Winforms: Windows 7中Taskbar的新效果（1）——概述

来源：互联网发布：和珅王刚知乎编辑：程序博客网时间：2024/06/06 15:47

Win7推出之后，很多用户发现Windows的界面漂亮了很多。在这些界面中，Taskbar是最引人注目的一个更新。在最新的Taskbar中，缩略图能显示更加丰富的信息。右键点击Taskbar上的按钮，弹出的菜单提供了很多选项以方便用户的操作。比如右键单击文件管理器Explorer的按钮，就会在弹出的菜单中列出用户最经常浏览的文件夹。

微软在推出新的Taskbar效果的同时，也推出了一系列对应的API。调用这些API，程序员可以开发出具有很酷效果的应用程序。在MSDN中，http://msdn.microsoft.com/en-us/library/dd378460(VS.85).aspx有这些API的详细用法介绍。

到目前为止，Winforms还没有提供对最新的Taskbar的支持。程序员如果想用Winforms开发出具有Win7效果的Taskbar，需要利用.NET提供的InterOp功能。我们用InterOp定义ITaskbarList4如下：

[ComImportAttribute()]

[GuidAttribute("c43dc798-95d1-4bea-9030-bb99e2983a1a")]

[InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]

internal interface ITaskbarList4

{

// ITaskbarList

[PreserveSig]

void HrInit();

[PreserveSig]

void AddTab(IntPtr hwnd);

[PreserveSig]

void DeleteTab(IntPtr hwnd);

[PreserveSig]

void ActivateTab(IntPtr hwnd);

[PreserveSig]

void SetActiveAlt(IntPtr hwnd);

// ITaskbarList2

[PreserveSig]

void MarkFullscreenWindow(

IntPtr hwnd,

[MarshalAs(UnmanagedType.Bool)] bool fFullscreen);

// ITaskbarList3

[PreserveSig]

void SetProgressValue(IntPtr hwnd, UInt64 ullCompleted, UInt64 ullTotal);

[PreserveSig]

void SetProgressState(IntPtr hwnd, TBPFLAG tbpFlags);

[PreserveSig]

void RegisterTab(IntPtr hwndTab, IntPtr hwndMDI);

[PreserveSig]

void UnregisterTab(IntPtr hwndTab);

[PreserveSig]

void SetTabOrder(IntPtr hwndTab, IntPtr hwndInsertBefore);

[PreserveSig]

void SetTabActive(IntPtr hwndTab, IntPtr hwndInsertBefore, uint dwReserved);

[PreserveSig]

HRESULT ThumbBarAddButtons(

IntPtr hwnd,

uint cButtons,

[MarshalAs(UnmanagedType.LPArray)] THUMBBUTTON[] pButtons);

[PreserveSig]

HRESULT ThumbBarUpdateButtons(

IntPtr hwnd,

uint cButtons,

[MarshalAs(UnmanagedType.LPArray)] THUMBBUTTON[] pButtons);

[PreserveSig]

void ThumbBarSetImageList(IntPtr hwnd, IntPtr himl);

[PreserveSig]

void SetOverlayIcon(

IntPtr hwnd,

IntPtr hIcon,

[MarshalAs(UnmanagedType.LPWStr)] string pszDescription);

[PreserveSig]

void SetThumbnailTooltip(

IntPtr hwnd,

[MarshalAs(UnmanagedType.LPWStr)] string pszTip);

[PreserveSig]

void SetThumbnailClip(

IntPtr hwnd,

ref RECT prcClip);

// ITaskbarList4

void SetTabProperties(IntPtr hwndTab, STPFLAG stpFlags);

}

internal enum TBPFLAG

{

TBPF_NOPROGRESS = 0,

TBPF_INDETERMINATE = 0x1,

TBPF_NORMAL = 0x2,

TBPF_ERROR = 0x4,

TBPF_PAUSED = 0x8

}

internal enum STPFLAG

{

STPF_NONE = 0x0,

STPF_USEAPPTHUMBNAILALWAYS = 0x1,

STPF_USEAPPTHUMBNAILWHENACTIVE = 0x2,

STPF_USEAPPPEEKALWAYS = 0x4,

STPF_USEAPPPEEKWHENACTIVE = 0x8

}

internal enum THBMASK

{

THB_BITMAP = 0x1,

THB_ICON = 0x2,

THB_TOOLTIP = 0x4,

THB_FLAGS = 0x8

}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]

internal struct THUMBBUTTON

{

/// <summary>

/// WPARAM value for a THUMBBUTTON being clicked.

/// </summary>

internal const int THBN_CLICKED = 0x1800;

[MarshalAs(UnmanagedType.U4)]

internal THBMASK dwMask;

internal uint iId;

internal uint iBitmap;

internal IntPtr hIcon;

[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]

internal string szTip;

[MarshalAs(UnmanagedType.U4)]

internal THBFLAGS dwFlags;

}

[Flags]

internal enum THBFLAGS

{

THBF_ENABLED = 0x00000000,

THBF_DISABLED = 0x00000001,

THBF_DISMISSONCLICK = 0x00000002,

THBF_NOBACKGROUND = 0x00000004,

THBF_HIDDEN = 0x00000008,

THBF_NONINTERACTIVE = 0x00000010

}

另外，我们还需要声明接口ITaskbarList4的一个实现如下：

[GuidAttribute("56FDF344-FD6D-11d0-958A-006097C9A090")]

[ClassInterfaceAttribute(ClassInterfaceType.None)]

[ComImportAttribute()]

internal class CTaskbarList { }

接下来我问定义类TaskbarManager来管理Taskbar，代码如下：

class TaskbarManager

{

// Hide the default constructor

private TaskbarManager()

{

}

// Best practice recommends defining a private object to lock on

private static Object syncLock = new Object();

// Internal implemenation of ITaskbarList4 interface

private ITaskbarList4 taskbarList;

internal ITaskbarList4 TaskbarList

{

get

{

if (taskbarList == null)

{

// Create a new instance of ITaskbarList3

lock (syncLock)

{

if (taskbarList == null)

{

taskbarList = (ITaskbarList4)new CTaskbarList();

taskbarList.HrInit();

}

return taskbarList;

}

private static volatile TaskbarManager instance;

/// <summary>

/// Represents an instance of the Windows Taskbar

/// </summary>

public static TaskbarManager Instance

{

get

{

ThrowIfNotSupport();

if (instance == null)

{

lock (syncLock)

{

if (instance == null)

instance = new TaskbarManager();

}

return instance;

}

public static void ThrowIfNotSupport()

{

bool isWin7 = Environment.OSVersion.Version.Major > 6;

bool isSever2008R2 = Environment.OSVersion.Version.Major == 6

&& Environment.OSVersion.Version.Minor >= 1;

if (!isWin7 && !isSever2008R2)

{

throw new PlatformNotSupportedException("Only supported on Windows 7/Sever2008 R2 or newer.");

}

运行ITaskbarList4至少需要Win7或者Server 2008 R2，因此在之前版本的Windows上我们只能抛出异常。

在接下来的几篇博客，我将详细介绍如果调用ITaskbarList4中的接口，实现Taskbar的最新效果。