gesture.kt

class MainActivity : FlutterActivity() {

    companion object {
        private const val CHANNEL = "sample/gesture";
    }

    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL)
                .setMethodCallHandler { call, result ->
                    if (call.method == "setSystemGestureExclusionRects") {
                        handleSetSystemGestureExclusionRectsCall(call, result)
                    } else {
                        result.notImplemented()
                    }
                }
    }

    private fun handleSetSystemGestureExclusionRectsCall(
            call: MethodCall,
            result: MethodChannel.Result
    ) {
        val arguments = call.arguments as? List<Map<String, Int>>

        if (arguments != null) {
            val decodedRects = decodeExclusionRects(arguments)
            setSystemGestureExclusionRects(decodedRects)
            result.success(null)
        } else {
            result.error(
                    "inputTypeError",
                    "Input type is incorrect. Ensure that a List<Map<String, int>> " +
                            "is passed as the input for " +
                            "SystemGestureExclusionRects.setSystemGestureExclusionRects.",
                    null
            )
        }
    }

    private fun decodeExclusionRects(inputRects: List<Map<String, Int>>): List<Rect> =
            inputRects.mapIndexed { index, item ->
                Rect(
                        item["left"] ?: error("rect at index $index doesn't contain 'left' property"),
                        item["top"] ?: error("rect at index $index doesn't contain 'top' property"),
                        item["right"] ?: error("rect at index $index doesn't contain 'right' property"),
                        item["bottom"] ?: error("rect at index $index doesn't contain 'bottom' property")
                )
            }


    private fun setSystemGestureExclusionRects(rects: List<Rect>) {
        ViewCompat.setSystemGestureExclusionRects(activity.window.decorView, rects)
    }
}