正确地同时更改字体样式

Question

How do I properly change the Font Style of the text without using a lot of if / else if conditions when checking multiple checkboxes?

PS. I know what to use when having multiple styles in one text but I d not want a long if/else conditions to achieve it.

Here's what I Have:

public void updateFont()
    {
        //Individual
        if (checkBox_Bold.Checked)
            fontStyle = fontFamily.Style | FontStyle.Bold;
        if (checkBox_Italic.Checked)
            fontStyle = fontFamily.Style | FontStyle.Italic;
        if (checkBox_Underlined.Checked)
            fontStyle = fontFamily.Style | FontStyle.Underline;
        if (checkBox_StrikeOut.Checked)
            fontStyle = fontFamily.Style | FontStyle.Strikeout;
        if (!checkBox_Bold.Checked && !checkBox_Italic.Checked && !checkBox_Underlined.Checked && !checkBox_StrikeOut.Checked)
            fontStyle = FontStyle.Regular;


        fontFamily = new Font(cbox_FontFamily.SelectedItem.ToString(), Convert.ToInt32(fontSize), fontStyle);
        pictureBox_Canvass.Invalidate();
    }

Answer 1

• Assign the related FontStyle to each CheckBox.Tag property (in the Form constructor, or Load event).
  

• Assign a single Event handler to all CheckBoxes CheckedChange event (it's set in the designer, here; but it of course you can add it in the constructor as well).
  

• FontStyle is a flag. You can use | to add it and &~ to remove it.
  

You could add a condition to mutually excludes the Underline and Strikeout styles, if required.

---

 FontStyle fontStyle = FontStyle.Regular;

 public form1()
 {
    InitializeComponent();

    this.chkBold.Tag = FontStyle.Bold;
    this.chkItalic.Tag = FontStyle.Italic;
    this.chkUnderline.Tag = FontStyle.Underline;
    this.chkStrikeout.Tag = FontStyle.Strikeout;
 }

 private void chkFontStyle_CheckedChanged(object sender, EventArgs e)
 {
    CheckBox checkBox = sender as CheckBox;
    FontStyle CurrentFontStyle = (FontStyle)checkBox.Tag;
    fontStyle = checkBox.Checked ? fontStyle | CurrentFontStyle : fontStyle &~CurrentFontStyle;
    lblTestFont.Font = new Font("Segoe UI", 10, fontStyle, GraphicsUnit.Point);
 }

Answer 2

As Jimi already mentioned, but here you can also achieve your goal using LINQ.

private void UpdateTextBoxFontStyle()
{
   var fs = System.Drawing.FontStyle.Regular;

   var checkedStyles = Controls.OfType<CheckBox>()
          .Where(x => x.Checked)
          .Where(x => x.Tag is System.Drawing.FontStyle)
          .Select(x => (System.Drawing.FontStyle) x.Tag).ToList();

   foreach (var style in checkedStyles) fs |= style;
   lblTestFont.Font = new System.Drawing.Font("Segoe UI", 9f, fs, System.Drawing.GraphicsUnit.Point);
}

And assign CheckedChanged event handler to each checkboxes.

foreach (Control control in Controls)
      if (control is CheckBox checkBox)
         checkBox.CheckedChanged += (s, e) => UpdateTextBoxFontStyle();