c#.net 文本编辑控件——设置RichTextBox的字体和字体大小

上一篇文章讨论了有关设置字体格式：粗体、斜体和下划线的问题，本文将要继续讨论的是如何设置字体和字体大小。字体和字体大小的设置与字体格式的设置道理是相同的，也要区分被选中文本的SelectionFont是否为空的问题。下面分别是设置字体种类和字体大小的相关代码。

/// <summary>
/// 设置字体种类,对应于字体下拉框选项
/// </summary>
/// <param name="fontName">被选中的字体名</param>
private void ChangeFont(string fontName)
{
if (fontName == string.Empty)
throw new System.Exception("字体名称参数错误，不能为空");

RichTextBox tempRichTextBox = new RichTextBox();  //用于保存被选中文本的副本

//curRichTextBox是当前文本，即原型
int curRtbStart = curRichTextBox.SelectionStart;
int len = curRichTextBox.SelectionLength;
int tempRtbStart = 0;

Font font = curRichTextBox.SelectionFont;
if (len <= 1 && null != font)
{
curRichTextBox.SelectionFont = new Font(fontName, font.Size, font.Style);
return;
}

tempRichTextBox.Rtf = curRichTextBox.SelectedRtf;
for (int i = 0; i < len; i++)  //逐个设置字体种类
{
tempRichTextBox.Select(tempRtbStart + i, 1);
tempRichTextBox.SelectionFont =
new Font(fontName, tempRichTextBox.SelectionFont.Size,
tempRichTextBox.SelectionFont.Style);
}

//将副本内容插入到到原型中
tempRichTextBox.Select(tempRtbStart, len);
curRichTextBox.SelectedRtf = tempRichTextBox.SelectedRtf;
curRichTextBox.Select(curRtbStart, len);
curRichTextBox.Focus();
}

/// <summary>
/// 设置字体大小,对应于字号下拉框选项
/// </summary>
/// <param name="fontSize">被选中的字号</param>
private void ChangeFontSize(float fontSize)
{
if (fontSize <= 0.0)
throw new InvalidProgramException("字号参数错误，不能小于等于0.0");

RichTextBox tempRichTextBox = new RichTextBox();

int curRtbStart = curRichTextBox.SelectionStart;
int len = curRichTextBox.SelectionLength;
int tempRtbStart = 0;

Font font = curRichTextBox.SelectionFont;
if (len <= 1 && null != font)
{
curRichTextBox.SelectionFont = new Font(font.Name, fontSize, font.Style);
return;
}

tempRichTextBox.Rtf = curRichTextBox.SelectedRtf;
for (int i = 0; i < len; i++)
{
tempRichTextBox.Select(tempRtbStart + i, 1);
tempRichTextBox.SelectionFont =
new Font(tempRichTextBox.SelectionFont.Name,
fontSize, tempRichTextBox.SelectionFont.Style);
}

tempRichTextBox.Select(tempRtbStart, len);
curRichTextBox.SelectedRtf = tempRichTextBox.SelectedRtf;
curRichTextBox.Select(curRtbStart, len);
curRichTextBox.Focus();
}