[SOLVED]How to delete an item from the treeview by droping an item to pushbutton or to an group box

[Ratzz]

I have a treeview where the items are listed (say item 1 to item 10) and for each item (say item 1 )there are some subitem (say item11 to item 19) . I have a pushbutton "Delete items" which deletes the root item when psuhbutton is pressed (item1). Now i want to implement using drag and drop . Is it possible to drag item and drop the item to pushbutton "delete items" so that the root item deletes along with subitem ??
Adjacent to treeview there is a group box (group box has lineedit ,combobox, label etc). Is it possible to drag item and drop the item to groupbox so that the root item deletes along with subitem ???

[mrjj]

Hi
Yeah that should be possible
if you set setAcceptDrops(true);
for your mainwind/dialog
and then handle
void Window::dragMoveEvent(QDragMoveEvent *event)
and
void Window::dropEvent(QDropEvent *event)

I think if you set the action to move, the Tree will remove it when
drop triggers but not sure.
Else you just need to do when you do when button is clicked.

Look here for info about drag/drop
http://www.informit.com/articles/article.aspx?p=1405546

Note: Entire window will be drop target so in DragMove event they seems to do
if (event->answerRect().intersects(dropFrame->geometry()))
to check if it was over the wanted area. In this case a frame but could be button.

[Ratzz]

@mrjj
Thanks for the reply .
I have set setAcceptDrops(true); ui->treeView->setAcceptDrops(true);
and created void Window::dragMoveEvent(QDragMoveEvent *event)
and
void Window::dropEvent(QDropEvent *event)

void Window::dragMoveEvent(QDragMoveEvent *event)
{
    Window *source = qobject_cast<Window *>(event->source());
    if (source && source != this) {
        event->setDropAction(Qt::MoveAction);
        event->accept();
    }
}
void Window::dropEvent(QDropEvent *event)
{
    Window *source =qobject_cast<Window *>(event->source());
    if (source && source != this)
    {
        event->setDropAction(Qt::MoveAction);
        event->accept();
    }
}

I am unaware of how to set condition .

[mrjj]

@Ratzz said:

Hmm. Maybe I misunderstood you,

You want to drag from the tree to outside. ?
so ui->treeView->setAcceptDrops(true);
tells treeview it can be drop target. ( dropped on)
Should also tell you MainWindow
so Window (which is your mainwindow ? )
Normally it would be named MainWindow but if Window is you mainwin then all fine.

"set condition " ?
you mean
if (event->answerRect().intersects(dropFrame->geometry()))
or ?

[Ratzz]

@mrjj
Yes , I want to drag the item from the tree to outside and to pushbutton "Delete item".
I have to set setAcceptDrops(true); to pushbutton and groupbox area right?
yes i meant if (event->answerRect().intersects(dropFrame->geometry()))

[mrjj]

Ok so your mainwindow is the drop target
and you should call etAcceptDrops(true); in constructor.

and this line
if (event->answerRect().intersects(dropFrame->geometry()))

should be used to check its actually dropped on the button.
dropFrame should just be the name of your delete button.
It says if the Area for the drop is within the dropFrame Area.
as it , "dropped on the frame"

sosomething like

void (Main?)Window::dropEvent(QDropEvent *event)
{
    Window *source =qobject_cast<Window *>(event->source());
    if (source && source != this &&  
     (event->answerRect().intersects(ui->ThatButton->geometry())))
    {
        event->setDropAction(Qt::MoveAction);
        event->accept();
    }

All "Window" should be "MainWindow" in case its normal project. Unless you did
rename name it to Window yourself :)

[Ratzz]

@mrjj
Is the answerRect() member of QDropevnt(); ?
Because i get error

 error: 'class QDropEvent' has no member named 'answerRect'
(event->answerRect().intersects(ui->pushButton_DeleteMinorFrame->geometry())))
         ^

[mrjj]

@Ratzz said:

event->answerRect()

Hi. sorry my bad. its part of QDragMoveEvent
so should check in ::dragMoveEvent instead.

[SGaist]

Hi,

Wouldn't it be simpler to subclass QPushButton and add the drag'n'drop logic directly in it ?

[mrjj]

@SGaist
Yeah that is also an option , but since normally you already have a QMainWindow
subclass, i thought it could be slightly faster to add
and would work with most widgets after.

[Ratzz]

@mrjj
Adding event dragMoveEvent will work ??
Should not i add QDropevnt() ??

void MyWindow::dragMoveEvent(QDragMoveEvent *event)
{
      MyWindow *source =qobject_cast<MyWindow *>(event->source());
    if (source && source != this &&
     (event->answerRect().intersects(ui->pushButton_Delete->geometry())))
    {
        event->setDropAction(Qt::MoveAction);
        event->accept();
    }
}

I added the above but did not .

[Ratzz]

@SGaist
How to subclass QPushButton and add the drag'n'drop logic directly in it ??

[SGaist]

The same you would any other widget. Take a look at the Drag And Drop chapter in Qt's documentation

[Ratzz]

@SGaist
As suggested by @mrjj should i add QDropevnt()??
how will the dragMoveEvent come to know that i have to delete ?? Just dragging to pushButton_Delete will work??
When to call slot of deleting items??

[mrjj]

@Ratzz
Hi yes you would still need the DropEvent.

This works with ListWidget with dragDrop mode set to DragOnly.
Since the DropAction is "move", it did remove the item from the list.
Your result may vary.

#ifndef DROPBUTTON_H
#define DROPBUTTON_H

#include <QPushButton>
#include <QDragMoveEvent>

class DropButton : public QPushButton {
  Q_OBJECT
 public:
  explicit  DropButton(QWidget* parent = 0) : QPushButton(parent) {
    setAcceptDrops(true);
  }
 protected:
  void dragEnterEvent(QDragEnterEvent* event) {
    event->acceptProposedAction();
  }

  void dropEvent(QDropEvent* event) {
    event->setDropAction(Qt::MoveAction);
    event->accept();
  }
};

#endif // DROPBUTTON_H

[Ratzz]

@mrjj
I tried this

#include <QDragMoveEvent>
#include <QDropEvent>
protected:
    void dragMoveEvent(QDragMoveEvent *event);
    void dropEvent(QDropEvent *event);

ui->pushButton_DeleteMinorFrame->setAcceptDrops(true);

void Window::dragMoveEvent(QDragMoveEvent *event)
{
    Window *source =qobject_cast<Window *>(event->source());
    if (source && source != this &&
            (event->answerRect().intersects(ui->pushButton_DeleteMinorFrame->geometry())))
    {
        event->acceptProposedAction();
    }
}

void Window::dropEvent(QDropEvent *event)
{
    event->setDropAction(Qt::MoveAction);
    event->accept();
}

But above does not work for me. Where did i miss??
Control does not come to these function dragMoveEvent/dropEvent when i drag and drop

[mrjj]

Hi you have to use the Dropbutton also.

That is why I though using Mainwindow would be easier.

Best way to do that is to use the promote feature.

1. save the code in a file called dropbutton.h
   (just to be safe, also create dropbutton.cpp as empty)
2. right click on your button you want to be a drop button.
   Select "Promote To..."
   In "Promoted classname" type
   DropButton
   (case Matters!)
   in
   header file : type
   dropbutton.h
   Then click "Add" and then Promote.
   Now when you run the program, the normal buttons becomes the DropButton.

[ClapCreative]

Thanks mates

[Ratzz]

@mrjj
Yes, i Tried you code which turns out to be a Dropbutton. How to implement it in my code ?

[mrjj]

@Ratzz
As I wrote in answer ?
Using the promote feature.
Which will runtime replace a normal button with the DropButton.
Or you can new a button you self
Like
Dropbutton *but=Dropbutton (this)
and insert into your window/layout.