Repeated MouseHover events in C#

Administrator — Tue, 24 Feb 2009 06:24:09 +0000

Due to a quirk in the way Windows handles events, once a mouse hover event has been triggered on a windows form control, another event cannot be triggered until the mouse leaves and re-enters the control. Sometimes you might need to process more than one MouseHover event, for example if you have a user control which has draws shapes on itself. As long as you have a record of where the shapes are (by storing them in a collection), you can use the method below as a workaround.

I used this to display a tooltip, so to prevent the MouseHover event being spammed, action is only taken when my tooltip is not visible.

private const uint TME_HOVER = 0x00000001;

private const uint TME_LEAVE = 0x00000002;

private const uint HOVER_DEFAULT = 0xFFFFFFFF;

[DllImport("user32.dll")]

public static extern bool TrackMouseEvent(ref TRACKMOUSEEVENT lpEventTrack);

public struct TRACKMOUSEEVENT {

public uint cbSize;

public uint dwFlags;

public IntPtr hwndTrack;

public uint dwHoverTime;

}

ToolTip toolTip = new ToolTip();toolTip.Location = new System.Drawing.Point(290, 80);

Rectangle currentActiveShape = new Rectangle(); // the currently active shape (over which the mouse is hovering)

this.MouseMove += delegate(object sender, MouseEventArgs e) {

foreach(Rectangle rect in myShapeCollection) {

if(rect.Contains(e.Location)) {if(currentActiveDay != day.Bounds) {

toolTip.Hide();

Console.WriteLine("Hide tooltip");

}

currentActiveShape = rect;

// Set location here

Console.WriteLine("Entered " + rect.ToString());

}

};

this.MouseHover += delegate(object sender, EventArgs e) {TRACKMOUSEEVENT trackMouseEvent = new TRACKMOUSEEVENT();

trackMouseEvent.hwndTrack = ((Control)sender).Handle;

trackMouseEvent.dwFlags = TME_HOVER;

trackMouseEvent.dwHoverTime = HOVER_DEFAULT;

trackMouseEvent.cbSize = (uint)System.Runtime.InteropServices.Marshal.SizeOf(trackMouseEvent);TrackMouseEvent(ref trackMouseEvent);

if(!toolTip.Active) {

toolTip.Show();

Console.WriteLine("Show tooltip");

}

};

As the mouse moves around the control, the location of the tooltip changes, but it’s not shown until the MouseHover event is triggerd.

lifan

Repeated MouseHover events in C#

当前主流的测试工具

Language

Hello world!