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:
QModelIndex a = valueToIndex(node_with_Changes);
dataChange.emit(a, a);
treeView.expand(a);
treeView.update(a);
It is working but sometimes I get this Exception:
Exception while executing queued connection: sender=N/A,
receiver=visu::RBRSMAB_Model(0x8424a78) public void
visu.RBRSMAB_Model.neueKinder(geom.tree.rbrsmabTree.RBRSMABNode,geom.tree.rbrsmabTree.RBRSMABNode,geom.tree.rbrsmabTree.RBRSMABNode,geom.tree.rbrsmabTree.RBRSMABNode,java.lang.String)
java.lang.IllegalArgumentException: inconsistency between childCount()
and expected child count. Expected 2, actual childCount() is 2
at
com.trolltech.qt.gui.QTreeModel.__qt_childrenInserted_QModelIndex_int_int(Native
Method)
at com.trolltech.qt.gui.QTreeModel.childrenInserted(QTreeModel.java:62)
at visu.RBRSMAB_Model.neueKinder(RBRSMAB_Model.java:64)
at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.trolltech.qt.internal.QtJambiInternal
$QMetaCallEvent.execute(QtJambiInternal.java:97)
at com.trolltech.qt.gui.QApplication.exec(Native Method)
at visu.Start.main(Start.java:119)
Sometimes the Exception says ... Expected 2, actual childCount() is
1 ...
What I am doing wrong? What Methods or Signals should i use to inform
the Model and the View???
The same Problem is with the
http://doc.trolltech.com/qtjambi-4.4/html/com/trolltech/qt/qtjambi-treemodel.html
example. The code of the file is in your qtjambi com/trolltech/examples
folder or see in the appendix.
If you create a new folder, the QTreeView doesn't show you the new
folder. If you collapse and expand, then you see the changes.(if you
create a new folder in the root, you cannot expand or collapse). What i
want is only that the view/model is updated immediately when the data
changes.
Thank you.
Best regards,
Waldemar (from Germany)
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**
** This file is part of Qt Jambi.
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package com.trolltech.examples;
import com.trolltech.qt.core.*;
import com.trolltech.qt.gui.*;
import java.util.*;
@QtJambiExample(name = "A Jambi Tree Model")
public class TreeModel extends QTreeView
{
private static class Model extends QTreeModel {
public Model(QObject parent) {
super(parent);
}
/**
* Returns the number of children this parent has.
*/
@Override
public int childCount(Object parent) {
return entryList(dir(parent)).size();
}
/**
* Converts the parent to a QDir and accesses its entry list to
* create a new QDir as the child.
*/
@Override
public Object child(Object parent, int row) {
QDir d = dir(parent);
return new QDir(d.absoluteFilePath(entryList(d).get(row)));
}
/**
* Converts the directory to a QDir and returns it.
*/
@Override
public String text(Object value) {
return ((QDir) value).dirName();
}
/**
* Convenience method for getting the entry list of a
* directory. This method also caches the previous entry list, as
* the same entry list is often used again and again.
*/
private List<String> entryList(QDir dir) {
if (dir == lastDirectory) {
return lastEntryList;
}
lastEntryList = dir.entryList(entryListFlags);
lastDirectory = dir;
return lastEntryList;
}
/**
* Convenience method for converting the object to a QDir. If the
* value is null, its the root.
*/
private QDir dir(Object value) {
return value != null ? (QDir) value : QDir.root();
}
private QDir lastDirectory;
private List<String> lastEntryList;
private QDir.Filters entryListFlags = new QDir.Filters(QDir.Filter.NoDotAndDotDot,
QDir.Filter.Dirs,
QDir.Filter.Files);
}
public TreeModel() {
this(null);
}
public TreeModel(QWidget parent) {
// Hide my header...
header().hide();
// Create our jambi file model
Model model = new Model(this);
setModel(model);
show();
// The QTreeModel does some caching of datastructures
// behind the scenes. To avoid memory pooling of this
// datastructure we can call the releaseChildren method to
// release parts of this pool when its no longer needed. One
// such case is when the view collapses a subtree and it is no
// longer visible.
collapsed.connect(model, "releaseChildren(QModelIndex)");
setWindowTitle("A Qt Jambi Tree Model");
setWindowIcon(new QIcon("classpath:com/trolltech/images/qt-logo.png"));
}
public static void main(String args[]) {
QApplication.initialize(args);
// Create the tree view.
TreeModel view = new TreeModel();
view.show();
// Spin the event loop
QApplication.exec();
}
}
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