Clipz - A Friendly Introduction to the Windows 7 Taskbar Features

//Copyright (c) Microsoft Corporation.  All rights reserved.

using System;
using System.Collections.ObjectModel;
using System.Text;
using Microsoft.WindowsAPICodePack.Shell;

namespace Microsoft.WindowsAPICodePack.Dialogs
{
    /// <summary>
    /// Stores the file extensions used when filtering files in File Open and File Save dialogs.
    /// </summary>
    public class CommonFileDialogFilter
    {
        // We'll keep a parsed list of separate 
        // extensions and rebuild as needed.

        private Collection<string> extensions;
        private string rawDisplayName;

        /// <summary>
        /// Creates a new instance of this class.
        /// </summary>
        public CommonFileDialogFilter()
        {
            extensions = new Collection<string>();
        }
        /// <summary>
        /// Creates a new instance of this class with the specified display name and 
        /// file extension list.
        /// </summary>
        /// <param name="rawDisplayName">The name of this filter.</param>
        /// <param name="extensionList">The list of extensions in 
        /// this filter. See remarks.</param>
        /// <remarks>The <paramref name="extensionList"/> can use a semicolon(";") 
        /// or comma (",") to separate extensions. Extensions can be prefaced 
        /// with a period (".") or with the file wild card specifier "*.".</remarks>
        /// <permission cref="System.ArgumentNullException">
        /// The <paramref name="extensionList"/> cannot be null or a 
        /// zero-length string. 
        /// </permission>
        public CommonFileDialogFilter(string rawDisplayName, string extensionList)
            : this()
        {
            if (String.IsNullOrEmpty(extensionList))
                throw new ArgumentNullException(
                    "extensionList",
                    "extensionList must be non-null.");

            this.rawDisplayName = rawDisplayName;

            // Parse string and create extension strings.
            // Format: "bat,cmd", or "bat;cmd", or "*.bat;*.cmd"
            // Can support leading "." or "*." - these will be stripped.
            string[] rawExtensions = extensionList.Split(',', ';');
            foreach (string extension in rawExtensions)
                extensions.Add(CommonFileDialogFilter.NormalizeExtension(extension));
        }
        /// <summary>
        /// Gets or sets the display name for this filter.
        /// </summary>
        /// <permission cref="System.ArgumentNullException">
        /// The value for this property cannot be set to null or a 
        /// zero-length string. 
        /// </permission>
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Globalization", "CA1305:SpecifyIFormatProvider", MessageId = "System.String.Format(System.String,System.Object,System.Object)", Justification = "We are not currently handling globalization or localization")]
        public string DisplayName
        {
            get
            {
                if (showExtensions)
                    return String.Format("{0} ({1})", 
                        rawDisplayName, CommonFileDialogFilter.GetDisplayExtensionList(extensions));
                else
                    return rawDisplayName;
            }

            set
            {
                if (String.IsNullOrEmpty(value))
                    throw new ArgumentNullException(
                        "value",
                        "DisplayName must be non-null.");
                rawDisplayName = value;
            }
        }

        /// <summary>
        /// Gets a collection of the individual extensions 
        /// described by this filter.
        /// </summary>
        public Collection<string> Extensions
        {
            get { return extensions; }
        }

        private bool showExtensions = true;
        /// <summary>
        /// Gets or sets a value that controls whether the extensions are displayed.
        /// </summary>
        public bool ShowExtensions
        {
            get { return showExtensions; }
            set { showExtensions = value; }
        }

        private static string NormalizeExtension(string rawExtension)
        {
            rawExtension = rawExtension.Trim();
            rawExtension = rawExtension.Replace("*.", null);
            rawExtension = rawExtension.Replace(".", null);
            return rawExtension;
        }

        private static string GetDisplayExtensionList(Collection<string> extensions)
        {
            StringBuilder extensionList = new StringBuilder();
            foreach (string extension in extensions)
            {
                if (extensionList.Length > 0)
                    extensionList.Append(", ");
                extensionList.Append("*.");
                extensionList.Append(extension);
            }

            return extensionList.ToString();
        }

        /// <summary>
        /// Internal helper that generates a single filter 
        /// specification for this filter, used by the COM API.
        /// </summary>
        /// <returns>Filter specification for this filter</returns>
        /// 
        internal ShellNativeMethods.COMDLG_FILTERSPEC GetFilterSpec()
        {
            StringBuilder filterList = new StringBuilder();
            foreach (string extension in extensions)
            {
                if (filterList.Length > 0)
                    filterList.Append(";");

                filterList.Append("*.");
                filterList.Append(extension);
                
            }
            return new ShellNativeMethods.COMDLG_FILTERSPEC(DisplayName, filterList.ToString());
        }

        /// <summary>
        /// Returns a string representation for this filter that includes
        /// the display name and the list of extensions.
        /// </summary>
        /// <returns>A <see cref="System.String"/>.</returns>
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Globalization", "CA1305:SpecifyIFormatProvider", MessageId = "System.String.Format(System.String,System.Object,System.Object)", Justification = "We are not currently handling globalization or localization")]
        public override string ToString()
        {
            return String.Format("{0} ({1})", 
                rawDisplayName, 
                CommonFileDialogFilter.GetDisplayExtensionList(extensions));
        }
    }
}