使用GDI C++制作正方形动画

我想为许多正方形的运动设置动画。在这个例子中，我创建了两个正方形。当我建造和运行时，我可以看到这两个方块，但它们没有移动。

我创建了一个表示正方形的类

#pragma once
#include <windows.h>
class Square {

private:
     int x,y;
     int moveWith_x, moveWith_y;
public:
    void DrawSquare(HDC,int,int,int,int);
    void MoveSquare(int,int);
    Square(void);
    ~Square(void);
};

和实现文件(这里我使用DrawSquare中的Rectangle函数创建正方形(，并尝试在MoveSquares中动画化运动：

    #include "Square.h"
    void Square::DrawSquare(HDC hdc,int rx,int ry, int lx, int ly) {
        Rectangle(hdc,rx,ry,lx,ly); 
    }
void Square::MoveSquare(int mod_x_Size,int mod_y_Size) {
        x=x+ moveWith_x;
        y=y+ moveWith_y;
            if ( x >= mod_x_Size - 30)  {
                 x= mod_x_Size - 30 ;
                 moveWith_x =  -moveWith_x++;
            }

            if ( y >= mod_y_Size -30) {
                  y=mod_y_Size - 30 ;
                 moveWith_y= -moveWith_y++;
            }
            if ( x < 30) {
             x=30;
             moveWith_x= -moveWith_x++;
            }
            if ( y <30) {
                 y=50;
                 moveWith_y= -moveWith_x++; 
            }
    }
 Square::Square(void) {
        x=0;
        y=0;
        moveWith_x = 0;
        moveWith_y = 0; 
    }
    Square::~Square(void) {
    }

在我的main.cpp中，我设置了一个计时器，创建并绘制给定数量的od正方形(用白色画笔(

#include <windows.h>
#include <windowsx.h>
#include "Square.h"
#define NUMARUL_DE_FIGURI  2

LRESULT CALLBACK WndProc (HWND,UINT,WPARAM,LPARAM);
void moveObject(int,int);
    //Coordonatele in caz de redimensionare a ferestrei
    static int mod_x_Size, mod_y_Size;
    // Crearea ferestrei de lucru
HWND hwnd;
int WINAPI WinMain (HINSTANCE hInt, HINSTANCE,LPSTR,int) {
char atitle[] = "Drawing with GDI";
char className[] = "Main Window";
MSG msg;
// Crearea si initializarea ferestrei principale
WNDCLASS wnd;
ZeroMemory(&wnd,sizeof(wnd));
wnd.lpfnWndProc = WndProc;
wnd.hInstance = hInt;
wnd.hIcon = LoadIcon (NULL,IDI_APPLICATION);
wnd.hCursor = LoadCursor (NULL,IDC_ARROW);
wnd.hbrBackground = GetStockBrush (BLACK_BRUSH);
wnd.lpszClassName = className;
// Inregistrarea clasei in SO
RegisterClass (&wnd);

    // Crearea unui timer
 SetTimer (hwnd, 1, 40, NULL) ;
hwnd = CreateWindow (className,atitle,WS_OVERLAPPEDWINDOW,200,200,600,600,HWND_DESKTOP,NULL,hInt,NULL);
//Afisarea ferestrei in mod obisnuit
ShowWindow (hwnd,SW_SHOWNORMAL);
// Daca aplicatia primeste mesaj de la SO are loc transmiterea p-u prelucrare
while (GetMessage(&msg,NULL,0,0)) DispatchMessage(&msg);
     return 0;
}
// Prelucrarea mesajelor
LRESULT CALLBACK WndProc (HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
    // Structura ce detine informatii despre dispozitivul de desenare
    PAINTSTRUCT ps;
    // Descriptorul dispozitivului de desen
    HDC hdc;
    Square square[NUMARUL_DE_FIGURI];
    // Culoarea figurii
    HBRUSH shapeColor;
    switch (msg) {
// Prelucrarea mesajelor primite la modificarea dimensiunilor ferestrei
case WM_SIZE :      
        //La fiecare redimensionare a ferestrei se reinnoiesc coordonatele speciale 
        mod_x_Size = LOWORD (lparam) ;
        mod_y_Size = HIWORD (lparam) ;
        break ;
// Prelucrarea mesajelor primite la fiecare interval al timerului
case WM_TIMER:
    InvalidateRect (hwnd, NULL, TRUE) ;
for (int i=0;i<NUMARUL_DE_FIGURI;i++) {
    square[i].MoveSquare( mod_x_Size, mod_y_Size);
}

// Prelucrarea mesajului de desenare 
case WM_PAINT: 
    // Permite desenarea pe dispozitivul de desenare
    hdc = BeginPaint(hwnd, &ps);
    // Crearea patratelor
   for (int i=0;i<NUMARUL_DE_FIGURI;i++) {
        shapeColor = (HBRUSH)SelectObject(hdc, CreateSolidBrush(RGB(255,255,255)));
        square[i].DrawSquare(hdc,mod_x_Size-((i*200)+50),mod_y_Size-((i*200)+50),mod_x_Size-((i*20)+100),mod_y_Size-((i*20)+100)); 
    }
  // 
    //ReleaseDC(hwnd,hdc);
   // Finiseaza procesul de desenare pe dispozitiv
    EndPaint(hwnd, &ps);
    break;
// Distrugerea ferestrei aplicatiei
case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hwnd, msg, wparam, lparam);
    }
    return 0;
}

我哪里错了？请原谅我的代码注释(这是我的语言(，如果你想让我在这个问题上更具体，请问。