quick-color-picker/quick-color-picker/ThemeManager.cs

using Microsoft.Win32;
using System;
using System.Drawing;
using System.Drawing.Text;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace quick_color_picker
{
    internal class ThemeManager
    {
        public static Color MainColorDark = Color.Black;
        public static Color BackColorDark = Color.FromArgb(32, 32, 32);
        public static Color SecondColorDark = Color.FromArgb(56, 56, 56);
        public static Color AccentColorDark = Color.FromArgb(73, 169, 207);

        private enum WindowCompositionAttribute
        {
            WCA_UNDEFINED = 0,
            WCA_NCRENDERING_ENABLED = 1,
            WCA_NCRENDERING_POLICY = 2,
            WCA_TRANSITIONS_FORCEDISABLED = 3,
            WCA_ALLOW_NCPAINT = 4,
            WCA_CAPTION_BUTTON_BOUNDS = 5,
            WCA_NONCLIENT_RTL_LAYOUT = 6,
            WCA_FORCE_ICONIC_REPRESENTATION = 7,
            WCA_EXTENDED_FRAME_BOUNDS = 8,
            WCA_HAS_ICONIC_BITMAP = 9,
            WCA_THEME_ATTRIBUTES = 10,
            WCA_NCRENDERING_EXILED = 11,
            WCA_NCADORNMENTINFO = 12,
            WCA_EXCLUDED_FROM_LIVEPREVIEW = 13,
            WCA_VIDEO_OVERLAY_ACTIVE = 14,
            WCA_FORCE_ACTIVEWINDOW_APPEARANCE = 15,
            WCA_DISALLOW_PEEK = 16,
            WCA_CLOAK = 17,
            WCA_CLOAKED = 18,
            WCA_ACCENT_POLICY = 19,
            WCA_FREEZE_REPRESENTATION = 20,
            WCA_EVER_UNCLOAKED = 21,
            WCA_VISUAL_OWNER = 22,
            WCA_HOLOGRAPHIC = 23,
            WCA_EXCLUDED_FROM_DDA = 24,
            WCA_PASSIVEUPDATEMODE = 25,
            WCA_USEDARKMODECOLORS = 26,
            WCA_LAST = 27
        };

        private struct WindowCompositionAttribData
        {
            public WindowCompositionAttribute Attribute;
            public IntPtr Data;
            public int SizeOfData;
        }

        [DllImport("uxtheme.dll", SetLastError = true, ExactSpelling = true, CharSet = CharSet.Unicode)]
        private static extern int SetWindowTheme(IntPtr hWnd, string pszSubAppName, string pszSubIdList);

        [DllImport("uxtheme.dll", EntryPoint = "#133", SetLastError = true, ExactSpelling = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
        private static extern bool AllowDarkModeForWindow(IntPtr hWnd, bool allow);

        [DllImport("uxtheme.dll", EntryPoint = "#135", SetLastError = true, ExactSpelling = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
        private static extern bool AllowDarkModeForApp(bool allow);

        [DllImport("user32.dll")]
        private static extern bool SetWindowCompositionAttribute(IntPtr hwnd, ref WindowCompositionAttribData data);

        private static void enableDarkTitlebar(IntPtr handle, bool dark)
        {
            AllowDarkModeForWindow(handle, dark);

            var sizeOfData = Marshal.SizeOf(dark);
            var dataPtr = Marshal.AllocHGlobal(sizeOfData);

            var data = new WindowCompositionAttribData
            {
                Attribute = WindowCompositionAttribute.WCA_USEDARKMODECOLORS,
                Data = dataPtr,
                SizeOfData = sizeOfData
            };
            SetWindowCompositionAttribute(handle, ref data);

            Marshal.FreeHGlobal(dataPtr);
        }

        public static void allowDarkModeForApp(bool dark)
        {
            AllowDarkModeForApp(dark);
        }

        public static void formHandleCreated(object sender, EventArgs e)
        {
            Form f = sender as Form;
            enableDarkTitlebar(f.Handle, true);
        }

        public static void setDarkModeToControl(IntPtr handle)
        {
            SetWindowTheme(handle, "DarkMode_Explorer", null);
        }

        public static bool isDarkTheme()
        {
            if (isWindows10())
            {
                try
                {
                    string root = "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize";
                    string str = Registry.GetValue(root, "AppsUseLightTheme", null).ToString();
                    return (str == "0");
                }
                catch
                {
                    return false;
                }
            }
            else
            {
                return false;
            }
        }

        public static bool isWindows10()
        {
            try
            {
                var reg = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
                string productName = (string)reg.GetValue("ProductName");
                return productName.StartsWith("Windows 10");
            }
            catch
            {
                return false;
            }
        }

        public static void PaintDarkGroupBox(object sender, PaintEventArgs p)
        {
            GroupBox box = (GroupBox)sender;

            SolidBrush brush = new SolidBrush(ThemeManager.SecondColorDark);
            Pen pen = new Pen(brush, 1);

            p.Graphics.Clear(ThemeManager.BackColorDark);

            p.Graphics.TextRenderingHint = TextRenderingHint.AntiAlias;
            p.Graphics.DrawString(box.Text, box.Font, Brushes.White, -1, -3);

            p.Graphics.DrawLine(pen, 0, 16, 0, box.Height - 2);
            p.Graphics.DrawLine(pen, 0, 16, box.Width - 1, 16);
            p.Graphics.DrawLine(pen, box.Width - 1, 16, box.Width - 1, box.Height - 2);
            p.Graphics.DrawLine(pen, 0, box.Height - 2, box.Width - 1, box.Height - 2);
        }
    }
}