C# 在不丢失格式的情况下更改richtextbox的字体

如何在不丢失格式的情况下更改richtextbox所有内容的字体

我正在尝试使用

rtb.SelectAll();
rtb.SelectionFont = new Font(fontName,...);

但是字体构造器除了字体类型外，还必须采用字体样式（粗体、斜体等）或字体大小。 因此，使用此选项将更改richtextbox所有内容的样式/大小

---

当然，这同样适用于richtextbox中的任何选择。

您可以为所需的任何参数传入新值，并使用

rtb

属性保留其他值。例如，如果要更改

字体系列

，但要保留

字体大小

，则应执行以下操作：

rtb.SelectionFont = new Font(fontName, rtb.Font.Size);

---

这将把

SelectionFont

系列更改为

fontName

，但保留字体大小。对于其他重载，您可以遵循相同的模式。

这是我过去使用过的RichTextBox。它由Stack Overflow和internet上的代码拼接而成：

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);
    }
  }
}

---

它添加了新属性，如SelectionBold、SelectionItalic等，您可以在其中应用该属性，而不会丢失文本的其他格式。

您可以通过使用现有的richtextbox字体属性传递新字体名，同时保持其他值不变。要仅更改选定文本的字体名称，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，只有在所有选定文本具有相同格式（字体大小、样式等）的情况下，上述代码才有效。这是通过首先检查SelectionFont属性检测到的，如果选择包含多种样式的混合，则该属性将为空

现在，要更改richtextbox所有内容的字体名称，同时保持其他格式不变，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);
}

for（int i=0；i

这将更改所选文本的字体属性。
样本：

---

不同的字体大小是什么意思？解释一下你想要达到的目标，然后也许我们能弄明白。不同的文本有不同的字体大小。无论如何，即使您的答案也会导致字体样式发生变化。请参阅。最终，pinvoking可能是最好的解决方案。你能更清楚地了解pinvoking吗？高科技，有时当我为包含粗体的大型选择更改字体时，粗体将丢失。当我单击ctrl+Z一次时，粗体将恢复。你知道为什么会发生这种情况吗？Thanks@Jerry如果您正在更改

SelectionFont

属性，则是，您告诉文档用新字体替换所有字体属性。要更改字体但保留属性，请尝试改用

SelectionFontName

或

SelectionFontSize

属性。另外，Ctrl-Z是撤销功能。谢谢，这就是问题所在。我忘记更新一个函数以使用

SelectionFontName

而不是

SelectionFont

。为什么会出现此错误

设计器无法处理第32行的未知名称“AutoScaleMode”。“InitializeComponent”方法中的代码由设计器生成，不应手动修改。请删除所有更改，然后再次尝试打开设计器

@AlexJolig AutoScaleMode是表单属性，而不是RichTextBox属性。拆下管路。

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

changeFont(FontStyle.Italic, [textbox_name])