孙鑫VC学习笔记：第十七讲 (一) 用剪贴板实现进程间的通信

最新推荐文章于 2017-12-04 14:17:57 发布

Savitch

最新推荐文章于 2017-12-04 14:17:57 发布

阅读量418

点赞数

分类专栏： Mfc

Mfc 专栏收录该内容

68 篇文章

订阅专栏

本文详细介绍了进程间通信的四种常见方式，包括剪贴板编程原理及操作流程，以及匿名管道、命名管道与邮槽的应用场景与实现方法。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

孙鑫教学视频笔记(17)进程间通信

---------------------------------------------------------------------------------

进程间通信的四种方式

剪贴板

匿名管道

命名管道

邮槽

---------------------------------------------------------------------------------

剪贴板编程

1.将数据存入剪贴板：

相关函数：

---------------------------------------------------------------------------------

CWnd::OpenClipboard

BOOL OpenClipboard( );

Return Value

Nonzero if the Clipboard is opened via CWnd, or 0 if another application or window has the Clipboard open.

Remarks

Opens the Clipboard. Other applications will not be able to modify the Clipboard until the CloseClipboard Windows function is called.

The current CWnd object will not become the owner of the Clipboard until the EmptyClipboard Windows function is called.

打开了剪贴板之后，还必须调用EmptyClipboard ，才能使当前窗口拥有剪贴板。

EmptyClipboard

The EmptyClipboard function empties the clipboard and frees handles to data in the clipboard. The function then assigns ownership of the clipboard to the window that currently has the clipboard open.

本函数将清空剪贴板释放数据句柄，然后将剪贴板的所有权分配给当前打开它的程序。

BOOL EmptyClipboard(VOID)

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

Before calling EmptyClipboard, an application must open the clipboard by using the OpenClipboard function. If the application specifies a NULL window handle when opening the clipboard, EmptyClipboard succeeds but sets the clipboard owner to NULL.

SetClipboardData

The SetClipboardData function places data on the clipboard in a specified clipboard format. The window must be the current clipboard owner, and the application must have called the OpenClipboard function. (When responding to the WM_RENDERFORMAT and WM_RENDERALLFORMATS messages, the clipboard owner must not callOpenClipboard before calling SetClipboardData.)

HANDLE SetClipboardData(
UINT uFormat, // clipboard format
HANDLE hMem // data handle
);

Parameters

uFormat

Specifies a clipboard format. This parameter can be a registered format or any of the standard clipboard formats. For more information, see Registered Clipboard Formats and Standard Clipboard Formats.

hMem

Handle to the data in the specified format. This parameter can be NULL, indicating that the window provides data in the specified clipboard format (renders the format) upon request. If a window delays rendering, it must process the WM_RENDERFORMAT and WM_RENDERALLFORMATS messages.

After SetClipboardData is called, the system owns the object identified by the hMem parameter. The application can read the data, but must not free the handle or leave it locked. If the hMem parameter identifies a memory object, the object must have been allocated using the GlobalAlloc function with the GMEM_MOVEABLE and GMEM_DDESHARE flags.

Return Values

If the function succeeds, the return value is the handle of the data.

If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

The uFormat parameter can identify a registered clipboard format, or it can be one of the standard clipboard formats. For more information, see Registered Clipboard Formats and Standard Clipboard Formats.

The system performs implicit data format conversions between certain clipboard formats when an application calls the GetClipboardData function. For example, if the CF_OEMTEXT format is on the clipboard, a window can retrieve data in the CF_TEXT format. The format on the clipboard is converted to the requested format on demand. For more information, see Synthesized Clipboard Formats.

GlobalAlloc

The GlobalAlloc function allocates the specified number of bytes from the heap. Win32 memory management does not provide a separate local heap and global heap.

Note The global functions are slower than other memory management functions and do not provide as many features. Therefore, new applications should use the heap functions. However, the global functions are still used with DDE, the clipboard functions, and OLE data objects.

This function is provided only for compatibility with 16-bit versions of Windows.

HGLOBAL GlobalAlloc(
UINT uFlags,// 指定如何分配内存，NULL则用缺省的GMEM_FIXED
DWORD dwBytes // number of bytes to allocate
);

Parameters

uFlags

Specifies how to allocate memory. If zero is specified, the default is GMEM_FIXED. This value can be one or more of the following flags, except for the incompatible combinations that are specifically noted.

可以有以下值的组合

GMEM_FIXED

如果指定为GMEM_FIXED，那么GlobalAlloc 分配内存将其地址直接转换为32位的HGLOBAL的值返回。也就是说直接返回内存分配的地址。

GMEM_MOVEABLE

如果指定的是GMEM_MOVEABLE，那么返回的HGLOBAL 的值不是实际分配的地址，而是一个指向进程中句柄表条目的指针，该条目包含实际分配的指针。剪贴板中要用这个值。

分配可移动的内存. In Win32, memory blocks are never moved in physical memory, but they can be moved within the default heap. 在Win32中，物理内存块是不能被移动的，但是它们可以在缺省的堆中被移动。当我们创建进程的时候，系统要为进程分配缺省的堆。

The return value is a handle to the memory object. To translate the handle into a pointer, use the GlobalLock function.

This flag cannot be combined with the GMEM_FIXED flag.

GPTR

Combines the GMEM_FIXED and GMEM_ZEROINIT flags.

GHND

Combines the GMEM_MOVEABLE and GMEM_ZEROINIT flags.

GMEM_DDESHARE

GMEM_SHARE

This flag is provided primarily for compatibility with 16-bit Windows. However, this flag may be used by some applications to enhance the performance of DDE operations and therefore can be specified if the memory is to be used for DDE. .

GMEM_DISCARDABLE