Possible Duplicate:
how to make screen screenshot with win32 in c++?
I am currently trying to create an application that saved a portion of the screen to a bmp. I have found BitBlt but I really don't know what to do with it. I have tried searching for some answers but I still haven't found a clarifying one using C++.
So, basically I want this function:
bool capturePartScreen(int x, int y, int w int, h, string dest){
//Capture part of screen according to coordinates, width and height.
//Save that captured image as a bmp to dest.
//Return true if success, false if failure
}
BitBlt:
BOOL BitBlt(
__in HDC hdcDest,
__in int nXDest,
__in int nYDest,
//The three above are the ones I don't understand!
__in int nWidth,
__in int nHeight,
__in HDC hdcSrc,
__in int nXSrc,
__in int nYSrc,
__in DWORD dwRop
);
What should that hdc be and how do I obtain the bmp?
It took a while, but I have now finally ended up with a functioning script.
Requirements:
#include <iostream>
#include <ole2.h>
#include <olectl.h>
Also you might(?) have to add ole32, oleaut32 and uuid to your linker.
screenCapturePart:
bool screenCapturePart(int x, int y, int w, int h, LPCSTR fname){
HDC hdcSource = GetDC(NULL);
HDC hdcMemory = CreateCompatibleDC(hdcSource);
int capX = GetDeviceCaps(hdcSource, HORZRES);
int capY = GetDeviceCaps(hdcSource, VERTRES);
HBITMAP hBitmap = CreateCompatibleBitmap(hdcSource, w, h);
HBITMAP hBitmapOld = (HBITMAP)SelectObject(hdcMemory, hBitmap);
BitBlt(hdcMemory, 0, 0, w, h, hdcSource, x, y, SRCCOPY);
hBitmap = (HBITMAP)SelectObject(hdcMemory, hBitmapOld);
DeleteDC(hdcSource);
DeleteDC(hdcMemory);
HPALETTE hpal = NULL;
if(saveBitmap(fname, hBitmap, hpal)) return true;
return false;
}
saveBitmap:
bool saveBitmap(LPCSTR filename, HBITMAP bmp, HPALETTE pal)
{
bool result = false;
PICTDESC pd;
pd.cbSizeofstruct = sizeof(PICTDESC);
pd.picType = PICTYPE_BITMAP;
pd.bmp.hbitmap = bmp;
pd.bmp.hpal = pal;
LPPICTURE picture;
HRESULT res = OleCreatePictureIndirect(&pd, IID_IPicture, false,
reinterpret_cast<void**>(&picture));
if (!SUCCEEDED(res))
return false;
LPSTREAM stream;
res = CreateStreamOnHGlobal(0, true, &stream);
if (!SUCCEEDED(res))
{
picture->Release();
return false;
}
LONG bytes_streamed;
res = picture->SaveAsFile(stream, true, &bytes_streamed);
HANDLE file = CreateFile(filename, GENERIC_WRITE, FILE_SHARE_READ, 0,
CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
if (!SUCCEEDED(res) || !file)
{
stream->Release();
picture->Release();
return false;
}
HGLOBAL mem = 0;
GetHGlobalFromStream(stream, &mem);
LPVOID data = GlobalLock(mem);
DWORD bytes_written;
result = !!WriteFile(file, data, bytes_streamed, &bytes_written, 0);
result &= (bytes_written == static_cast<DWORD>(bytes_streamed));
GlobalUnlock(mem);
CloseHandle(file);
stream->Release();
picture->Release();
return result;
}