Custom editor for a delegate

Maser

Hi.
Im trying to make a custom editor for a delegate in a tableview. I tried to subclass QWidget and use it as a editor. Problem is, when i start it standalone, if works. If i pass it in the delegates createEditor and setEditorData, its blinks fast and goes right to setModelData without waiting for input. and its shown as a regulan window, but i want it without the close, minimize and fullscreen buttons and right on the top over my tableview where i startet it and in a size i spezify without disturbing the tableview. I think i dont get the basics right. Can someone give me an outline how i have to define my class for that and what function i need to implement or override?

mrjj

hi
". and its shown as a regular window, "

Are you sure u assign a parent?

QWidget *myw=new QWidget(this); // "this" is parent

QWidget *myw=new QWidget(); // no parent /default NULL)

Maser

No))) Well i was, but i forgot to call standard constructor from QWidget in my cpp. Now it pressing my editor in the cell of the tableview. Can i draw on top of the view?

Joel Bodenmann

To add to what @mrjj mentioned with the parent: You are actually supposed to assign the parent passed to the createEditor() function:

QWidget* ComboboxDelegate::createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
    Q_UNUSED(option)
    Q_UNUSED(index)

    QComboBox* combobox = new QComboBox(parent);
    combobox->addItems({"Foo", "Bar", "mrjj"});

    return combobox;
}

Maser

@Joel. yes, i did.

mrjj

@Maser said:

Can i draw on top of the view?

yes , you can override paintEvent and call base paint then then draw your self but
often there are better ways :)

Can I ask why you want to draw on view?

Maser

Well, my editor contains a number of images, from where i can choose one or several. as a markup that images are chosen i draw a red circle, around the activated ones. And the pictures are bigger, so they dont fit in the cell and the cell have to be resized when i draw it in the cell. So i figured i just draw it on top with a predefined size of a editorwidget.

mrjj

@Maser
ok. So its when you select the images, you want to draw over the view ? or
after you selected an image?

Im not sure how will it will work with scrolling etc.

Maser

No, no. I want my editor widget drawn on top when i start editing the cell. After i made the editing, the editor is gone and the changed state or whatever in inside the cell. Just for editing.

Maser

So any suggestions how i do this painting over? I suppose i have to somehow get the coordinates of the cell, then draw a barebone widget und maybe adjust it in the tableview frame. But i dont know where to start. Are there some examples on that?

mrjj

@Maser
Hi,
Maybe you should look into a delegate ?
http://doc.qt.io/qt-5/qtwidgets-itemviews-stardelegate-example.html

A delegate is the normal way to change how content is drawn in each cell.

Painting on the actual view will often have side effects with scrolling etc.

If you want to see, you will override the paintEvent virtual function
and paint there.

Maser

Im using a delegate. but i want the editor of the delegate drawn over the cell. I just need a hin how i connect the coordinates and draw a barebone widget. In wont have to be scrollable (yet).

mrjj

@Maser

Ok. Im not really following what u need. sorry.

In any case, you can override paintEvent for any widget and draw.
Notice that you cannot draw outside of the widgets client area so
make sure u override the paint for the actual widget u want to draw on.

Maser

It seems overriding paintevent doesnt work. What does work(at least partially) is reimplementing updateEditorGeometry from the delegate. When i give the specific cell a bigger size for the editor it paints it bigger. Even the choosing works, but not when there is another cell under from the tableview under my editor-buttons. Dont yet know how to solve that.

mrjj

@Maser
ok, can we see pic ?

Maser

http://www.picfront.org/d/9q7X
I marked the cell from which the editor has been activated. Problem is, as long is the items are of this cell or outside of the table, i can click them. if the are above other cells, the editor closes.

mrjj

@Maser
Could you not just pop a dialog with
all the images and let user select one?

Or use a combobox with a delegate ?
http://www.qtcentre.org/threads/26376-Using-images-in-QComboBox

Maser

This is a good idea)
But since im trying to learn Qt, i will save it for the emergency plan)
When i have a customer who wants it the exact way he described it, i wanna know how to do it, no matter of the cost)
Have you an idea why the over cells interfere with my editor and how i can solve it?

mrjj

@Maser said:

Have you an idea why the over cells interfere with my editor and how i can solve it?

I assume that click goes to real cell as the images is just painted over it
so u can not click on them as such.

Maser

No, i can. I told you. if i aim right in the black marked cell, i can click and unclick the three left items, i can also click the three right items. Just when i click anywhere in the tablecells, the editor is gone.

PS: Maybe i have to somehow resize the "working area" of the cell to to fit my editor. I mean the clickable area associated with the cell. Idea on that?

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