Sunji-posv-net/pos/POSV.Core/Utils/DpiUtils.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;

namespace POSV.Utils
{
    /// <summary>
    /// dpi转换工具类
    /// </summary>
    public class DpiUtils
    {
        static NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger();
        public static int GetOneMmPointInt(int dpi)
        {
            int mmPoint = 0;
            switch (dpi)
            {
                case 200:
                case 203:
                    mmPoint = 8;
                    break;
                case 300:
                    mmPoint = 12;
                    break;
                case 600:
                    mmPoint = 24;
                    break;
            }
            return mmPoint;
        }

        /// <summary>
        /// 打印机点转像素
        /// </summary>
        /// <param name="dots"></param>
        /// <param name="dpi"></param>
        /// <returns></returns>
        public static int DotsToPixels(float screenDpi, int dots, int printerDpi)
        {
            int mmPoint = GetOneMmPointInt(printerDpi);
            double milli = ((double)dots / (double)mmPoint);
            return Convert.ToInt32(MillimetersToPixels(screenDpi, milli));
        }
        
        /// <summary>
        /// 像素转打印机点
        /// </summary>
        /// <param name="pixel"></param>
        /// <param name="dpi"></param>
        /// <returns></returns>
        public static int PixelsToDots(float screenDpi, int pixel, int printerDpi)
        {
            double milli = PixelsWidthToMillimeters(screenDpi, pixel);
            return MillimetersToDots(printerDpi, milli);
        }

        /// <summary>
        /// 毫米转打印机点数
        /// </summary>
        /// <param name="dpi"></param>
        /// <param name="milli"></param>
        /// <returns></returns>
        public static int MillimetersToDots(int dpi, double milli)
        {
            int oneMMPoint = GetOneMmPointInt(dpi);
            return Convert.ToInt16(milli * oneMMPoint);
        }

        /// <summary>
        /// 显示器像素转换为毫米
        /// </summary>
        /// <param name="pixel"></param>
        /// <returns></returns>
        public static double PixelsWidthToMillimeters(float screenDpi, int pixel)
        {
            double oneMilliPixels = MillimetersToPixels(screenDpi, 1.0);
            return ((double)pixel / oneMilliPixels);
        }

        /// <summary>
        /// 获取当前显示器毫米转换为像素
        /// </summary>
        /// <param name="length">毫米</param>
        /// <returns></returns>
        public static int MillimetersToPixels(double length) //length是毫米，1厘米=10毫米
        {
            return MillimetersToPixels(GetScreenDpi(), length);
        }

        /// <summary>
        /// 获取指定显示器dpi毫米转换为像素
        /// </summary>
        /// <param name="screenDpi">显示器dpi</param>
        /// <param name="length">毫米</param>
        /// <returns></returns>
        public static int MillimetersToPixels(float screenDpi, double length) //length是毫米，1厘米=10毫米
        {
            //IntPtr hdc = g.GetHdc();
            //int width = GetDeviceCaps(hdc, 4);     // HORZRES 
            //int pixels = GetDeviceCaps(hdc, 8);     // BITSPIXEL
            ////int result = Convert.ToInt16(length / 25.38 * GetDeviceCaps(hdc, 88) + 0.5);
            //g.ReleaseHdc(hdc);
            //return Convert.ToInt16((((double)pixels / (double)width) * (double)length));
            // return result;
            int result = Convert.ToInt16(screenDpi / 25.4f * length);
            
            return result;
        }

        public static int GetStrNumOneRow(int printerDpi, double milli)
        {
            var totalDot = MillimetersToDots(printerDpi, milli);
            return totalDot / 12;
        }

        /// <summary>
        /// 获取显示器Dpi
        /// </summary>
        /// <returns></returns>
        public static float GetScreenDpi()
        {
            float result = 0;
            System.Windows.Forms.Panel p = new System.Windows.Forms.Panel();
            System.Drawing.Graphics g = System.Drawing.Graphics.FromHwnd(p.Handle);
            result = g.DpiX;
            g.Dispose();
            return result;
        }

        [DllImport("gdi32.dll")]
        private static extern int GetDeviceCaps(IntPtr hdc, int Index);
    }
}