WPF 开发的实用小工具（附源码）持续更新（七）根据应用首个字的首字母按键定位

var _key = Win32Api.GetCharFromKey(e.Key).ToString().ToUpper();
            if (string.IsNullOrWhiteSpace(_key))
                return;
            double offset = 0.0;
            ScrollViewer scrollViewer = ControlsHelper.FindChild<ScrollViewer>(this.AppSwitchList, "PART_ScrollViewer");
            var elementList = ControlsHelper.FindVisualChildren<Border>(this.AppSwitchList).ToList();
            bool isFind = false;
            for (int i = 0; i < elementList.Count; i++)
            {
                var element = elementList[i];
                if (isFind) break;
                if (element.Tag != null)
                {
                    offset += element.ActualHeight;
                    if (element.Tag.ToString().Equals(_key))
                    {
                        offset -= element.ActualHeight;
                        scrollViewer.ScrollToVerticalOffset(offset);
                        isFind = true;
                    }
                }

            }
            this.KeyDownText.Text = _key;
            this.KeyDownPanel.Visibility = Visibility.Visible;

public enum MapType : uint
        {
            MAPVK_VK_TO_VSC = 0x0,
            MAPVK_VSC_TO_VK = 0x1,
            MAPVK_VK_TO_CHAR = 0x2,
            MAPVK_VSC_TO_VK_EX = 0x3,
        }

        [DllImport("user32.dll")]
        public static extern int ToUnicode(
            uint wVirtKey,
            uint wScanCode,
            byte[] lpKeyState,
            [Out, MarshalAs(UnmanagedType.LPWStr, SizeParamIndex = 4)]
            StringBuilder pwszBuff,
            int cchBuff,
            uint wFlags);

        [DllImport("user32.dll")]
        public static extern bool GetKeyboardState(byte[] lpKeyState);

        [DllImport("user32.dll")]
        public static extern uint MapVirtualKey(uint uCode, MapType uMapType);

        public static char GetCharFromKey(Key key)
        {
            char ch = ‘ ‘;

            int virtualKey = KeyInterop.VirtualKeyFromKey(key);
            byte[] keyboardState = new byte[256];
            GetKeyboardState(keyboardState);

            uint scanCode = MapVirtualKey((uint)virtualKey, MapType.MAPVK_VK_TO_VSC);
            StringBuilder stringBuilder = new StringBuilder(2);

            int result = ToUnicode((uint)virtualKey, scanCode, keyboardState, stringBuilder, stringBuilder.Capacity, 0);
            switch (result)
            {
                case -1:
                    break;
                case 0:
                    break;
                case 1:
                    {
                        ch = stringBuilder[0];
                        break;
                    }
                default:
                    {
                        ch = stringBuilder[0];
                        break;
                    }
            }
            return ch;
        }

  Thread.Sleep(300);
            this.KeyDownPanel.Visibility = Visibility.Collapsed;