小网站要备案吗,免费创建网站的软件,个人网站做打赏流程,做的网站怎么样才能再网上看到自定义QGraphicsItem和QGraphicsView 说明示例myitem.hmyitem.cppmyview.hmyview.cpp调用main.cpp 效果 说明
在使用Qt的图形视图框架实现功能时#xff0c;一般会在其基础上进行自定义功能实现。 如#xff1a;滚轮对场景的缩放#xff0c;鼠标拖动场景中的项#xff0c;… 自定义QGraphicsItem和QGraphicsView 说明示例myitem.hmyitem.cppmyview.hmyview.cpp调用main.cpp 效果 说明
在使用Qt的图形视图框架实现功能时一般会在其基础上进行自定义功能实现。 如滚轮对场景的缩放鼠标拖动场景中的项以及可以在场景中进行右键操作等。
示例
myitem为自定义QGraphicsItem实现了边框、重绘事件、鼠标悬停、按键、右键菜单等功能。
myitem.h
#ifndef MYITEM_H
#define MYITEM_H#include QGraphicsItemclass MyItem : public QGraphicsItem
{
public:MyItem();// 边框virtual QRectF boundingRect() const override;// 重绘事件virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,QWidget *widget) override;// 设置笔刷inline void setColor(const QColor color) {brushColor color;}protected:// 鼠标按下函数设置被点击的图形项得到焦点并改变光标外观virtual void keyPressEvent(QKeyEvent *event) override;// 键盘按下函数判断是不是向下方向键若是是则向下移动图形项virtual void mousePressEvent(QGraphicsSceneMouseEvent *event) override;// 悬停事件函数设置光标外观和提示virtual void hoverEnterEvent(QGraphicsSceneHoverEvent *event) override;// 右键菜单函数为图形项添加一个右键菜单virtual void contextMenuEvent(QGraphicsSceneContextMenuEvent *event) override;private:QColor brushColor; // 笔刷颜色
};
#endif // MYITEM_Hmyitem.cpp
#include myitem.h
#include QPainter
#include QCursor
#include QKeyEvent
#include QGraphicsSceneHoverEvent
#include QGraphicsSceneContextMenuEvent
#include QMenu#define WIDTH 40
#define HEIGHT 40#define POS 20MyItem::MyItem()
{brushColor Qt::black;setFlag(QGraphicsItem::ItemIsFocusable);setFlag(QGraphicsItem::ItemIsMovable);setAcceptHoverEvents(true);}QRectF MyItem::boundingRect() const
{qreal adjust 0.5; // 返回上下左右0.5个像素return QRectF(-POS - adjust, -POS - adjust,WIDTH adjust, HEIGHT adjust);
}void MyItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *,QWidget *)
{if (hasFocus()) {painter-setPen(QPen(QColor(255, 255, 255)));} else {painter-setPen(QPen(QColor(100, 100, 100)));}painter-setBrush(brushColor);painter-drawRect(-POS, -POS, WIDTH, HEIGHT);
}void MyItem::mousePressEvent(QGraphicsSceneMouseEvent *e)
{setFocus();// 设置光标为手握下的形状setCursor(Qt::ClosedHandCursor);QGraphicsItem::mousePressEvent(e);
}void MyItem::keyPressEvent(QKeyEvent *event)
{if (Qt::Key_Down event-key())moveBy(0, 10);else if(Qt::Key_Up event-key())moveBy(0, -10);else if(Qt::Key_Left event-key())moveBy(-10, 0);else if(Qt::Key_Right event-key())moveBy(10, 0);else{}QGraphicsItem::keyPressEvent(event);
}void MyItem::hoverEnterEvent(QGraphicsSceneHoverEvent *)
{// 设置光标为手张开的形状setCursor(Qt::OpenHandCursor);setToolTip(click me);
}void MyItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{QMenu menu;QAction *moveAction menu.addAction(move origin);QAction *selectedAction menu.exec(event-screenPos());if (selectedAction moveAction) {setPos(0, 0);}
}
myview.h
myview继承QGraphicsView重新实现了滚轮事件可对场景进行缩放操作
#ifndef MYVIEW_H
#define MYVIEW_H#include QObject
#include QGraphicsViewclass MyView : public QGraphicsView
{Q_OBJECT
public:explicit MyView(QWidget *parent 0);protected:// 滚轮事件缩放virtual void wheelEvent(QWheelEvent *event) override;
};
#endif // MYVIEW_H
myview.cpp
#include myview.h#include myview.h
#include QKeyEventMyView::MyView(QWidget *parent) :QGraphicsView(parent)
{
}void MyView::wheelEvent(QWheelEvent *event)
{if(event-delta() 0){scale(1.1, 1.1);}else{scale(0.9, 0.9);}// 加上这个否则在场景和图形项中就没法再接收到该事件了QGraphicsView::wheelEvent(event);
}
调用
main.cpp
#include QApplication#include myitem.h
#include myview.h
#include QTime
#include QtMath#include QDebugint main(int argc, char* argv[ ])
{QApplication app(argc, argv);qsrand(QTime(0, 0, 0).secsTo(QTime::currentTime()));QGraphicsScene scene;// 设置场景尺寸减少动态渲染scene.setSceneRect(-300, -225, 600, 450);// 创建项for (int i 0; i 5; i) {MyItem *item new MyItem;item-setColor(QColor(qrand() % 256, qrand() % 256, qrand() % 256));item-setPos(i * 50 - 100, -50);scene.addItem(item);}// 声明视图MyView view;view.setScene(scene);// 设置背景刷view.setBackgroundBrush(QBrush(QColor(220, 220, 220)));view.show();return app.exec();
}效果
显示效果如下 自定义图形视图
