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October 1st, 2013, 10:32 AM
#1
Screenshot to base64 string
Hi, I have a problem when I try to convert the buffer of the image into a base64 string. Here is the code:
Code:
#include <windows.h>
#include <stdio.h>
#include <gdiplus.h>
#include "ScreenCap.h"
#include <wchar.h>
#include "base64.h"
#include <sstream>
using namespace Gdiplus;
int GetEncoderClsid(WCHAR *format, CLSID *pClsid)
{
unsigned int num = 0, size = 0;
GetImageEncodersSize(&num, &size);
if(size == 0) return -1;
ImageCodecInfo *pImageCodecInfo = (ImageCodecInfo *)(malloc(size));
if(pImageCodecInfo == NULL) return -1;
GetImageEncoders(num, size, pImageCodecInfo);
for(unsigned int j = 0; j < num; ++j){
if(wcscmp(pImageCodecInfo[j].MimeType, format) == 0){
*pClsid = pImageCodecInfo[j].Clsid;
free(pImageCodecInfo);
return j;
}
}
free(pImageCodecInfo);
return -1;
}
std::string GetScreeny(ULONG uQuality)
{
//this work ---->
ULONG_PTR gdiplusToken;
GdiplusStartupInput gdiplusStartupInput;
GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
HDC hdcScreen = CreateDC("DISPLAY", NULL, NULL, NULL);
HDC hdcCapture = CreateCompatibleDC(hdcScreen);
int nWidth = GetDeviceCaps(hdcScreen, HORZRES),
nHeight = GetDeviceCaps(hdcScreen, VERTRES),
nBPP = GetDeviceCaps(hdcScreen, BITSPIXEL);
LPBYTE lpCapture;
BITMAPINFO bmiCapture = { {
sizeof(BITMAPINFOHEADER), nWidth, -nHeight, 1, nBPP, BI_RGB, 0, 0, 0, 0, 0,
} };
HBITMAP hbmCapture = CreateDIBSection(hdcScreen, &bmiCapture,
DIB_PAL_COLORS, (LPVOID *)&lpCapture, NULL, 0);
if(!hbmCapture){
DeleteDC(hdcCapture);
DeleteDC(hdcScreen);
GdiplusShutdown(gdiplusToken);
}
int nCapture = SaveDC(hdcCapture);
SelectObject(hdcCapture, hbmCapture);
BitBlt(hdcCapture, 0, 0, nWidth, nHeight, hdcScreen, 0, 0, SRCCOPY);
RestoreDC(hdcCapture, nCapture);
DeleteDC(hdcCapture);
DeleteDC(hdcScreen);
CLSID imageCLSID;
Bitmap *pScreenShot = new Bitmap(hbmCapture, (HPALETTE)NULL);
EncoderParameters encoderParams;
encoderParams.Count = 1;
encoderParams.Parameter[0].NumberOfValues = 1;
encoderParams.Parameter[0].Guid = EncoderQuality;
encoderParams.Parameter[0].Type = EncoderParameterValueTypeLong;
encoderParams.Parameter[0].Value = &uQuality;
GetEncoderClsid(L"image/jpeg", &imageCLSID);
//<----- until here
IStream *pStream = NULL;
LARGE_INTEGER liZero = {};
ULARGE_INTEGER pos = {};
STATSTG stg = {};
ULONG bytesRead=0;
HRESULT hrRet=S_OK;
BYTE* buffer = NULL; // this is your buffer that will hold the jpeg bytes
DWORD dwBufferSize = 0; // this is the size of that buffer;
hrRet = CreateStreamOnHGlobal(NULL, TRUE, &pStream);
hrRet = pScreenShot->Save(pStream, &imageCLSID, &encoderParams) == 0 ? S_OK : E_FAIL;
hrRet = pStream->Seek(liZero, STREAM_SEEK_SET, &pos);
hrRet = pStream->Stat(&stg, STATFLAG_NONAME);
// allocate a byte buffer big enough to hold the jpeg stream in memory
buffer = new BYTE[stg.cbSize.QuadPart];
hrRet = (buffer == NULL) ? E_OUTOFMEMORY : S_OK;
dwBufferSize = stg.cbSize.QuadPart;
// copy the stream into memory
hrRet = pStream->Read(buffer, stg.cbSize.QuadPart, &bytesRead);
// now go save "buffer" and "dwBufferSize" off somewhere. This is the jpeg buffer
// don't forget to free it when you are done
// After success or if any of the above calls fail, don't forget to release the stream
std::string encodedstring = base64_encode(buffer, dwBufferSize);
if (pStream)
{
pStream->Release();
}
delete pScreenShot;
DeleteObject(hbmCapture);
GdiplusShutdown(gdiplusToken);
return encodedstring;
}
The base64 code is here: http://www.adp-gmbh.ch/cpp/common/base64.html
Code run but the output is wrong. I think the problem is "std::string encodedstring = base64_encode(buffer, dwBufferSize);" but I can't figure the solution. Any idea? Thanks.
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