editor/mygraphicsview.cpp

#include "mygraphicsview.h"
#include <QMimeData>
#include <QCursor>
#include <QGraphicsScene>
#include <QDebug>

MyGraphicsView::MyGraphicsView(QWidget *parent)
    : QGraphicsView(parent)
{
    setAcceptDrops(true);
    viewport()->setAcceptDrops(true);
    setRenderHint(QPainter::Antialiasing);
    setFocusPolicy(Qt::StrongFocus); // 让view能接收键盘事件
}

void MyGraphicsView::dragEnterEvent(QDragEnterEvent *event)
{
    if (event->mimeData()->hasFormat("application/x-component"))
        event->acceptProposedAction();
    else
        event->ignore();
}

void MyGraphicsView::dragMoveEvent(QDragMoveEvent *event)
{
    if (event->mimeData()->hasFormat("application/x-component"))
        event->acceptProposedAction();
    else
        event->ignore();
}

void MyGraphicsView::dropEvent(QDropEvent *event)
{
    if (!event->mimeData()->hasFormat("application/x-component")) {
        event->ignore();
        return;
    }

    QString type = QString::fromUtf8(event->mimeData()->data("application/x-component"));

    QPointF scenePos = mapToScene(event->pos());
    Item *item = new Item(type);
    item->setPos(scenePos);

    if (scene())
        scene()->addItem(item);

    event->acceptProposedAction();
}

void MyGraphicsView::keyPressEvent(QKeyEvent *event)
{
    if (event->key() == Qt::Key_Delete && scene()) {
        // 删除所有被选中的图元
        QList<QGraphicsItem*> selectedItems = scene()->selectedItems();
        for (QGraphicsItem* item : selectedItems) {
            scene()->removeItem(item);
            delete item;
        }
    } else {
        QGraphicsView::keyPressEvent(event);
    }
}