最近用到richtextbox，一些操作记录在下面：

1 禁止自动换行

  richtextbox1.WordWrap = false;

  wordwrap 属性：指示多行文本控件是否在必要时自动换到下一行的开始处；

2 调整字体大小

  richtextbox.Font = new System.Drawing.Font(FontFamily.GenericMonospace, 10);

3 调整行间距

先写一个类：

class CSetLineSpace
    {
        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;
        }

        [DllImport("user32", CharSet = CharSet.Auto)]
        private static extern IntPtr SendMessage(HandleRef hWnd, int msg, int wParam, ref PARAFORMAT2 lParam);

        /// <summary>
        /// 设置行距
        /// </summary>
        /// <param name="ctl">控件</param>
        /// <param name="dyLineSpacing">间距</param>
        public static void SetLineSpace(Control ctl, int dyLineSpacing)
        {
            PARAFORMAT2 fmt = new PARAFORMAT2();
            fmt.cbSize = Marshal.SizeOf(fmt);
            fmt.bLineSpacingRule = 4;// bLineSpacingRule;
            fmt.dyLineSpacing = dyLineSpacing;
            fmt.dwMask = PFM_LINESPACING;
            try
            {
                SendMessage(new HandleRef(ctl, ctl.Handle), EM_SETPARAFORMAT, 0, ref fmt);
            }
            catch
            {

            }
        }
    }

SetLineSpace(richtextbox1, 300);

第三个参考自网上资源，一个博客，但现在找不到出处了，在这里谢谢他吧！