Двойная буферизация ( утечка памяти )

#include <windows.h>
#include <cmath>
#define ID_TIMER_H 1000
#define IDC_BUTTON 100
 
/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
 
/*  Make the class name into a global variable  */
char szClassName[ ] = "CodeBlocksWindowsApp";
 
int WINAPI WinMain (HINSTANCE hThisInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR lpszArgument,
                     int nCmdShow)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */
 
    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);
 
    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default colour as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
 
    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;
 
    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "Code::Blocks Template Windows App",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           544,                 /* The programs width */
           375,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );
 
    /* Make the window visible on the screen */
    ShowWindow (hwnd, nCmdShow);
 
    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }
 
    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}
 
 
/*  This function is called by the Windows function DispatchMessage()  */
 
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static float visota;
    static float ugol;
    static HDC hdc;
 
    RECT rect;
    HBITMAP hBmp;
    PAINTSTRUCT ps;
    HWND hButton;
 
    switch (message)                  /* handle the messages */
    {
        case WM_CREATE:
            visota = 100; ugol = 0;
            hButton = CreateWindow( "button", "OK", WS_VISIBLE | WS_CHILD | BS_CENTER,
                                   20, 20, 100, 30, hwnd, ( HMENU ) IDC_BUTTON, GetModuleHandle( NULL ), 0 );
 
            break;
        case WM_COMMAND:
            switch( wParam )
            {
                case IDC_BUTTON:
                    SetTimer( hwnd, ID_TIMER_H, 30, 0 );
                    break;
            }
            break;
 
        case WM_PAINT:
            hdc= BeginPaint( hwnd, &ps );
 
            GetClientRect( hwnd, &rect );
            HDC hdcPic;
             hdcPic = CreateCompatibleDC( hdc );
 
          hBmp = CreateCompatibleBitmap(hdc, rect.right, rect.bottom );
           DeleteObject( SelectObject( hdcPic, hBmp ) ) ;
 
            HBRUSH brush;
            HBRUSH brushBack;
            brush = CreateSolidBrush( RGB( 255,0, 0 ) );
            brushBack = CreateSolidBrush( RGB( 255, 255, 255 ) );
            POINT point[ 4 ];
            point[0] = { 100, 300 };
            point[ 1 ] = { 200, 300 };
            point[ 2 ] = { 200, visota };
            point[ 3 ] = { 100, visota };
 
            FillRect( hdcPic, &rect, brushBack );
            DeleteObject( SelectObject( hdcPic, brush ) );
            Polygon( hdcPic, point, 4 );
            SaveDC( hdcPic );
            BitBlt(hdc, 0, 0, rect.right, rect.bottom, hdcPic, 0, 0, SRCCOPY );
            EndPaint( hwnd, &ps );
            DeleteObject( brush );
            DeleteObject( brushBack );
            ReleaseDC( hwnd, hdcPic );
            
            break;
        case WM_TIMER:
            switch( wParam )
            {
                case ID_TIMER_H:
                ugol += 0.02;
                visota = 100 + 50* sin( ugol );
                InvalidateRect( hwnd, 0, 0 );
                if( ugol > 6.28 )
                    KillTimer(hwnd, ID_TIMER_H );
                break;
            }
            break;
        case WM_DESTROY:
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }
 
    return 0;
}

// Во-первых, не забывай удалять hBmp:
DeleteObject (hBmp);
// А во-вторых, объект, созданный CreateCompatibleDC, удаляется
// не через ReleaseDC, а через 
DeleteDC(hdcPic);