Double Buffering in Win32 API

[James]

Having some trouble here. Trying to get double buffering working properly. Here is what I'm working with:

Basically, the flickering is gone, but it consumes more memory than I want it to and after sometime, it doesn't crash, but it just locks up so I assume there is a memory leak. Can anyone tell me please what I can do to resolve this?

#include <windows.h>
#include <stdio.h>

int screenWidth = 0;
int screenHeight = 0;

//Center Window
VOID CenterWindow(HWND hwnd, HWND hwndParent, int Width, int Height)
{
    /* Variables */
    RECT rc;
 
    /* If Parent Window Is Set As Null, Get The Desktop Window */
    if(hwndParent == NULL)
    {
        hwndParent = GetDesktopWindow();
    }
 
    /* Get Parent Client Area Measurements */
    GetClientRect(hwndParent, &rc);
 
    /* Center The Window */
    MoveWindow(hwnd, (rc.right - rc.left - Width) / 2, (rc.bottom - rc.top - Height) / 2, Width, Height, TRUE);
 
    return;
}

bool isRunning()
{
    //This checks if the process is already running so you don't have multiple instances running.
    HANDLE handle = CreateMutex(NULL, true, "myPong");
    if(GetLastError() != ERROR_SUCCESS)
    {
        MessageBox(0, "Process is already running", "Warning", MB_ICONWARNING);
        return false;
    }
    else
        return true;
}

RECT initRecArea(int left, int top, int width, int height) 
{ 
    RECT rec = {left, top, width, height}; 
    return rec; 
} 

void DrawFilledRect( HWND hWnd, HDC hDC, RECT& r) 
{ 
    hDC = GetDC(hWnd);
    HDC hdcMem = CreateCompatibleDC(hDC);
    HBITMAP hBmMem = CreateCompatibleBitmap(hDC, screenWidth, screenHeight);
    HBITMAP hBmOld = (HBITMAP) SelectObject(hdcMem, hBmMem);

    RECT rec = initRecArea(rec.left, rec.top, 0, 0);
    
    FillRect(hDC, &rec, CreateSolidBrush(RGB(0, 0, 255))); 
    BitBlt(hDC, 0, 0, screenWidth, screenHeight, hdcMem, 0, 0, SRCCOPY);
    
    InvalidateRect(hWnd,&rec,TRUE);
    ReleaseDC(hWnd, hDC);
    DeleteObject(hBmMem);
    DeleteDC(hdcMem);
} 

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hdc;
    RECT rc = {0};
    HBRUSH hBr;
    HGDIOBJ hOld;

    switch (message)
    {
        
        case WM_ERASEBKGND:
        {
            return TRUE;
        }
        break;

        case WM_PAINT:
        {
            hdc = GetDC(hWnd);
            ReleaseDC( hWnd, hdc );
            hdc = BeginPaint(hWnd, &ps);            

            // TODO: Add any drawing code here...
            GetClientRect( hWnd, &rc ); 
            AdjustWindowRectEx( &rc, WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU, FALSE, NULL ); 
            DrawFilledRect(hWnd, hdc, rc);
            ReleaseDC( hWnd, hdc );
            InvalidateRect(hWnd,&rc,TRUE);

            EndPaint(hWnd, &ps);
        }
        break;

        case WM_CREATE:
        {
            SetTimer( hWnd, NULL, USER_TIMER_MINIMUM, NULL );
        }
        break;

        case WM_TIMER:
        {
            GetClientRect( hWnd, &rc );
            InvalidateRect( hWnd, &rc, TRUE );
        }
        break;

        case WM_KEYDOWN:
        {
             if(wParam == VK_ESCAPE) 
             {
                 int ret = MessageBox(NULL, TEXT("Are you sure to quit?"), TEXT("Message"), MB_OKCANCEL);
                 
                 if(ret == IDOK) 
                 {
                     SendMessage(hWnd, WM_CLOSE, 0, 0);
                 }
             }
        }
        break;

        case WM_DESTROY:
            PostQuitMessage(0);
        break;

        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

int APIENTRY WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow )
{
    //Check if this process is running
    if(isRunning() == false)
        return 0;
    
    char szWindowClass[] = "myPong_Game";
    MSG msg;

    WNDCLASSEX wcex        = {0};
    wcex.cbSize            = sizeof(WNDCLASSEX);
    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.hInstance      = hInstance;
    wcex.hCursor        = LoadCursor( NULL, IDC_ARROW );
    wcex.hbrBackground    = (HBRUSH)GetStockObject(BLACK_BRUSH);
    wcex.lpszClassName  = szWindowClass;
    wcex.hIcon            = LoadIcon(NULL, IDI_APPLICATION);
    wcex.hIconSm        = LoadIcon(NULL, IDI_APPLICATION);
    RegisterClassEx( &wcex );

            
    //Main Application Window
    HWND hWnd = CreateWindowEx(0, szWindowClass, "myPong", WS_POPUPWINDOW | WS_CAPTION | WS_MAXIMIZEBOX, 0, 0, 600, 400, NULL, NULL, hInstance, NULL);
    
    // Do stuff here

    //End

    if(!hWnd)
    {
        return FALSE;
    }

    //Activate our Main Window
    CenterWindow(hWnd, NULL, 600, 400);
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    while(GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage( &msg );
        DispatchMessage( &msg );
    }

    return (int) msg.wParam;
} 

Here are a few other things I tried:

void DrawFilledRect( HWND hWnd, HDC hDC, RECT& r) 
{ 
    HBRUSH hBrush; 
    RECT rec = initRecArea(rec.left, rec.top, 0, 0); 
    
    //We take our color from above and color the rectangle 
    
    hBrush = CreateSolidBrush(RGB(0, 0, 255));
    FillRect(hDC, &rec, hBrush); 
    DeleteObject (hBrush); 
} 

and

void DrawFilledRect( HWND hWnd, HDC hDC, RECT& r) 
{ 
      //hDC = GetDC(hWnd);
    HDC memDC = CreateCompatibleDC(hDC);
    HBITMAP hMemBmp = CreateCompatibleBitmap(hDC, screenWidth, screenHeight);
    HBITMAP hOldBmp = (HBITMAP)SelectObject(memDC, hMemBmp);

        RECT rec = initRecArea(rec.left, rec.top, 0, 0); 
    
        //We take our color from above and color the rectangle    
        FillRect(hDC, &rec, CreateSolidBrush(RGB(0, 0, 255)));
    // As a last step copy the memdc to the hdc
    BitBlt(hDC, 0, 0, screenWidth, screenHeight, memDC, 0, 0, SRCCOPY);

    ReleaseDC( NULL, hDC );
        SelectObject(memDC, hOldBmp);
    DeleteObject(hMemBmp);
    DeleteObject(hOldBmp); //added
    DeleteDC(memDC); 
    DeleteDC(hDC); //added
} 

[wargamer]

At line 58 of the first bit of code you do the following:

RECT rec = initRecArea(rec.left, rec.top, 0, 0); 

Which you're not allowed to do, it will define rec as REC but not fill it's values (thus rec is not initialized) after which you try to pass rec.left and left.top to initRecArea. That could lead to a crash or at least my debugger sincerely disliked it but it's dangerous either way.
What you probably meant to do there:

RECT rec = initRecArea(r.left, r.top, 0, 0); 

Not sure if that will fix the lockup you speak of but I though I'd post that straight away.
Will have a closer look at your code tomorrow or so.

[James]

Don't I feel like a rytard (In the wise words of Alan)... Anywho, made the change. and I'm testing it out. I'm sure I have alot of code that may not be necessary but I been testing several things. The instant that I am doing any rendering it literally jumps in double+ the size. The app is only 9kb and for it to be using up 2 MB is IMO absurd. I do appreciate you to take a look at this though!