Too slow adding & defining items to QTreeWidget

[Billy Lee Black]

You could try QTableView and a custom model. This way you can optimise item insertion to the maximum, but without any numbers it's hard to say whether it will be fast enough for you (some people reported 10x speed increase with custom model).

About the numbers, I am talking about 10.000 more items in the item view. It is just like the program Wireshark (Ethereal). So, I will need it very fast, because I am receiveing packages every time to show to the users.

But thanks for the tip. I will try the QTableView

[Billy Lee Black]

Well, I´ve made a custom Model and tried it with QTreeView and QTableView.

But both are still too slow even though my model is really simple.

In my application, I have like 8 columns in the view. I have to sniff network packets and print them in the view when I receive them. So, I am adding items to the view a lot of times, and each time I have to fill all the columns for each item added.

I really don't know anymore what to do. Will I have to implement a custom view too?

[jacek]

How do you add items to the model? One cell at a time or whole rows/subtrees?

[Billy Lee Black]

Well, I made a class that stores the data for all the columns of a row.

I set all the texts for the entire row and after that I add the row to the model.

[wysota]

Can we see the code?

[Billy Lee Black]

This is my method for adding one item( a row ) to the tableview:

void AkViewItemModel::addItem(AkViewWidgetItem *newItem)
{
  if(!newItem)
    return;
  int position = mItemsList.count();
  beginInsertRows(QModelIndex(), position, position);
  newItem->mViewWidget = mHeaderItem->akViewWidget();
  mItemsList.append(newItem);
  endInsertRows();
}

void AkViewItemModel::addItem(AkViewWidgetItem *newItem)
{
  if(!newItem)
    return;
  int position = mItemsList.count();
  beginInsertRows(QModelIndex(), position, position);
  newItem->mViewWidget = mHeaderItem->akViewWidget();
  mItemsList.append(newItem);
  endInsertRows();
}

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And below is the method to add a list of items:

void AkViewItemModel::addItems(QList<AkViewWidgetItem *> items)
{
  int beginRow = mItemsList.count();
  int numItems = items.count();
  beginInsertRows(QModelIndex(), beginRow, beginRow+numItems-1);
 
  AkViewWidgetItem *item = NULL;
  for(int i = 0; i < numItems; i++)
  {
    item = items[i];
    item->mViewWidget = mHeaderItem->akViewWidget();
    mItemsList.append(item);
  }
  endInsertRows();
}

void AkViewItemModel::addItems(QList<AkViewWidgetItem *> items)
{
  int beginRow = mItemsList.count();
  int numItems = items.count();
  beginInsertRows(QModelIndex(), beginRow, beginRow+numItems-1);
  
  AkViewWidgetItem *item = NULL;
  for(int i = 0; i < numItems; i++)
  {
    item = items[i];
    item->mViewWidget = mHeaderItem->akViewWidget();
    mItemsList.append(item);
  }
  endInsertRows();
}

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When I add a lot of single items, it is really slow! But if I accumulate some items in my application and then add them through a list, it becomes a lot faster and solves my problem.

Why are these methods beginInsertRows and endInsertRows so slow?

[wysota]

These methods are not slow. But they cause some signals to be emitted and each emition triggers a redraw of all the views displaying the model. So if you add 100 items a second then your application is busy refreshing the views. That's why it's better to accumulate changes and update the model in chunks.