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// Copyright 2005-2010 Gallio Project - http://www.gallio.org/
// Portions Copyright 2000-2004 Jonathan de Halleux
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using Gallio.Common.Platform;

namespace Gallio.UI.Controls
{
    /// <summary>
    /// An extension of the Button class that displays the "Shield" icon when
    /// privilege elevation is required.
    /// </summary>
    public class ShieldButton : Button
    {
        private bool shield;

        /// <summary>
        /// Creates a shield button.
        /// </summary>
        public ShieldButton()
        {
            FlatStyle = FlatStyle.System;
        }

        /// <summary>
        /// An event raised when the value of <see cref="Shield" /> has changed.
        /// </summary>
        public event EventHandler ShieldChanged;

        /// <summary>
        /// Gets or sets whether the shield icon should be displayed.
        /// </summary>
        public bool Shield
        {
            get { return shield; }
            set
            {
                if (value != shield)
                {
                    shield = value;
                    UpdateShield();
                    OnShieldChanged(EventArgs.Empty);
                }
            }
        }

        /// <summary>
        /// Raises the <see cref="ShieldChanged" /> event.
        /// </summary>
        /// <param name="e">The event arguments.</param>
        protected virtual void OnShieldChanged(EventArgs e)
        {
            if (ShieldChanged != null)
                ShieldChanged(this, e);
        }

        private void UpdateShield()
        {
            if (! DotNetRuntimeSupport.IsUsingMono)
            {
                Native.SendMessage(new HandleRef(this, Handle), Native.BCM_SETSHIELD,
                    new IntPtr(0), new IntPtr(shield ? 1 : 0));
            }
        }
    }
}