I am using the following code to take a screenshot , compress it to jpg and save it. I am trying to compress the image more, e.g. from 200kb --> 100kb. Let's say about 60% of original quality. Could you guys, please help me find out how to do this?
#include "stdafx.h"
#include <windows.h>
#include <GdiPlus.h>
#include <string>
using namespace std;
#pragma comment( lib, "gdiplus" )
int GetEncoderClsid(const WCHAR* format, CLSID* pClsid);
void gdiscreen(string save_path_s)
{
using namespace Gdiplus;
GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
{
HDC scrdc, memdc;
HBITMAP membit;
scrdc = ::GetDC(0);
int Height = GetSystemMetrics(SM_CYSCREEN);
int Width = GetSystemMetrics(SM_CXSCREEN);
memdc = CreateCompatibleDC(scrdc);
membit = CreateCompatibleBitmap(scrdc, Width, Height);
HBITMAP hOldBitmap =(HBITMAP) SelectObject(memdc, membit);
BitBlt(memdc, 0, 0, Width, Height, scrdc, 0, 0, SRCCOPY);
Gdiplus::Bitmap bitmap(membit, NULL);
CLSID clsid;
GetEncoderClsid(L"image/jpeg", &clsid);
wstring save_path(save_path_s.length(), L' ');
copy(save_path_s.begin(), save_path_s.end(), save_path.begin());
bitmap.Save(save_path.c_str(), &clsid);
SelectObject(memdc, hOldBitmap);
DeleteObject(memdc);
DeleteObject(membit);
::ReleaseDC(0,scrdc);
}
GdiplusShutdown(gdiplusToken);
}
int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
using namespace Gdiplus;
UINT num = 0; // number of image encoders
UINT size = 0; // size of the image encoder array in bytes
ImageCodecInfo* pImageCodecInfo = NULL;
GetImageEncodersSize(&num, &size);
if(size == 0)
return -1; // Failure
pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
if(pImageCodecInfo == NULL)
return -1; // Failure
GetImageEncoders(num, size, pImageCodecInfo);
for(UINT j = 0; j < num; ++j)
{
if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
{
*pClsid = pImageCodecInfo[j].Clsid;
free(pImageCodecInfo);
return j; // Success
}
}
free(pImageCodecInfo);
return 0;
}
void main()
{
gdiscreen("C:\\Users\\Shadow\\Documents\\screenshot.jpg");
}