Platform_Integration.md

Platform Integration Notes

This document summarizes research and implementation notes regarding integrating Bridge with various platforms.

Android Integration

Android integration involves several key areas:

Android WebView

The Android WebView component has evolved significantly over time:

• Early versions were embedded in the Android OS and couldn't be updated independently
• Modern versions (KitKat and later) are updated through Google Play Services
• WebView runs in a separate process from the main application on newer Android versions

Key files:

• AndroidWebView.txt - Details on WebView implementation and capabilities
• AndroidAPI.txt - Android API version information and compatibility notes
• AndroidDev.txt - Android development tools and workflows

Android Graphics Integration

Bridge uses SurfaceTexture and GL_TEXTURE_EXTERNAL_OES for efficient texture sharing between WebView and Unity:

// Key concepts in integrating WebView with Unity textures
SurfaceTexture surfaceTexture = new SurfaceTexture(textureId);
surface = new Surface(surfaceTexture);
// Allow rendering WebView to this surface

See SurfaceTexture.txt and ZeroCopy.txt for details.

iOS Integration

WKWebView and UIWebView

Bridge has adapted to Apple's transition from UIWebView to WKWebView:

• UIWebView: In-process, no JIT, easier to access directly from native code
• WKWebView: Out-of-process, JIT enabled, requires message passing

The change required a major architectural shift in how Bridge communicates between JavaScript and Unity.

Key files:

• WkWebView.txt - Implementation details and limitations
• AppTransportSecurity.txt - Handling network security in iOS

IOSurface for Texture Sharing

Bridge uses IOSurface for zero-copy texture sharing between processes on iOS:

// IOSurface is the macOS/iOS API for sharing GPU memory between processes
IOSurfaceRef surface = IOSurfaceCreate(properties);
// Bind to GL texture
CGLTexImageIOSurface2D(context, target, internalFormat, width, height, format, type, surface, 0);

See IOSurface.txt for implementation details.

macOS Integration

macOS integration presents unique challenges:

• Conflicts with Unity Editor's use of Chromium Embedded Framework (CEF)
• Options for browser embedding: Native WebView, WKWebView, CEF, or Electron
• Direct texture sharing using IOSurface

Key files:

• OSX.txt - macOS-specific implementation notes
• OSXOpenGL.txt - OpenGL integration on macOS
• OSXSharedLibraries.txt - Dynamic library loading

WebGL Platform

The WebGL platform requires unique approaches since the Unity application itself runs within the browser:

• No need for embedded browser - can use the host browser directly
• WebAssembly memory sharing for efficient texture and data transfer
• P/Invoke and jslib for bridging between C# and JavaScript

Key files:

• UnityWeBGLTextures.txt - Texture handling in WebGL builds
• WebBrowser.txt - Browser component integration details

Windows Integration

Windows integration explores several approaches:

• Chrome Embedding Framework (CEF)
• Electron
• Native browser components

See Windows.txt for implementation details.