我发现我能够通过从表派生并没有使用来完成此ToolStripDropDown在所有。此类模拟工具提示的功能，并允许自定义淡入/淡出参数。您可以订阅一个控件或任何为MouseEnter和MouseLeave定义和实现ITooltipTarget的类。
public abstract class CustomTooltip : Form
{
#region Static
protected static readonly int FadeInterval = 25;
protected static readonly IntPtr HWND_TOPMOST = (IntPtr)(-1);
private const int SWP_NOSIZE = 0x0001;
private const int SWP_NOMOVE = 0x0002;
private const int SWP_NOACTIVATE = 0x0010;
private const int WS_POPUP = unchecked((int)0x80000000);
private const int WS_EX_TOPMOST = 0x00000008;
private const int WS_EX_NOACTIVATE = 0x08000000;
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
#endregion
protected Dictionary<object, object> subscriptions;
protected Timer popupTimer;
protected Timer fadeTimer;
protected bool isFading = false;
protected int fadeDirection = 1;
[DefaultValue(500)]
/// <summary>
/// Delay in milliseconds before the tooltip is shown. 0 means no delay.
/// </summary>
public int PopupDelay
{
get
{
return _popupDelay;
}
set
{
_popupDelay = value;
if (value > 0)
popupTimer.Interval = value;
else
popupTimer.Interval = 1;
}
}
private int _popupDelay = 500;
[DefaultValue(0)]
/// <summary>
/// How long to spend fading in and out in milliseconds. 0 means no fade.
/// </summary>
public int FadeTime
{
get
{
return _fadeTime;
}
set
{
_fadeTime = value;
}
}
private int _fadeTime = 0;
public virtual new object Tag
{
get
{
return base.Tag;
}
set
{
base.Tag = value;
OnTagChanged(EventArgs.Empty);
}
}
public CustomTooltip()
{
this.SetStyle(ControlStyles.Selectable, false);
subscriptions = new Dictionary<object, object>();
popupTimer = new Timer();
popupTimer.Interval = PopupDelay;
popupTimer.Tick += new EventHandler(popupTimer_Tick);
fadeTimer = new Timer();
fadeTimer.Interval = FadeInterval;
fadeTimer.Tick += new EventHandler(fadeTimer_Tick);
this.Visible = false;
this.ShowInTaskbar = false;
this.FormBorderStyle = FormBorderStyle.None;
this.ControlBox = false;
this.StartPosition = FormStartPosition.Manual;
}
protected override CreateParams CreateParams
{
get
{
CreateParams cp = base.CreateParams;
cp.Style |= WS_POPUP;
cp.ExStyle |= WS_EX_TOPMOST | WS_EX_NOACTIVATE;
return cp;
}
}
protected override bool ShowWithoutActivation
{
get
{
return true;
}
}
protected virtual void Subscribe(Control control, object tag)
{
subscriptions.Add(control, tag);
control.MouseEnter += new EventHandler(Item_MouseEnter);
control.MouseLeave += new EventHandler(Item_MouseLeave);
}
protected virtual void Subscribe(ITooltipTarget item, object tag)
{
subscriptions.Add(item, tag);
item.MouseEnter += new EventHandler(Item_MouseEnter);
item.MouseLeave += new EventHandler(Item_MouseLeave);
}
public virtual void Unsubscribe(Control control)
{
control.MouseEnter -= new EventHandler(Item_MouseEnter);
control.MouseLeave -= new EventHandler(Item_MouseLeave);
subscriptions.Remove(control);
}
public virtual void Unsubcribe(ITooltipTarget item)
{
item.MouseEnter -= new EventHandler(Item_MouseEnter);
item.MouseLeave -= new EventHandler(Item_MouseLeave);
subscriptions.Remove(item);
}
public void ClearSubscriptions()
{
foreach (object o in subscriptions.Keys)
{
if (o is Control)
Unsubscribe((Control)o);
else if (o is ITooltipTarget)
Unsubscribe((ITooltipTarget)o);
}
}
protected virtual void OnTagChanged(EventArgs e)
{
}
protected override void OnSizeChanged(EventArgs e)
{
base.OnSizeChanged(e);
}
protected override void OnMouseEnter(EventArgs e)
{
base.OnMouseEnter(e);
Item_MouseLeave(null, EventArgs.Empty);
}
private void Item_MouseEnter(object sender, EventArgs e)
{
Tag = subscriptions[sender];
popupTimer.Start();
}
private void Item_MouseLeave(object sender, EventArgs e)
{
if (FadeTime > 0)
FadeOut();
else
this.Hide();
popupTimer.Stop();
}
protected virtual void FadeIn()
{
isFading = true;
Opacity = 0;
fadeDirection = 1;
fadeTimer.Start();
}
protected virtual void FadeOut()
{
isFading = true;
Opacity = 1;
fadeDirection = -1;
fadeTimer.Start();
}
private void popupTimer_Tick(object sender, EventArgs e)
{
if (isFading)
this.Hide();
if (FadeTime > 0)
FadeIn();
Location = new Point(Cursor.Position.X, Cursor.Position.Y + Cursor.Size.Height);
SetWindowPos(Handle, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOACTIVATE | SWP_NOMOVE | SWP_NOSIZE);
Show();
popupTimer.Stop();
}
private void fadeTimer_Tick(object sender, EventArgs e)
{
if (Opacity == 0 && fadeDirection == -1)
{
isFading = false;
fadeTimer.Stop();
this.Hide();
}
else if (Opacity == 1 && fadeDirection == 1)
{
fadeTimer.Stop();
isFading = false;
}
else
{
double change = ((double)fadeTimer.Interval/(double)FadeTime) * (double)fadeDirection;
Opacity += change;
}
}
}
public interface ITooltipTarget
{
event EventHandler MouseEnter;
event EventHandler MouseLeave;
}
要使用上述类，您只需从CustomTooltip派生自定义绘制的工具提示。派生类将使用Tag属性来确定显示的内容。例如，如果我想将图像与对象相关联，并绘制该图像的工具提示，我会做这样的事情：
public class CustomImageTooltip : CustomTooltip
{
public Image Image
{
get
{
if (Tag is Image)
return Tag as Image;
else
return null;
}
}
public CustomImageTooltip()
{
InitializeComponent();
this.SetStyle(ControlStyles.DoubleBuffer |
ControlStyles.AllPaintingInWmPaint |
ControlStyles.UserPaint, true);
}
public void Subscribe(Control control, Image image)
{
base.Subscribe(control, image);
}
public void Subscribe(ITooltipTarget item, Image image)
{
base.Subscribe(item, image);
}
protected override void OnTagChanged(EventArgs e)
{
base.OnTagChanged(e);
if (Image != null)
this.Size = Image.Size;
}
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
g.Clear(Color.White);
if (Image != null)
g.DrawImage(
Image,
new RectangleF(0, 0, ClientSize.Width, ClientSize.Height),
new RectangleF(0, 0, Image.Size.Width, Image.Size.Height),
GraphicsUnit.Pixel
);
g.DrawRectangle(Pens.Black, 0, 0, ClientRectangle.Width - 1, ClientRectangle.Height - 1);
}
}
而且为了在应用程序中使用这个CustomImageTooltip类，你需要只订阅和取消订阅该课程的单个实例：
// Constructor
customImageTooltip = new CustomImageTooltip();
foreach (CustomObject o in myCustomObjects)
{
customImageTooltip.Subscribe(o, o.Image);
}
// Destructor
foreach (CustomObject o in myCustomObjects)
{
customImageTooltip.Unsubscribe(o);
}