QGraphicsPixmapItem与QGraphicsScene的编程实例_qgraphicspixmapitem和qgraphicsitem

本文转载自：http://blog.csdn.net/ghostyu/article/details/7017112  【 支持原作者 】

qt中提供了QGphicsView，QGraphicsScene，QGraphicsItem，QGraphicsPixmapItem是QGraphicsItem的子类

分辨创建它们的实例：view，scene，item，然后通过各自的方法scene->addItem(item);view->setScene(scene);就可以达到类似下图的效果，想要进一步定制，则要继承QGraphicsItem或QGraphicsPixmapItem，然后重写paint()、boundingRect()等方法，此外如果还想要获取鼠标事件，重写mousePressEvent等事件就好了，注意，一旦重写了mousePressEvent方法，就以为了qt不会再自动处理item的任何press事件了，可以在你重写的mousePressEvent方法中最后添加QGraphicsItem::mousePressEvent(event);解决这个问题，就是说你获取到了鼠标事件，但是依然让qt处理这个鼠标事件。

程序中的item可以水平拖动，拖动的同时图标大小会渐变，中间最大，两边渐小。

mainwindow.h与main.cpp是qt自动产生的代码，我没有产生窗口ui

myscene.h与某与scene.cpp是定义了类MyScene，继承自QGraphicsScene，我的目的是要获取其鼠标事件

nodeui.h与nodeui.cpp是定义了类NodeUI，继承自QGraphicsPixmapItem，目的相当多。

下面具体的源文件：myscene.h与myscene.cpp相对简单，就实现了一个功能

myscene.h

#ifndef MYSCENE_H #define MYSCENE_H #include <QGraphicsScene> class MyScene : public QGraphicsScene { Q_OBJECT public: explicit MyScene(QObject *parent = 0); private: void mouseMoveEvent(QGraphicsSceneMouseEvent *event); void mousePressEvent(QGraphicsSceneMouseEvent *event); void mouseReleaseEvent(QGraphicsSceneMouseEvent *event); signals: void isMoving(QPointF &pos); public slots: private: QPointF beforePos; QPointF releasePos; }; #endif // MYSCENE_H
myscene.cpp #include "myscene.h" #include <QGraphicsSceneMouseEvent> #include <QPointF> #include <QDebug> MyScene::MyScene(QObject *parent) : QGraphicsScene(parent) { } void MyScene::mouseMoveEvent(QGraphicsSceneMouseEvent *event) { //QPointF pos = event->scenePos(); QPointF pos(event->scenePos().x()-beforePos.x(),event->scenePos().y()-beforePos.y()); emit isMoving(pos); //qDebug()<<"x:"<<pos.x()<<"y:"<<pos.y(); //QGraphicsScene::mouseMoveEvent(event); } void MyScene::mousePressEvent(QGraphicsSceneMouseEvent *event) { beforePos = event->scenePos(); QGraphicsScene::mousePressEvent(event); } void MyScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *event) { releasePos = event->scenePos(); QGraphicsScene::mouseReleaseEvent(event); }

再看nodeui.h与nodeui.cpp，在原来的QGraphicsPixmapItem基础上又假如了点自己的东西

#ifndef NODEUI_H #define NODEUI_H #include <QGraphicsPixmapItem> #include <QGraphicsItem> #include <QStyleOptionGraphicsItem> #include <QPainter> #include <QGraphicsSceneMouseEvent> #include <QPointF> class NodeUI : public QObject,public QGraphicsPixmapItem { Q_OBJECT public: NodeUI(); NodeUI(QString &file,QString &text,int imagesize=80); //setup function void setMyPixmap(QString &file,int size); void setMyText(QString &text); QString getMyText(); //virtual function QRectF boundingRect() const; void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget); QPainterPath shape() const; signals: void nodeIsMoving(QPointF &pos); void nodeIsPressed(); void nodeIsRelease(); protected: void mousePressEvent(QGraphicsSceneMouseEvent *event); void mouseReleaseEvent(QGraphicsSceneMouseEvent *event); private: //QString myImage; QString myText; }; #endif // NODEUI_H

nideui.cpp

#include "nodeui.h" #include <QPixmap> #include <iostream> #include <QDebug> NodeUI::NodeUI() { } /*note: imagesize = 80 is in the nodeui.h*/ NodeUI::NodeUI(QString &file,QString &text,int imagesize) { setMyText(text); setMyPixmap(file,imagesize); } void NodeUI::setMyText(QString &text) { myText = text; } void NodeUI::setMyPixmap(QString &file,int size) { //myImage = file; QPixmap pixmap; pixmap.load(file); pixmap= pixmap.scaled(size,size,Qt::IgnoreAspectRatio, Qt::SmoothTransformation); setPixmap(pixmap); } QRectF NodeUI::boundingRect() const { QRect rect = this->pixmap().rect(); //return QRectF(rect); return QRectF(0,0,rect.width(),rect.width()+15); } void NodeUI::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) { QPixmap pixmap = this->pixmap(); QRect rect = pixmap.rect(); painter->drawPixmap(rect,pixmap); //print name,calculate the text's heigh & width for center layout QPen pen(Qt::black); painter->setPen(pen); painter->setRenderHint(QPainter::Antialiasing); QFont font("Verdana",8, QFont::Normal); painter->setFont(font); painter->drawText(QRectF(0,rect.height(),rect.width(),15),Qt::AlignCenter,myText); if (option->state & QStyle::State_Sunken) { QRectF rect1 = boundingRect(); //QPen pen(Qt::darkGreen); painter->setPen(QPen(Qt::darkGreen)); painter->drawRoundRect(rect1, 10,10); }else { } } QPainterPath NodeUI::shape() const { QRectF rect = boundingRect(); QPainterPath path; path.addRoundRect(rect, 5,5); return path; } void NodeUI::mousePressEvent(QGraphicsSceneMouseEvent *event) { emit nodeIsPressed(); qDebug()<<"pressed"; QGraphicsItem::mousePressEvent(event); } void NodeUI::mouseReleaseEvent(QGraphicsSceneMouseEvent *event) { emit nodeIsRelease(); update(boundingRect()); QGraphicsItem::mouseReleaseEvent(event); } QString NodeUI::getMyText() { return myText; }
最后是scene与item的文件mainwindow.cpp，继承了QMainWindow，作用就是画一个应用程序框架

mainwindow.h

#ifndef MAINWINDOW_H #define MAINWINDOW_H #include <QtGui/QMainWindow> #include <QGraphicsView> #include <QGraphicsScene> #include <QPointF> #include "nodeui.h" #include "myscene.h" #include <QMap> class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = 0); ~MainWindow(); NodeUI *selectedNodeUI(); bool isNodeUiClicked(); void nodeUiSizeAdjust(); //var protected: private: void GetScreenInfo(); QGraphicsView *view; //QGraphicsScene *scene; MyScene *scene; //instead of (NodeUI *nodeui;)&(QPointF nodeUiPos;) //目前弃用，由于QMap的顺序无法人为设定，按照内部key自动升序 //QMap<NodeUI*,QPointF>nodeUiMaps; //NodeUI *currentNodeUI; //nodeui pressed or released volatile bool mPressed; QList<NodeUI*> nodeUiLists; QList<QPointF> nodeUiPosLists; QList<QPixmap> nodeUiPixmapLists; /* struct { QList<NodeUI*> nodelists; QList<QPointF> poslists; }ss; */ //弃用 NodeUI *nodeui; QPointF nodeUiPos; //sceen size info; qint16 sceenSizeX; qint16 sceenSizeY; private slots: void isMoving(QPointF &pos); void isPressed(); void isReleased(); void selectionChanged(); signals: void nodeUiClicked(NodeUI* node); }; #endif // MAINWINDOW_H mainwindow.cpp #include "mainwindow.h" #include <QDesktopWidget> #include <QApplication> #include <QPixmap> #include <QGraphicsItem> #include <QMouseEvent> #include <QWidget> #include <QGraphicsPixmapItem> #include <QMessageBox> #include <QDebug> const qreal MY_NODEUI_POS_Y = 200; const qreal MY_NODEUI_DIS = 110; const qreal MY_NODEUI_STA = 90; const int MYNODEUI_SIZE = 100; const int MYNODEUI_SIZE_M = 20; const int SCREEN_SIZE = 800; MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { //初始化 mPressed = false; //get windows size GetScreenInfo(); view = new QGraphicsView; scene = new MyScene(); scene->setSceneRect(0,0,800,480); //new QString file; QString text; QPointF pos; NodeUI* node; //HOME:1 file = QString(":/images/home.png"); text = QString("Home"); pos = QPointF(MY_NODEUI_STA,MY_NODEUI_POS_Y); node = new NodeUI(file,text,MYNODEUI_SIZE); node->setPos(pos); nodeUiLists.append(node); nodeUiPosLists.append(pos); nodeUiPixmapLists.append(node->pixmap()); /* here cannot delete node!!!!!!!!!!!!!!! delete node; */ //VIDIO:2 file = QString(":/images/securitycamera.png"); text = QString("Vidio"); pos = QPointF(MY_NODEUI_STA+MY_NODEUI_DIS*1,MY_NODEUI_POS_Y); node = new NodeUI(file,text,MYNODEUI_SIZE); node->setPos(pos); nodeUiLists.append(node); nodeUiPosLists.append(pos); nodeUiPixmapLists.append(node->pixmap()); //APPLICATION:3 file = QString(":/images/application.png"); text = QString("Application"); pos = QPointF(MY_NODEUI_STA+MY_NODEUI_DIS*2,MY_NODEUI_POS_Y); node = new NodeUI(file,text,MYNODEUI_SIZE); node->setPos(pos); nodeUiLists.append(node); nodeUiPosLists.append(pos); nodeUiPixmapLists.append(node->pixmap()); //NETWORK:4 file = QString(":/images/network-2.png"); text = QString("Network"); pos = QPointF(MY_NODEUI_STA+MY_NODEUI_DIS*3,MY_NODEUI_POS_Y); node = new NodeUI(file,text,MYNODEUI_SIZE); node->setPos(pos); nodeUiLists.append(node); nodeUiPosLists.append(pos); nodeUiPixmapLists.append(node->pixmap()); //COMPUTER:5 file = QString(":/images/smartphone.png"); text = QString("Phone"); pos = QPointF(MY_NODEUI_STA+MY_NODEUI_DIS*4,MY_NODEUI_POS_Y); node = new NodeUI(file,text,MYNODEUI_SIZE); node->setPos(pos); nodeUiLists.append(node); nodeUiPosLists.append(pos); nodeUiPixmapLists.append(node->pixmap()); //CUSTOMIZE:5 file = QString(":/images/customize.png"); text = QString("Setting"); pos = QPointF(MY_NODEUI_STA+MY_NODEUI_DIS*5,MY_NODEUI_POS_Y); node = new NodeUI(file,text,MYNODEUI_SIZE); node->setPos(pos); nodeUiLists.append(node); nodeUiPosLists.append(pos); nodeUiPixmapLists.append(node->pixmap()); //重新计算UiSize nodeUiSizeAdjust(); int i = 0; foreach(NodeUI* node_temp,nodeUiLists) { node_temp->setFlags(QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsSelectable); qDebug()<<"name:"<<node_temp->getMyText()<<nodeUiPosLists.at(i); scene->addItem(node_temp); //NodeUI signal connect(node_temp,SIGNAL(nodeIsPressed()),this,SLOT(isPressed())); connect(node_temp,SIGNAL(nodeIsRelease()),this,SLOT(isReleased())); i++; } //signal connect(scene,SIGNAL(isMoving(QPointF&)),this,SLOT(isMoving(QPointF&))); connect(scene,SIGNAL(selectionChanged()),this,SLOT(selectionChanged())); //用于按钮的单机 view->setScene(scene); //set drag mode //view->setDragMode(QGraphicsView::RubberBandDrag); view->setRenderHints(QPainter::Antialiasing); //no menu view->setContextMenuPolicy(Qt::NoContextMenu); view->setBackgroundBrush(QImage(":/images/shuibo2.jpg")); //view->setViewportUpdateMode(QGraphicsView::BoundingRectViewportUpdate); //view->setCacheMode(QGraphicsView::CacheBackground); setCentralWidget(view); setWindowTitle(tr("Main Window")); } //槽，当scene鼠标拖拽是执行 //控制UI图标的水平 void MainWindow::isMoving(QPointF &pos) { int i=0; if(mPressed){ foreach(NodeUI* node,nodeUiLists) { node->setPos(nodeUiPosLists.at(i).x()+pos.x(),MY_NODEUI_POS_Y); i++; } nodeUiSizeAdjust(); } } //槽，当nodeui鼠标按下时执行,调用selectedNodeUI函数，更新currentNodeUI变量 //除此之外，selectionChanged()也是一个槽，由scene调用 void MainWindow::isPressed() { selectionChanged(); mPressed = true; } //槽，当nodeui鼠标释放时执行 //应当设置标志位，让UI图片停止对鼠标拖动事件的响应 void MainWindow::isReleased() { mPressed = false; if(isNodeUiClicked()) qDebug()<<"clicked"; qDebug()<<"release"; } //槽，当scene的selectedItem变化时，发送同名信号到此槽 void MainWindow::selectionChanged() { int i=0,j=0; QList<QGraphicsItem *> items = scene->selectedItems(); if (items.count() == 1) { //当前所选择的UI图标的坐标 QPointF pos = items.first()->pos(); NodeUI* node_temp = dynamic_cast<NodeUI *>(items.first()); qDebug()<<"items.x:"<<pos.x()<<"items.y:"<<pos.y(); foreach(NodeUI* node,nodeUiLists) { if(node == node_temp) break; i++; } j=i; i=0; foreach(QPointF ppos,nodeUiPosLists) { nodeUiPosLists[i].setX((i-j)*MY_NODEUI_DIS+pos.x()); nodeUiPosLists[i].setY(MY_NODEUI_POS_Y); i++; } } else { return; } } //判断是否Nodeui接收的是否是单击信号。 //判断依据是当前单击的nodeui对象的pos与存储在nodeUiPosListsd的位置比较，相等则为单击 bool MainWindow::isNodeUiClicked() { int i=-1; QList<QGraphicsItem *> items = scene->selectedItems(); if (items.count() == 1) { QPointF pos = items.first()->pos(); NodeUI* node_temp = dynamic_cast<NodeUI *>(items.first()); i = nodeUiLists.indexOf(node_temp); if(pos ==nodeUiPosLists.at(i)){ //emit nodeUiClicked(node_temp); QMessageBox::information(this,"New Window","will open : "+node_temp->getMyText()); return true; } } return false; } void MainWindow::nodeUiSizeAdjust() { quint16 i=0; foreach(NodeUI* node,nodeUiLists) { //qDebug()<<"i= "<<i; QPointF pos=node->pos(); pos.setX(node->pos().x()+MYNODEUI_SIZE/2); //pos.setX(node->pos().x()+node->pixmap().width()); if(pos.x()>=0 && pos.x()<=SCREEN_SIZE/2) { //(MYNODEUI_SIZE-MYNODEUI_SIZE_M)/(SCREEN_SIZE/2)==(size-20)/pos.x() quint16 size=pos.x()/5+20; QPixmap pixmap = nodeUiPixmapLists.at(i); //QPixmap pixmap = nodeUiLists.at(i)->pixmap(); pixmap = pixmap.scaled(size,size,Qt::IgnoreAspectRatio, Qt::SmoothTransformation); nodeUiLists[i]->setPixmap(pixmap); } //if(pos.x()>SCREEN_SIZE/2 && pos.x()<=SCREEN_SIZE) if(pos.x()>SCREEN_SIZE/2 && pos.x()<=SCREEN_SIZE+10) { //(MYNODEUI_SIZE-MYNODEUI_SIZE_M)/(SCREEN_SIZE/2)==(size-20)/pos.x() quint16 size=(SCREEN_SIZE-pos.x())/5+20; QPixmap pixmap = nodeUiPixmapLists.at(i); //QPixmap pixmap = nodeUiLists.at(i)->pixmap(); pixmap = pixmap.scaled(size,size,Qt::IgnoreAspectRatio, Qt::SmoothTransformation); nodeUiLists[i]->setPixmap(pixmap); } i++; } } MainWindow::~MainWindow() { } //获取设备分辨率的呢个信息 void MainWindow::GetScreenInfo() { QDesktopWidget* desktopWidget = QApplication::desktop(); //获取可用桌面大小 //QRect deskRect = desktopWidget->availableGeometry(); //获取设备屏幕大小 QRect screenRect = desktopWidget->screenGeometry(); sceenSizeX = screenRect.width(); sceenSizeY = screenRect.height(); //获取系统设置的屏幕个数（屏幕拷贝方式该值为1） //g_nScreenCount = desktopWidget->screenCount(); } 最后是main.cpp

实例化MainWindow

#include <QtGui/QApplication> #include "mainwindow.h" int main(int argc, char *argv[]) { QApplication a(argc, argv); MainWindow w; w.setWindowOpacity(1); w.setWindowFlags(Qt::FramelessWindowHint); w.setAttribute(Qt::WA_TranslucentBackground); w.show(); //w.showFullScreen(); return a.exec(); }
大概都写了注解了，其实看看一个名称也该大概了解其作用

本文转载自：http://blog.csdn.net/ghostyu/article/details/7017112  【 支持原作者 】