kyle watson wrote:
I'm trying to implement a shift up and shift down capability for
children of a given node in a class i've derived from QTreeModel. I
make the changed in my underlining data structure but i'm currently
unable to notify qt of the change. Since there isn't a swap function i
have to remove the node i'm shifting from the model using
childrenRemoved but then i'm unable to notify qt that i've inserted a
node. The childrenInserted method is only be able to append to the end
of the children and emitting the dataChanged signal isn't causing my
QTreeView to update. Emitting a layoutChanged does cause the updates
but it destroys the current state of the tree. Any help would be great.
Thanks,
Kyle
Hi Kyle,
In my general purpose QTreeModel testing application I have no problems
with swapping child nodes etc. See the swap() function for how its done.
Its just a matter of updating the model with childrenRemoved() followed
by a childrenInserted().
Emitting dataChanged() indicates that the data for a given entry has
changed. It doesn't notify the view of any changes to the tree structure
it self.
best regards,
Gunnar
/****************************************************************************
**
** Copyright (C) 1992-$THISYEAR$ $TROLLTECH$. All rights reserved.
**
** This file is part of $PRODUCT$.
**
** $JAVA_LICENSE$
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/
package com.trolltech.tests;
import com.trolltech.qt.core.*;
import com.trolltech.qt.gui.*;
import java.util.*;
/**
* A pretty basic node implementation...
*/
class Node {
public Node(String s, Model model, Node parent) {
this.text = s;
this.model = model;
this.parent = parent;
}
@Override
public String toString() { return text + ":" + counter; }
List<Node> children = new ArrayList<Node>();
String text;
int counter;
Model model;
Node parent;
}
/**
* An example model implementation. It reimplements child(), childCount() and
text() to
* represent the data in a tree of Node's
*/
class Model extends QTreeModel {
/**
* Called to query the child of parent at index. If parent is null we have
only one child,
* the root.
*/
@Override
public Object child(Object parent, int index) {
if (parent == null)
return root;
return ((Node) parent).children.get(index);
}
/**
* Called to query the number of children of the given object or the number
of root objects if
* parent is null.
*/
@Override
public int childCount(Object parent) {
int count = parent == null ? 1 : ((Node) parent).children.size();
return count;
}
/**
* Convenience virtual function to get the textual value of an object. I
could also
* implement icon() for pixmap data or the data() function for other types
of roles.
*/
@Override
public String text(Object value) {
return "" + value;
}
public Node root() { return root; }
private Node root = new Node("Root", this, null);
}
/**
* A simple test application. It adds four actions, "add", "remove" and
* "increment" and "swap" to test that we can add, remove and change the
* value of nodes in the tree.
*/
public class TreeModelTester extends QTreeView {
public TreeModelTester() {
this(null);
}
public TreeModelTester(QWidget parent) {
super(parent);
setModel(model);
QAction add = new QAction(this);
add.setShortcut("Ctrl+A");
add.triggered.connect(this, "add()");
QAction remove = new QAction(this);
remove.setShortcut("Ctrl+R");
remove.triggered.connect(this, "remove()");
QAction increment = new QAction(this);
increment.setShortcut("Ctrl+I");
increment.triggered.connect(this, "increment()");
QAction swap = new QAction(this);
swap.setShortcut("Ctrl+S");
swap.triggered.connect(this, "swap()");
addAction(add);
addAction(remove);
addAction(increment);
addAction(swap);
}
public void setModel(Model model) {
this.model = model;
super.setModel(model);
}
private void swap() {
System.out.println("Swapping?");
List<QModelIndex> pos = selectedIndexes();
for (QModelIndex i : pos) {
Node me = (Node) model.indexToValue(i);
Node parent = me.parent;
if (me.parent != null) {
int mepos = parent.children.indexOf(me);
if (mepos < parent.children.size() - 1) {
Node other = parent.children.get(mepos);
QModelIndex parentIndex = model.valueToIndex(parent);
parent.children.remove(me);
model.childrenRemoved(parentIndex, mepos, mepos);
parent.children.add(mepos + 1, me);
model.childrenInserted(parentIndex, mepos + 1, mepos + 1);
} else {
System.out.println("cannot swap last element...");
}
} else {
System.out.println("cannot swap the root node..");
}
}
}
private void add() {
List<QModelIndex> pos = selectedIndexes();
for (QModelIndex i : pos) {
Node n = (Node) model.indexToValue(i);
assert n != null;
int size = n.children.size();
Node child = new Node(names[(int) (Math.random() * names.length)],
model, n);
n.children.add(child);
model.childrenInserted(i, size, size);
}
}
@SuppressWarnings("unused")
private void remove() {
List<QModelIndex> pos = selectedIndexes();
for (QModelIndex i : pos) {
Node n = (Node) model.indexToValue(i);
assert n != null;
if (n == model.root())
continue;
QModelIndex parentIndex = model.parent(i);
Node parent = (Node) model.indexToValue(parentIndex);
parent.children.remove(n);
model.childrenRemoved(parentIndex, i.row(), i.row());
}
}
@SuppressWarnings("unused")
private void increment() {
List<QModelIndex> pos = selectedIndexes();
for (QModelIndex i : pos) {
Node n = (Node) model.indexToValue(i);
n.counter++;
model.dataChanged.emit(i, i);
}
}
private Model model = new Model();
private String names[] = { "Alpha", "Beta", "Gamma", "Delta" };
public static void main(String args[]) {
QApplication.initialize(args);
TreeModelTester w = new TreeModelTester();
w.setWindowTitle("Tree Model Tester");
w.show();
if (args.length > 0 && args[0].equals("--extra-view")) {
for (int i=0; i<3; ++i) {
TreeModelTester t = new TreeModelTester();
t.setWindowTitle("Extra view: " + (i+1));
t.disableGarbageCollection();
t.show();
t.setModel(w.model);
}
}
QApplication.exec();
}
}
_______________________________________________
Qt-jambi-interest mailing list
[email protected]
http://lists.trolltech.com/mailman/listinfo/qt-jambi-interest
