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using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Windows.Forms;
using Microsoft.VisualStudio;

namespace Microsoft.VisualStudio.Project
{
    public class ImageHandler : IDisposable
    {
        private ImageList imageList;
        private List<IntPtr> iconHandles;
        private static volatile object Mutex;
        private bool isDisposed;

        /// <summary>
        /// Initializes the <see cref="RDTListener"/> class.
        /// </summary>
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1810:InitializeReferenceTypeStaticFieldsInline")]
        static ImageHandler()
        {
            Mutex = new object();
        }

        /// <summary>
        /// Builds an empty ImageHandler object.
        /// </summary>
        public ImageHandler()
        {
        }

        /// <summary>
        /// Builds an ImageHandler object from a Stream providing the bitmap that
        /// stores the images for the image list.
        /// </summary>
        public ImageHandler(Stream resourceStream)
        {
            if(null == resourceStream)
            {
                throw new ArgumentNullException("resourceStream");
            }
            imageList = Utilities.GetImageList(resourceStream);
        }

        /// <summary>
        /// Builds an ImageHandler object from an ImageList object.
        /// </summary>
        public ImageHandler(ImageList list)
        {
            if(null == list)
            {
                throw new ArgumentNullException("list");
            }
            imageList = list;
        }

        /// <summary>
        /// Closes the ImageHandler object freeing its resources.
        /// </summary>
        public void Close()
        {
            if(null != iconHandles)
            {
                foreach(IntPtr hnd in iconHandles)
                {
                    if(hnd != IntPtr.Zero)
                    {
                        NativeMethods.DestroyIcon(hnd);
                    }
                }
                iconHandles = null;
            }

            if(null != imageList)
            {
                imageList.Dispose();
                imageList = null;
            }
        }

        /// <summary>
        /// Add an image to the ImageHandler.
        /// </summary>
        /// <param name="image">the image object to be added.</param>
        public void AddImage(Image image)
        {
            if(null == image)
            {
                throw new ArgumentNullException("image");
            }
            if(null == imageList)
            {
                imageList = new ImageList();
            }
            imageList.Images.Add(image);
            if(null != iconHandles)
            {
                iconHandles.Add(IntPtr.Zero);
            }
        }

        /// <summary>
        /// Get or set the ImageList object for this ImageHandler.
        /// </summary>
        public ImageList ImageList
        {
            get { return imageList; }
            set
            {
                Close();
                imageList = value;
            }
        }

        /// <summary>
        /// Returns the handle to an icon build from the image of index
        /// iconIndex in the image list.
        /// </summary>
        public IntPtr GetIconHandle(int iconIndex)
        {
            // Verify that the object is in a consistent state.
            if((null == imageList))
            {
                throw new InvalidOperationException();
            }
            // Make sure that the list of handles is initialized.
            if(null == iconHandles)
            {
                InitHandlesList();
            }

            // Verify that the index is inside the expected range.
            if((iconIndex < 0) || (iconIndex >= iconHandles.Count))
            {
                throw new ArgumentOutOfRangeException("iconIndex");
            }

            // Check if the icon is in the cache.
            if(IntPtr.Zero == iconHandles[iconIndex])
            {
                Bitmap bitmap = imageList.Images[iconIndex] as Bitmap;
                // If the image is not a bitmap, then we can not build the icon,
                // so we have to return a null handle.
                if(null == bitmap)
                {
                    return IntPtr.Zero;
                }

                iconHandles[iconIndex] = bitmap.GetHicon();
            }

            return iconHandles[iconIndex];
        }

        private void InitHandlesList()
        {
            iconHandles = new List<IntPtr>(imageList.Images.Count);
            for(int i = 0; i < imageList.Images.Count; ++i)
            {
                iconHandles.Add(IntPtr.Zero);
            }
        }

        #region IDisposable Members

        /// <summary>
        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
        /// </summary>
        public void Dispose()
        {
            this.Dispose(true);
            GC.SuppressFinalize(this);
        }
        #endregion

        private void Dispose(bool disposing)
        {
            if(!this.isDisposed)
            {
                lock(Mutex)
                {
                    if(disposing)
                    {
                        this.imageList.Dispose();
                    }

                    this.isDisposed = true;
                }
            }
        }
    }
}