A TaskScheduler For Background Tasks on an STA Thread

Question

在1.NET 4.0应用(WPF)中,我们改用SHGetFileInfo,以获得一个 director树的壳体。由于有时需要相当一段时间(即网络驱动力无法达到,或用于喷气驱动力),我们希望这样做,然后在阅读时更新icon。

这一呼吁基本相同,现在刚刚在read子里执行。因为有人说,read子必须是STA,以便工作,所以我们使用Thread而不是ThreadPool进行测试,结果相同。使用<代码>ThreadPool 也没有工作。

<代码>SHGetFileInfo > 继承(第1条),但结构中的hIcon成员为零。

IntPtr GetIcon(string name)
{
    Shell32.SHFILEINFO shfi = new Shell32.SHFILEINFO();
    uint flags = Shell32.SHGFI_ICON | Shell32.SHGFI_USEFILEATTRIBUTES | Shell32.SHGFI_SMALLICON;

    Shell32.SHGetFileInfo(
        name, System.IO.Directory.Exists(name) ? Shell32.FILE_ATTRIBUTE_DIRECTORY : Shell32.FILE_ATTRIBUTE_NORMAL,
        ref shfi, 
        (uint) System.Runtime.InteropServices.Marshal.SizeOf(shfi), 
        flags );
    return shfi.hIcon;
}

同样的法典从德国马克的深层中操作。必须做些什么,才能使职能从一个单独的侧面上发挥作用,或者使其发挥作用,同时又不阻挡全球倡议的透镜?

Update: The code around this is basically this:

var thread = new System.Threading.Thread(() => {
    var result = GetIcon("C:\");
    // ... do something with the result
});
thread.SetApartmentState(System.Threading.ApartmentState.STA);
thread.Start();

如果只剩下read子,则会做罚款(但根基深省当然是这样)。

最新情况:我们现在仅凭Invoke打电话到SHGetFileInfo,以使之发挥作用。这样做的好处是,原始问题(在所有电灯被装上之前,档案页面没有显示)已经解决,不过这意味着每个电灯的 page。但至少用户现在至少看到一些事情在进行。我们仍然寻求实际解决这一问题。

Answer 1

我认为没有任何问题。你们不需要使用《四方协议》。根据文件。你确实需要称之为“共同参与”或“Olegitialize”,但我认为,这本论坛本应呼吁你。

我在下文中创建了一个简单的世界森林基金应用程序。罚款。 SHGetFile 信息在不同的侧面上传到ID的透镜和sh。 h Icon不是零。

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        Debug.WriteLine(Thread.CurrentThread.ManagedThreadId);
        Task<IntPtr> task = Task.Factory.StartNew(() => GetIcon("C:\"));
    }

    private IntPtr GetIcon(string name)
    {
        Debug.WriteLine(Thread.CurrentThread.ManagedThreadId);

        var shfi = new Shell32.SHFILEINFO();
        uint flags = Shell32.SHGFI_ICON | Shell32.SHGFI_USEFILEATTRIBUTES | Shell32.SHGFI_SMALLICON;

        Shell32.SHGetFileInfo(
            name,
            Directory.Exists(name) ? Shell32.FILE_ATTRIBUTE_DIRECTORY : Shell32.FILE_ATTRIBUTE_NORMAL,
            ref shfi,
            (uint) Marshal.SizeOf(shfi),
            flags);

        Debug.WriteLine(shfi.hIcon);

        return shfi.hIcon;
    }
}


public class Shell32
{
    public const int MAX_PATH = 256;

    // Browsing for directory.
    public const uint BIF_RETURNONLYFSDIRS = 0x0001;
    public const uint BIF_DONTGOBELOWDOMAIN = 0x0002;
    public const uint BIF_STATUSTEXT = 0x0004;
    public const uint BIF_RETURNFSANCESTORS = 0x0008;
    public const uint BIF_EDITBOX = 0x0010;
    public const uint BIF_VALIDATE = 0x0020;
    public const uint BIF_NEWDIALOGSTYLE = 0x0040;
    public const uint BIF_USENEWUI = (BIF_NEWDIALOGSTYLE | BIF_EDITBOX);
    public const uint BIF_BROWSEINCLUDEURLS = 0x0080;
    public const uint BIF_BROWSEFORCOMPUTER = 0x1000;
    public const uint BIF_BROWSEFORPRINTER = 0x2000;
    public const uint BIF_BROWSEINCLUDEFILES = 0x4000;
    public const uint BIF_SHAREABLE = 0x8000;

    public const uint SHGFI_ICON = 0x000000100; // get icon
    public const uint SHGFI_DISPLAYNAME = 0x000000200; // get display name
    public const uint SHGFI_TYPENAME = 0x000000400; // get type name
    public const uint SHGFI_ATTRIBUTES = 0x000000800; // get attributes
    public const uint SHGFI_ICONLOCATION = 0x000001000; // get icon location
    public const uint SHGFI_EXETYPE = 0x000002000; // return exe type
    public const uint SHGFI_SYSICONINDEX = 0x000004000; // get system icon index
    public const uint SHGFI_LINKOVERLAY = 0x000008000; // put a link overlay on icon
    public const uint SHGFI_SELECTED = 0x000010000; // show icon in selected state
    public const uint SHGFI_ATTR_SPECIFIED = 0x000020000; // get only specified attributes
    public const uint SHGFI_LARGEICON = 0x000000000; // get large icon
    public const uint SHGFI_SMALLICON = 0x000000001; // get small icon
    public const uint SHGFI_OPENICON = 0x000000002; // get open icon
    public const uint SHGFI_SHELLICONSIZE = 0x000000004; // get shell size icon
    public const uint SHGFI_PIDL = 0x000000008; // pszPath is a pidl
    public const uint SHGFI_USEFILEATTRIBUTES = 0x000000010; // use passed dwFileAttribute
    public const uint SHGFI_ADDOVERLAYS = 0x000000020; // apply the appropriate overlays
    public const uint SHGFI_OVERLAYINDEX = 0x000000040; // Get the index of the overlay

    public const uint FILE_ATTRIBUTE_DIRECTORY = 0x00000010;
    public const uint FILE_ATTRIBUTE_NORMAL = 0x00000080;

    [DllImport("Shell32.dll")]
    public static extern IntPtr SHGetFileInfo(
        string pszPath,
        uint dwFileAttributes,
        ref SHFILEINFO psfi,
        uint cbFileInfo,
        uint uFlags
        );

    #region Nested type: BROWSEINFO

    [StructLayout(LayoutKind.Sequential)]
    public struct BROWSEINFO
    {
        public IntPtr hwndOwner;
        public IntPtr pidlRoot;
        public IntPtr pszDisplayName;
        [MarshalAs(UnmanagedType.LPTStr)] public string lpszTitle;
        public uint ulFlags;
        public IntPtr lpfn;
        public int lParam;
        public IntPtr iImage;
    }

    #endregion

    #region Nested type: ITEMIDLIST

    [StructLayout(LayoutKind.Sequential)]
    public struct ITEMIDLIST
    {
        public SHITEMID mkid;
    }

    #endregion

    #region Nested type: SHFILEINFO

    [StructLayout(LayoutKind.Sequential)]
    public struct SHFILEINFO
    {
        public const int NAMESIZE = 80;
        public IntPtr hIcon;
        public int iIcon;
        public uint dwAttributes;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAX_PATH)] public string szDisplayName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = NAMESIZE)] public string szTypeName;
    };

    #endregion

    #region Nested type: SHITEMID

    [StructLayout(LayoutKind.Sequential)]
    public struct SHITEMID
    {
        public ushort cb;
        [MarshalAs(UnmanagedType.LPArray)] public byte[] abID;
    }

    #endregion
}

/// <summary>
/// Wraps necessary functions imported from User32.dll. Code courtesy of MSDN Cold Rooster Consulting example.
/// </summary>
public class User32
{
    /// <summary>
    /// Provides access to function required to delete handle. This method is used internally
    /// and is not required to be called separately.
    /// </summary>
    /// <param name="hIcon">Pointer to icon handle.</param>
    /// <returns>N/A</returns>
    [DllImport("User32.dll")]
    public static extern int DestroyIcon(IntPtr hIcon);
}

Answer 2

就像这项工作一样,也取得了成功。此前,在视力室外运行时,该飞机发生故障。在此之前,我们往往撤回对档案类型的缺省,而不是正确无误的缺省(因为我们在档案中重新提出,而不是目录)。

A summary of the factors to consider.

As discussed already, interacting with the Shell requires using a STA thread which pumps messages. A BackgroundWorker isn t going to be enough here.
When you initialize SHFILEINFO, set both string properties (display name and type name) to string.Empty. This isn t shown in most samples, but failing to do this was causing a crash for us. (In debug mode it meant that the first icon we got back was wrong, which could be the same as your problem.)
Check your interop declarations are right. For example, the SHFILEINFO class should presumably have a [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode, Pack = 4)] attribute.

A TaskScheduler For Background Tasks on an STA Thread

我们重新使用该工作队的平行图书馆,因此希望有一个工作队,负责安排适当的背景阅读工作。下面的法典样本是那些暴露了可用于此目的的客户财产的类别。

请注意,在我们这个类别中,我们有一个在申请整个一生中延续下去的单一例子,因此我们无法执行。如果你想制造/des,你需要处理。

namespace MyNamespace
{
    using System;
    using System.ComponentModel.Composition;
    using System.Threading;
    using System.Threading.Tasks;
    using System.Windows;
    using System.Windows.Threading;

    /// <summary>
    /// Exposes a <see cref="TaskScheduler"/> that schedules its work on a STA background thread.
    /// </summary>
    [Export]
    public class StaTaskSchedulerSource
    {
        /// <summary>
        /// A window that is used for message pumping.
        /// </summary>
        private Window window;

        /// <summary>
        /// Thread on which work is scheduled.
        /// </summary>
        private Thread thread;

        /// <summary>
        /// The <see cref="TaskScheduler"/> exposed by this class.
        /// </summary>
        private TaskScheduler taskScheduler;

        /// <summary>
        /// Initializes a new instance of the <see cref="StaTaskSchedulerSource"/> class.
        /// </summary>
        public StaTaskSchedulerSource()
        {
            using (ManualResetEvent re = new ManualResetEvent(false))
            {
                this.thread = new Thread(
                    () =>
                    {
                        this.window = new Window();

                        re.Set();

                        Dispatcher.Run();
                    });

                this.thread.IsBackground = true;
                this.thread.SetApartmentState(ApartmentState.STA);

                this.thread.Start();

                re.WaitOne();
            }

            this.window.Dispatcher.Invoke(
                new Action(
                    () =>
                    {
                        this.taskScheduler = TaskScheduler.FromCurrentSynchronizationContext();
                    }));
        }

        /// <summary>
        /// Gets a <see cref="TaskScheduler"/> that schedules work on a background STA
        /// thread.
        /// </summary>
        public TaskScheduler TaskScheduler
        {
            get
            {
                return this.taskScheduler;
            }
        }
    }
}

当然,这整件事情只是用发送者来援引另一线电话。这可能是缓慢的。因此,如果处理许多电灯,最好打好。而且,我们已经找回的奇迹,因此我们不需要在前后的任何时候第二次使用温壳。

SafeIconHandle

您还可以找到一个“icon”处理程序的以下总结。来源于 SafeHandle,并确保你icon在任何情况下都得到适当销毁。

namespace UnmanagedResourceLib
{
    using System;
    using System.Runtime.ConstrainedExecution;
    using System.Runtime.InteropServices;
    using System.Security;
    using System.Security.Permissions;
    using Microsoft.Win32.SafeHandles;

    /// <summary>
    /// A <see cref="SafeHandle"/> implementation for HICON icon handles.
    /// </summary>
    [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode = true)]
    [SecurityPermission(SecurityAction.Demand, UnmanagedCode = true)]
    internal class SafeIconHandle : SafeHandleZeroOrMinusOneIsInvalid
    {
        /// <summary>
        /// Prevents a default instance of the <see cref="SafeIconHandle"/> class from being created.
        /// </summary>
        private SafeIconHandle()
            : base(true)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="SafeIconHandle"/> class.
        /// </summary>
        /// <param name="nativeHandle">The HICON to wrap.</param>
        /// <param name="ownsHandle"><c>true</c> if finalization of this object should cause the icon to be destroyed.</param>
        public SafeIconHandle(IntPtr nativeHandle, bool ownsHandle)
            : base(ownsHandle)
        {
            this.handle = nativeHandle;
        }

        /// <inheritdoc />
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        override protected bool ReleaseHandle()
        {
            return NativeMethods.DestroyIcon(this.handle);
        }

        /// <summary>
        /// Exposes Windows API call to destroy an icon.
        /// </summary>
        [SuppressUnmanagedCodeSecurity]
        internal static class NativeMethods
        {
            /// <summary>
            /// Destroys an icon and frees any memory the icon occupied. 
            /// </summary>
            /// <param name="hIcon">A handle to the icon to be destroyed.</param>
            /// <returns><c>true</c> if the function succeeds.</returns>
            [System.Runtime.InteropServices.DllImport("user32.dll", SetLastError = true)]
            public static extern bool DestroyIcon(IntPtr hIcon);
        }
    }
}

A TaskScheduler For Background Tasks on an STA Thread

SafeIconHandle

友情链接