JPEG Screenshot RDLL

dllmain.cpp

// dllmain.cpp : Defines the entry point for the DLL application.
#include "stdafx.h"

#include "Screenshot.h"

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
					 )
{
	switch (ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
		takeScreenshot();
		break;
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
	case DLL_PROCESS_DETACH:
		break;
	}
	return TRUE;
}

Screenshot.cpp

// Screenshot.cpp : Defines the exported functions for the DLL application.
//

// Taken from https://gist.github.com/ebonwheeler/3865787
// Add gdiplus.lib as a Linker > Input > Additional Dependencies

#include "stdafx.h"

#include <iostream>
#include <Windows.h>
#include <objidl.h>

#include <gdiplus.h>
#pragma comment(lib,"Gdiplus.lib")

using namespace Gdiplus;
using namespace std;

#define SCREENSHOT_EXPORTS
#include "Screenshot.h"

int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
	UINT num = 0;
	UINT size = 0;

	ImageCodecInfo* pImageCodecInfo = NULL;

	GetImageEncodersSize(&num, &size);
	if(size == 0)
	{
		return -1;
	}

	pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
	if(pImageCodecInfo == NULL)
	{
		return -1;
	}

	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;
		}
	}

	return -1;
}

void BitmapToJpg(HBITMAP hbmpImage, int width, int height)
{
	Bitmap *p_bmp = Bitmap::FromHBITMAP(hbmpImage, NULL);
	CLSID pngClsid;
	int result = GetEncoderClsid(L"image/jpeg", &pngClsid);
	if (result != -1)
	{
		std::cout << "Encoder succeeded" << std::endl;
	}
	else
	{
		std::cout << "Encoder failed" << std::endl;
	}
	p_bmp->Save(L"c:\\windows\\temp\\screen.jpg", &pngClsid, NULL);
	delete p_bmp;
}

bool ScreenCapture(int x, int y, int width, int height, char *filename)
{
	HDC hDc = CreateCompatibleDC(0);
	HBITMAP hBmp = CreateCompatibleBitmap(GetDC(0), width, height);
	SelectObject(hDc, hBmp);
	BitBlt(hDc, 0, 0, width, height, GetDC(0), x, y, SRCCOPY);
	BitmapToJpg(hBmp, width, height);
	DeleteObject(hBmp);

	return true;
}

int takeScreenshot()
{
	GdiplusStartupInput gdiplusStartupInput;
	ULONG_PTR gdiplusToken;
	GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

	int x1 = 0;
	int y1 = 0;
	int x2 = GetSystemMetrics(SM_CXSCREEN);
	int y2 = GetSystemMetrics(SM_CYSCREEN);
	ScreenCapture(x1, y1, x2 - x1, y2 - y1, "screen.jpg");

	GdiplusShutdown(gdiplusToken);

	return 0;

}

Screenshot.h

#pragma once

#ifdef SCREENSHOT_EXPORTS
#define SCREENSHOT extern "C" __declspec(dllexport)
#else
#define SCREENSHOT extern "C" __declspec(dllimport)
#endif

SCREENSHOT int takeScreenshot();