|  | Home · Examples

# Code for Draggable Icons Example

    package com.trolltech.examples;

    import com.trolltech.qt.*;
    import com.trolltech.qt.core.*;
    import com.trolltech.qt.gui.*;

    @QtJambiExample(name = "Draggable Icons")
    public class DraggableIcons extends QFrame
    {

        public DraggableIcons()
        {
            setMinimumSize(200, 200);
            setFrameStyle(QFrame.Shadow.Sunken.value() | QFrame.Shape.StyledPanel.value());
            setAcceptDrops(true);

            QLabel boatIcon = new QLabel(this);
            boatIcon.setPixmap(new QPixmap("classpath:com/trolltech/examples/images/boat.png"));
            boatIcon.move(20, 20);

            QLabel carIcon = new QLabel(this);
            carIcon.setPixmap(new QPixmap("classpath:com/trolltech/examples/images/car.png"));
            carIcon.move(120, 20);

            QLabel houseIcon = new QLabel(this);
            houseIcon.setPixmap(new QPixmap("classpath:com/trolltech/examples/images/house.png"));
            houseIcon.move(20, 120);
        }

        protected void dragEnterEvent(QDragEnterEvent event)
        {
            if (event.mimeData().hasFormat("application/x-dnditemdata")) {
                if (event.source().equals(this)) {
                    event.setDropAction(Qt.DropAction.MoveAction);
                    event.accept();
                } else {
                    event.acceptProposedAction();
                }
            } else {
                event.ignore();
            }
        }

        protected void dragMoveEvent(QDragMoveEvent event)
        {
            if (event.mimeData().hasFormat("application/x-dnditemdata")) {
                if (event.source().equals(this)) {
                    event.setDropAction(Qt.DropAction.MoveAction);
                    event.accept();
                } else {
                    event.acceptProposedAction();
                }
            } else {
                event.ignore();
            }
        }

        protected void dropEvent(QDropEvent event)
        {
            if (event.mimeData().hasFormat("application/x-dnditemdata")) {
                QByteArray itemData = event.mimeData().data("application/x-dnditemdata");
                QDataStream dataStream = new QDataStream(itemData, QIODevice.OpenModeFlag.ReadOnly);

                QPixmap pixmap = new QPixmap();
                QPoint offset = new QPoint();
                pixmap.readFrom(dataStream);
                offset.readFrom(dataStream);

                QLabel newIcon = new QLabel(this);
                newIcon.setPixmap(pixmap);
                newIcon.move(event.pos().subtract(offset));
                newIcon.show();
                newIcon.setAttribute(Qt.WidgetAttribute.WA_DeleteOnClose);

                if (event.source().equals(this)) {
                    event.setDropAction(Qt.DropAction.MoveAction);
                    event.accept();
                } else {
                    event.acceptProposedAction();
                }
            } else {
                event.ignore();
            }
        }

        protected void mousePressEvent(QMouseEvent event)
        {
            QLabel child = (QLabel) childAt(event.pos());
            if (child == null)
                return;

            QPixmap pixmap = child.pixmap();

            QByteArray itemData = new QByteArray();
            QDataStream dataStream = new QDataStream(itemData, QIODevice.OpenModeFlag.WriteOnly);
            pixmap.writeTo(dataStream);
            event.pos().subtract(child.pos()).writeTo(dataStream);

            com.trolltech.qt.core.QMimeData mimeData = new com.trolltech.qt.core.QMimeData();
            mimeData.setData("application/x-dnditemdata", itemData);

            QDrag drag = new QDrag(this);
            drag.setMimeData(mimeData);
            drag.setPixmap(pixmap);
            drag.setHotSpot(event.pos().subtract(child.pos()));

            QPixmap tempPixmap = new QPixmap(pixmap);
            QPainter painter = new QPainter();
            painter.begin(tempPixmap);
            painter.fillRect(pixmap.rect(), new QBrush(new QColor(127, 127, 127, 127)));
            painter.end();

            child.setPixmap(tempPixmap);

            if (drag.exec(new Qt.DropActions(Qt.DropAction.CopyAction,
                Qt.DropAction.MoveAction, Qt.DropAction.CopyAction)) == Qt.DropAction.MoveAction)
                child.close();
            else {
                child.show();
                child.setPixmap(pixmap);
            }
        }

        public static void main(String args[])
        {
            QApplication.initialize(args);

            QWidget mainWidget = new QWidget();
            QHBoxLayout horizontalLayout = new QHBoxLayout();
            horizontalLayout.addWidget(new DraggableIcons());
            horizontalLayout.addWidget(new DraggableIcons());

            mainWidget.setLayout(horizontalLayout);
            mainWidget.setWindowTitle("Draggable Icons");
            mainWidget.show();

            QApplication.exec();
        }
    }