C#自定义RichTextBox实现：行间距设置与获取行数

1。获取文本框行数
        //获取文本框行数
        [DllImport("user32.dll", EntryPoint = "SendMessageA")]
        private static extern int SendMessage(IntPtr hwnd, int wMsg, IntPtr wParam, string lParam);
        private static int EM_GETLINECOUNT = 0x00BA;//获取总行数的消息号

        public static int GetLineCount(Control ctl)
        {
            int linecount = 0;
            try
            {
                linecount = SendMessage(ctl.Handle, EM_GETLINECOUNT, IntPtr.Zero, "");
            }
            catch
            {
                linecount = 0;
            }
            return linecount;
        }


2。设置richtextbox行距
        #region 设置richtextbox行距
        ///////////////////////////////////////////////////////////////////////////
        //set richtextbox linespace
        ///////////////////////////////////////////////////////////////////////////
        public const int WM_USER = 0x0400;
        public const int EM_GETPARAFORMAT = WM_USER + 61;
        public const int EM_SETPARAFORMAT = WM_USER + 71;

        public const long MAX_TAB_STOPS = 32;
        public const uint PFM_LINESPACING = 0x00000100;
        [StructLayout(LayoutKind.Sequential)]
        private struct PARAFORMAT2
        {
            public int cbSize;
            public uint dwMask;
            public short wNumbering;
            public short wReserved;
            public int dxStartIndent;
            public int dxRightIndent;
            public int dxOffset;
            public short wAlignment;
            public short cTabCount;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
            public int[] rgxTabs;
            public int dySpaceBefore;
            public int dySpaceAfter;
            public int dyLineSpacing;
            public short sStyle;
            public byte bLineSpacingRule;
            public byte bOutlineLevel;
            public short wShadingWeight;
            public short wShadingStyle;
            public short wNumberingStart;
            public short wNumberingStyle;
            public short wNumberingTab;
            public short wBorderSpace;
            public short wBorderWidth;
            public short wBorders;