dragEnterEvent from external file issue

UnitScan

I have a situation like this: http://imgur.com/a/4BpNv
I have a sublclass derived from QTableWidget, modified to accept drag'n drop both internal row and external file. When I drag a file from a Window folder to the TableWidget, the dnd animation stop ath the edge of the TableWidget, preventing me to freely move the mouse inside the TableWidget to select the point where I run the drop. This only happens when I drag file directly from Windows folders, while if I drag files from the Qt API QFileDialog::getOpenFileName() dialog the the dnd works as I would like.

This is the subclass:

#include <QtGui>
#include <QDrag>
#include <QPainter>
#include <QDropEvent>
#include <QCursor>
#include "dtablewidget.h"

DTableWidget::DTableWidget(QWidget *parent) : QTableWidget(parent) {
    //set widget default properties:

    viewport()->setAcceptDrops(true); //set accept drop on viewport
    setDragEnabled(true);
    setDragDropOverwriteMode(false); //set drag drop overwrite to false
    setDragDropMode(QAbstractItemView::DragDrop); //enable internal drag drop on tablular dispaly
    setSelectionBehavior(QAbstractItemView::SelectRows); //enable selection of entire row
    setEditTriggers(QAbstractItemView::NoEditTriggers);//preventing editing
    setAlternatingRowColors(true);
    setSelectionBehavior(QAbstractItemView::SelectRows);
    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    setShowGrid(false);
    setAcceptDrops(true);
    setWordWrap(false);
    setStyleSheet("selection-background-color: yellow;"
                  "selection-color: #002041;"
                  "font-size: 75%;"
                  );

}

void DTableWidget::dragEnterEvent(QDragEnterEvent *event) {
    qDebug() << "dragEnterEvent";
    event->accept();
}

void DTableWidget::dragMoveEvent(QDragMoveEvent *event) {
    qDebug() << "dragMoveEvent";
    if (event->source() != this) {
        QDrag *drag = new QDrag(this);
        QMimeData *mimeData = new QMimeData;
        mimeData->setUrls(event->mimeData()->urls());
        drag->setMimeData(mimeData);
        drag->exec(Qt::LinkAction);
}
    else {
        event->acceptProposedAction();
        event->setDropAction(Qt::LinkAction);
    }
}

void DTableWidget::dropEvent(QDropEvent *event) {
    event->acceptProposedAction();
    event->setDropAction(Qt::LinkAction);
    qDebug() << "dropEvent" << event << event->mimeData()->urls().count();
    if (event->mimeData()->urls().count() > 0) {
        emit dropped(event->mimeData());
        qDebug() << "dropEvent" << event->mimeData()->urls().count();
    }
    else {
        QPoint old_coordinates = QPoint(-1,-1);
        if(currentItem() != NULL) //Check if user is not accessing empty cell
        {
            old_coordinates = QPoint(currentItem()->row(), currentItem()->column());
        }
        if(this->itemAt(event->pos().x(), event->pos().y()) != NULL && old_coordinates != QPoint(-1, -1))
        {
            emit moved(old_coordinates.x(), itemAt( event->pos().x(), event->pos().y())->row());
        }
    }
}

void DTableWidget::dragLeaveEvent(QDragLeaveEvent *event) {
    qDebug() << "dragLeaveEvent";
}

void DTableWidget::keyPressEvent(QKeyEvent *event) {
    emit keyboard(event);
}

void DTableWidget::startDrag(Qt::DropActions supportedActions) {
    QModelIndexList indexes = selectedIndexes();
    if (indexes.count() > 0) {
        QMimeData *data = model()->mimeData(indexes);
        if (!data)
            return;
        QDrag *drag = new QDrag(this);
        drag->setMimeData(data);
        Qt::DropAction defaultDropAction = Qt::IgnoreAction;
        if (defaultDropAction != Qt::IgnoreAction && (supportedActions & defaultDropAction))
            defaultDropAction = defaultDropAction;
        else if (supportedActions & Qt::CopyAction && dragDropMode() != QAbstractItemView::InternalMove)
            defaultDropAction = Qt::MoveAction;
        drag->exec(defaultDropAction);
    }
}

Can you help me?

raven-worx

@UnitScan said in dragEnterEvent from external file issue:

void DTableWidget::dragMoveEvent

i stopped reading after i saw your implementation of the dragMoveEvent() becasue its so horribly wrong :)

Why do you create a new QDrag there?
When you receive a dragMoveEvent it means that there is already a drag currently happening, otherwise you wouldn't receive the event in the first place.

Just remove the whole if (event->source() != this) block and it should work.
If you really have to check if the drag origins from inside your application do event->source(). If it returns a null-pointer the drag comes from outside your application.

UnitScan

I created a new QDrag because I wish to change the horrible mouse cursor pixmap that appears during dragMoveEvent, and replace it with a simple Leftarrow, without the preview of the file I'm dragging, with the small symbol of the link at the bottom right of the cursor.

void DTableWidget::dragMoveEvent(QDragMoveEvent *event) {

    qDebug() << "dragMoveEvent";
    if (event->source() != this) {
        QDrag *drag = new QDrag(this);
        QCursor cursor;
        cursor.setShape(Qt::ArrowCursor);

        drag->setPixmap(cursor.pixmap());
        this->cursor().setShape(Qt::ArrowCursor);
        drag->setDragCursor(this->cursor().pixmap(),Qt::LinkAction);
        QMimeData *mimeData = new QMimeData;
        mimeData->setUrls(event->mimeData()->urls());
        drag->setMimeData(mimeData);
        drag->exec(Qt::LinkAction);
}
    else {

        event->acceptProposedAction();
        event->setDropAction(Qt::LinkAction);
    }
}

If there is a better way to do that, what is?

raven-worx

@UnitScan said in dragEnterEvent from external file issue:

event->setDropAction(Qt::LinkAction);

you mean like you do in the else-block afterwards?
Basically it's only possible to set the cursor during a drag to 4 states:
Copy, Move, Link, NoAction. The operating system decides how to show them.

Thus setting it to a "plain" cursor isn't possible.

UnitScan

I don't want a plain cursor, but a dragCursor(Qt::LinkAction). How can I do it?

raven-worx

you are already doing it in the else-block (event->setDropAction()) like i already said in my previous post!
The "drag image" cannot be removed. Not via Qt API at least.

UnitScan

I noticed that with Clementine, player made with QT5 libraries, when you drag an external file to the playlist appears only a LeftArrorw with a small square at the bottom right with the "+" symbol, while with me appears, beyond Leftarrow, a gigantic preview of the file I'm dragging and an abnormal word "Link" at the bottom right :'-(
Changing event->setDropAction(Qt::LinkAction) to event->setDropAction(Qt::CopyAction) replace only the abnormal text label from "Link" to "Copy"

raven-worx

@UnitScan
And you are sure they just use the Qt API for Drag-n-Drop handling?!
Anyway you can check the source code how they do it.

UnitScan

There are other way out of Qt to handle drag'n drop?

raven-worx

@UnitScan
using the native API directly for example

But again to make sure: On the same machine (same OS) the Clementine player doesn't show the drag image while your application does?

UnitScan

@raven-worx Yes. on Windows Clementine shows only the small "+" on the bottom right, while my app show the gigantic file preview and the "Link" text