Native Android (Kotlin)

Integrate FaceGuard into native Android apps using WebView.

Setup

Add camera permission to AndroidManifest.xml:

AndroidManifest.xml

<uses-permission android:name="android.permission.CAMERA" />

Implementation

FaceGuardActivity.kt

class FaceGuardActivity : AppCompatActivity() {

    private lateinit var webView: WebView

    fun startVerification(token: String) {
        webView = findViewById(R.id.webview)

        webView.settings.apply {
            javaScriptEnabled = true
            domStorageEnabled = true
            mediaPlaybackRequiresUserGesture = false
        }

        // Camera permission
        webView.webChromeClient = object : WebChromeClient() {
            override fun onPermissionRequest(request: PermissionRequest) {
                if (request.resources.contains(PermissionRequest.RESOURCE_VIDEO_CAPTURE)) {
                    request.grant(request.resources)
                }
            }
        }

        // Listen for postMessage
        webView.addJavascriptInterface(object {
            @JavascriptInterface
            fun onMessage(json: String) {
                val data = JSONObject(json)
                if (data.optString("action") == "close") {
                    val reason = data.optString("reason")
                    val confidence = data.optDouble("confidence", 0.0)
                    runOnUiThread {
                        when (reason) {
                            "approved", "bypass_active" -> handleApproved(confidence)
                            "rejected" -> handleRejected(confidence)
                            "canceled" -> handleCanceled()
                            "error", "no_base_photo" ->
                                handleError(data.optString("error", reason))
                        }
                    }
                }
            }
        }, "SurtBridge")

        // Inject bridge script
        webView.webViewClient = object : WebViewClient() {
            override fun onPageFinished(view: WebView, url: String) {
                view.evaluateJavascript("""
                    window.addEventListener('message', function(e) {
                        if (e.data && (e.data.type === 'surt:ready' || e.data.action === 'close')) {
                            SurtBridge.onMessage(JSON.stringify(e.data));
                        }
                    });
                """, null)
            }
        }

        webView.loadUrl("https://faceguard.surt.com/intro?token=$token")
    }

    fun handleApproved(confidence: Double) { /* Grant access */ }
    fun handleRejected(confidence: Double) { /* Deny access */ }
    fun handleCanceled() { /* User closed */ }
    fun handleError(message: String) { /* Show error */ }
}

How the Bridge Works

Android WebView doesn't natively receive postMessage events. The @JavascriptInterface method and injected bridge script forward events from the FaceGuard iframe to native Kotlin code.

Camera Permission

Both the manifest permission (CAMERA) and the onPermissionRequest handler are required. The manifest declares the permission, and the handler grants it to the WebView at runtime.