这是我学到的：
问题不完全在于ToolStripControlHost 类，而在于DateTimePicker 控件本身，更具体地说——它与FlowLayoutPanels 以及可能的其他类似控件的交互。而且我不确定这是一个错误还是预期的行为，但看起来更像是一个错误。
它的工作原理如下：
如果有另一个可以明显激活的控件（例如TextBox），则离开DatePickerControl 意味着激活另一个控件。但是，如果另一个控件是空容器，或者 没有可以激活的控件的容器 - 尽管 DateTimePicker 控件不再处于活动状态，但不会触发 Leave 事件。
为什么要让没有活动控件的容器本身处于活动状态？我使用FlowLayoutPanel 生成只读、不可编辑的报告。它不可编辑，但我希望它可滚动，并且我不希望 DateTimePicker 控件从 FlowLayoutPanel 窃取焦点 - 所以在这种情况下 FlowLayoutPanel 是一个活动控件。 p>
当然不能这样。要实现这种行为还需要更多解决方法，例如从包含表单接收鼠标事件，但正确的 Focus/LeaveLeave 行为是一个好的开始。
所以事不宜迟，我完美的ToolsStripDateTimePicker 控件，已修复焦点故障：
DesignerToolStripControlHost类：
namespace System.Windows.Forms {
/// <summary>
/// Fixes ToolStripControlHost broken designer behavior
/// </summary>
public class DesignerToolStripControlHost : ToolStripControlHost {
/// <summary>
/// Fixes designer bug by creating a constructor allowing to create ToolStripControlHost
/// without parameter
/// </summary>
public DesignerToolStripControlHost() : base(new UserControl()) { }
/// <summary>
/// Initializes a new instance of the System.Windows.Forms.DesignerToolStripControlHost
/// class that hosts the specified control
/// </summary>
/// <param name="c"></param>
public DesignerToolStripControlHost(Control c) : base(c) { }
/// <summary>
/// Initializes a new instance of the System.Windows.Forms.DesignerToolStripControlHost
/// class that hosts the specified control and that has the specified name
/// </summary>
/// <param name="c"></param>
/// <param name="name"></param>
public DesignerToolStripControlHost(Control c, string name) : base(c, name) { }
}
}
ToolStripDateTimePicker类：
using System.ComponentModel;
using System.Windows.Forms;
using System.Windows.Forms.Design;
namespace System.Windows.Controls {
[ToolStripItemDesignerAvailability(ToolStripItemDesignerAvailability.All)]
public partial class ToolStripDateTimePicker : DesignerToolStripControlHost, IComponent {
public ToolStripDateTimePicker() : base(new DateTimePicker() { Margin = new Padding(0, 0, 0, 0), Width = 150, Value = DateTime.Now.Date }) { }
#region Properties
[Browsable(true)]
[Category("Design")]
[Description("Internal ToolStrip hosted control.")]
public DateTimePicker DateTimePickerControl { get { return Control as DateTimePicker; } }
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[Category("Behavior")]
[Description("Gets or sets the tab order of the control within its container.")]
public int TabIndex { get { return DateTimePickerControl.TabIndex; } set { DateTimePickerControl.TabIndex = value; } }
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[Category("Behavior")]
[Description("Gets or sets a value indicating whether the user can give the focus to this control using the TAB key.")]
public bool TabStop { get { return DateTimePickerControl.TabStop; } set { DateTimePickerControl.TabStop = value; } }
[Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
[Description("This property is ignored.")]
public override string Text { get { return DateTimePickerControl.Value.ToString(); } set { DateTimePickerControl.Value = DateTime.Parse(value); } }
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[Category("Behavior")]
[Description("The current date/time value for this control.")]
public DateTime Value { get { return DateTimePickerControl.Value; } set { DateTimePickerControl.Value = value; } }
#endregion
#region Events
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[Category("Focus")]
[Description("Occurs when the input focus enters the control.")]
public new EventHandler Enter;
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[Category("Focus")]
[Description("Occurs when the input focus leaves the control.")]
public new EventHandler Leave;
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[Category("Behavior")]
[Description("Occurs when the value of the control changes.")]
public event EventHandler ValueChanged;
#endregion
#region Event Handlers
protected void OnEnter(object sender, EventArgs e) { EventHandler handler = Enter; if (handler != null) handler(this, e); }
protected void OnLeave(object sender, EventArgs e) { EventHandler handler = Leave; if (handler != null) handler(this, e); }
protected override void OnGotFocus(EventArgs e) {
base.OnGotFocus(e);
if (Enter != null) {
if (DateTime.Now.Ticks - _FocusGlitchFix_LastEvent > _FocusGlitchFixTickWindow) Enter.Invoke(this, e);
_FocusGlitchFix_LastEvent = DateTime.Now.Ticks;
}
}
protected override void OnLostFocus(EventArgs e) {
base.OnLostFocus(e);
if (Leave != null) {
if (DateTime.Now.Ticks - _FocusGlitchFix_LastEvent > _FocusGlitchFixTickWindow) Leave.Invoke(this, e);
_FocusGlitchFix_LastEvent = DateTime.Now.Ticks;
}
}
protected void OnValueChanged(object sender, EventArgs e) { EventHandler handler = ValueChanged; if (handler != null) handler(this, e); }
protected override void OnSubscribeControlEvents(Control control) {
base.OnSubscribeControlEvents(control);
DateTimePickerControl.ValueChanged += new EventHandler(OnValueChanged);
}
protected override void OnUnsubscribeControlEvents(Control control) {
base.OnUnsubscribeControlEvents(control);
DateTimePickerControl.ValueChanged -= new EventHandler(OnValueChanged);
}
#endregion
#region Focus Glitch Workaround data
private long _FocusGlitchFix_LastEvent = 0;
private readonly long _FocusGlitchFixTickWindow = 100000; // 10ms
#endregion
}
}
解决方法说明：
- 原始 DTP
OnGotFocus() 和 OnLostFocus() 事件处理程序被覆盖以触发我的新控件 Enter 和 Leave 事件。请注意，它们几乎是正确触发的。
- 当控件是唯一可以激活的控件时，当控件第一次离开时，它会立即激活和停用 - 这意味着双倍（冗余）
Enter 和 Leave 事件。我们不想要这些，所以我检查事件之间的时间，如果它小于 10 毫秒，我会忽略以后的事件。
-
DesignerToolStripControlHost 用于修复损坏的设计器行为。如果您直接使用ToolStripControlHost，您会在尝试显示控件的设计器视图时遇到异常，因为设计器尝试不带参数实例化此类，而此类没有不带参数的构造函数。所以我的新课就是这样。
- 当包含
ToolStripDateTimePicker 的表单的设计器视图中断时，您可以通过看到 DTP 消失来判断，只需关闭设计器视图并再次打开它。在您再次编译或调试您的应用程序之前，它将正常工作。
故障修复已在 1 毫秒时间窗口内进行了测试，并且运行良好。所以我选择了 10ms 以确保它在速度较慢或负载更多的机器上工作，但它仍然足够短，可以捕获来自用户交互的任何事件。