printer_data_utils.dart

import 'package:blue_thermal_printer/blue_thermal_printer.dart';

class PrintData {
  static double printPageWidth = 50; // 打印纸宽度 50mm
  static double printTextWidth = 3; // 打印文字的宽度 3mm
  static double printBaseUnitValue = 0.125; // 打印基准值 0.125mm

  /// 初始化打印机
  static initPrinter() {
    return PrinterCommands.initPrinter;
  }

  /// 设置左边距
  static printMarginLeft(int left) {
    return PrinterCommands.printMarginLeft(left: left);
  }

  /// 空行
  static printNewLine() {
    return PrinterCommands.FEED_LINE;
  }

  /// 打印文字
  /// message 文本
  /// size 文字放大倍数
  /// bold 是否加粗
  /// charset 文本编码
  /// space 文本间隙
  static printText(String message,
      {int size = 1,
      bool bold = false,
      CHARSET charset = CHARSET.GBK,
      int space = 0}) {
    List<int> data = [];
    var textList = splitText(message, size, space);
    for (var value in textList) {
      data.addAll(_printLineText(value, size, bold, charset, space));
    }
    return data;
  }

  /// 打印一行
  static List<int> _printLineText(
      String text, int size, bool bold, CHARSET charset, int space) {
    List<int> data = [];
    // 左边距 = 打印纸宽度 - 文字宽度 ~/ 2
    var left = getLeftMargin(text, size, space);
    var textLeftMargin = PrinterCommands.printMarginLeft(left: left);
    var textBold = PrinterCommands.bold(bold: bold);
    var textSize = PrinterCommands.fontSizeSetBig(size: size);
    var textSpace = PrinterCommands.setCharHSpace(charSpace: space);
    List<int> content = [];
    if (charset == CHARSET.GBK) {
      content.addAll(gbk.encode(text));
    } else {
      content.addAll(utf8.encode(text));
    }
    var feedLine = PrinterCommands.FEED_LINE;
    data.addAll(textLeftMargin);
    data.addAll(textSize);
    data.addAll(textBold);
    data.addAll(textSpace);
    data.addAll(content);
    data.addAll(feedLine);
    return data;
  }

  // 文字内容拆分多行
  static List splitText(String text, int size, int space) {
    var list = [];
    var lineTextCount = getLineTextCount(size, space);
    for (var i = 0; i < text.length; i = i + lineTextCount) {
      list.add(text.substring(i, min(text.length, i + lineTextCount)));
    }
    return list;
  }

  // 一行显示的字数
  // 字数 = 打印纸宽度 ~/ (打印字字宽度 * 字体放大倍数)
  static int getLineTextCount(sizeMul, space) {
    var textHSpace = 2 * space * printBaseUnitValue; // 字符左右边距
    return printPageWidth ~/ ((printTextWidth + textHSpace) * sizeMul);
  }

  // 左边距 = 打印纸宽度 - 文字宽度 ~/ 2
  static int getLeftMargin(String text, sizeMul, int space) {
    return (printPageWidth - getLineTextWidth(text, sizeMul, space)) ~/ 2 - 1;
  }

  // 一行字的宽度
  // 一行字的总宽度 = 字数 * 打印字字宽度(字符宽度+字间距宽度) * 字体放大倍数
  static double getLineTextWidth(String text, sizeMul, int space) {
    var textHSpace = 2 * space * printBaseUnitValue; // 字符左右边距
    var doubleCharCount = matchDoubleCharCount(text); // 双字节字符数量
    var doubleCharWidth = doubleCharCount * (printTextWidth + textHSpace);
    var singleCharWidth =
        (text.length - doubleCharCount) * (printTextWidth / 2 + textHSpace);
    // 字节宽度（单字节+双字节） * 字体放大倍数
    return (doubleCharWidth + singleCharWidth) * sizeMul;
  }

  // 双字节字符个数
  static matchDoubleCharCount(String text) {
    int count = 0;
    RegExp regDoubleChar = RegExp("[^\x00-\xff]");
    for (var i = 0; i < text.length; i++) {
      var char = text.substring(i, i+1);
      if (regDoubleChar.hasMatch(char)) {
        count++;
      }
    }
    return count;
  }

  // 打印条形码
  static printBarCode(String info, {CHARSET charset = CHARSET.UTF_8}) {
    Uint8List infoByte;
    if (charset == CHARSET.GBK) {
      infoByte = Uint8List.fromList(gbk.encode(info));
    } else {
      infoByte = Uint8List.fromList(utf8.encode(info));
    }
    return PrinterCommands.createBarCode(infoByte);
  }

  /// 打印二维码
  static printQRCode(String info, {CHARSET charset = CHARSET.UTF_8}) {
    List<int> data = [];
    ///设置二维码模块大小
    var QRCodeSize = [0x1D,0x28,0x6B,0x03,0x00,0x31,0x43,8];

    ///将二维码数据存储到符号存储区
    //第一步
    String str = info.toString();
    var kLength = str.length + 3;
    var pL = kLength % 256;
    var pH = kLength ~/ 256;
    var QRCodeInfo = [0x1D,0x28,0x6B,pL,pH,0x31,0x50,48];
    //第二步
    Uint8List infoByte;
    if (charset == CHARSET.GBK) {
      infoByte = Uint8List.fromList(gbk.encode(info));
    } else {
      infoByte = Uint8List.fromList(utf8.encode(info));
    }
    ///打印之前存储的二维码信息
    var printStoredQRData = [0x1D,0x28,0x6B,0x03,0x00,0x31,0x51,48];
    ///组装
    data.addAll(QRCodeSize);
    data.addAll(QRCodeInfo);
    data.addAll(infoByte);
    data.addAll(printStoredQRData);
    return data;
  }
}

/// 字体
enum CHARSET {
  UTF_8,
  GBK,
}