[C#]使用SharpShell實現Shell Icon Overlay功能

namespace ReadOnlyFileIconOverlayHandler { /// <summary> /// The ReadOnlyFileIconOverlayHandler is an IconOverlayHandler that shows /// a padlock icon over files that are read only. /// </summary> [ComVisible(true)] public class ReadOnlyFileIconOverlayHandler : SharpIconOverlayHandler { /// <summary> /// Called by the system to get the priority, which is used to determine /// which icon overlay to use if there are multiple handlers. The priority /// must be between 0 and 100, where 0 is the highest priority. /// </summary> /// <returns> /// A value between 0 and 100, where 0 is the highest priority. /// </returns> protected override int GetPriority() { // The read only icon overlay is very low priority. return 90; }

    /// &lt;summary&gt;
    /// Determines whether an overlay should be shown for the shell item with the path 'path' and
    /// the shell attributes 'attributes'.
    /// &lt;/summary&gt;
    /// &lt;param name="path"&gt;The path for the shell item. This is not necessarily the path
    /// to a physical file or folder.&lt;/param&gt;
    /// &lt;param name="attributes"&gt;The attributes of the shell item.&lt;/param&gt;
    /// &lt;returns&gt;
    ///   &lt;c&gt;true&lt;/c&gt; if this an overlay should be shown for the specified item; otherwise, &lt;c&gt;false&lt;/c&gt;.
    /// &lt;/returns&gt;
    protected override bool CanShowOverlay(string path, FILE_ATTRIBUTE attributes)
    {
        try
        {
            //  Get the file attributes.
            var fileAttributes = new FileInfo(path);

            //  Return true if the file is read only, meaning we'll show the overlay.
            return fileAttributes.IsReadOnly;
        }
        catch (Exception)
        {
            return false;
        }
    }

    /// &lt;summary&gt;
    /// Called to get the icon to show as the overlay icon.
    /// &lt;/summary&gt;
    /// &lt;returns&gt;
    /// The overlay icon.
    /// &lt;/returns&gt;
    protected override System.Drawing.Icon GetOverlayIcon()
    {
        //  Return the read only icon.
        return Properties.Resources.ReadOnly;
    }
}

}