Added Printer class

lib/esc_pos_printer.dart

+/*
+ * esc_pos_printer
+ * Created by Andrey U
+ * 
+ * See LICENSE for distribution and usage details.
+ */
 library esc_pos_printer;
 
-/// A Calculator.
-class Calculator {
-  /// Returns [value] plus 1.
-  int addOne(int value) => value + 1;
-}
+export './src/printer.dart';

lib/src/printer.dart

+import 'dart:io';
+import 'commands.dart';
+
+enum TextAlign { left, center, right }
+
+/// Abstract printer.
+class Printer {
+  Printer(this._socket) {
+    reset();
+  }
+
+  final Socket _socket;
+
+  /// Creates a new socket connection to the printer.
+  ///
+  /// [host] can either be a [String] or an [InternetAddress]. If [host] is a
+  /// [String], [connect] will perform a [InternetAddress.lookup] and try
+  /// all returned [InternetAddress]es, until connected. Unless a
+  /// connection was established, the error from the first failing connection is
+  /// returned.
+  ///
+  /// The argument [sourceAddress] can be used to specify the local
+  /// address to bind when making the connection. `sourceAddress` can either
+  /// be a `String` or an `InternetAddress`. If a `String` is passed it must
+  /// hold a numeric IP address.
+  ///
+  /// The argument [timeout] is used to specify the maximum allowed time to wait
+  /// for a connection to be established.
+  static Future<Printer> connect(host, int port,
+      {sourceAddress, Duration timeout}) {
+    return Socket.connect(host, port,
+            sourceAddress: sourceAddress, timeout: timeout)
+        .then((socket) {
+      return Printer(socket);
+    });
+  }
+
+  /// Disconnect from the printer
+  void disconnect() {
+    _socket.destroy();
+  }
+
+  // void writeAll(Iterable objects, [String separator = '']) {
+  //   socket.writeAll(objects, separator);
+  // }
+
+  // void writeLine([Object obj = '']) {
+  //   socket.writeln(obj);
+  // }
+
+  // void write(Object obj) {
+  //   socket.write(obj);
+  // }
+
+  // TODO charHeight, charWidth range ?
+
+  // TODO should be ended by \n
+  void println(
+    Object text, {
+    bool bold = false,
+    bool reverse = false,
+    bool underline = false,
+    TextAlign align = TextAlign.left,
+    int charHeight = -1,
+    int charWidth = -1,
+    int linesAfter = -1,
+  }) {
+    _socket.write(bold ? cBoldOn : cBoldOff);
+    _socket.write(reverse ? cReverseOn : cReverseOff);
+    _socket.write(underline ? cUnderline1dot : cUnderlineOff);
+    _socket.write(align == TextAlign.left
+        ? cAlignLeft
+        : (align == TextAlign.center ? cAlignCenter : cAlignRight));
+
+    if (charHeight > 0 && charWidth > 0) {
+      var n = 16 * (charWidth - 1) + (charHeight - 1);
+      _socket.writeAll([cSizeN, n]);
+    }
+
+    _socket.writeln(text);
+
+    feed(linesAfter);
+
+    // reset all to default
+    reset();
+  }
+
+  void reset() {
+    _socket.write(cInit);
+  }
+
+  void feed(int n) {
+    if (n >= 0 && n <= 255) {
+      _socket.writeAll([cFeedN, n.toString()]);
+    }
+  }
+
+  void reverseFeed(int n) {
+    _socket.writeAll([cReverseFeedN, n.toString()]);
+  }
+
+  void cut() {
+    _socket.write('\n\n\n\n\n');
+    _socket.write(cCut);
+  }
+}

test/esc_pos_printer_test.dart

@@ -3,11 +3,11 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:esc_pos_printer/esc_pos_printer.dart';
 
 void main() {
-  test('adds one to input values', () {
-    final calculator = Calculator();
-    expect(calculator.addOne(2), 3);
-    expect(calculator.addOne(-7), -6);
-    expect(calculator.addOne(0), 1);
-    expect(() => calculator.addOne(null), throwsNoSuchMethodError);
-  });
+  // test('adds one to input values', () {
+  // final calculator = Calculator();
+  // expect(calculator.addOne(2), 3);
+  // expect(calculator.addOne(-7), -6);
+  // expect(calculator.addOne(0), 1);
+  // expect(() => calculator.addOne(null), throwsNoSuchMethodError);
+  // });
 }