C# RichTextBox制作文本编辑器

本文利用一个简单的小例子【文本编辑器】，讲解richtextbox的用法。

windows窗体中的richtextbox控件用于显示，输入和操作格式化的文本，richtextbox除了拥有textbox控件的所有功能外，还可以显示字体，颜色，链接，从文件中读取和加载图像，以及查找指定的字符。richtextbox控件通常用于提供类似字体处理程序（如microsoft word）的文本操作和显示功能。richtextbox控件可以显示滚动条，且默认根据需要进行显示。

涉及知识点：

• selectionfont 获取或设置当前选定文本或插入点的字体。
• fontstyle 指定应用到文本的字形信息。
• selectionalignment  获取或设置应用到当前选定内容或插入点的对齐方式。
• selectionindent 获取或设置所选内容开始行的缩进距离（以像素为单位）。
• selectioncharoffset 获取或设置控件中的文本是显示在基线上、作为上标还是作为基线下方的下标。
• selectioncolor 获取或设置当前选定文本或插入点的文本颜色。
• selectionbackcolor   获取或设置在 system.windows.forms.richtextbox 控件中选中文本时文本的颜色。
• selectionbullet 获取或设置一个值，通过该值指示项目符号样式是否应用到当前选定内容或插入点。
• clipboard paste 粘贴指定剪贴板格式的剪贴板内容【插入图片时使用】。
• find 在对搜索应用特定选项的情况下，在 system.windows.forms.richtextbox 控件的文本中搜索位于控件内特定位置的字符串。
  

效果图如下【以下设置文本对应的格式】：

核心代码如下

using system;
using system.collections.generic;
using system.drawing;
using system.drawing.printing;
using system.linq;
using system.text;
using system.threading.tasks;
using system.windows.forms;

namespace demorichtext.model
{
 public class defaultrickformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {

  }
 }

 /// <summary>
 /// 加粗格式
 /// </summary>
 public class boldrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   font oldfont = rtbinfo.selectionfont;
   font newfont;
   if (oldfont.bold)
   {
    newfont = new font(oldfont, oldfont.style & ~fontstyle.bold);//支持位于运算
   }
   else
   {
    newfont = new font(oldfont, oldfont.style | fontstyle.bold);
   }
   rtbinfo.selectionfont = newfont;
  }
 }

 /// <summary>
 /// 斜体
 /// </summary>
 public class italicrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   font oldfont = rtbinfo.selectionfont;
   font newfont;
   if (oldfont.italic)
   {
    newfont = new font(oldfont, oldfont.style & ~fontstyle.italic);
   }
   else
   {
    newfont = new font(oldfont, oldfont.style | fontstyle.italic);
   }
   rtbinfo.selectionfont = newfont;
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 下划线
 /// </summary>
 public class underlinerichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   font oldfont = rtbinfo.selectionfont;
   font newfont;
   if (oldfont.underline)
   {
    newfont = new font(oldfont, oldfont.style & ~fontstyle.underline);
   }
   else
   {
    newfont = new font(oldfont, oldfont.style | fontstyle.underline);
   }
   rtbinfo.selectionfont = newfont;
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 删除线
 /// </summary>
 public class strikelinerichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   font oldfont = rtbinfo.selectionfont;
   font newfont;
   if (oldfont.underline)
   {
    newfont = new font(oldfont, oldfont.style & ~fontstyle.strikeout);
   }
   else
   {
    newfont = new font(oldfont, oldfont.style | fontstyle.strikeout);
   }
   rtbinfo.selectionfont = newfont;
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 左对齐
 /// </summary>
 public class leftrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   rtbinfo.selectionalignment = horizontalalignment.left;
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 居中对齐
 /// </summary>
 public class centerrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   if (rtbinfo.selectionalignment == horizontalalignment.center)
   {
    rtbinfo.selectionalignment = horizontalalignment.left;
   }
   else
   {
    rtbinfo.selectionalignment = horizontalalignment.center;
   }

   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 右对齐
 /// </summary>
 public class rightrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   if (rtbinfo.selectionalignment == horizontalalignment.right)
   {
    rtbinfo.selectionalignment = horizontalalignment.left;
   }
   else
   {
    rtbinfo.selectionalignment = horizontalalignment.right;
   }

   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 缩进对齐
 /// </summary>
 public class indentrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   //每次以10个像素进行缩进
   rtbinfo.selectionindent = rtbinfo.selectionindent + 10;
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 缩进对齐
 /// </summary>
 public class outindentrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   //每次以10个像素进行缩进
   rtbinfo.selectionindent = rtbinfo.selectionindent - 10;
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 下标
 /// </summary>
 public class subscriptrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   if (rtbinfo.selectioncharoffset < 0)
   {
    rtbinfo.selectioncharoffset = 0;
   }
   else {
    rtbinfo.selectioncharoffset = -5;
   }
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 上标
 /// </summary>
 public class superscriptrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   if (rtbinfo.selectioncharoffset > 0)
   {
    rtbinfo.selectioncharoffset = 0;
   }
   else {
    rtbinfo.selectioncharoffset = 5;
   }
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 字体
 /// </summary>
 public class fontrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   fontdialog f = new fontdialog();
   if (f.showdialog() == dialogresult.ok)
   {
    fontfamily family = f.font.fontfamily;
    rtbinfo.selectionfont = new font(family, rtbinfo.selectionfont.size, rtbinfo.selectionfont.style);
   }
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 文本颜色
 /// </summary>
 public class forecolorrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   colordialog f = new colordialog();
   if (f.showdialog() == dialogresult.ok)
   {

    rtbinfo.selectioncolor = f.color;
   }
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 文本背景颜色
 /// </summary>
 public class bgcolorrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   colordialog f = new colordialog();
   if (f.showdialog() == dialogresult.ok)
   {

    rtbinfo.selectionbackcolor = f.color;
   }
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// ul列表,项目符号样式
 /// </summary>
 public class ulrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   if (rtbinfo.selectionbullet)
   {
    rtbinfo.selectionbullet = false;
   }
   else {
    rtbinfo.selectionbullet = true;
    rtbinfo.bulletindent = 10;
   }
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 图片插入
 /// </summary>
 public class picrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   openfiledialog o = new openfiledialog();
   o.initialdirectory = appdomain.currentdomain.basedirectory;
   o.title = "请选择图片";
   o.filter = "jpeg|*.jpeg|jpg|*.jpg|png|*.png|gif|*.gif"; 
   if (o.showdialog() == dialogresult.ok) {
    string filename = o.filename;
    try
    {
     image bmp = image.fromfile(filename);
     clipboard.setdataobject(bmp);

     dataformats.format dataformat = dataformats.getformat(dataformats.bitmap);
     if (rtbinfo.canpaste(dataformat))
     {
      rtbinfo.paste(dataformat);
     }
      
    }
    catch (exception exc)
    {
     messagebox.show("图片插入失败。" + exc.message, "提示",
         messageboxbuttons.ok, messageboxicon.information);
    }

   }
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 删除
 /// </summary>
 public class delrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   rtbinfo.selectedtext = "";
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 查找
 /// </summary>
 public class searchrichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   string find = rtbinfo.tag.tostring();
   int index= rtbinfo.find(find, 0,richtextboxfinds.none);
   int startpos = index;
   int nextindex = 0;
   while (nextindex != startpos)//循环查找字符串，并用蓝色加粗12号times new roman标记之 
   {
    rtbinfo.selectionstart = index;
    rtbinfo.selectionlength = find.length;
    rtbinfo.selectioncolor = color.blue;
    rtbinfo.selectionfont = new font("times new roman", (float)12, fontstyle.bold);
    rtbinfo.focus();
    nextindex = rtbinfo.find(find, index + find.length, richtextboxfinds.none);
    if (nextindex == -1)//若查到文件末尾，则充值nextindex为初始位置的值，使其达到初始位置，顺利结束循环，否则会有异常。 
    {
     nextindex = startpos;
    }
    index = nextindex;
   }
   rtbinfo.focus();
  }
 }

 /// <summary>
 /// 打印
 /// </summary>
 public class printrichformat : baserichformat
 {
  private richtextbox richtextbox;

  public override void setformat(richtextbox rtbinfo)
  {
   this.richtextbox = rtbinfo;
   printdocument pd = new printdocument();
   pd.printpage += new printpageeventhandler(pd_printpage);
   // 打印文档
   pd.print();
  }

  private void pd_printpage(object sender, printpageeventargs ev)
  {
   //ev.graphics.drawstring(richtextbox.text);
   //ev.hasmorepages = true;
  }
 }

 /// <summary>
 /// 字体大小
 /// </summary>
 public class fontsizerichformat : baserichformat
 {
  public override void setformat(richtextbox rtbinfo)
  {
   string fontsize = rtbinfo.tag.tostring();
   float fsize = 0.0f;
   if (float.tryparse(fontsize, out fsize)) {
    rtbinfo.selectionfont = new font(rtbinfo.font.fontfamily, fsize, rtbinfo.selectionfont.style);
   }
   rtbinfo.focus();
  }
 }
} 

页面代码【由于实现了代码封装，所有页面代码较少】

using demorichtext.model;
using system;
using system.collections.generic;
using system.componentmodel;
using system.data;
using system.drawing;
using system.linq;
using system.text;
using system.threading.tasks;
using system.windows.forms;

namespace demorichtext
{
 public partial class mainform : form
 {
  public mainform()
  {
   initializecomponent();
  }
  

  public void btnbuttonclick(object sender, eventargs e) {
   button btn = (button)sender;
   btntype btntype;
   if (enum.tryparse<btntype>(btn.tag.tostring(), out btntype)) {
    if (btntype == btntype.search) {
     if (!string.isnullorempty(this.txtsearch.text.trim()))
     {
      this.rtbinfo.tag = this.txtsearch.text.trim();
     }
     else {
      return;
     }
     
    }
    irichformat richfomat = richformatfactory.createrichformat(btntype);
    richfomat.setformat(this.rtbinfo);
   }
  }

  private void combfontsize_selectedindexchanged(object sender, eventargs e)
  {
   float fsize = 12.0f;
   if (combfontsize.selectedindex > -1) {
    if (float.tryparse(combfontsize.selecteditem.tostring(), out fsize)) {
     rtbinfo.tag = fsize.tostring();
     irichformat richfomat = richformatfactory.createrichformat(btntype.fontsize);
     richfomat.setformat(this.rtbinfo);
    }
    return;
   }
  }
 }
}

richtextbox是一个功能丰富的控件，值得学习。

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