HYTOS

using System;

using System.ComponentModel;

using System.Runtime.InteropServices;

using System.Security;

using System.Threading;

using System.Windows.Forms;

/// <summary>

/// This class helps to avoid some synchornization issues between WinForms UI and Eyeshot parallel execution. More details here: https://stackoverflow.com/questions/35535580/why-does-parallel-for-execute-the-winforms-message-pump-and-how-to-prevent-it

/// The problem (huge delay) was reproducible switching between two tabs of the EyeshotDemo that build a BRep (for example Bracket and Flange) and moving the mouse cursor very fast on the control surface just after tab switch.

/// A similar problem (flickering) was present in the MarchingCubes sample.

/// </summary>

public class CustomSynchronizationContext : SynchronizationContext

{

    public static void Install()

    {

        var currentContext = Current;

        if (currentContext is CustomSynchronizationContext) return;

        WindowsFormsSynchronizationContext.AutoInstall = false;

        SetSynchronizationContext(new CustomSynchronizationContext(currentContext));

    }

    public static void Uninstall()

    {

        var currentContext = Current as CustomSynchronizationContext;

        if (currentContext == null) return;

        SetSynchronizationContext(currentContext.baseContext);

    }

    private WindowsFormsSynchronizationContext baseContext;

    private CustomSynchronizationContext(SynchronizationContext currentContext)

    {

        baseContext = currentContext as WindowsFormsSynchronizationContext  ?? new WindowsFormsSynchronizationContext();

        SetWaitNotificationRequired();

    }

    public override SynchronizationContext CreateCopy() { return this; }

    public override void Post(SendOrPostCallback d, object state) { baseContext.Post(d, state); }

    public override void Send(SendOrPostCallback d, object state) { baseContext.Send(d, state); }

    public override void OperationStarted() { baseContext.OperationStarted(); }

    public override void OperationCompleted() { baseContext.OperationCompleted(); }

    public override int Wait(IntPtr[] waitHandles, bool waitAll, int millisecondsTimeout)

    {

        int result = WaitForMultipleObjectsEx(waitHandles.Length, waitHandles, waitAll, millisecondsTimeout, false);

        if (result == -1) throw new Win32Exception();

        return result;

    }

    [SuppressUnmanagedCodeSecurity]

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]

    private static extern int WaitForMultipleObjectsEx(int nCount, IntPtr[] pHandles, bool bWaitAll, int dwMilliseconds, bool bAlertable);

}