Virtual ComboBox

The virtual ComboBox acts like the regular ComboBox, but is based on the framework's virtual infrastructure.

Preview Image

widget/virtualcombobox.png

Features

  • Pointer and keyboard support.
  • Items with plain text and/or icons
  • Ellipsis: If the label does not fit into the widget's bounds an ellipsis (”...”) is rendered at the end of the label.
  • Supports filtering, sorting, grouping, data binding and custom rendering like the Virtual List.

Pointer and keyboard behavior:

       
  keyboard open drop-down key down; key up;
    close drop-down esc; enter
  pointer open drop-down tap on arrow button
    close drop-down tap on item; click outside drop-down
drop-down closed keyboard select next not possible
    select previous not possible
    select first not possible
    select last not possible
  pointer select next not possible
    select previous not possible
drop-down open keyboard select next key down then enter
    select previous key up then enter
    select first page up then enter
    select last page down then enter
  pointer select next tap on item
    select previous tap on item
    wrap in list no
    preselect pointer over; key up; key down
    select drop-down item on open yes, first item in the list which begins with value

Description

The qx.ui.form.VirtualComboBox is based on the virtual infrastructure. The virtual SelectBox has both a TextField and a Virtual List drop-down. The drop-down can be used to predefine values which the user can select.

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.

The virtual ComboBox uses the same qx.ui.list.core.IListDelegate interface as the Virtual List to configure the ComboBox's behavior (item and group renderer configuration, filtering, sorting, grouping, etc.).

Note

At the moment we only support widget based rendering for list and group 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 ComboBox example with 2500 items, sorting the items (ascending) and log each value change.

//create the model data
var rawData = [];
for (var i = 0; i < 2500; i++) {
  rawData[i] = "Item No " + i;
}
var model = qx.data.marshal.Json.createModel(rawData);

//create the SelectBox
var comboBox = new qx.ui.form.VirtualComboBox(model);

//configure the ComboBox's behavior
var delegate = {
  sorter : function(a, b) {
    return a > b ? 1 : a < b ? -1 : 0;
  }
};
comboBox.setDelegate(delegate);

//log value changes
comboBox.addListener("changeValue", function(e) {
  this.debug("Value: " + e.getData());
}, this);

Demos

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

API

Here is a link to the API of the widget:
qx.ui.form.VirtualComboBox
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