QTableWidget issues

[Djony]

Thanx for replies and sorry for stupid questions . What methods I need to reimplement in order to get my QItemDelegate to paint only 6th colum? Secondly, the painting depends on data (3 integer variables), as you can see on picture. How can I send those integers to QItemDelegate so the delegate can paint cell properly? Is there another way?

[wysota]

What methods I need to reimplement in order to get my QItemDelegate to paint only 6th colum?

paint() and/or drawDisplay(), depending on which class you subclass. It also depends how you install the delegate. You can install it for a single column only or for all columns (then you have to reimplement paint() to call the base class implementation for columns other then 6th.

Secondly, the painting depends on data (3 integer variables), as you can see on picture. How can I send those integers to QItemDelegate so the delegate can paint cell properly? Is there another way?

There are different ways to do this. I'd suggest using different item roles for each "colour" or setting a list of values as the data for the display role (setData(6, Qt::DisplayRole, QList<int>() << 1 << 2 << 3)) and then retrieve each value from within the delegate.

And I think it would be easier for you to subclass QItemDelegate and reimplement its paint() method than to go for drawDisplay().

[Djony]

paint() and/or drawDisplay(), depending on which class you subclass. It also depends how you install the delegate. You can install it for a single column only or for all columns (then you have to reimplement paint() to call the base class implementation for columns other then 6th.

How can I install delegate for just single column? I have decided to use QItemDelegate and to reimplement it's paint metod.

There are different ways to do this. I'd suggest using different item roles for each "colour" or setting a list of values as the data for the display role (setData(6, Qt:isplayRole, QList<int>() << 1 << 2 << 3)) and then retrieve each value from within the delegate.

Maybe I've explained it wrong in previous post The data shown in that "colored column" will not be changed by the user. It should be shown and "colored" by the delegate based upon the values that some other class reads from SQLITE 3 database. If you mean't the same thing, which methods from QItemDelegate I need to reimplement and how (in which direction, I don't have any idea)? How can I "send" those integers to delegate so he can color cells?

[wysota]

How can I install delegate for just single column?

First thing to do is to browse QAbstractItemView docs and find the answer there.

If you mean't the same thing,

I did.

which methods from QItemDelegate I need to reimplement and how (in which direction, I don't have any idea)? How can I "send" those integers to delegate so he can color cells?

My previous answer still stands. Please read about item roles and Qt MVC implementation.

[Djony]

Thank you for replies. I've read documentation about item roles, models, views, delegates etc. If I understood you right, you are suggesting me to create model and reimplement it's setData() method and to store list of values in it (I am wondering at the moment which model class should I use, considering the fact that I am using QTableWidget. Should it be QStandardItemModel or I need to subclass QAbstractItemModel class?). After that, my delegate class will with data() get list of values and based on those values color the cell. That's cool.
But, when reimplementing paint() method I need to know cordinates (and dimensions) of whole cell, so I can paint properly. How can I retrieve cordinates (and dimensions) of whole cell in delegate class? (Maybe I've asked this before, but I don't get it...)
Again, thanx for replies

[wysota]

If you use QTableWidget, then you don't need to touch the model, as QTableWidget already implements one for you. Just use QTableWidgetItem::setData() to store data and implement a custom delegate to display it.

[Djony]

OK, but can you please tell me how can I retrieve width of table cell in my delegate class?

[wysota]

QStyleOptionViewItem::rect

[Djony]

Thanx
I have subclassed QTableWidgetItem and implemented setData() and data() methods. But, I have now problem with storing data (sending those 3 ints). Don't know how to store a list of ints a pass them as QVariant. This is my code:

listVariant2.clear();   	     	   
 
   listVariant2.append(QVariant(countOfFail));  
 
  //countOfFail is int, listVariant is QList <QVariant>  type
 
  listVariant2.append(QVariant(countOfPass)); //countOfPass is int
   listVariant2.append(QVariant(countOfNA));   //countOfNA is int
 
   	     tableItem->setData(Qt::DisplayRole,QVariant(listVariant2)); /*tableItem is type of class  which inherits QTableWidgetItem class
*/

listVariant2.clear();   	     	   
   	     	   
   listVariant2.append(QVariant(countOfFail));  

  //countOfFail is int, listVariant is QList <QVariant>  type
 
  listVariant2.append(QVariant(countOfPass)); //countOfPass is int
   listVariant2.append(QVariant(countOfNA));   //countOfNA is int
   	     	
   	     tableItem->setData(Qt::DisplayRole,QVariant(listVariant2)); /*tableItem is type of class  which inherits QTableWidgetItem class
*/

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I have debugged and discovered that code crashes when calling last instruction (I got segmentation fault, SIGSEV). Probably because of that "QVariant thing"...
This is probably wrong way of thinking (I am talking about my code), but the best I could think of right now. Could you please give me instructions where to look to find better way to pass those 3 integers ? How to store them in a list as QVariant? Or some example/solution? Thanx for any reply

[wysota]

I have subclassed QTableWidgetItem and implemented setData() and data() methods.

What for? What was wrong with them?

But, I have now problem with storing data (sending those 3 ints). Don't know how to store a list of ints a pass them as QVariant.

QVariantList lst;
lst << 1 << 2 << 3;
tableItem->setData(QVariant(lst), Qt::DisplayRole);

QVariantList lst;
lst << 1 << 2 << 3;
tableItem->setData(QVariant(lst), Qt::DisplayRole);

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[Djony]

What for? What was wrong with them?

Aren't they virtual?

[wysota]

If a function is virtual it doesn't mean you have to reimplement it but that you may do it if you need to.

[Djony]

Thank you, you are right. But, now, that I've solved this, paint method of my delegate's class is never called (code never enters in that function). I set delegate for whole table like this:

tableTestSuits->setItemDelegate(new TableDelegate (this)); 
//tableSuits is QTableWidget type and TableDelegate inherits QItemDelegate

tableTestSuits->setItemDelegate(new TableDelegate (this)); 
//tableSuits is QTableWidget type and TableDelegate inherits QItemDelegate

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What can be wrong?

[jpn]

The signature of the function must match exactly, including return type, argument types, constness and such:

void paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const

[Djony]

Thank you, you are right (const at the end was missing). But now I have weird behaviour of application. All cells are empty (before implementing delegate there were strings shown in cells). Here is the body of paint method of my delegate's class:

QRect tempRect,rectangleCell=option.rect;
 
   int widthCell=rectangleCell.width();
 
   if (index.column()==4)
   {
       //painting only for 5th column
 
 
      tempVariant=index.model()->data(index,Qt::DisplayRole); 
 
             //retrieving data from appropriate model
 
      listOfVariants=tempVariant.toList();
      numberOfFails=listOfVariants.at(0).toInt();  //listOfVariants is QList <QVariant> 
      numberOfPass=listOfVariants.at(1).toInt();
      numberOfNa=listOfVariants.at(2).toInt();      
 
      //retrieving numbers to color in proper way
 
     .....
 
     //piece of code which fills rectangle with adequate color, manipulation with values  
    // that are stored in rectangleCell
 
   }
}

QRect tempRect,rectangleCell=option.rect;

   int widthCell=rectangleCell.width();

   if (index.column()==4)
   {
       //painting only for 5th column

    
      tempVariant=index.model()->data(index,Qt::DisplayRole); 

             //retrieving data from appropriate model

      listOfVariants=tempVariant.toList();
      numberOfFails=listOfVariants.at(0).toInt();  //listOfVariants is QList <QVariant> 
      numberOfPass=listOfVariants.at(1).toInt();
      numberOfNa=listOfVariants.at(2).toInt();      
   
      //retrieving numbers to color in proper way
    
     .....

     //piece of code which fills rectangle with adequate color, manipulation with values  
    // that are stored in rectangleCell
            	
   }
}

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Do you have any idea what is wrong? Thanx for reply

[jpn]

As if I understood, you are painting only some specific column(s). Other colums don't get painted at all. Maybe you want something like this:

if (index.column()==4)
{
    // your custom painting for the 5th column
}
else
{
    // let QItemDelegate paint when other columns in question
    QItemDelegate::paint(painter, option, index);
}

if (index.column()==4)
{
    // your custom painting for the 5th column
}
else
{
    // let QItemDelegate paint when other columns in question
    QItemDelegate::paint(painter, option, index);
}

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[Djony]

You rock! Now I have problem with retrieving integers from QVariant that I've previosly stored via setData() (look above how wysota showed me to store integers in qvariantlist). I am getting very wierd values for integers. Here is my code where I try to retrieve integers:

tempVariant=index.model()->data(index,Qt::DisplayRole);
      listOfVariants=tempVariant.toList();
      numberOfFails=listOfVariants.at(0).toInt(); //numberOfFails is int
      numberOfPass=listOfVariants.at(1).toInt(); //numberOfPass is int
      numberOfNa=listOfVariants.at(2).toInt();   //numberOfNa is int
//those 3 integers I later use for painting my cell

tempVariant=index.model()->data(index,Qt::DisplayRole);
      listOfVariants=tempVariant.toList();
      numberOfFails=listOfVariants.at(0).toInt(); //numberOfFails is int
      numberOfPass=listOfVariants.at(1).toInt(); //numberOfPass is int
      numberOfNa=listOfVariants.at(2).toInt();   //numberOfNa is int
//those 3 integers I later use for painting my cell

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I don't know what I am doing wrong. Is there better way to retrieve integers?

[jpn]

I can't spot anything particular in the code above that could be causing the problem. The bug must be elsewhere. I suggest you to double check the part of the code which sets the values.

Nevertheless you could check if the conversion from variant to int succeeds:

bool ok = false;
numberOfFails=listOfVariants.at(0).toInt(&ok);
if (!ok)
   // failed

bool ok = false;
numberOfFails=listOfVariants.at(0).toInt(&ok);
if (!ok)
   // failed

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By the way,

tempVariant=index.model()->data(index,Qt::DisplayRole);
// could be simply written as
tempVariant=index.data(Qt::DisplayRole);
// or even as
tempVariant=index.data();

tempVariant=index.model()->data(index,Qt::DisplayRole);
// could be simply written as
tempVariant=index.data(Qt::DisplayRole);
// or even as
tempVariant=index.data();

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It actually ends up calling the same what you have written but is more readable, isn't it..?

[Djony]

You are right, values are OK. Can you tell me, when I do inside my delegate:

QRect rectangleCell=option.rect;

QRect rectangleCell=option.rect;

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Does rectangleCell then holds the dimensions of whole table or just current cell?

[jpn]

It contains the geometry of the index to be painted, so the current cell.