Am Montag, den 23.06.2008, 09:20 +0200 schrieb Gunnar Sletta:
> Waldemar Wittmann wrote:
> > Hi all,
> >
> > i am vizualising a real Tree Datastructure. It's a binary Tree where
> > each Node has always 2 Childs (leafs have 0 childs) and one parent (in
> > the case of the root node no parent).
> > I have extended QTreeView and I extended QTreeModel. The problem is, the
> > Tree Datastructure changes, for example new nodes are inserted or nodes
> > are deleted and i want to see immediately the changes in the QTreeView
> > without clicking (it's a vizualisation).
> > My tree-node class extends the QSignalEmitter and sends signals to my
> > methods in the extended QTreeModel class. So i have the required
> > information on which node the change is, for example that a node had 0
> > childs and now 2 childs.
> > I looked for Methods how to inform the QTreeModel or the QTreeView about
> > the changes but didn't really find them. I tried the following in the
> > slot method (the signals from the tree-nodes are connected with this
> > method) in my extended QTreeModel class:
> >
> Hi Waldemar,
>
> The methods you are looking for are childrenInserted and childrenRemoved:
>
> http://doc.trolltech.com/qtjambi-4.4/html/com/trolltech/qt/gui/QTreeModel.html#childrenInserted(com.trolltech.qt.core.QModelIndex,%20int,%20int)
> http://doc.trolltech.com/qtjambi-4.4/html/com/trolltech/qt/gui/QTreeModel.html#childrenRemoved(com.trolltech.qt.core.QModelIndex,%20int,%20int)
>
> As for the Treemodel file example, its more an example bug. The example
> should really listen to filesystem using QFileSystemWatcher and updated
> repeadedly but it currently doesn't ;-)
>
> The attached example illustrates adding and removing items programatically.
>
> best regards,
> Gunnar
Hi all,
Gunnar, thank you very much for your answer and your example :)
1)
You used the
model.dataChanged.emit(i, i);
signal to update the node (text) in the view. Calling the
view.update(i);
method works too, or should i better use the signal? makes this a
difference?
2)
Perhaps you can see in the application you sent that inserting into a
node without children doesn't update the node. You don't see after
inserting, that you can expand it. Not until you click on it or
somewhere else. Is it a Bug?
That was the reason why I thought there is no suitable method in the
QTreeModel for the insertion. I tried to use the childrenInserted Method
but didn't see the insertion ...
What I do now for my tree is simply calling expand(i); after the
insertion:
model.childrenInserted(i, l, r);
expand(i);
I keep my tree alway expanded, because i want to see always the whole
tree. If someone doesn't want to keep the tree expanded but wants to see
that after the insertion the node is expandable could do simply
something like that:
Node n = (Node) model.indexToValue(i);
//before the insertion:
size = n.children.size();
// <- here should be the code for the insertion of r-l+1 Elements into
node n
model.childrenInserted(i, l, r);
if(size==0) {
expand(i);
collapse(i);
}
The childrenRemoved method updates the tree and the childrens and the
whole tree under them disappear. That is working.
3)
My tree datastructure is doing Rotations. So a node n with QModelIndex i
becomes the two subtrees of two other nodes one/two levels under it. I
handle it with
childrenRemoved(i, 0, 1);
childrenInserted(i, 0, 1);
treeView.expand(i);
it seems to work. the view seemingly builds the tree below "i" new. My
problem is that only the node "i" expands. I want to see always the
whole tree expanded. Under "i" could be a bigger subtree. Is there an
other possibility to solve it excepting treeView.expandAll(); ?
The expandAll(); method costs a lot of time and performance how i have
seen during tests. For example I have 500 Nodes in my tree and the whole
tree is expanded. After the rotation i do the operations
(childrenRemoved, childrenInserted, expand) on a node with about 10
nodes under it. Now i can only see the two children of n. and only a few
nodes should be expanded that the whole tree is expanded. but if i do
now expandAll() it seems that it goes top down through all nodes and
tries to expand them? looks like that because the cpu load goes high. is
it possible to full expand the subtree under a node with less cpu load?
how?
4)
I want to have 2 different modes how to display the text of all nodes in
the tree. i switch in my model.text(Object o) method between them. I
want that the whole tree displays immediately the Text of all Nodes in
the selected mode. I change the mode in the text(Object o) method and do
an treeView.collapseAll() and treeView.expandAll(). It works but is
there a better possibility to update the text of all nodes of the whole
tree in the view?
5)
The QTreeModel class is not included in Qt, so there must be a
QTreeModel.java file, but i could not find it in the source download of
qt jambi.
6)
How must I modify my extended QTreeView class, so that the tree
structure is painted like a tree datastructure:
for example:
not:
root
|-root.l
| |-root.l.l
| |-root.l.r
|-root.r
|-root.r.l
| |-root.r.l.l
| |-root.r.l.r
|-root.r.r
but:
|-root.l.l
|-root.l-|
| |-root.l.r
root-|
| |-root.r.l.l
| |-root.r.l-|
| | |-root.r.l.r
|-root.r-|
|-root.r.r
see appendix, if the trees are blurred.
sorry, for so many questions. but i think that would be all for now ;)
best regards,
Waldemar
root
|-root.l
| |-root.l.l
| |-root.l.r
|-root.r
|-root.r.l
| |-root.r.l.l
| |-root.r.l.r
|-root.r.r
|-root.l.l
|-root.l-|
| |-root.l.r
root-|
| |-root.r.l.l
| |-root.r.l-|
| | |-root.r.l.r
|-root.r-|
|-root.r.r
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