Thread: drawing outside client area

I'm working on a "breakout" game and everything worked fine until i tried to add in double buffering.
I tried to take out double buffering since i couldn't get it to work and now, it draws everything from the top left corner of the screen instead of in the client area. If i leave it on for a while, things start disapearing from my screen. Any idea what could have caused this?

[edit]ok, i found out why it was leaking GDI objects... now, how come it draws on the corner?[/edit]

Show the code that draws the objects.

Code:

void C_Graphics::DrawAll(C_Brick Bricks[])
{
    hbr = CreateSolidBrush(RGB(0,0,0));
    RECT r;
    r = Player.Get_BallInfo();
    Ellipse(hdc, r.left, r.top, r.right, r.bottom);
    FillRect(hdc, Player.Get_PlankInfo(), hbr);
    for(int i = 0; i < 20; i++)
    {
        if (Bricks[i].Get_Life() > 0)
            FillRect(hdc, Bricks[i].Get_Info_ptr(), hbr);
    }
    DeleteObject(hbr);
}

void C_Graphics::ClearScreen()
{
    hbr = CreateSolidBrush(RGB(255, 255, 255));
    RECT r;
    GetClientRect(g_hwnd, &r);
    FillRect(hdc, &r, hbr);
    DeleteObject(hbr);
}

If g_hwnd is 0, it will not draw in your window but rather the screen as a whole.
[edit] Actually, hdc would have to have been obtained by using 0 as the window[/edit]

Code:

    if (!g_hwnd)
        MessageBox(g_hwnd, "ERROR", "g_hwnd", MB_OK);

Code:

    itoa((int)g_hwnd, sz_temp, 10);
    TextOut(hdc, 260, 130, sz_temp, sizeof(sz_temp));

its not 0

Please post the code where you get/create 'hdc'.

Please post the code where you get the rectangle to draw on.

Otherwise, guessing from the limited code supplied, you are drawing on the main screen not your apps screen.

A conversion using ClientToScreen() might hide the problem.

Code:

C_Graphics::C_Graphics()
{
    RECT ClientRect;
    GetClientRect(g_hwnd, &ClientRect); //i forgot what these were for...
    hdc = GetDC(g_hwnd);
    if (!hdc)
        MessageBox(g_hwnd, "GetDC(g_hwnd);", "ERROR", MB_OK);
}

What value is in the g_hwnd when the constructor is called?

ie has the window/dialog been created at this point or is it still being created?

What values are in the Client rect?

If you use NULL (or g_hwnd == NULL) then you will get the screen rect and hdc. This would explain your drawing on the top left of the screen.

GetDC(NULL) will not return an empty hdc, it will return the mainscreen hdc.

Oh... I called the constructor before g_hwnd was defined
thanks