Qt 5.9.2 QTreeView - Drag & Drop Broken ?

Dariusz

Been going nuts for past 4 hours as I had a complex treeView system and took me a while to just do a basic test and realize that the QT is apparently broken?

The gif showing the workflow to reproduce the issue > https://imgur.com/a/pRKTh

I cant Upload my files so here is the content...

main.cpp

#include <iostream>
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    mainWindow widget;
    widget.show();
    return a.exec();
}

mainWindow.h

#ifndef QT_03_TREEVIEW_DRAGDROP_HIERISSUE_MAINWINDOW_H
#define QT_03_TREEVIEW_DRAGDROP_HIERISSUE_MAINWINDOW_H
#pragma once
#include <QMainWindow.h>
#include "QVBoxLayout"
#include "QTreeView"
#include "QLabel"
#include "QPushButton"
#include <QHeaderView>
#include <QStandardItemModel>
using namespace std;
class mainWindow : public QMainWindow {
public:
    mainWindow(QWidget *parent = 0);
    ~mainWindow();
private:
    QVBoxLayout *layout;
    QTreeView *tree;
    QStandardItemModel *iModel;
    void addLayer(int a);
};
#endif //QT_03_TREEVIEW_DRAGDROP_HIERISSUE_MAINWINDOW_H

mainWindow.cpp

#include "mainWindow.h"
mainWindow::mainWindow(QWidget *parent) : QMainWindow(parent) {
    QWidget *w = new QWidget;
    setCentralWidget(w);
    setGeometry(500, 500, 1000, 1000);
    layout = new QVBoxLayout;
    layout->addWidget(new QLabel("TestTree"));
    centralWidget()->setLayout(layout);
    QPushButton *btn_layer = new QPushButton("Layer");
    connect(btn_layer, &QPushButton::clicked, this, &mainWindow::addLayer);
    layout->addWidget(btn_layer);
    iModel = new QStandardItemModel();
    tree = new QTreeView(this);
    tree->setModel(iModel);
    tree->setSelectionMode(QAbstractItemView::ExtendedSelection);
    tree->setAcceptDrops(true);
    tree->setDragEnabled(true);
    tree->setAutoScroll(true);
    tree->setDragDropMode(QAbstractItemView::InternalMove);
    tree->setDropIndicatorShown(true);
    tree->setAlternatingRowColors(true);
    iModel->setHorizontalHeaderLabels({"Name", "xx1", "xx2", "xx3"});
    tree->setSelectionMode(QAbstractItemView::ExtendedSelection);
    layout->addWidget(tree);
}

void mainWindow::addLayer(int a) {
    QStandardItem *itm = new QStandardItem();
    itm->setText(QString("Hey you Im parent  ") + to_string(a).c_str());
    itm->setCheckable(true);
    itm->isDragEnabled();
    itm->isDropEnabled();
    itm->setCheckState(Qt::Checked);
    QStandardItem *itm2 = new QStandardItem();
    itm2->setCheckable(true);
    itm2->setCheckState(Qt::Unchecked);
    QStandardItem *itm3 = new QStandardItem();
    itm3->setText("xx2");
    QStandardItem *itm4 = new QStandardItem();
    itm4->setText("xx3");
    iModel->appendRow({itm, itm2, itm3, itm4});
}
mainWindow::~mainWindow() {
}

Can any1 confirm the bug & suggest a fix perhaps?

Specs:
cLion & QtCreator 4.4.1
Visual Studio 2015/2017 - community editions
X64 build - if that make sense
Win 10x64 Pro

Regards
Dariusz

kenchan

Hi @Dariusz.

So what OS and toolchain are you using?
I tried your code on macOS 10.13.1 High Sierra clang and xCode Version 9.1 (9B55). I did not see the issue you describe in the video.

Dariusz

@kenchan said in Qt 5.9.2 QTreeView - Drag & Drop Broken ?:

Hi @Dariusz.

So what OS and toolchain are you using?
I tried your code on macOS 10.13.1 High Sierra clang and xCode Version 9.1 (9B55). I did not see the issue you describe in the video.

I added details at the bottom of the topic, sorry for not getting it initially.

kenchan

OK, I have a similar windows setup as you so I will try it on that later and let you know how it goes.

kenchan

I built that on my Windows 10x64 Qt 5.9.2 Visual Studio 2015 pro.
I did not see the issue you describe in the video.

Dariusz

@kenchan said in Qt 5.9.2 QTreeView - Drag & Drop Broken ?:

I built that on my Windows 10x64 Qt 5.9.2 Visual Studio 2015 pro.
I did not see the issue you describe in the video.

Using the same code? - just 2x checking. This is nuts then ! I have no idea how to even approach something like that o.o. Will try to run the code on my laptop see if he produces the same issue.

kenchan

Yes I copied and pasted the code you posted and tested it on macOS and windows.
I did not see what you show in the video.

Dariusz

This makes no sense at all. I dug out my laptop/tabled that is mostly facebook used. Spend 1h setting up visual studio qt and clion. Coded up the test from the ground up, drag/drop and I'm getting the same incorrect behavior I described above. What the hell is going on o.o ?! I now have 2 separate pcs that have that issue ;/

mrjj

Hi
Win 10, Qt 5.9. visual 2015.
I cannot make it break.

Dariusz

@mrjj said in Qt 5.9.2 QTreeView - Drag & Drop Broken ?:

Hi
Win 10, Qt 5.9. visual 2015.
I cannot make it break.

Thanks for testing it !

Are you dragging the 1st item from 1st group and 1st item from a group in 1st group? I mean like on the gif? I noticed if I drag it differently then it works but if I do that exact move then it breaks. I don't know how only I have the issues with 2 different pcs...

mrjj

@Dariusz
Yes I tried following video.
Could have missed something but did try multiple times.

Dariusz

@mrjj said in Qt 5.9.2 QTreeView - Drag & Drop Broken ?:

@Dariusz
Yes I tried following video.
Could have missed something but did try multiple times.

Black magic. In any case I reported it as bug and they - I think - have reproduced it as its now marked as P2. https://bugreports.qt.io/browse/QTBUG-64445

Thanks for ur time folks! Fingers cross QT team will fix it :- )

mrjj

@Dariusz
Super. good work.