How to paint a table from an item delegate?

I have a table where I display mostly text, however in some cases some cells have a list of values.

I wanted to render those lists as a one column table within the cell. For that reason I made my own item delegate and overloaded the QitemDelegate : : paint() function.

Inside, if I do not detect a list I just pass the flow :

Code:

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QItemDelegate::paint( painter, option, index );

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However, if I have a list I want to build that table. For testing I have:

Code:

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QTableWidget* tableWidget = new QTableWidget(0); 
  tableWidget->setRowCount(4);
  tableWidget->setColumnCount(1);
 
  tableWidget->setItem(0, 0, new QTableWidgetItem("x"));
  tableWidget->setItem(1, 0, new QTableWidgetItem("x"));
  tableWidget->setItem(2, 0, new QTableWidgetItem("x"));
  tableWidget->setItem(3, 0, new QTableWidgetItem("x"));

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Now my idea was to use that QTableWidget to paint the table, an so far the only way I saw to pass a QPainter parameter was with the render function:

Code:

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tableWidget->render(painter);

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That does not work and the cell looks empty (with/within saving/restoring the state before using render() ). Any idea about how could I reuse the painter of QTableWidget to draw that table???

Why don't you just draw the items directly?

I want to have have the list separated by lines, later I might need to add a second column. I did not like the idea of reimplementing the table widget/view painter... plus, I would like to learn how to reuse the painter of other widgets

Quote:

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Originally Posted by frank100

I did not like the idea of reimplementing the table widget/view painter...

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Creating a new widget every time some other widget is painted is a very bad idea.

Quote:

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plus, I would like to learn how to reuse the painter of other widgets

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When painting yourself, you'd be doing the exact same thing when it comes to "reusing the painter of another widget".

Thanks for the help, I realize I did not make a clear question :-(

Quote:

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Originally Posted by wysota

Creating a new widget every time some other widget is painted is a very bad idea.

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That was not my intention. Although I do that in my example, actually I defined one static QTableWidget instance inside the constructor of my item delegate. I rewrote that part within the paint() function of the question to make it less cluttered with code.

Quote:

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Originally Posted by wysota

When painting yourself, you'd be doing the exact same thing when it comes to "reusing the painter of another widget".

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That is what I want. For drawing a table within a cell I must align the text and draw lines for the grid. I expected that if the QTableView/QTableWidget have a painter doing what I want, there should be a way to reuse it.

Somehow I suppose I can give them the QPainter I receive from one of the parameters and let them do the drawing for me.

I could also make the question more generic. I have a table with a custom item delegate and I want this delegate to draw tables within some of the cells. I thought that painting myself was the way to go :confused:

Quote:

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Originally Posted by frank100

That was not my intention. Although I do that in my example, actually I defined one static QTableWidget instance inside the constructor of my item delegate. I rewrote that part within the paint() function of the question to make it less cluttered with code.

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But you still have to repopulate the widget each time you paint a cell.

Quote:

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That is what I want. For drawing a table within a cell I must align the text and draw lines for the grid. I expected that if the QTableView/QTableWidget have a painter doing what I want, there should be a way to reuse it.

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I think you misinterpret what "painter" is.