如何使用NvAPI_DISP_GetDisplayConfig？

Question

在使用NVAPI时，我在NvAPI_DISP_GetDisplayConfig上遇到了问题。我在第二个打给AppCrash的电话上得到了一个NvAPI_DISP_GetDisplayConfig。似乎不知道为什么。

NvU32 count = 0;
status = NvAPI_DISP_GetDisplayConfig(&count, NULL);
if (status != NVAPI_OK) 
    PrintError(status);
printf("Configs: %i\n", count);
NV_DISPLAYCONFIG_PATH_INFO *configinfos = new NV_DISPLAYCONFIG_PATH_INFO[count];
configinfos[0].version = NV_DISPLAYCONFIG_PATH_INFO_VER;
status = NvAPI_DISP_GetDisplayConfig(&count, configinfos);
if (status != NVAPI_OK) 
    PrintError(status);

在我的系统中，第一次呼叫后计数=2。NvAPI_DISP_GetDisplayConfig上的注释说：

NVAPI_INTERFACE NvAPI_DISP_GetDisplayConfig( __inout NvU32 * pathInfoCount， __out_ecount_full_opt *pathInfoCount NV_DISPLAYCONFIG_PATH_INFO * pathInfo ) 描述:此API允许调用方检索当前全局显示。 配置。 用法:调用者可能需要调用三次才能获取所需的所有 配置细节如下： 第一次传递:调用方应该使用NvAPI_DISP_GetDisplayConfig()集调用pathInfo () 若要空，则获取pathInfoCount。 第二次传递:为pathInfo分配与 pathInfoCount(从第一次传递)到获取//！//！targetInfoCount。如果 需要sourceModeInfo分配内存，也可以将其初始化为NULL。 第三次通过(可选，只有在需要目标信息时才需要)：分配 targetInfo的内存相对于 targetInfoCount(从第二关开始)。支持操作系统: Windows及更高版本

谢谢。

编辑:我还尝试将configinfos.sourceModeInfo = NULL设置为无效。我还试图对数组进行迭代，将所有的.version和.sourceModeInfo设置为无效(在我看到的文档中的一个示例，只设置了数组中第一项的版本)

Answer 1

这应该适用于你：

NvAPI_Status status = NVAPI_OK;
NvU32 deviceCount = 0;
NV_DISPLAYCONFIG_PATH_INFO_V2 *  pathInfo = NULL;

status = NvAPI_Initialize();
if (status == NVAPI_OK) {
    status = NvAPI_DISP_GetDisplayConfig(&deviceCount, pathInfo);
    if ((status == NVAPI_OK) && (deviceCount > 0)) {
        pathInfo = new NV_DISPLAYCONFIG_PATH_INFO_V2[deviceCount];
        for (int i = 0; i < deviceCount; i++)
        {
            pathInfo[i].targetInfo = 0;
            pathInfo[i].targetInfoCount = 0;
            pathInfo[i].version = NV_DISPLAYCONFIG_PATH_INFO_VER2;
            pathInfo[i].sourceModeInfo = 0;
            pathInfo[i].reserved = 0;
        }

        status = NvAPI_DISP_GetDisplayConfig(&deviceCount, pathInfo);

        if (status == NVAPI_OK) {
            for (int i = 0; i < deviceCount; i++)
            {
                pathInfo[i].sourceModeInfo = new NV_DISPLAYCONFIG_SOURCE_MODE_INFO_V1;
                pathInfo[i].sourceModeInfo->reserved = 0;
                pathInfo[i].targetInfo = new NV_DISPLAYCONFIG_PATH_TARGET_INFO_V2[pathInfo[i].targetInfoCount];
                for (int j = 0; j < pathInfo[i].targetInfoCount; j++) {
                    pathInfo[i].targetInfo[j].details = 0;
                }
            }
        }

        status = NvAPI_DISP_GetDisplayConfig(&deviceCount, pathInfo);

        for (int i = 0; i < deviceCount; i++)
        {
            if (pathInfo[i].sourceModeInfo) delete pathInfo[i].sourceModeInfo;
            if (pathInfo[i].targetInfo) delete [] pathInfo[i].targetInfo;
        }
        delete[] pathInfo;
    }
}

Answer 2

马科斯的回答更彻底。我认为，代码中的具体问题是没有初始化第二个pathInfo。因此，您需要添加：

configinfos[1].version = NV_DISPLAYCONFIG_PATH_INFO_VER;

这也是一个很好的形式，总是使你的记忆无效。因此，在分配之后，您应该立即这样做：

memset(configinfos, 0, sizeof(NV_DISPLAYCONFIG_PATH_INFO) * count);

或者您可以单独设置值。

Answer 3

在示例代码中有一个名为DisplayConfiguration的示例，它与NvAPI一起提供，它完全利用了GetDisplayConfig。从DisplayConfiguration.cpp复制粘贴函数：

NvAPI_Status AllocateAndGetDisplayConfig(NvU32* pathInfoCount, NV_DISPLAYCONFIG_PATH_INFO** pPathInfo)
{
    NvAPI_Status ret;

    // Retrieve the display path information
    NvU32 pathCount                         = 0;
    NV_DISPLAYCONFIG_PATH_INFO *pathInfo    = NULL;

    ret = NvAPI_DISP_GetDisplayConfig(&pathCount, NULL);
    if (ret != NVAPI_OK)    return ret;

    pathInfo = (NV_DISPLAYCONFIG_PATH_INFO*) malloc(pathCount * sizeof(NV_DISPLAYCONFIG_PATH_INFO));
    if (!pathInfo)
    {
        return NVAPI_OUT_OF_MEMORY;
    }

    memset(pathInfo, 0, pathCount * sizeof(NV_DISPLAYCONFIG_PATH_INFO));
    for (NvU32 i = 0; i < pathCount; i++)
    {
        pathInfo[i].version = NV_DISPLAYCONFIG_PATH_INFO_VER;
    }

    // Retrieve the targetInfo counts
    ret = NvAPI_DISP_GetDisplayConfig(&pathCount, pathInfo);
    if (ret != NVAPI_OK)
    {
        return ret;
    }

    for (NvU32 i = 0; i < pathCount; i++)
    {
        // Allocate the source mode info
        pathInfo[i].sourceModeInfo = (NV_DISPLAYCONFIG_SOURCE_MODE_INFO*) malloc(sizeof(NV_DISPLAYCONFIG_SOURCE_MODE_INFO));
        if (pathInfo[i].sourceModeInfo == NULL)
        {
            return NVAPI_OUT_OF_MEMORY;
        }
        memset(pathInfo[i].sourceModeInfo, 0, sizeof(NV_DISPLAYCONFIG_SOURCE_MODE_INFO));

        // Allocate the target array
        pathInfo[i].targetInfo = (NV_DISPLAYCONFIG_PATH_TARGET_INFO*) malloc(pathInfo[i].targetInfoCount * sizeof(NV_DISPLAYCONFIG_PATH_TARGET_INFO));
        if (pathInfo[i].targetInfo == NULL)
        {
            return NVAPI_OUT_OF_MEMORY;
        }
        // Allocate the target details
        memset(pathInfo[i].targetInfo, 0, pathInfo[i].targetInfoCount * sizeof(NV_DISPLAYCONFIG_PATH_TARGET_INFO));
        for (NvU32 j = 0 ; j < pathInfo[i].targetInfoCount ; j++)
        {
            pathInfo[i].targetInfo[j].details = (NV_DISPLAYCONFIG_PATH_ADVANCED_TARGET_INFO*) malloc(sizeof(NV_DISPLAYCONFIG_PATH_ADVANCED_TARGET_INFO));    
            memset(pathInfo[i].targetInfo[j].details, 0, sizeof(NV_DISPLAYCONFIG_PATH_ADVANCED_TARGET_INFO));
            pathInfo[i].targetInfo[j].details->version = NV_DISPLAYCONFIG_PATH_ADVANCED_TARGET_INFO_VER;
        }
    }

    // Retrieve the full path info
    ret = NvAPI_DISP_GetDisplayConfig(&pathCount, pathInfo);
    if (ret != NVAPI_OK)    
    {
        return ret;
    }

    *pathInfoCount = pathCount;
    *pPathInfo = pathInfo;
    return NVAPI_OK;
}

现在这个函数可以很容易地使用，就像：

NV_DISPLAYCONFIG_PATH_INFO *pathInfo = NULL;
NvU32 pathCount = 0;
_allocateAndGetDisplayConfig(&pathCount, &pathInfo);
// Do whatever you need with the queried display data here