Project Layout

Project Layout

• core: Core emulator code, shared among all platforms
• desktop: Desktop frontend and backend code
• render: Rendering backends code
• swf: Crate to handle SWF and AS parsing
• web: Web frontend and backend code
  • packages/demo: The web demo page (served at https://ruffle.rs/demo/)

Core

The core directory contains the Flash Player emulation code. This is used on all platforms to parse and execute the SWF file. The Player struct is the main entry point of the core code.

SWF

The swf directory contains a library for reading and writing SWF files and ActionScript bytecode.

Backends

There are several different types of backends to handle platform-specific behavior. There is a trait defining the interface for each type of backend. In addition, a "null" backend is provided for "no-op" behavior during development (for example, NullAudioBackend does not play any audio).

An instance of each backend type is passed into Player when it is created. Player uses trait objects to reference the backends, allowing for the backends to be dynamically chosen at runtime.

Rendering backend

The rendering backend handles drawing vector art, bitmaps, and text in whatever way suits the platform. The interface is defined by the RenderBackend trait.

Current rendering backends:

• Desktop
  • WgpuRenderBackend (using lyon for vector art tessellation and wgpu for rendering)
• Web
  • WebCanvasRenderBackend (using HTML5 CanvasRenderingContext2d)
  • WebGlRenderBackend
• NullRenderBackend

Potential future changes:

• Desktop
  • Add Pathfinder backend
  • Add software rendering backend?

Audio backend

The audio backend controls the playback, mixing, and dynamic control of audio from the SWF file. The interface is defined by the AudioBackend trait.

Current audio backends:

• NullAudioBackend
• CpalAudioBackend (desktop, using cpal)
• WebAudioBackend (web, using Web Audio API).

Potential future changes:

• Web
  • Decode audio on the fly and playback using ScriptProcessorNode. (possibly as an option).
  • Use AudioWorklet as they become standardized.

UI Backend

Not yet implemented. This backend will handle things such as changing mouse pointer state.

Navigator Backend

Not yet implemented. This backend will handle things such as loading external content, HTTP calls, or browsing to different pages.