dxvahd.h Microsoft 头文件中的#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) 何时变为真

2022-01-20 00:00:00 conditional-statements conditional visual-c++ c++ conditional-compilation

您好，我有 2 个 VC++ 解决方案A"和B"(VS2008)都具有相同的代码库(只有几行代码不同).在两者中都使用 DXVAHD.h.

Hi I am having 2 VC++ solutions "A" & "B" (VS2008) both are having the same codebase (with just few lines of code different). Using DXVAHD.h in both.

dxvahd.h 是一个标准的 Microsoft 头文件.如果我们打开这个头文件，我们会看到有一个条件 if"#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)"

dxvahd.h is a standard Microsoft header file. If we open this header file, we see there is a conditional if "#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)"

我看到在 VC++ 解决方案A"中，上面的条件 #if 语句是假的，因此整个 dxvahd 头文件变灰 &不是甚至编译！

I see that in VC++ solution "A", the above conditional #if statement is false, hence the whole dxvahd header file gets greyed out & is not even compiled!!

而在另一个解决方案B"中，这个条件 #if 为真，因此没有问题 &它工作正常.

Whereas in another solution "B", this conditional #if is true,hence no issues & its working fine.

谁能告诉我如何在解决方案A"中解决此问题，其中上述#if 变灰/未编译.请帮助我.

提前致谢.

推荐答案

看winapifamily.h，您可以看到这些宏用于确定您拥有什么平台以及哪些 API 适合您的平台.

Looking at winapifamily.h, you can see that these macros are used to determine what platform you have and what API's are suitable for your platform.

/*
 *  Windows APIs can be placed in a partition represented by one of the below bits.   The 
 *  WINAPI_FAMILY value determines which partitions are available to the client code.
 */

#define WINAPI_PARTITION_DESKTOP   0x00000001
#define WINAPI_PARTITION_APP       0x00000002    

/*
 * A family may be defined as the union of multiple families. WINAPI_FAMILY should be set
 * to one of these values.
 */
#define WINAPI_FAMILY_APP          WINAPI_PARTITION_APP
#define WINAPI_FAMILY_DESKTOP_APP  (WINAPI_PARTITION_DESKTOP | WINAPI_PARTITION_APP)    

/*
 * A constant that specifies which code is available to the program's target runtime platform.
 * By default we use the 'desktop app' family which places no restrictions on the API surface. 
 * To restrict the API surface to just the App API surface, define WINAPI_FAMILY to WINAPI_FAMILY_APP.
 */
#ifndef WINAPI_FAMILY
#define WINAPI_FAMILY WINAPI_FAMILY_DESKTOP_APP
#endif

/* Macro to determine if a partition is enabled */
#define WINAPI_FAMILY_PARTITION(Partition)  ((WINAPI_FAMILY & Partition) == Partition)

/* Macro to determine if only one partition is enabled from a set */
#define WINAPI_FAMILY_ONE_PARTITION(PartitionSet, Partition) ((WINAPI_FAMILY & PartitionSet) == Partition)

因此，只有在系统的桌面系列上运行时，才会设置您的 WINAPI_PARTITION_DESKTOP.

So your WINAPI_PARTITION_DESKTOP would only be set if you are running on a Desktop family of the the system.

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