在 ExportToFileCallback 中,我想使用我在 SaveMsg 中分配的文件,但我似乎无法从指向 FilePCDMsg 的指针中获取它。
type
FilePCDMsg = File of PCDKMsg;
PFilePCDMsg = ^FilePCDMsg;
procedure TfrmMain.SaveMsg( pMsg: PCDKMsg; fn: String = '' );
var
myFile: FilePCDMsg;
pFile : PFilePCDMsg;
begin
if fn.IsEmpty then
fn := TPath.GetTempFileName;
CodeSite.Send( 'SaveMsg fn', fn );
AssignFile( myFile, fn );
Rewrite( myFile );
pFile := Addr( myFile );
CDKMsgExport( pMsg, ExportToFileCallBack, pFile );
end;
function ExportToFileCallBack( pData: PUInt8; len: UInt32; pUser: Pointer ): Integer; cdecl;
var
pFile : PFilePCDMsg;
myFile: FilePCDMsg;
begin
// this is the C code for what I want to do
// return fwrite(pData, 1, len, (FILE*)pUser) == len;
pFile := PFilePCDMsg( pUser );
myFile := FilePCDMsg( pFile ); // will not compile
end;
这个 DLL 是由第三方提供的,它有回调来做事。在这里,我试图查询一个摄像头的配置,回调被调用了三次。我认为它正在将它要我附加到我分配的文件的数据传回给我。
这是我试图在 Delphi 中复制的 C 代码。
#ifdef WIN32
#include <windows.h>
#include "../../include/external/stdint.h"
#include "../../include/external/inttypes.h"
#endif
#ifdef LINUX
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <inttypes.h>
#endif
#include <stdio.h>
#include "../../include/CDK.h"
const char* strAddress = NULL;
uint16_t uPort = 10001;
const char* strOptions = NULL;
const char* strPathOut = ".";
void help()
{
printf("Command line:\n");
printf(" receive address [-port port] [-options options] [-output outputpath]\n");
printf(" Port default value : 10001\n");
printf(" Output path default value : .\n");
}
int parseCommandLine(int argc, char* argv[])
{
int i;
if (argc < 2)
{
return 0;
}
strAddress = argv[1];
for (i=2;i<argc;++i)
{
if (strcmp(argv[i], "-port") == 0)
{
++i;
if (i >= argc)
return 0;
uPort = atoi(argv[i]);
}
else if (strcmp(argv[i], "-options") == 0)
{
++i;
if (i >= argc)
return 0;
strOptions = argv[i];
}
else if (strcmp(argv[i], "-output") == 0)
{
++i;
if (i >= argc)
return 0;
strPathOut = argv[i];
}
}
return 1;
}
void traceCallback(CDK* pSrc, unsigned char level, const char* strTrace, void* pUser )
{
printf("[%u] %s\n", level, strTrace);
}
int32_t exportToFileCallback(const uint8_t* pData, uint32_t len, void* pUser)
{
return fwrite(pData, 1, len, (FILE*)pUser) == len;
}
void parseConfig(CDKMsg *pMsg)
{
CDKMsgElement* pEltConfig = NULL;
CDKMsgElement* pEltDevice = NULL;
CDKMsgElement* pEltCameras = NULL;
const char* str;
uint32_t i = 0;
uint32_t j = 0;
pEltConfig = CDKMsgChild(pMsg);
if(NULL == pEltConfig)
{
return;
}
pEltDevice = CDKMsgElementFirstChild(pEltConfig, "device");
if (NULL != pEltDevice )
{
str = CDKMsgElementAttributeValue(pEltDevice, "name");
if (str)
printf("Name : %s\n", str);
}
pEltCameras = CDKMsgElementFirstChild(pEltConfig, "cameras");
if (NULL != pEltCameras )
{
CDKMsgElement* pEltCamera = CDKMsgElementFirstChild(pEltCameras,NULL);
CDKMsgElement* pEltCameraParam = NULL;
while(pEltCamera)
{
/* camera attributes */
printf("%s : \n", CDKMsgElementName(pEltCamera));
for(i = 0; i < CDKMsgElementAttributeCount(pEltCamera); i++)
{
str = CDKMsgElementAttributeName(pEltCamera,i);
printf("* \t %s : %s\n", str,CDKMsgElementAttributeValue(pEltCamera,str));
}
/* camera parameters */
pEltCameraParam = CDKMsgElementFirstChild(pEltCamera,NULL);
while(pEltCameraParam)
{
printf("* \t %s : \n", CDKMsgElementName(pEltCameraParam));
for(j = 0; j < CDKMsgElementAttributeCount(pEltCameraParam); j++)
{
str = CDKMsgElementAttributeName(pEltCameraParam,j);
printf("** \t\t %s : %s\n", str,CDKMsgElementAttributeValue(pEltCameraParam,str));
}
pEltCameraParam = CDKMsgElementNextChild(pEltCamera,pEltCameraParam,NULL);
}
pEltCamera = CDKMsgElementNextChild(pEltCameras,pEltCamera,NULL);
}
}
}
int main(int argc, char* argv[])
{
CDK* pCDK = NULL;
FILE* pFile = NULL;
char strFileName[256];
CDKMsg * pMsgRequest = NULL;
CDKMsg * pMsgAnswer = NULL;
CDKSetTraceFunction(traceCallback, NULL);
printf("App launched\n");
printf("CDK version : %s\n", CDKGetVersion());
/* command line */
if (!parseCommandLine(argc, argv))
{
help();
return -1;
}
printf("Get config from %s:%u in %s\n", strAddress, uPort, strPathOut);
if (strOptions)
{
printf(" Options : %s\n", strOptions);
}
pCDK = CDKCreate();
if (!CDKBind(pCDK, strAddress, uPort, strOptions))
{
printf("CDKBind failed : %s\n", CDKGetLastError(pCDK));
goto labelEnd;
}
if(!CDKWaitForConnection(pCDK,30000))
{
printf("ERROR : %s\n", CDKGetLastError(pCDK));
goto labelEnd;
}
/* get config */
pMsgRequest = CDKMsgCreate();
CDKMsgSetChild(pMsgRequest, CDKMsgElementCreate("getConfig"));
pMsgAnswer = CDKSendRequest(pCDK, pMsgRequest, 30000);
CDKMsgDestroy(pMsgRequest);
if (NULL == pMsgAnswer )
{
printf("ERROR : %s\n", CDKGetLastError(pCDK));
goto labelEnd;
}
/* export config msg */
sprintf(strFileName, "%s/config.cdkmsg", strPathOut);
pFile = fopen(strFileName, "wb");
if (NULL == pFile)
{
printf("Unable to create output file, does the output path exist?");
goto labelEnd;
}
if (!CDKMsgExport(pMsgAnswer, &exportToFileCallback, pFile))
{
printf("Message export failed : %s", CDKGetLastError(pMsgAnswer));
goto labelEnd;
}
/* Parse config */
parseConfig(pMsgAnswer);
labelEnd:
if (pFile)
{
fclose(pFile);
}
if (pMsgAnswer)
{
CDKMsgDestroy(pMsgAnswer);
}
if (pCDK)
{
CDKDestroy(pCDK);
}
return 0;
}
最佳答案
是我多虑了。答案其实很简单
procedure TfrmMain.SaveMsg(pMsg: PCDKMsg);
begin
CDKMsgExport( pMsg, ExportToFileCallBack, nil );
end;
function ExportToFileCallBack( pData: PUInt8; len: UInt32; pUser: Pointer ): Integer; cdecl;
var
FileName: string;
Stream : TStream;
begin
FileName := 'Config.xml';
if TFile.Exists( FileName ) then
Stream := TFileStream.Create( FileName, fmOpenReadWrite )
else
Stream := TFileStream.Create( FileName, fmCreate );
try
Stream.Seek( 0, soFromEnd );
Stream.WriteBuffer( Pointer( pData )^, len );
CodeSite.SendStreamAsText( 'ExportToFileCallBack', Stream );
finally
Stream.Free;
end;
end;
非常感谢你帮助我
关于c - 如何在 delphi 中创建文件并将其传递给 C DLL 并在回调中使用该文件?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58707202/