How to Define an Extra Style Field

Extra style fields allow to customize a widget by configuring graphical elements of the widget from the stylesheet. Extra fields are only relevant to a specific widget type and its subtypes. A widget type can support up to 7 extra fields. The value of an extra field may be represented as an int, a float or any object, and it can not be inherited from parent widgets.

Defining an extra field ID

The recommended practice is to add a public constant for the ID of the new extra field in the widget subtype. This ID should be an integer with a value between 0 and 6.

Every extra field ID has to be unique within the widget type. However, two unrelated widget types may define an extra field with the same ID.

For example, the following snippet defines an extra field for a secondary color:

public static final int SECONDARY_COLOR_FIELD = 0;

Setting an extra field in the stylesheet

The value of an extra field may be set in the stylesheet in a similar fashion to built-in style fields, using one of the setExtraXXX() methods of EditableStyle.

For example, the following snippet sets the value of an extra field for all the instances of a widget subtype:

EditableStyle style = stylesheet.getSelectorStyle(new TypeSelector(MyWidget.class));
style.setExtraInt(MyWidget.SECONDARY_COLOR_FIELD, Colors.RED);

Getting an extra field during rendering

The value of an extra field may be retrieved from the style of a widget in a similar fashion to built-in style fields, using one of the getExtraXXX() methods of Style. When calling one of these methods, a default value has to be given in case the extra field is not set for this widget.

For example, the following snippet gets the value of an extra field of the widget:

Style style = getStyle();
int secondaryColor = style.getExtraInt(SECONDARY_COLOR_FIELD, Colors.BLACK);