[移动开发]UniAPP Android 蓝牙 ESCPOS打印机 打印图片和二维码

移动端打印的实现方式参考

上一篇：DCloud UniAPP Android 蓝牙连接ESCPOS打印机

本片来实现 上一篇中 打印图片中 的 img （图片点阵灰度数据）??

var img=XXXXX //图片点阵灰度数据
printer.printImg(img);

对应的实现方式使用C#实现,draw2PxPoint方法将指定图片转成ESCPOS打印机可以识别的图片打印指令

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;

namespace CommonPrint.ImageUtil
{
    public class ImageHelper
    {
        public static Image UrlToImage(string url)
        {
            WebClient mywebclient = new WebClient();
            byte[] Bytes = mywebclient.DownloadData(url);
            using (MemoryStream ms = new MemoryStream(Bytes))
            {
                Image outputImg = Image.FromStream(ms);
                return outputImg;
            }
        }

        public static int[] draw2PxPoint(Bitmap bmp)
        {
            //第一步调整图片高宽 到目标大小 商米设备最大支持124~125个点位的图片打印
            int newWidth = 120;
            int newHeight = 120;
            bmp = ZoomImage(bmp, newWidth, newHeight);

            List<int> data = new List<int>();
            //设置行距为0的指令
            data.Add(0x1B);
            data.Add(0x33);
            data.Add(0x00);

            int temp = 0;
            int turn = 0;
            // 逐行打印
            for (int j = 0; j < bmp.Height / 12f; j++)
            {
                //打印图片的指令
                data.Add(0x1B);
                data.Add(0x2A);
                data.Add(32);//单精度
                data.Add((byte)(bmp.Width % 256)); //nL  因为一个Byte最大255 表示大于255的数据需要用2位来处理（ nL+nH×256）
                data.Add((byte)(bmp.Width / 256)); //nH
                                                   //对于每一行，逐列打印
                for (int i = 0; i < bmp.Width; i++)
                {
                    每一列24个像素点，分为3个字节存储
                    for (int m = 0; m < 3; m++)
                    {
                        StringBuilder sb = new StringBuilder();
                        //一次性读4个点 单精度 需要放大Y轴方向的数据 所以取一个点占2位
                        for (int n = 0; n < 4; n++)
                        {
                            var p = px2Byte(i, j * 12 + m * 4 + n, bmp);
                            //每个点Y轴方向重复一次 占2位
                            sb.Append(p);
                            sb.Append(p);
                        }
                        //Java上 byte 是-128 ~ 127  255=-1
                        int res = Convert.ToInt32(sb.ToString().Substring(1, 7), 2);
                        if (res > 127) {
                            res = res - 256;
                        }
                        data.Add((byte)res);
                    }
                }
                data.Add(10);//换行
            }
            bmp.Dispose();
            return data.ToArray();
        }

        public static byte px2Byte(int x, int y, Bitmap bmp)
        {
            if (x < bmp.Width && y < bmp.Height)
            {
                byte b;
                Color color = bmp.GetPixel(x, y);
                int gray = (int)(0.29900 * color.R + 0.58700 * color.G + 0.11400 * color.B);
                if (gray > 128)
                {
                    b = 0;
                }
                else
                {
                    b = 1;
                }
                return b;
            }
            return 0;
        }

        /// <summary>
        /// 等比例缩放图片
        /// </summary>
        /// <param name="bitmap">图片</param>
        /// <param name="destHeight">高度</param>
        /// <param name="destWidth">宽度</param>
        /// <returns></returns>
        private static Bitmap ZoomImage(Bitmap bitmap, int destHeight, int destWidth)
        {
            try
            {
                System.Drawing.Image sourImage = bitmap;
                int width = 0, height = 0;
                //按比例缩放
                int sourWidth = sourImage.Width;
                int sourHeight = sourImage.Height;
                if (sourHeight > destHeight || sourWidth > destWidth)
                {
                    if ((sourWidth * destHeight) > (sourHeight * destWidth))
                    {
                        width = destWidth;
                        height = (destWidth * sourHeight) / sourWidth;
                    }
                    else
                    {
                        height = destHeight;
                        width = (sourWidth * destHeight) / sourHeight;
                    }
                }
                else
                {
                    width = sourWidth;
                    height = sourHeight;
                }
                Bitmap destBitmap = new Bitmap(destWidth, destHeight);
                Graphics g = Graphics.FromImage(destBitmap);
                g.Clear(Color.Transparent);
                //设置画布的描绘质量
                g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                g.DrawImage(sourImage, new Rectangle((destWidth - width) / 2, (destHeight - height) / 2, width, height), 0, 0, sourImage.Width, sourImage.Height, GraphicsUnit.Pixel);
                g.Dispose();
                //设置压缩质量
                System.Drawing.Imaging.EncoderParameters encoderParams = new System.Drawing.Imaging.EncoderParameters();
                long[] quality = new long[1];
                quality[0] = 100;
                System.Drawing.Imaging.EncoderParameter encoderParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
                encoderParams.Param[0] = encoderParam;
                sourImage.Dispose();
                return destBitmap;
            }
            catch
            {
                return bitmap;
            }
        }
    }
}