VirtualTree

The VirtualTree is a widget based on the framework's virtual infrastructure.

Preview Image

Description

The qx.ui.tree.VirtualTree is based on the virtual infrastructure and supports single selection, multi selection, data binding and custom rendering.

Using the virtual infrastructure has considerable advantages when there is a huge amount of model items to render: Widgets are created only for visible items and reused. This saves both creation time and memory.

With the qx.ui.tree.core.IVirtualTreeDelegate interface it is possible to configure the tree's behavior (item renderer configuration, etc.).

Note

At the moment we only support widget based rendering for tree items, but we are planning to also support HTML based rendering in a future release.

Code Example

Here's an example. We create a simple tree example with 2500 items and log each selection change.

//create the model data
var nodes = [];
for (var i = 0; i < 2500; i++)
{
  nodes[i] = {name : "Item " + i};

  // if its not the root node
  if (i !== 0)
  {
    // add the children in some random order
    var node = nodes[parseInt(Math.random() * i)];

    if(node.children == null) {
      node.children = [];
    }
    node.children.push(nodes[i]);
  }
}
// converts the raw nodes to qooxdoo objects
nodes = qx.data.marshal.Json.createModel(nodes, true);

// creates the tree
var tree = new qx.ui.tree.VirtualTree(nodes.getItem(0), "name", "children").set({
  width : 200,
  height : 400
});

//log selection changes
tree.getSelection().addListener("change", function(e) {
  this.debug("Selection: " + tree.getSelection().getItem(0).getName());
}, this);

Demos

Here are some links that demonstrate the usage of the widget:

• Example for the VirtualTree widget
• Example with custom items as columns
• Example which loads items dynamically when a nodes is opened

API

Here is a link to the API of the widget:

qx.ui.tree.VirtualTree