使用ToolStripDropDown模拟工具提示功能

Question

我创建了一个自定义UserControl，它在ToolStripDropDown中显示自己以模拟ToolTip功能。当我订阅他们的MouseEnter和MouseLeave事件时，它对任何控件都很好。

我还想将它用于自定义对象（而不是控件）。我已经创建了一个定义MouseEnter和MouseLeave事件的界面，这样我就可以向该工具提示订阅任何对象（例如自定义绘制的基本体）。这些类自己决定何时触发MouseEnter和MouseLeave。

我的问题是，当显示工具提示时，我的包含自定义对象的UserControls不会接收MouseMove事件，即使工具提示显示在鼠标的侧面而不是下面。如果鼠标不再位于有问题的对象上，我将基于在MouseMove中的检查生成我自己的MouseLeave事件。但显然，如果没有MouseMove事件，MouseLeave就永远不会开火。

当我在控件上显示工具提示时，会发生同样的事情（没有MouseMove事件），只是MouseLeave仍然会触发。

1） 如何模拟MouseLeave功能？我必须使用p/invoke来SetCapture鼠标移动吗？或者有人知道更简单的方法吗？

2） 当工具提示显示时，即使ToolStripDropDown或其中的UserControl都没有触发"GotFocus"事件，只要工具提示显示，我仍然会失去键盘焦点，这也是不理想的工具提示行为。我能避免吗？

基本上，我希望它是一个完全不可聚焦，无干扰的工具提示。我看过一个名为SuperTooltip的示例项目，但它也有同样的缺陷。我尝试过设置ControlStyles。可选择为false，但没有注意到任何更改。

这是我创建工具提示UserControl:的代码

public CustomTooltip()
{
    this.SetStyle(ControlStyles.Selectable, false);
    dropDown = new ToolStripDropDown();
    dropDown.AutoSize = false;
    dropDown.Margin = Padding.Empty;
    dropDown.Padding = Padding.Empty;
    host = new ToolStripControlHost(this);
    host.AutoSize = false;
    host.Margin = Padding.Empty;
    host.Padding = Padding.Empty;
    this.Location = new Point(0, 0);
    dropDown.Items.Add(host);
}

我用显示

dropDown.Show(
    new Point(Cursor.Position.X, Cursor.Position.Y + Cursor.Current.Size.Height),
    ToolStripDropDownDirection.BelowRight
);

Answer 1

我发现我可以通过从Form派生而完全不使用ToolStripDropDown来实现这一点。此类模拟工具提示的功能，并允许自定义淡入/淡出参数。您可以为MouseEnter和MouseLeave订阅控件或任何定义并实现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，您只需要从CustomTooltip派生，即可制作自己的自定义工具提示。派生类将使用Tag属性来确定显示的内容。例如，如果我想要一个将图像与对象关联起来并绘制该图像的工具提示，我会执行以下操作：

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);
    }
}

为了在应用程序中使用这个CustomImageTooltip类，您只需要订阅和取消订阅该类的一个实例：

// Constructor
customImageTooltip = new CustomImageTooltip();
foreach (CustomObject o in myCustomObjects)
{
    customImageTooltip.Subscribe(o, o.Image);
}
// Destructor
foreach (CustomObject o in myCustomObjects)
{
    customImageTooltip.Unsubscribe(o);
}