using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
namespace XCommon.Image
{
    /// <summary>
    /// 像素与物理长度的计算操作类
    /// </summary>
    public class PixelsCalculationHelper
    {
        #region Win32 API
        [DllImport("user32.dll")]
        static extern IntPtr GetDC(IntPtr ptr);
        [DllImport("gdi32.dll")]
        static extern int GetDeviceCaps(
        IntPtr hdc, // handle to DC
        int nIndex // index of capability
        );
        [DllImport("user32.dll", EntryPoint = "ReleaseDC")]
        static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDc);
        #endregion

        #region DeviceCaps常量
        const int HORZRES = 8;//物理屏幕宽度mm
        const int VERTRES = 10;//物理屏幕高度mm
        const int LOGPIXELSX = 88;//逻辑像素x
        const int LOGPIXELSY = 90;//逻辑像素y
        const int DESKTOPVERTRES = 117;//桌面高度
        const int DESKTOPHORZRES = 118;//桌面宽度
        #endregion

        #region 属性
        /// <summary>
        /// 宽度转化 length是毫米，1厘米=10毫米
        /// </summary>
        /// <param name="length"></param>
        /// <returns></returns>
        public static double MillimetersToPixelsWidth(double length)
        {
            System.Drawing.Graphics g = System.Drawing.Graphics.FromHwnd(IntPtr.Zero);
            IntPtr hdc = g.GetHdc();
            int width = GetDeviceCaps(hdc, 4); // HORZRES
            int pixels = GetDeviceCaps(hdc, 8); // BITSPIXEL
            double fg = pixels / width;
            g.ReleaseHdc(hdc);
            return (((double)pixels / (double)width) * (double)length);
        }

        /// <summary>
        /// 高度转化 length是毫米，1厘米=10毫米
        /// </summary>
        /// <param name="length"></param>
        /// <returns></returns>
        public static double MillimetersToPixelsHeight(double length)
        {
            System.Drawing.Graphics g = System.Drawing.Graphics.FromHwnd(IntPtr.Zero);
            IntPtr hdc = g.GetHdc();
            int height = GetDeviceCaps(hdc, 6); // HORZRES
            int pixels = GetDeviceCaps(hdc, 10); // BITSPIXEL
            double fg = pixels / height;
            g.ReleaseHdc(hdc);
            return (((double)pixels / (double)height) * (double)length);
        }

        /// <summary>
        /// 获取屏幕分辨率当前物理大小
        /// </summary>
        public static Size WorkingArea
        {
            get
            {
                IntPtr hdc = GetDC(IntPtr.Zero);
                Size size = new Size();
                size.Width = GetDeviceCaps(hdc, HORZRES);
                size.Height = GetDeviceCaps(hdc, VERTRES);
                ReleaseDC(IntPtr.Zero, hdc);
                return size;
            }
        }
        /// <summary>
        /// 当前系统DPI_X 大小 一般为96
        /// </summary>
        public static int DpiX
        {
            get
            {
                IntPtr hdc = GetDC(IntPtr.Zero);
                int DpiX = GetDeviceCaps(hdc, LOGPIXELSX);
                ReleaseDC(IntPtr.Zero, hdc);
                return DpiX;
            }
        }
        /// <summary>
        /// 当前系统DPI_Y 大小 一般为96
        /// </summary>
        public static int DpiY
        {
            get
            {
                IntPtr hdc = GetDC(IntPtr.Zero);
                int DpiX = GetDeviceCaps(hdc, LOGPIXELSY);
                ReleaseDC(IntPtr.Zero, hdc);
                return DpiX;
            }
        }
        /// <summary>
        /// 获取真实设置的桌面分辨率大小
        /// </summary>
        public static Size DESKTOP
        {
            get
            {
                IntPtr hdc = GetDC(IntPtr.Zero);
                Size size = new Size();
                size.Width = GetDeviceCaps(hdc, DESKTOPHORZRES);
                size.Height = GetDeviceCaps(hdc, DESKTOPVERTRES);
                ReleaseDC(IntPtr.Zero, hdc);
                return size;
            }
        }

        /// <summary>
        /// 获取宽度缩放百分比
        /// </summary>
        public static float ScaleX
        {
            get
            {
                IntPtr hdc = GetDC(IntPtr.Zero);
                int t = GetDeviceCaps(hdc, DESKTOPHORZRES);
                int d = GetDeviceCaps(hdc, HORZRES);
                float ScaleX = (float)GetDeviceCaps(hdc, DESKTOPHORZRES) / (float)GetDeviceCaps(hdc, HORZRES);
                ReleaseDC(IntPtr.Zero, hdc);
                return ScaleX;
            }
        }

        /// <summary>
        /// 获取高度缩放百分比
        /// </summary>
        public static float ScaleY
        {
            get
            {
                IntPtr hdc = GetDC(IntPtr.Zero);
                float ScaleY = (float)(float)GetDeviceCaps(hdc, DESKTOPVERTRES) / (float)GetDeviceCaps(hdc, VERTRES);
                ReleaseDC(IntPtr.Zero, hdc);
                return ScaleY;
            }
        }
        #endregion

        #region 1个像素代表的实际长度
        /// <summary>
        /// 1个像素代表的实际长度
        /// </summary>
        /// <param name="pixels">像素大小</param>
        /// <param name="dpi">每英寸点数</param>
        /// <returns></returns>
        public static double PixelsToInches(int pixels, int dpi)
        {
            return (double)(pixels) / dpi * 25.4;
        }
        #endregion
    }
}