将特定窗口的屏幕快照另存为窗口中的bmp

Question

I need to get a screen view of a specific window as .bmp format. In other words I need to have the functionality of alt+printscreen and it needs to work even the window is at back or minimized. So I wrote a function below which returns a HBITMAP type in order to save the view as .bmp file with another function later.

HBITMAP CaptureWindowBitmap(HWND MyHWND)
{

HDC hWindowDC = GetWindowDC(MyHWND);     
HDC hMemoryDC = CreateCompatibleDC(hWindowDC);

int x = GetDeviceCaps(hWindowDC, HORZRES);
int y = GetDeviceCaps(hWindowDC, VERTRES);

HBITMAP hBitmap = CreateCompatibleBitmap(hWindowDC, x, y);
HBITMAP hBitmapOld = (HBITMAP)SelectObject(hMemoryDC, hBitmap);

BitBlt(hMemoryDC, 0, 0, x, y, hWindowDC, 0, 0, SRCCOPY);
hBitmap = (HBITMAP)SelectObject(hMemoryDC, hBitmapOld);

DeleteDC(hMemoryDC);
DeleteDC(hWindowDC);
return hBitmap;
}

However my function gets the image of the whole screen. How can I fix this?

Answer 1

Here is the solution i found from elsewhere:

HBITMAP CaptureWindowBitmap(HWND MyHWND)
{
RECT rc;
GetClientRect(MyHWND, &rc);

HDC hdcScreen = GetDC(NULL);
HDC hdc = CreateCompatibleDC(hdcScreen);
HBITMAP hbmp = CreateCompatibleBitmap(hdcScreen, rc.right - rc.left, rc.bottom - rc.top);
SelectObject(hdc, hbmp);

PrintWindow(MyHWND, hdc, PW_CLIENTONLY);

DeleteDC(hdc);
ReleaseDC(NULL, hdcScreen);

return hbmp;
}

Window is captured by the function below:

BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
char buffer[128];
int written = GetWindowTextA(hwnd, buffer, 128);
if (written && strstr(buffer,WindowName) ) {
    *(HWND*)lParam = hwnd;
    return FALSE;
}
return TRUE;
}

HWND GetHwnd()
{
HWND hWnd = NULL;
EnumWindows(EnumWindowsProc, (LPARAM)&hWnd);
return hWnd;
}

where LPCTSTR WindowName is a global variable containing the name or partial name of the window.