IVsDataHostService.InvokeOnUIThread Method

Synchronously executes a specified method on the main thread running in the Visual Studio process, with the specified list of arguments.

Namespace:  Microsoft.VisualStudio.Data.Core
Assembly:  Microsoft.VisualStudio.Data.Core (in Microsoft.VisualStudio.Data.Core.dll)

Syntax

'宣言
Function InvokeOnUIThread ( _
    method As Delegate, _
    ParamArray args As Object() _
) As Object
'使用
Dim instance As IVsDataHostService
Dim method As Delegate
Dim args As Object()
Dim returnValue As Object

returnValue = instance.InvokeOnUIThread(method, _
    args)

Object InvokeOnUIThread(
    Delegate method,
    params Object[] args
)

Object^ InvokeOnUIThread(
    Delegate^ method, 
    ... array<Object^>^ args
)

function InvokeOnUIThread(
    method : Delegate, 
    ... args : Object[]
) : Object

Parameters

• method
  Type: System.Delegate

  A delegate to a method that takes parameters of the same number and type that are contained in the args parameter.

• args
  Type: []

  An array of objects to pass as arguments to the specified method. This parameter can be a null reference (Nothing in Visual Basic) if the method takes no arguments.

Return Value

Type: System.Object

An Object that contains the return value from the delegate being invoked, or a null reference (Nothing in Visual Basic) if the delegate has no return value.

Exceptions

Remarks

This method is useful for multithreaded scenarios that do the majority of work on a background thread but periodically need to execute code that will run only on the UI thread. Such code includes accessing global Visual Studio services, especially those implemented as single-threaded COM components in native code.

When this method is called, it adds a message to the UI thread’s windows message queue, which on processing calls the specified method. This method is synchronous, meaning the calling thread is blocked until the UI thread has completed processing the method.

Examples

The following code demonstrates one use of this method to call a native Visual Studio service that cannot be accessed from a background thread.

using System;
using System.Threading;
using Microsoft.VisualStudio.Data.Core;
using Microsoft.VisualStudio.Shell.Interop;

public class DdexHostSvcExample7
{
    public static void UpdateUI(IVsDataHostService hostService)
    {
        if (hostService.UIThread == Thread.CurrentThread)
        {
            // Called on UI thread, directly call method
            ActuallyUpdateUI(hostService);
        }
        else
        {
            // Called from background thread, invoke on UI thread
            hostService.InvokeOnUIThread(
                new UpdateUIDelegate(ActuallyUpdateUI),
                hostService);
        }
    }

    private delegate void UpdateUIDelegate(IVsDataHostService hostService);

    private static void ActuallyUpdateUI(IVsDataHostService hostService)
    {
        IVsUIShell uiShell = hostService.GetService<IVsUIShell>();
        uiShell.UpdateCommandUI(0); // fImmediateUpdate == false
    }
}

Permissions

• Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.

See Also

Reference

IVsDataHostService Interface

IVsDataHostService Members

Microsoft.VisualStudio.Data.Core Namespace