C++取屏幕分辨率

#include "windows.h"    
#include "assert.h"    
int main()    
{    
    // 获取窗口当前显示的监视器    
    // 使用桌面的句柄.    
    HWND hWnd = GetDesktopWindow();    
    HMONITOR hMonitor = MonitorFromWindow(hWnd, MONITOR_DEFAULTTONEAREST);    
    // 获取监视器逻辑宽度与高度    
    MONITORINFOEX miex;    
    miex.cbSize = sizeof(miex);    
    GetMonitorInfo(hMonitor, &miex);    
    int cxLogical = (miex.rcMonitor.right - miex.rcMonitor.left);    
    int cyLogical = (miex.rcMonitor.bottom - miex.rcMonitor.top);    
    // 获取监视器物理宽度与高度    
    DEVMODE dm;    
    dm.dmSize = sizeof(dm);    
    dm.dmDriverExtra = 0;    
    EnumDisplaySettings(miex.szDevice, ENUM_CURRENT_SETTINGS, &dm);    
    int cxPhysical = dm.dmPelsWidth;    
    int cyPhysical = dm.dmPelsHeight;    
    // 缩放比例计算  实际上使用任何一个即可    
    double horzScale = ((double)cxPhysical / (double)cxLogical);    
    double vertScale = ((double)cyPhysical / (double)cyLogical);    
    assert(horzScale == vertScale);    
    return 0;    
}

C# API 获取系统DPI缩放倍数跟分辨率大小

using System;
using System.Drawing;
using System.Runtime.InteropServices;
 
namespace XYDES
{
    public class PrimaryScreen
    {
        #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;
                const int VERTRES = 10;
                const int LOGPIXELSX = 88;
                const int LOGPIXELSY = 90;
                const int DESKTOPVERTRES = 117;
                const int DESKTOPHORZRES = 118;
        #endregion
 
        #region 属性
        /// <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
    }
}