coloritem.cpp Example File

graphicsview/dragdroprobot/coloritem.cpp
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#include <QtWidgets> #include "coloritem.h" ColorItem::ColorItem() : color(qrand() % 256, qrand() % 256, qrand() % 256) { setToolTip(QString("QColor(%1, %2, %3)\n%4") .arg(color.red()).arg(color.green()).arg(color.blue()) .arg("Click and drag this color onto the robot!")); setCursor(Qt::OpenHandCursor); setAcceptedMouseButtons(Qt::LeftButton); } QRectF ColorItem::boundingRect() const { return QRectF(-15.5, -15.5, 34, 34); } void ColorItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) { Q_UNUSED(option); Q_UNUSED(widget); painter->setPen(Qt::NoPen); painter->setBrush(Qt::darkGray); painter->drawEllipse(-12, -12, 30, 30); painter->setPen(QPen(Qt::black, 1)); painter->setBrush(QBrush(color)); painter->drawEllipse(-15, -15, 30, 30); } void ColorItem::mousePressEvent(QGraphicsSceneMouseEvent *) { setCursor(Qt::ClosedHandCursor); } void ColorItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event) { if (QLineF(event->screenPos(), event->buttonDownScreenPos(Qt::LeftButton)) .length() < QApplication::startDragDistance()) { return; } QDrag *drag = new QDrag(event->widget()); QMimeData *mime = new QMimeData; drag->setMimeData(mime); static int n = 0; if (n++ > 2 && (qrand() % 3) == 0) { QImage image(":/images/head.png"); mime->setImageData(image); drag->setPixmap(QPixmap::fromImage(image).scaled(30, 40)); drag->setHotSpot(QPoint(15, 30)); } else { mime->setColorData(color); mime->setText(QString("#%1%2%3") .arg(color.red(), 2, 16, QLatin1Char('0')) .arg(color.green(), 2, 16, QLatin1Char('0')) .arg(color.blue(), 2, 16, QLatin1Char('0'))); QPixmap pixmap(34, 34); pixmap.fill(Qt::white); QPainter painter(&pixmap); painter.translate(15, 15); painter.setRenderHint(QPainter::Antialiasing); paint(&painter, 0, 0); painter.end(); pixmap.setMask(pixmap.createHeuristicMask()); drag->setPixmap(pixmap); drag->setHotSpot(QPoint(15, 20)); } drag->exec(); setCursor(Qt::OpenHandCursor); } void ColorItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *) { setCursor(Qt::OpenHandCursor); }