Неправильно работающая программа. Win32, Direct2D

#ifndef UNICODE
#define UNICODE
#endif // !UNICODE

#include <Windows.h>
#include <d2d1.h>
#include <cstdlib>
#include <time.h>
LRESULT CALLBACK WProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
ID2D1Factory *pD2D1Factory = NULL;
HRESULT hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &pD2D1Factory);
template<class T>
void SafeRelease(T **ppT)
{
    if (*ppT)
    {
        (*ppT)->Release();
        *ppT = NULL;
    }
}
void DrawSquars(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow)
{
    const wchar_t CLASS_NAME[] = L"Window Class";
    WNDCLASS wc = {};
    wc.hInstance = hInstance;
    wc.lpfnWndProc = WProc;
    wc.lpszClassName = CLASS_NAME;
    RegisterClass(&wc);
    HWND hwnd = CreateWindowEx(0, CLASS_NAME, L"Wind Name", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL);
    ShowWindow(hwnd, nCmdShow);
    MSG msg = {};
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
}
LRESULT CALLBACK WProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
    case WM_DESTROY:
        SafeRelease(&pD2D1Factory);
        PostQuitMessage(0);
        return 0;
    case WM_PAINT:
        DrawSquars(hwnd, uMsg, wParam, lParam);
        return 0;
    }
    DefWindowProc(hwnd, uMsg, wParam, lParam);
}
void DrawSquars(HWND hwnd,UINT uMsg,WPARAM wParam, LPARAM lParam)
{
    if (SUCCEEDED(hr))
    {
        RECT rc;
        GetClientRect(hwnd, &rc);
        ID2D1HwndRenderTarget *pRT;
        hr = pD2D1Factory->CreateHwndRenderTarget(D2D1::RenderTargetProperties(), D2D1::HwndRenderTargetProperties(hwnd, D2D1::SizeU(rc.right - rc.left, rc.bottom - rc.top)), &pRT);
        if (SUCCEEDED(hr))
        {
            pRT->BeginDraw();
            pRT->Clear(D2D1::ColorF(D2D1::ColorF::White));
            //pRT->EndDraw();
            srand(time(NULL));
            ID2D1SolidColorBrush *pSCB;
            int length_square = rc.bottom / 123;
            if (length_square == 0)
                length_square = 1;
            for (int i = 0; i <= rc.bottom; i += length_square)
            {
                for (int j = 0; j <= rc.right; j += length_square)
                {
                    float r = rand() % 100;
                    r = r / 100;
                    float g = (rand() % 100);
                    g = g / 100;
                    float b = rand() % 100;
                    b = b / 100;
                    pRT->CreateSolidColorBrush(D2D1::ColorF(r, g, b), &pSCB);
                    //pRT->BeginDraw();
                    pRT->FillRectangle(D2D1::RectF(j, i, j + length_square, i + length_square), pSCB);
                    //pRT->EndDraw();
                }
            }
            pRT->EndDraw();
            SafeRelease(&pSCB);
        }
        SafeRelease(&pRT);
    }
}

Картинка почему то постоянно обновляется, и происходит постоянное выделение памяти без освобождения.