Firefox OS/1UA Multi-Screen

Introduction

Goal

Our mission is to support "1 UA multi-screen" rendering on FxOS. Try imagine the following scenario, you have a computer set up in duel monitors, launch a Firefox browser on your primary display, launch another Firefox browser(or open a link in new window), and drag that new window to the secondary monitor. Our concept is similar but slightly different, where the baseline of this project is to allow a FxOS device connect and render contents to any non-FxOS display, or device that doesn't support Firefox browser.

Requirements

• Connect with external displays
  • For wireless connection, we have implemented Wifi Display with Miracast protocol. That is, any device capable of being a Miracast Sink, can be connected with a FxOS device.
  • For wired connection, we have implemented the HDMI output. This requires the support of hotplug detection in Hardware Composer.
• Open multiple top-level windows on FxOS
  • Gecko supports opening multiple top-level windows on browser naturally, while the FxOS supports single top-level window only, thus we are going to bring this ability back for FxOS.
• Manage multi-screen in System App

Advantages

• Having multiple top-level windows means that we will have multiple DOM trees and layer trees exist in the system. The secondary window should have no difference regarding to functionality then the original one, which means that we should be able to launch WebApps, web pages, and multimedia on this secondary window.
• With the case of "1 UA multi-screen" rendering, contents of remote screen are rendered by primary device, but in the resolution of its display.
• Open arbitrary number of top-level windows and associate each of them to a display device is doable theoretically, but it depends on the support of hardware capability.

Architecture Designs

Overview

This is an overview structure design from top to down.

Gecko

Design structure of gecko's part.

Gaia

Design structure of gaia's part.