dragwidget.cpp Example File

draganddrop/draggabletext/dragwidget.cpp
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#include <QtWidgets> #include "dragwidget.h" static QLabel *createDragLabel(const QString &text, QWidget *parent) { QLabel *label = new QLabel(text, parent); label->setAutoFillBackground(true); label->setFrameShape(QFrame::Panel); label->setFrameShadow(QFrame::Raised); return label; } static QString hotSpotMimeDataKey() { return QStringLiteral("application/x-hotspot"); } DragWidget::DragWidget(QWidget *parent) : QWidget(parent) { QFile dictionaryFile(QStringLiteral(":/dictionary/words.txt")); dictionaryFile.open(QIODevice::ReadOnly); QTextStream inputStream(&dictionaryFile); int x = 5; int y = 5; while (!inputStream.atEnd()) { QString word; inputStream >> word; if (!word.isEmpty()) { QLabel *wordLabel = createDragLabel(word, this); wordLabel->move(x, y); wordLabel->show(); wordLabel->setAttribute(Qt::WA_DeleteOnClose); x += wordLabel->width() + 2; if (x >= 245) { x = 5; y += wordLabel->height() + 2; } } } setAcceptDrops(true); setMinimumSize(400, qMax(200, y)); setWindowTitle(tr("Draggable Text")); } void DragWidget::dragEnterEvent(QDragEnterEvent *event) { if (event->mimeData()->hasText()) { if (event->source() == this) { event->setDropAction(Qt::MoveAction); event->accept(); } else { event->acceptProposedAction(); } } else { event->ignore(); } } void DragWidget::dropEvent(QDropEvent *event) { if (event->mimeData()->hasText()) { const QMimeData *mime = event->mimeData(); QStringList pieces = mime->text().split(QRegularExpression(QStringLiteral("\\s+")), QString::SkipEmptyParts); QPoint position = event->pos(); QPoint hotSpot; QByteArrayList hotSpotPos = mime->data(hotSpotMimeDataKey()).split(' '); if (hotSpotPos.size() == 2) { hotSpot.setX(hotSpotPos.first().toInt()); hotSpot.setY(hotSpotPos.last().toInt()); } for (const QString &piece : pieces) { QLabel *newLabel = createDragLabel(piece, this); newLabel->move(position - hotSpot); newLabel->show(); newLabel->setAttribute(Qt::WA_DeleteOnClose); position += QPoint(newLabel->width(), 0); } if (event->source() == this) { event->setDropAction(Qt::MoveAction); event->accept(); } else { event->acceptProposedAction(); } } else { event->ignore(); } for (QWidget *widget : findChildren<QWidget *>()) { if (!widget->isVisible()) widget->deleteLater(); } } void DragWidget::mousePressEvent(QMouseEvent *event) { QLabel *child = qobject_cast<QLabel*>(childAt(event->pos())); if (!child) return; QPoint hotSpot = event->pos() - child->pos(); QMimeData *mimeData = new QMimeData; mimeData->setText(child->text()); mimeData->setData(hotSpotMimeDataKey(), QByteArray::number(hotSpot.x()) + ' ' + QByteArray::number(hotSpot.y())); qreal dpr = window()->windowHandle()->devicePixelRatio(); QPixmap pixmap(child->size() * dpr); pixmap.setDevicePixelRatio(dpr); child->render(&pixmap); QDrag *drag = new QDrag(this); drag->setMimeData(mimeData); drag->setPixmap(pixmap); drag->setHotSpot(hotSpot); Qt::DropAction dropAction = drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction); if (dropAction == Qt::MoveAction) child->close(); }