更改richtextbox的字体而不会丢失格式
如何在不丢失格式的情况下更改richtextbox的所有内容的字体？
我正在尝试使用
rtb.SelectAll(); rtb.SelectionFont = new Font(fontName,...); 但是字体构造函数除了字体类型之外还必须采用字体样式（粗体，斜体，…）或字体大小。 因此，使用它会改变richtextbox的所有内容的样式/大小。
当然，同样适用于richtextbox中的任何选择。
这是我过去使用过的RichTextBox。 它是通过Stack Overflow和整个互联网上的代码拼接在一起的：
public class RichBox : RichTextBox { private const UInt32 CFM_BOLD = 0x00000001; private const UInt32 CFM_ITALIC = 0x00000002; private const UInt32 CFM_UNDERLINE = 0x00000004; private const UInt32 CFM_STRIKE = 0x00000008; private const UInt32 CFM_FACE = 0x20000000; private const UInt32 CFM_SIZE = 0x80000000; private const int WM_PAINT = 0xF; private const int WM_SETREDRAW = 0xB; private const int WM_USER = 0x400; private const int EM_SETCHARFORMAT = (WM_USER + 68); private const int SCF_SELECTION = 0x0001; private const int EM_GETEVENTMASK = WM_USER + 59; private const int EM_SETEVENTMASK = WM_USER + 69; private const int EM_GETSCROLLPOS = WM_USER + 221; private const int EM_SETSCROLLPOS = WM_USER + 222; [StructLayout(LayoutKind.Sequential)] private struct CHARFORMAT { public int cbSize; public uint dwMask; public uint dwEffects; public int yHeight; public int yOffset; public int crTextColor; public byte bCharSet; public byte bPitchAndFamily; [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)] public char[] szFaceName; public short wWeight; public short sSpacing; public int crBackColor; public int LCID; public uint dwReserved; public short sStyle; public short wKerning; public byte bUnderlineType; public byte bAnimation; public byte bRevAuthor; } [DllImport("kernel32.dll", CharSet = CharSet.Auto)] private static extern IntPtr LoadLibrary(string lpFileName); [DllImport("user32", CharSet = CharSet.Auto)] private static extern int SendMessage(IntPtr hWnd, int msg, int wParam, ref CHARFORMAT lParam); [DllImport("user32.dll")] private static extern IntPtr SendMessage(IntPtr hWnd, Int32 wMsg, Int32 wParam, ref Point lParam); [DllImport("user32.dll")] private static extern IntPtr SendMessage(IntPtr hWnd, Int32 wMsg, Int32 wParam, IntPtr lParam); private bool frozen = false; private Point lastScroll = Point.Empty; private IntPtr lastEvent = IntPtr.Zero; private int lastIndex = 0; private int lastWidth = 0; protected override CreateParams CreateParams { get { var cp = base.CreateParams; if (LoadLibrary("msftedit.dll") != IntPtr.Zero) { cp.ClassName = "RICHEDIT50W"; } return cp; } } [Browsable(false)] [DefaultValue(typeof(bool), "False")] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public bool FreezeDrawing { get { return frozen; } set { if (value != frozen) { frozen = value; if (frozen) { this.SuspendLayout(); SendMessage(this.Handle, WM_SETREDRAW, 0, IntPtr.Zero); SendMessage(this.Handle, EM_GETSCROLLPOS, 0, ref lastScroll); lastEvent = SendMessage(this.Handle, EM_GETEVENTMASK, 0, IntPtr.Zero); lastIndex = this.SelectionStart; lastWidth = this.SelectionLength; } else { this.Select(lastIndex, lastWidth); SendMessage(this.Handle, EM_SETEVENTMASK, 0, lastEvent); SendMessage(this.Handle, EM_SETSCROLLPOS, 0, ref lastScroll); SendMessage(this.Handle, WM_SETREDRAW, 1, IntPtr.Zero); this.Invalidate(); this.ResumeLayout(); } } } } [Browsable(false)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public Font CurrentFont { get { Font result = this.Font; if (this.SelectionLength == 0) { result = SelectionFont; } else { using (RichBox rb = new RichBox()) { rb.FreezeDrawing = true; rb.SelectAll(); rb.SelectedRtf = this.SelectedRtf; rb.Select(0, 1); result = rb.SelectionFont; } } return result; } } [Browsable(false)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public string SelectionFontName { get { return CurrentFont.FontFamily.Name; } set { CHARFORMAT cf = new CHARFORMAT(); cf.cbSize = Marshal.SizeOf(cf); cf.szFaceName = new char[32]; cf.dwMask = CFM_FACE; value.CopyTo(0, cf.szFaceName, 0, Math.Min(31, value.Length)); IntPtr lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(cf)); Marshal.StructureToPtr(cf, lParam, false); SendMessage(this.Handle, EM_SETCHARFORMAT, SCF_SELECTION, lParam); } } [Browsable(false)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public float SelectionFontSize { get { return CurrentFont.Size; } set { CHARFORMAT cf = new CHARFORMAT(); cf.cbSize = Marshal.SizeOf(cf); cf.dwMask = CFM_SIZE; cf.yHeight = Convert.ToInt32(value * 20); IntPtr lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(cf)); Marshal.StructureToPtr(cf, lParam, false); SendMessage(this.Handle, EM_SETCHARFORMAT, SCF_SELECTION, lParam); } } [Browsable(false)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public bool SelectionBold { get { return CurrentFont.Bold; } set { CHARFORMAT cf = new CHARFORMAT(); cf.cbSize = Marshal.SizeOf(cf); cf.dwMask = CFM_BOLD; cf.dwEffects = value ? CFM_BOLD : 0; IntPtr lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(cf)); Marshal.StructureToPtr(cf, lParam, false); SendMessage(this.Handle, EM_SETCHARFORMAT, SCF_SELECTION, lParam); } } [Browsable(false)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public bool SelectionItalic { get { return CurrentFont.Italic; } set { CHARFORMAT cf = new CHARFORMAT(); cf.cbSize = Marshal.SizeOf(cf); cf.dwMask = CFM_ITALIC; cf.dwEffects = value ? CFM_ITALIC : 0; IntPtr lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(cf)); Marshal.StructureToPtr(cf, lParam, false); SendMessage(this.Handle, EM_SETCHARFORMAT, SCF_SELECTION, lParam); } } [Browsable(false)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public bool SelectionStrikeout { get { return CurrentFont.Strikeout; } set { CHARFORMAT cf = new CHARFORMAT(); cf.cbSize = Marshal.SizeOf(cf); cf.dwMask = CFM_STRIKE; cf.dwEffects = value ? CFM_STRIKE : 0; IntPtr lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(cf)); Marshal.StructureToPtr(cf, lParam, false); SendMessage(this.Handle, EM_SETCHARFORMAT, SCF_SELECTION, lParam); } } [Browsable(false)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public bool SelectionUnderline { get { return CurrentFont.Underline; } set { CHARFORMAT cf = new CHARFORMAT(); cf.cbSize = Marshal.SizeOf(cf); cf.dwMask = CFM_UNDERLINE; cf.dwEffects = value ? CFM_UNDERLINE : 0; IntPtr lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(cf)); Marshal.StructureToPtr(cf, lParam, false); SendMessage(this.Handle, EM_SETCHARFORMAT, SCF_SELECTION, lParam); } } }
它添加了诸如SelectionBold，SelectionItalic等新属性，您可以在其中应用属性，而不会丢失文本的其他格式。
您可以使用现有的richtextbox字体属性传递新的字体名称，同时保持其他值不变。 要仅更改所选文本的字体名称，您需要执行以下操作：
if (rtb.SelectionFont !=null) rtb.SelectionFont = new Font(fontName, rtb.SelectionFont.Size, rtb.SelectionFont.Style);
请注意，如果所有选定的文本具有相同的格式（字体大小，样式等），则上述代码才有效。 这是通过首先检查SelectionFont属性来检测的，如果选择包含样式的混合，它将为null。
现在要更改richtextbox的所有内容的字体名称，同时保持其他格式不变，您需要遍历richtextbox的所有字符并逐个应用字体名称。
for (int i = 0; i < rtb.TextLength; i++) { rtb.Select(i, 1); rtb.SelectionFont = new Font(fontName, rtb.SelectionFont.Size, rtb.SelectionFont.Style); }
您可以为所需的任何参数传递新值，并使用rtb属性来保留其他值。 例如，如果要更改font family但希望保留font size ，则可以执行以下操作：
rtb.SelectionFont = new Font(fontName, rtb.Font.Size);
这会将SelectionFont系列更改为fontName但会保留字体大小。 您可以按照相同的模式进行其他重载。
Private Sub changeFont(ByVal fontz As FontStyle, getStr As RichTextBox) Dim currentFont As System.Drawing.Font = txt.SelectionFont Dim newFontStyle As System.Drawing.FontStyle newFontStyle = fontz getStr.SelectionFont = New Font(currentFont.FontFamily, currentFont.Size, newFontStyle) End Sub
这将更改所选文本的字体属性。
样品：
changeFont(FontStyle.Italic, [textbox_name])