        if(--m_rollCount)
        {
          if(dir == 1)
            nextItem();
          else
            previousItem();
        }
        break;
      }
    }
    else
    {
      //按计算好的移动单位移动一次
      itemList[i]->setPos(QPointF(itemList[i]->pos().x()+unitList[i],itemList[i]->pos().y()));
      //转换因子不是1.0时进行转换设置
      if(transScaleList[i] != (qreal)1.0)
      {
        itemList[i]->setScale(itemList[i]->scale()*transScaleList[i]);
      }
    }
    m_scene->invalidate();
  }
}
void MainWindow::rollItem(int rollDir, unsigned rollCount)
{
  if(m_timer->isActive())
    return;
  //清除之前的空间差列表和移动单位列表
  m_rollCount = rollCount;
  spaceList.clear();
  unitList.clear();
  transScaleList.clear();
  dir = rollDir;
  qDebug()<<"rollCount"<<rollCount;
  for(int i = 0; i<8; i++)
  {
    spaceList.append(midLine.pointAt(pointList[getIndexByRules(i,dir)]).x()-itemList[i]->pos().x());//计算移动总距离
    unitList.append(spaceList[i]/(FPS*DURATION_MS/1000));//计算移动单个距离
    transScaleList.append(pow(pixmapScaleList[getIndexByRules(i,dir)]/pixmapScaleList[i],\
               (qreal)1/(FPS*DURATION_MS/1000)));//计算增长倍数
  }

  //启动定时器
  m_timer->start();

}

void MainWindow::nextItem()
{
  rollItem(1,1);
}

void MainWindow::previousItem()
{
  rollItem(-1,1);
}

看完上述内容，是不是对Qt转动轮播图的实现方法有进一步的了解，如果还想学习更多内容，欢迎关注亿速云行业资讯频道。

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