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// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
using System;
using System.Windows;
using System.Windows.Input;
using System.Windows.Threading;
namespace ICSharpCode.AvalonEdit.Rendering
{
/// <summary>
/// Encapsulates and adds MouseHover support to UIElements.
/// </summary>
public class MouseHoverLogic : IDisposable
{
UIElement target;
DispatcherTimer mouseHoverTimer;
Point mouseHoverStartPoint;
MouseEventArgs mouseHoverLastEventArgs;
bool mouseHovering;
/// <summary>
/// Creates a new instance and attaches itself to the <paramref name="target" /> UIElement.
/// </summary>
public MouseHoverLogic(UIElement target)
{
if (target == null)
throw new ArgumentNullException("target");
this.target = target;
this.target.MouseLeave += MouseHoverLogicMouseLeave;
this.target.MouseMove += MouseHoverLogicMouseMove;
this.target.MouseEnter += MouseHoverLogicMouseEnter;
}
void MouseHoverLogicMouseMove(object sender, MouseEventArgs e)
{
Vector mouseMovement = mouseHoverStartPoint - e.GetPosition(this.target);
if (Math.Abs(mouseMovement.X) > SystemParameters.MouseHoverWidth
|| Math.Abs(mouseMovement.Y) > SystemParameters.MouseHoverHeight)
{
StartHovering(e);
}
// do not set e.Handled - allow others to also handle MouseMove
}
void MouseHoverLogicMouseEnter(object sender, MouseEventArgs e)
{
StartHovering(e);
// do not set e.Handled - allow others to also handle MouseEnter
}
void StartHovering(MouseEventArgs e)
{
StopHovering();
mouseHoverStartPoint = e.GetPosition(this.target);
mouseHoverLastEventArgs = e;
mouseHoverTimer = new DispatcherTimer(SystemParameters.MouseHoverTime, DispatcherPriority.Background, OnMouseHoverTimerElapsed, this.target.Dispatcher);
mouseHoverTimer.Start();
}
void MouseHoverLogicMouseLeave(object sender, MouseEventArgs e)
{
StopHovering();
// do not set e.Handled - allow others to also handle MouseLeave
}
void StopHovering()
{
if (mouseHoverTimer != null) {
mouseHoverTimer.Stop();
mouseHoverTimer = null;
}
if (mouseHovering) {
mouseHovering = false;
OnMouseHoverStopped(mouseHoverLastEventArgs);
}
}
void OnMouseHoverTimerElapsed(object sender, EventArgs e)
{
mouseHoverTimer.Stop();
mouseHoverTimer = null;
mouseHovering = true;
OnMouseHover(mouseHoverLastEventArgs);
}
/// <summary>
/// Occurs when the mouse starts hovering over a certain location.
/// </summary>
public event EventHandler<MouseEventArgs> MouseHover;
/// <summary>
/// Raises the <see cref="MouseHover"/> event.
/// </summary>
protected virtual void OnMouseHover(MouseEventArgs e)
{
if (MouseHover != null) {
MouseHover(this, e);
}
}
/// <summary>
/// Occurs when the mouse stops hovering over a certain location.
/// </summary>
public event EventHandler<MouseEventArgs> MouseHoverStopped;
/// <summary>
/// Raises the <see cref="MouseHoverStopped"/> event.
/// </summary>
protected virtual void OnMouseHoverStopped(MouseEventArgs e)
{
if (MouseHoverStopped != null) {
MouseHoverStopped(this, e);
}
}
bool disposed;
/// <summary>
/// Removes the MouseHover support from the target UIElement.
/// </summary>
public void Dispose()
{
if (!disposed) {
this.target.MouseLeave -= MouseHoverLogicMouseLeave;
this.target.MouseMove -= MouseHoverLogicMouseMove;
this.target.MouseEnter -= MouseHoverLogicMouseEnter;
}
disposed = true;
}
}
}
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