c# - NumericUpDown 控件应仅在滚动完成时触发 ValueChanged 事件

Question

我有一个 numericUpDown 控件(Windows 窗体)。

我想听ValueChanged事件。

我在属性中设置它并且它有效。

但是:

我希望我可以向上或向下“滚动”。 (如果我把它做得更长，它会更快)

当我完成“滚动”后，我希望现在触发事件 xyz 而不是在滚动期间。

我该怎么做？

Answer 1

尝试使用 mouseup 事件。当您将手指从鼠标左键上移开时它会触发，因此理论上它应该可以解决您的问题。

[詹姆斯编辑]在您的表单上试试这个控件。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Example.CustomControl
{
    /// <summary>
    /// Provides an extra event for the numericUpDown control that fires after the value stops scrolling.
    /// </summary>
    public class NumericDelayedChange : NumericUpDown
    {
        /// <summary>
        /// Flag that the value has actually changed.
        /// </summary>
        /// <devdoc>
        /// Just in case the control was clicked somewhere other than the up/down buttons.
        /// </devdoc>
        private bool valueHasChanged = false;

        /// <summary>
        /// Fires when the value has stopped being scrolled.
        /// </summary>
        public event EventHandler OnAfterScollValueChanged;

        /// <summary>
        /// Captures that value as having changed.
        /// </summary>
        /// <param name="e"></param>
        protected override void OnValueChanged(EventArgs e)
        {
            valueHasChanged = true;
            base.OnValueChanged(e);
        }

        /// <summary>
        /// Captures the mouse up event to identify scrolling stopped when used in combination with the value changed flag.
        /// </summary>
        /// <param name="mevent"></param>
        protected override void OnMouseUp(MouseEventArgs mevent)
        {
            base.OnMouseUp(mevent);
            if (mevent.Button == System.Windows.Forms.MouseButtons.Left)
            {
                PerformOnAfterScollValueChanged();
            }
        }

        /// <summary>
        /// Captures the key up/down events to identify scrolling stopped when used in combination with the value changed flag.
        /// </summary>
        /// <param name="mevent"></param>
        protected override void OnKeyUp(KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Up || e.KeyCode == Keys.Down)
            {
                PerformOnAfterScollValueChanged();
            }
            base.OnKeyUp(e);
        }

        /// <summary>
        /// Checks the value changed flag and fires the OnAfterScollValueChanged event.
        /// </summary>
        private void PerformOnAfterScollValueChanged()
        {
            if (valueHasChanged)
            {
                valueHasChanged = false;
                if (OnAfterScollValueChanged != null) { OnAfterScollValueChanged(this, new EventArgs()); }
            }
        }
    }
}