added new printImage method using ESC * command

lib/src/printer.dart

@@ -315,10 +315,10 @@ class Printer {
     return res;
   }
 
-  /// Print image
+  /// Print image using GS v 0 (obsolete command)
   ///
   /// [image] is an instanse of class from [Image library](https://pub.dev/packages/image)
-  void printImage(Image image) {
+  void printImageRaster(Image image) {
     const bool highDensityHorizontal = true;
     const bool highDensityVertical = true;
 
@@ -355,4 +355,63 @@ class Printer {
 
     sendRaw(List.from(header)..addAll(res));
   }
+
+  /// Print image using ESC *
+  ///
+  /// [image] is an instanse of class from [Image library](https://pub.dev/packages/image)
+  void printImage(Image image) {
+    const bool highDensityHorizontal = true;
+    const bool highDensityVertical = true;
+
+    invert(image);
+    final Image imageRotated = copyRotate(image, 270);
+    // TODO(Andrey): Mirror image (FLIP_LEFT_RIGHT)
+
+    const int lineHeight = highDensityVertical ? 3 : 1;
+    final List<List<int>> blobs = _toColumnFormat(imageRotated, lineHeight * 8);
+    print(blobs.length);
+    print(blobs[0].length);
+
+    final int widthPx = imageRotated.width;
+    const int densityByte =
+        (highDensityHorizontal ? 1 : 0) + (highDensityVertical ? 32 : 0);
+
+    // header = ESC + b"*" + six.int2byte(density_byte) + _int_low_high(width_pixels, 2)
+    final List<int> header = List.from(cBitImg.codeUnits);
+    header.add(densityByte);
+    header.addAll(_intLowHigh(widthPx, 2));
+
+    // Adjust line spacing (for 16-unit line feeds): ESC 3 0x10 (HEX: 0x1b 0x33 0x10)
+    sendRaw([27, 51, 16]);
+    for (int i = 0; i < blobs.length; ++i) {
+      sendRaw(List.from(header)..addAll(blobs[i])..addAll('\n'.codeUnits));
+    }
+    // Reset line spacing: ESC 2 (HEX: 0x1b 0x32)
+    sendRaw([27, 50]);
+  }
+
+  /// Extract slices of an image as equal-sized blobs of column-format data.
+  ///
+  /// [image] Image to extract from
+  /// [lineHeight] Printed line height in dots
+  List<List<int>> _toColumnFormat(Image image, int lineHeight) {
+    final int widthPx = image.width;
+    final int heightPx = image.height;
+    int left = 0;
+    List<List<int>> blobs = [];
+
+    int i = 0;
+    // TODO(Andrey): We lose a part of image here -> use while(left < widthPx)
+    while ((left - widthPx).abs() >= lineHeight) {
+      final Image slice = copyCrop(image, left, 0, lineHeight, heightPx);
+      // File('slice_$i.png')..writeAsBytesSync(encodePng(slice));
+      final Uint8List bytes = slice.getBytes(format: Format.luminance);
+      blobs.add(_convert1bit(bytes));
+
+      i++;
+      left += lineHeight;
+    }
+
+    return blobs;
+  }
 }