printCanvas method
开始打印画布内容
Implementation
@override
Future<Map<String, dynamic>> printCanvas(int count) async {
var rr = await _methodChannel.invokeMethod(
Constants.METHOD_CANVAS_PRINT_CANVAS, {ParamConstants.COUNT: count});
// 显式转换
Map<String, dynamic> result = Map<String, dynamic>.from(rr);
return result;
}