Question

我@app.route('/admin/dashboard', methods=['GET', 'POST']) def admin_dashboard(): if request.method == 'GET': return render_template("/admin/dashboard.html") if request.method == 'POST': if request.form['submit'] == 'fred': admin.log("Shutting down...") #os._exit(1) else: return render_template("/admin/dashboard.html") return render_template("/admin/dashboard.html") TextBox设为10，但按Enter键时接受11个字符。看起来它将 \ n \ r 计为1个字符而不是2个字符。反正有没有把它计算为 \ n \ r 两个字符长度？

Answer 1

如果您真的想在文本框中设置换行符并限制其文本长度，我会看到两个选项：

通过转换器绑定MaxLength，以便根据文本包含的换行符（\r\n）更改其值，如this question

或者，您可以定义自己的附加属性MaxLength，以正确计算文本长度。这可能看起来有点像以下（作为一个例子，你需要调整它以考虑特殊情况等）。

public class TextBoxExtensions: DependencyObject
{
    public static readonly DependencyProperty MaxLengthProperty = DependencyProperty.RegisterAttached(
        "MaxLength", typeof (int), typeof (MaxLengthBehavior), new PropertyMetadata(default(int), PropertyChangedCallback));

    public static void SetMaxLength(DependencyObject element, int value)
    {
        element.SetValue(MaxLengthProperty, value);
    }

    public static int GetMaxLength(DependencyObject element)
    {
        return (int) element.GetValue(MaxLengthProperty);
    }

    private static void PropertyChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs args)
    {
        var tb = dependencyObject as TextBox;
        if (tb != null)
        {
            tb.KeyDown -= TbOnKeyDown;
            tb.KeyDown += TbOnKeyDown;
        }
    }

    private static void TbOnKeyDown(object sender, KeyRoutedEventArgs args)
    {
        var tb = sender as TextBox;
        if (tb != null)
        {
            int max = GetMaxLength(tb);
            if (tb.Text.Length >= max)
                args.Handled = true;
        }
    }
}

<TextBox local:TextBoxExtensions.MaxLength="10" />

WinRT TextBox MaxLength不将\ n \ r计为两个字符

1 个答案: