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:

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#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;
}

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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.

Quote:

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Originally Posted by Brain_Storm

Hi, I have a problem when I try to convert the buffer of the image into a base64 string. Here is the code:
...

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Is this case you chose a wrong Forum which is for

Quote:

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Visual C++ Bugs & Fixes
Share bugs and fixes for source code on this site. Also use this to share bugs/fixes in the various class libraries etc. of use to VC++ developers. This is NOT for general programming questions.

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Quote:

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Originally Posted by Brain_Storm

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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Did you try to debug your code?

Sorry, I thought wrong. I'm newbie of c++ programming. I use Visual Studio 2010.

You are setting hrRet in several places, but never testing this for failure.

Suggestion?

Quote:

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Originally Posted by Brain_Storm

Suggestion?

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Three, so far:
1. Move this to the appropriate forum.
2. Debug.
3. Check the return values from API calls.
:)