Create a custom Feathers UI theme
Feathers UI provides a system for styling all UI components in the same project by packaging all of the skins and styling code into single unit, called a theme. Many projects will a require custom look and feel that conveys a certain mood or integrates with established branding guidelines. The best way to add these styling requirements to a project is to create a custom theme.
The theme class
To start building a new theme from scratch, create a subclass of ClassVariantTheme. This base class makes it easy to register a function that sets styles on a particular type of UI component.
package com.example;
import feathers.themes.ClassVariantTheme;
class CustomTheme extends ClassVariantTheme {
public function new() {
super();
initialize();
}
private function initialize():Void {
}
}
Set UI component styles
Typically, a theme will define a number of functions to style different types of UI components. For example, the following function might be used to set the default styles for all Button components.
private function setButtonStyles(button:Button):Void {
var backgroundSkin = new RectangleSkin();
backgroundSkin.border = SolidColor(1.0, 0xff0000);
backgroundSkin.fill = SolidColor(0xffffff);
backgroundSkin.cornerRadius = 10.0;
button.backgroundSkin = backgroundSkin;
var downSkin = new RectangleSkin();
downSkin.border = SolidColor(1.0, 0xcc0000);
downSkin.fill = SolidColor(0xffeeee);
downSkin.cornerRadius = 10.0;
button.setSkinForState(ButtonState.DOWN, downSkin);
var format = new TextFormat("_sans", 16, 0xff0000);
button.textFormat = format;
var downFormat = new TextFormat("_sans", 16, 0xcc0000);
button.setTextFormatForState(ButtonState.DOWN, downFormat);
button.paddingTop = 10.0;
button.paddingBottom = 10.0;
button.paddingLeft = 20.0;
button.paddingRight = 20.0;
}
Inside the initialize() method of the theme class, register this function with the theme by adding the following call to setStyleFunction().
styleProvider.setStyleFunction(Button, null, setButtonStyles);
setStyleFunction() accepts three arguments.
- The UI component class that should be styled. In this case, it's
Button. - An optional variant. We aren't using a variant here, so we pass
null. - A function that will receive a UI component instance and set its styles.
Variants
If a project uses the same type of UI component in multiple places, but different instances need different appearances, a variant may be registered for that type of component. For example, a button that performs a destructive action (such as deleting data) might be given a red appearance.
Similar to above, here's another function that styles a Button with fancier styles.
private function setFancyButtonStyles(button:Button):Void {
var backgroundSkin = new RectangleSkin();
backgroundSkin.cornerRadius = 10.0;
backgroundSkin.border = Gradient(2, GradientType.LINEAR, [0xff9999, 0xcc0000], [1.0, 1.0], [0, 255], 90 * Math.PI / 180);
backgroundSkin.fill = Gradient(GradientType.LINEAR, [0xff9999, 0xff0000], [1.0, 1.0], [0, 255], 90 * Math.PI / 180);
button.backgroundSkin = backgroundSkin;
var downSkin = new RectangleSkin();
downSkin.cornerRadius = 10.0;
downSkin.border = Gradient(2, GradientType.LINEAR, [0xff0000, 0xcc0000], [1.0, 1.0], [0, 255], 90 * Math.PI / 180);
downSkin.fill = Gradient(GradientType.LINEAR, [0xff9999, 0xff0000], [1.0, 1.0], [0, 255], 270 * Math.PI / 180);
button.setSkinForState(ButtonState.DOWN, downSkin);
var format = new TextFormat("_sans", 20, 0xffeeee, true, true);
button.textFormat = format;
button.paddingTop = 10.0;
button.paddingBottom = 10.0;
button.paddingLeft = 20.0;
button.paddingRight = 20.0;
}
The call to setStyleFunction() will look similar, but this time, it should include a variant string.
styleProvider.setStyleFunction(Button, "fancy-button", setFancyButtonStyles);
This same string may be passed to the variant property of an individual UI component.
var button = new Button();
button.variant = "fancy-button";
As a best practice, it's a good idea to define custom variants as constants in the theme class.
public static final VARIANT_FANCY_BUTTON:String = "fancy-button";
Then, use the constant instead of the string value, for better compiler checking.
button.variant = CustomTheme.VARIANT_FANCY_BUTTON;