Bitmap disappearing when program is minimized - c++

Question

I'm a student for c++ game-programming. We have to program a textadventure on console for windows.
We get points for the implementation of bitmaps.
I have the following code to Display the bitmap. It works well but when i minimize my window, my bitmap disappears.
Where's the problem?
bool DisplayBitmap(char *szBitmap, int PosX = -1, int PosY = -1, bool AutoZoom = false)
{
HWND hWnd = FindWindow("ConsoleWindowClass",NULL); // Konsolen-Fenster identifizieren
if (!hWnd) return false;
HDC hDC = GetDC(hWnd); // Device Context des Fensters ermitteln
if (!hDC) return false;
HDC hBitmapDC = CreateCompatibleDC(hDC); // Device Context für Bitmap bereitstellen
if (!hBitmapDC) return false;
HBITMAP hBitmap = (HBITMAP)LoadImage(NULL,szBitmap, // Bild aus Datei laden
IMAGE_BITMAP,0,0,LR_LOADFROMFILE);
if (!hBitmap) return false;
BITMAP bmp;
GetObject(hBitmap,sizeof(bmp),&bmp); // Zeiger auf Bitmap-Objekt anfordern
RECT Client;
GetClientRect(hWnd, &Client); // Fenstergröße bestimmen
if (PosX == -1) PosX = ((Client.right-Client.left)-bmp.bmWidth) / 2;
if (PosY == -1) PosY = 250-bmp.bmHeight; // ggfs. automatisch zentrieren
if (PosY < 0) PosY = 0; // und Zoomfaktor berechnen
double ZoomFactor = (Client.right-Client.left-2*PosX) / double(bmp.bmWidth);
SelectObject(hBitmapDC,hBitmap); // Bitmap kopieren (evtl. mit Zoom)
if (!AutoZoom) BitBlt(hDC,PosX,PosY,bmp.bmWidth,bmp.bmHeight,hBitmapDC,0,0,SRCCOPY);
else StretchBlt(hDC,PosX,PosY,int(bmp.bmWidth*ZoomFactor),int(bmp.bmHeight*ZoomFactor),hBitmapDC,0,0,bmp.bmWidth,bmp.bmHeight,SRCCOPY);
DeleteObject(hBitmap); // Objekte und Device Contexts wieder freigeben
ReleaseDC(hWnd,hBitmapDC);
ReleaseDC(hWnd,hDC);
return true;
}

Answer 1

The bitmap disappears because the console window is repainted when restored and the repainting procedure knows nothing about your bitmap.
Windows are repainted quite often: every time your window is brought up or resized or restored from iconic state the window is repainted (well, may be not every time, because the system can make some caching... but still). When the window should be repainted, Windows sends WM_PAINT message to the window. Tha application handles this message and redraws the window contents in the window DC. This is how GUI-applications work. But if you use console, you can not handle window messages -- the system does it for you, and you can not change the repainting procedure.
If you want your bitmap to be always there, you should create your own window and process the WM_PAINT message (or, you can use some predefined control intended for displaying bitmaps). To do this you must create a GUI-application. You can not do this with console application.
The code you provided is just a hack and it is not supporsed to work as you expect. When the code is executed the bitmap is drawn. But once the part of the window is hidden beyond another window the image will be lost and nobody will restore it.
By the way, if your professor gave you this example, probably he will be satisfied by the result it produces. But never do like this in real life :)