FocusEngine Framer Module

The FocusEngine module allows you to simulate the grid focus behavior seen on streaming media players like Apple TV and Roku. Use the keyboard, RemoteLayer, or another mechanism to direct focus around your prototype’s canvas.

Once initialized, any visible layer can be brought into focus, even if it’s off screen. This permits the activation of off-screen menus. Visual appearance of focused elements can be customized.

Installation

Manual installation

Copy or save the FocusEngine.coffee file into your project's modules folder.

Adding It to Your Project

In your Framer project add the following:

fe = require "FocusEngine"

API

Customize focused and unfocused states

fe.focusStyle.scale = <number>
fe.focusStyle.shadowX = <number>
fe.focusStyle.shadowY = <number>
fe.focusStyle.shadowColor = <string> (hex or rgba)
fe.focusStyle.shadowBlur = <number>
fe.focusStyle.shadowSpread = <number>

fe.unfocusStyle.shadowX = <number>
fe.unfocusStyle.shadowY = <number>
fe.unfocusStyle.shadowColor = <string> (hex or rgba)
fe.unfocusStyle.shadowBlur = <number>
fe.unfocusStyle.shadowSpread = <number>

(Unfocused scale is always assumed to be the layer’s original scale. This need not be 1. You may get better visual results by drawing your layer slightly larger than needed and setting its initial scale to something less than 1.)

Collect layers that will participate into an array

myFocusableLayers = [layerA, layerB, layerC]

Initialize the engine with your array

fe.initialize(myFocusableLayers)

Add a layer created post-initialization

fe.addLayer(layerD)

Optionally attach changeFocus() to keyboard events

document.addEventListener "keydown", (event) ->
    keyCode = event.which
    switch keyCode
        when 13 then fe.changeFocus("select")
        when 37 then fe.changeFocus("left")
        when 38 then fe.changeFocus("up")
        when 39 then fe.changeFocus("right")
        when 40 then fe.changeFocus("down")
        else null

Place initial focus

fe.placeFocus(layerA)

focusPrevious() is available to use in conjunction with FlowComponent's showPrevious()

fe.focusPrevious()

(Note that focus cannot be placed on a layer whose visibility, or whose ancestor’s visibility, is false. You may need to delay calling focusPrevious() until the FlowComponent’s transition is ended, perhaps by using .onTransitionEnd.)

Layers can trigger behavior upon receiving or losing focus, or being selected

layerA.on "focus", ->
layerA.on "unfocus", ->
layerA.on "selected", ->

Integration with RemoteLayer

RemoteLayer = require "RemoteLayer"
myRemote = new RemoteLayer
    clickAction: -> fe.changeFocus("select")
    swipeUpAction: -> fe.changeFocus("up")
    swipeDownAction: -> fe.changeFocus("down")
    swipeLeftAction: -> fe.changeFocus("left")
    swipeRightAction: -> fe.changeFocus("right")

Enable debug mode to log focus changes

fe.debug = true

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