Drag and Drop different item text in two QListWidgets

Mr-Workalot

I have two QListWidgets , one named “Commands” on the left side and other named “XML Script” on the right side , I am able to drag and drop items from one List to another, How ever, when I drag one item, I don’t want drop that same item text, I want some changed text to be dropped.

Example: In this example when I dragged “SetScroll Command” from “commands” QListWidget and I am trying to drop this in “XML Script” QListWidget , I need some different text to be dropped like If I drag ‘Pause Command’ from “Commands”, the dropped item in “XML Script ”should have item with text like “This is a Pause Command”

?? How can I achieve this, I am intending to keep a Map data structure which will have key as “Pause Command” and Value as “This is a Pause Command”. Whenever key text is dragged , value text shall be dropped,

Any help appreciated.

Bonnie

You can add user data to QListWidgetItem

QListWidgetItem *item = new QListWidgetItem("Pause Command");
item->setData(Qt::UserRole, QString("This is a Pause Command"));

And in the mimeData function which you has reimplemented, use

item->data(Qt::UserRole).toString()

instead of item->text()
*Note: If you want to drop different text to different text editers, then this won't work.

You can even define more user roles to store different datas

#define MIME_TEXT_ROLE Qt::UserRole + 1
#define MIME_HTML_ROLE Qt::UserRole + 2

Mr-Workalot

Can you please code the mimeData Function ??

Bonnie

@Mr-Workalot
It's just the reimplemented QListWidget::mimeData function, I think you already implemented it in your previous post.

protected:
    QMimeData* mimeData(const QList<QListWidgetItem*> items) const
    {
        QMimeData* mime= QListWidget::mimeData(items);
        QString text;
        for (QListWidgetItem* item : items)
            text.append(item->data(Qt::UserRole).toString()).append('\n');
        mime->setText(text);
        return mime;
    }

Mr-Workalot

@Bonnie i tried the above mimeData function , when i drag from one QListWIdget to another QListWidget, it only transfers "Pause Command" and not its data i.e"This is a Pause Command",

However, when i drag from QListWidget to QTextEdit , after dragging it shows "This is a Pause Command".

VRonin

No need to reimplement QListWidget::mimeData. See https://forum.qt.io/post/444126

Mr-Workalot

@VRonin Thanks for this, i got slight hope that my problem is solvable , but still kind of helpless here, in my case i want to drag item from one QListWidget-1 to QListWidget-2 but after dragging the text of that item in List widget -2 should change.

How can i acheive this ? , can you please provide code for Drop EVent ?

SGaist

Hi,

You have the code in the link @VRonin provided.

Mr-Workalot

@SGaist Okay, But in my case this function does not gets executed, so, before

void MainWindow::dropEvent(QDropEvent* event)

gets invoked , do i need to enter any other function ??

SGaist

Why are you implementing that method for your MainWindow ?

Bonnie

@Mr-Workalot
Oh, sorry, I was misunderstanding your need, thinking you need to drop the text to a text edit.
If you reimplement dropEvent, I think you should create a new class for listwidget-2 and reimplement there.

Mr-Workalot

@SGaist Yeah, that's what, it kind of felt wrong to me, the place from where i am dragging is a modified QListWIdget,

std::map<QString, QString> commands;
bool first_time = true;

class ListWidget : public QListWidget {
private:

   //  map<QString, QString>::iterator it;
public:
   using QListWidget::QListWidget; 
protected: 
   QMimeData* mimeData(const QList<QListWidgetItem*> items) const
   {
       
       QMimeData* md = QListWidget::mimeData(items);
       QStringList texts;
       for (QListWidgetItem* item : selectedItems())
       {
         auto it = commands.find(item->text());
          texts << it->second;
       }
       if (first_time == true)
       {
           QString end = "</Script>";
           md->setText("<?xml version=\"1.0\" encoding=\"utf - 8\"?> \n <Script> \n"  + texts.join(QStringLiteral("\n")));
           first_time = false;
           return md;
       }
       else
       {
           md->setText(texts.join(QStringLiteral("\n")));
           return md;
       }
   }
};

and where i am dropping is a normal QListWidget,

should , i create a DropEvent for where i am dropping, right ??

and how do i create that , im very new to QT ?

Mr-Workalot

@Bonnie said in Drag and Drop different item text in two QListWidgets:

If you reimplement dropEvent, I think you should create a new class for listwidget-2 and reimplement there.

oh okay, thanks for clarifying. and how can i reimpliment drop event for listwidget-2 ??
what are the steps ??
, i know im asking too much but if you help me once, im gonna learn this for life.

Bonnie

@Mr-Workalot
Hmm..I tried to find an easiest way to handle this...
The QDataStream decode/encode thing may need to subclass the model, too.
So I think you just let it drop in the normal way, and then change it.

protected:
    bool dropMimeData(int index, const QMimeData *data, Qt::DropAction action)
    {
        if(QListWidget::dropMimeData(index, data, action)) {
            if(QListWidgetItem *dropped = item(index)) {
                dropped->setData(Qt::DisplayRole, dropped->data(Qt::UserRole));
            }
            return true;
        }
        return false;
    }

This is only working when you'll only accept drops from a item which you need to change its text to its Qt::UserRole.
If you want to accept drops from other items, you may need to add some conditional statements.