Qt Graphic-View框架学习代码示例

#include "mainwindow.h" #include "ui_mainwindow.h" #include <QtMath> MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); setFixedSize(1200,1000); init(); } MainWindow::~MainWindow() { delete ui; } void MainWindow::init() { scene = new QGraphicsScene; for(int col=0;col<colNum;col++) { int x = col*200+itemWidth; for(int row=0;row<rowNum;row++) { //添加一个矩形 QGraphicsRectItem *item=new QGraphicsRectItem(-0.25*itemWidth,-0.25*itemHeight,itemWidth,itemHeight);//x,y 为左上角的图元局部坐标，图元中心点为0,0 item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable); item->setBrush(QBrush(Qt::yellow)); item->setPos(x,row*(itemHeight+20)); item->setData(rowKey,row+1); item->setData(colKey,col+1); scene->addItem(item); // 创建文字项 QString text = QString("col%1,row%2").arg(col+1).arg(row+1); QGraphicsTextItem* textItem = new QGraphicsTextItem(text); textItem->setPos(item->sceneBoundingRect().center() - textItem->sceneBoundingRect().center()); scene->addItem(textItem); scene->clearSelection(); } } connect(scene,&QGraphicsScene::focusItemChanged,this,&MainWindow::on_focusItemChanged); ui->graphicsView->setScene(scene); } void MainWindow::on_btnChange_clicked() { QString text = ui->btnChange->text(); if(text=="修改") { ui->btnChange->setText("取消"); ui->btnSet->setEnabled(true); isDrawing = true; } else if(text=="取消") { ui->btnChange->setText("修改"); ui->btnSet->setEnabled(false); isDrawing = false; // 获取场景中的所有图形项 QList<QGraphicsItem*> items = scene->items(); // 遍历图形项列表，筛选出 QGraphicsLineItem foreach (QGraphicsItem* item, items) { if (item->type() == QGraphicsLineItem::Type || item->type() == QGraphicsPolygonItem::Type) { //QGraphicsLineItem* line = qgraphicsitem_cast<QGraphicsLineItem*>(item); // 执行操作或获取所需的 QGraphicsLineItem // ... scene->removeItem(item); } } } } void MainWindow::on_focusItemChanged(QGraphicsItem *newFocusItem, QGraphicsItem *oldFocusItem, Qt::FocusReason reason) { if(reason != Qt::FocusReason::MouseFocusReason) { return; } if(newFocusItem==nullptr || oldFocusItem==nullptr) { return; } if(oldFocusItem->data(colKey)!=1 || newFocusItem->data(colKey)!=2) { return; } if(!isDrawing) { return; } QGraphicsLineItem *item=new QGraphicsLineItem(-100,0,100,0);//x,y 为左上角的图元局部坐标，图元中心点为0,0 item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable); QPen pen(Qt::green); pen.setWidth(3); item->setPen(pen); QPointF startPoint = QPointF(oldFocusItem->sceneBoundingRect().right(),oldFocusItem->sceneBoundingRect().center().y()); QPointF endPoint = QPointF(newFocusItem->sceneBoundingRect().left(),newFocusItem->sceneBoundingRect().center().y()); item->setLine(QLineF(startPoint, endPoint)); scene->addItem(item); // 计算箭头的位置和方向 QPointF direction = endPoint - startPoint; direction = direction / qSqrt(direction.x() * direction.x() + direction.y() * direction.y()); // 单位向量 QPointF arrowP1 = endPoint - direction * 10 + QPointF(direction.y(), -direction.x()) * 5; QPointF arrowP2 = endPoint - direction * 10 + QPointF(-direction.y(), direction.x()) * 5; // 创建箭头形状 QPolygonF arrowHead; arrowHead << endPoint << arrowP1 << arrowP2; QGraphicsPolygonItem* arrowItem = new QGraphicsPolygonItem(arrowHead); arrowItem->setBrush(Qt::green); scene->addItem(arrowItem); scene->clearSelection(); item->setSelected(true); }