Ubuntu.Components.StateSaver

Attached properties to save component property states. More...

Properties

• enabled : bool
• properties : string

Detailed Description

StateSaver attached object provides the ability to save component property values that can be restored after an inproper application close. The properties subject of serialization must be given in the properties as a string, separated with commas. The serialization will happen automatically on component's completion time, as well as when the application is deactivated. Automatic serialization of a component can be turned off by simply setting false to enabled property.

Note: The application name must be set correctly to the package name so that state saving can work (e.g. com.ubuntu.calendar) through MainView's applicationName property.

States saved are discarded when the application is closed properly. The state loading is ignored (but not discarded) when the application is launched through UriHandler.

Example:

import QtQuick 2.4
import Ubuntu.Components 1.2
TextField {
id: input
StateSaver.properties: "text"
StateSaver.enabled: input.enabled
}

In this example the state saver is synchronized with the attachee's one.

Group properties can also be serialized by specifying the path to their individual properties.

Rectangle {
id: rect
color: "gray"
border {
color: "blue"
width: units.gu(1)
}
StateSaver.properties: "color, border.color, border.width"
}

StateSaver computes a unique identifier for the attachee using the component's and all its parents' id. Therefore attachee component as well as all its parents must have a valid ID set.

The following example will give error for the input, as the root component has no id specified:

Item {
//[...]
Item {
id: parent
//[...]
TextField {
id: input
StateSaver.properties: "text"
}
}
}

but the following example will successfully save the text field content

Item {
id: root
//[...]
Item {
id: parent
//[...]
TextField {
id: input
StateSaver.properties: "text"
}
}
}

When used with Repeater, each created item from the Repeater's delegate will be saved separately. Note that due to the way Repeater works, Repeaters do not need to have id specified.

Item {
id: root
// [...]
Repeater {
model: 10
Rectangle {
id: rect
width: 50; height: 50
StateSaver.properties: "width, height"
}
}
// [...]
}

It can be used in the same way in ListView or GridView, except that both ListView and GridView must have an id set.

The StateSaver can save all QML base types, Objects, list of objects or variants containing any of these cannot be saved.

Property Documentation

The property drives the automatic state saving. When disabled, state saving will not happen on properties.

The default value is true.

List of properties to be serialized, separated with commas. Properties must be writable and can only be QML base types.

A custom single line input which saves the text, placeholderText, font and color would look as follows:

TextField {
id: input
StateSaver.properties: "text, placeholderText, font, color"
}