wpf,how to restrict MaxLength of TextBox?

<TextBox Height="？" Width="?" AcceptRetur开发者_如何学Gon="true" />

Height=Random; Width=Random; For example,Height is 60, Width is 100. How to control inputed lentgh of text less than size of TextBox

Use MaxLength

EDIT:

Wait, what? You want to restrict the number of chars to the width of the TextBox? Why that?

EDIT2:

You can measure the length of a string by using Graphics.MeasureString. Here's an extension method that does what you want:

public static class TextBoxExtension
{
    public static int VisibleCharCount(this textBox textBox)
    {
        int count = 0;

        do {
            count++;
            var testString = new string('X', count);
            var stringWidth = System.Drawing.Graphics.MeasureString(testString, textBox.Font);                
        } while (stringWidth < textBox.Width);

        if (stringWidth == textBox.Width) 
            return count;
        else
            return count-1;
    }
}

Use it like this:

myTextBox.MaxLength = myTextBox.VisibleCharCount();

EDIT3:

If your TexBox is MultiLine and you also want to take the height into account, you can use the overload of MeasureString that takes a Size. I leave it up to you to modify my example accordingly.

Use the MaxLength property on TextBox, which can be quite static once initialized.

OR

You can cancel the text input with the PreviewTextInput event:

textbox.PreviewTextInput += textbox_PreviewTextInput;

void textbox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
   TextBox box = (TextBox) sender;
   e.Handled = box.Text.Length > 5;
}