//---------------------------------------------------------------------------
//
// <copyright file="SafeHandles.cs" company="Microsoft">
//    Copyright (C) Microsoft Corporation.  All rights reserved.
// </copyright>
// 
//
// Description: Various SafeHandles used by UIA
//
//---------------------------------------------------------------------------
using System;
using System.Runtime.InteropServices;
using System.Windows.Automation;
using System.Windows.Automation.Provider;
 
// PRESHARP: In order to avoid generating warnings about unkown message numbers and unknown pragmas.
#pragma warning disable 1634, 1691
 
namespace MS.Internal.Automation
{
    internal sealed class SafeNodeHandle : SafeHandle
    {
        // Called by P/Invoke when returning SafeHandles
        // (Also used by UiaCoreApi to create invalid handles.)
        internal SafeNodeHandle()
            : base(IntPtr.Zero, true)
        {
        }
 
        // No need to provide a finalizer - SafeHandle's critical finalizer will
        // call ReleaseHandle for you.
        public override bool IsInvalid
        {
            get { return handle == IntPtr.Zero; }
        }
 
        override protected bool ReleaseHandle()
        {
            return UiaCoreApi.UiaNodeRelease(handle);
        }
    }
 
 
    // Internal Class that wraps the IntPtr to the Pattern
    internal sealed class SafePatternHandle : SafeHandle
    {
        // Called by P/Invoke when returning SafeHandles
        // (Also used by UiaCoreApi to create invalid handles.)
        internal SafePatternHandle()
            : base(IntPtr.Zero, true)
        {
        }
        // No need to provide a finalizer - SafeHandle's critical finalizer will
        // call ReleaseHandle for you.
        public override bool IsInvalid
        {
            get { return handle == IntPtr.Zero; }
        }
 
        override protected bool ReleaseHandle()
        {
            return UiaCoreApi.UiaPatternRelease(handle);
        }
    }
 
 
    // Internal Class that wraps the IntPtr to the Event
    internal sealed class SafeEventHandle : SafeHandle
    {
        internal SafeEventHandle()
            : base(IntPtr.Zero, true)
        {
        }
 
        public override bool IsInvalid
        {
            get { return handle == IntPtr.Zero; }
        }
 
        override protected bool ReleaseHandle()
        {
            UiaCoreApi.UiaRemoveEvent(handle);
            return true;
        }
    }
}