Screen capture CreateDIBSection doesn't capture LayeredWindow

Hello, I am trying to capture a screen shot using this code:

...
HWND hwnd=0;
hdc = GetWindowDC(hwnd);
memdc = CreateCompatibleDC(hdc);
...
hbmp = CreateDIBSection(hdc, &bmpinfo, DIB_PAL_COLORS, &pBits, NULL, 0)
SelectObject(memdc, hbmp);
...

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But I layered windows doesn't appear inside the shot, it is like them were invisible, only the desktop and other windows are captured.

Using "print screen" I get a full screen shot including layered window, then how can I correct that ?

Thanks
LVL 1
Greg2FSAsked:
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pgnatyukConnect With a Mentor Commented:
It's Delphi:
http://users.telenet.be/ws36637/transparent2.html
People say to use CAPTUREBLT together with SRCCOPY in BitBlt. They also use CreateCompatibleBitmap instead of CreateDIBSection.
 
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pgnatyukCommented:
The code you posted does not contain BitBlt call or any other operation that will copy the pixels. It is also not clear from where to where you copy.
CreateDIBSection creates a DIB section. It does not capture any screen. Mainly, it is a way to create HBITMAP. pBits - this is the array of the pixels.
Sorry if I simplified too much.
In this EE article "Win32: Capture an image" (http://www.experts-exchange.com/A_1739.html) you can find the code that works. There is an example that takes screenshots from the desktop.
About the layered window (if your need):
Win32: Semi-Transparent Window: http://www.experts-exchange.com/A_1783.html 
 (There is the screenshot as an evidence for you).
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Greg2FSAuthor Commented:
Sorry I didn't know exactly what does the job of taking the screenshot, but my code was longer and it seems that the code you link does exactly the same: the screenshot is taken but my layered window is not captured...
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pgnatyukCommented:
No problem.
If you need the screenshots, you need to take the code from the article:
Win32: Capture an image
http://www.experts-exchange.com/A_1739.html 
 
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Greg2FSAuthor Commented:
I tried this code and said it does the same thing as mine.
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pgnatyukCommented:
Yes. You are right. GetDC from the desktp does not help for the window with the WS_EX_LAYERED.
For a test, I took the screenshot of the layered window itself.

#include <Windows.h>

BOOL Capture(HDC, LPRECT, LPCWSTR);

int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, 
                      LPWSTR lpCmdLine, int nCmdShow)
{
    HWND hWnd;
    HDC hDC;
    RECT rect;
    hWnd = FindWindow(NULL, L"Semi-Transparent Window");
    SetForegroundWindow(hWnd);
    ::GetWindowRect(hWnd, &rect);
    ScreenToClient(hWnd, (LPPOINT)&rect);
    ScreenToClient(hWnd, (LPPOINT)&rect.right);
    hDC = GetDC(hWnd);

    Capture(hDC, &rect, L"capture.bmp");
    return 0;
}

BOOL Capture(HDC hDC, LPRECT lpRect, LPCWSTR lpszFile)
{
    BITMAPINFO bmi = { 0 };

    LPBYTE pBits = NULL;
    bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bmi.bmiHeader.biWidth = lpRect->right - lpRect->left;
    bmi.bmiHeader.biHeight = lpRect->bottom - lpRect->top;
    bmi.bmiHeader.biPlanes = 1;
    bmi.bmiHeader.biBitCount = 32;
    bmi.bmiHeader.biCompression = BI_RGB;
    HBITMAP hBitmap = CreateDIBSection(hDC, &bmi, 
        DIB_RGB_COLORS, (LPVOID*)&pBits, NULL, 0);

    HDC hMemDC = CreateCompatibleDC(hDC);
    HGDIOBJ hOld = SelectObject(hMemDC, hBitmap);
    BitBlt(hMemDC, 0, 0, 
        lpRect->right - lpRect->left,
        lpRect->bottom - lpRect->top,
        hDC, lpRect->left, lpRect->top, SRCCOPY);
    SelectObject(hMemDC, hOld);
    DeleteDC(hMemDC);

    DWORD nImageSize = ((((bmi.bmiHeader.biWidth * 
        bmi.bmiHeader.biBitCount) 
        + 31) & ~31) >> 3) 
        * bmi.bmiHeader.biHeight;

    BITMAPFILEHEADER header = { 0 };
    header.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + 
        (DWORD)sizeof(BITMAPINFOHEADER); 
    header.bfSize = nImageSize + sizeof(BITMAPFILEHEADER) + 
        sizeof(BITMAPINFOHEADER);
    header.bfType = 0x4D42;

    HANDLE hFile = CreateFile(lpszFile, GENERIC_WRITE,
        0, NULL, CREATE_ALWAYS, 
        FILE_ATTRIBUTE_NORMAL, NULL);   

    if (hFile != INVALID_HANDLE_VALUE) 
    {
        DWORD nWritten = 0;;
        WriteFile(hFile, (LPVOID)&header, 
            sizeof(BITMAPFILEHEADER), 
            &nWritten, NULL);
        WriteFile(hFile, (LPVOID)&bmi, 
            sizeof(BITMAPINFOHEADER), 
            &nWritten, NULL);
        WriteFile(hFile, (LPVOID)pBits, nImageSize, 
            &nWritten, NULL);
        CloseHandle(hFile);
    }

    return TRUE;
}

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Greg2FSAuthor Commented:
Yes just using SRCCOPY|CAPTUREBLT works !
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Greg2FSAuthor Commented:
Thanks
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pgnatyukCommented:
:)
I've already made a short example for you.
You are welcome.
 

#include <Windows.h>

BOOL Capture(HDC, LPRECT, LPCWSTR);

int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, 
                      LPWSTR lpCmdLine, int nCmdShow)
{

    HWND hWnd = GetDesktopWindow();
    HDC hDC = GetDC(hWnd);

    RECT rect = { 100, 100, 500, 500 };
    HDC hDCMem = ::CreateCompatibleDC(hDC);
    HBITMAP hBitmap = ::CreateCompatibleBitmap(hDC, 500, 500);
    HBITMAP hBmpOld = (HBITMAP)::SelectObject(hDCMem, hBitmap);

    BOOL bRet = ::BitBlt(hDCMem, 0, 0, 500, 500, hDC, 100, 100, SRCCOPY | CAPTUREBLT);

    Capture(hDCMem, &rect, L"capture.bmp");

    ::SelectObject(hDCMem, hBmpOld);
    ::DeleteObject(hBitmap);
    ::DeleteDC(hDCMem);
    return 0;
}

BOOL Capture(HDC hDC, LPRECT lpRect, LPCWSTR lpszFile)
{
    BITMAPINFO bmi = { 0 };

    LPBYTE pBits = NULL;
    bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bmi.bmiHeader.biWidth = lpRect->right - lpRect->left;
    bmi.bmiHeader.biHeight = lpRect->bottom - lpRect->top;
    bmi.bmiHeader.biPlanes = 1;
    bmi.bmiHeader.biBitCount = 32;
    bmi.bmiHeader.biCompression = BI_RGB;
    HBITMAP hBitmap = CreateDIBSection(hDC, &bmi, 
        DIB_RGB_COLORS, (LPVOID*)&pBits, NULL, 0);

    HDC hMemDC = CreateCompatibleDC(hDC);
    HGDIOBJ hOld = SelectObject(hMemDC, hBitmap);
    BitBlt(hMemDC, 0, 0, 
        lpRect->right - lpRect->left,
        lpRect->bottom - lpRect->top,
        hDC, lpRect->left, lpRect->top, CAPTUREBLT | SRCCOPY);
    SelectObject(hMemDC, hOld);
    DeleteDC(hMemDC);

    DWORD nImageSize = ((((bmi.bmiHeader.biWidth * 
        bmi.bmiHeader.biBitCount) 
        + 31) & ~31) >> 3) 
        * bmi.bmiHeader.biHeight;

    BITMAPFILEHEADER header = { 0 };
    header.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + 
        (DWORD)sizeof(BITMAPINFOHEADER); 
    header.bfSize = nImageSize + sizeof(BITMAPFILEHEADER) + 
        sizeof(BITMAPINFOHEADER);
    header.bfType = 0x4D42;

    HANDLE hFile = CreateFile(lpszFile, GENERIC_WRITE,
        0, NULL, CREATE_ALWAYS, 
        FILE_ATTRIBUTE_NORMAL, NULL);   

    if (hFile != INVALID_HANDLE_VALUE) 
    {
        DWORD nWritten = 0;;
        WriteFile(hFile, (LPVOID)&header, 
            sizeof(BITMAPFILEHEADER), 
            &nWritten, NULL);
        WriteFile(hFile, (LPVOID)&bmi, 
            sizeof(BITMAPINFOHEADER), 
            &nWritten, NULL);
        WriteFile(hFile, (LPVOID)pBits, nImageSize, 
            &nWritten, NULL);
        CloseHandle(hFile);
    }

    return TRUE;
}

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capture.bmp
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