Help with WinApi ?

This is a discussion on Help with WinApi ? within the Windows Programming forums, part of the Platform Specific Boards category; Even tough this is only a c++ forum, I hope some one can help me with my C WinApi problem. ...

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    Angry Help with WinApi ?

    Even tough this is only a c++ forum, I hope some one can help me with my C WinApi problem. I have posted this question on CodeGuru Forums but no helpfull reply at all.
    I have homework for school and we were instructed to write a game in plain c with conio2.h for graphical output. But I hvae decided to make it in WinApi.

    Now here is my problem I have a function CheckStatus() which verifies if the game is over and if it is it asks the user play again or quit. If I put this function in WM_KEYDOWN it works ok, but if I move the function to the end of WM_PAINT, the window won't repaint on a new game unless you completley resize it or move arround the blank screen a few times. Does any 1 know what that could be?

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <time.h>
    #include <windows.h>
    #include <commctrl.h>
    
    #define WIDTH 1378
    #define HEIGHT 820
    #define WM_START 0x1337
    #define IDM_FILE_NEW 1
    #define IDM_FILE_REPLAY 2
    #define IDM_FILE_DIFFICULTY 3
    #define IDM_FILE_OPTIONS 4
    #define IDM_FILE_QUIT 5
    
    HINSTANCE Instance;
    int GameOver = 0;
    int GameDevelopment = 1;
    int Misek;
    int Resizing = 0;
    int Tezavnost = 2;
    int Vertical = 0;
    
    struct Cat{
    	int X, Y;
    	int prevX, prevY;
    }Cat;
    struct Mice{
    	char status;
    	int X, Y;
    }Mouse[50];
    struct Dogs{
    	int X, Y;
    }Dog[200];
    
    LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
    void LoadAndBlitCat(HDC hWinDC);
    void LoadAndBlitMice(HDC hWinDC);
    void LoadAndBlitDogs(HDC hWinDC);
    void InitializeAnimals(HWND hwnd);
    void CheckStatus(HWND hwnd);
    void AddMenus(HWND hwnd);
    
    int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance,
    			LPSTR lpCmdLine, int nCmdShow )
    {
      MSG  msg ;    
      WNDCLASS wc = {0};
      wc.lpszClassName = TEXT( "Windows" );
      wc.hInstance     = hInstance ;
      wc.hbrBackground = GetSysColorBrush(COLOR_3DFACE);
      wc.lpfnWndProc   = WndProc ;
      wc.hCursor       = LoadCursor(0,IDC_ARROW);
      
      RegisterClass(&wc);
      CreateWindow(wc.lpszClassName, TEXT("Windows"),
                    WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_THICKFRAME | 
                        WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_VISIBLE,
                    GetSystemMetrics(SM_CXSCREEN)/9, 
    				GetSystemMetrics(SM_CYSCREEN)/12,
    				WIDTH, HEIGHT, 0, 0, hInstance, 0);  
    
      while( GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
      }
      return (int) msg.wParam;
    }
    
    LRESULT CALLBACK WndProc( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam ){
      HDC hdc;
      PAINTSTRUCT ps;
      switch(msg)  
      {
        case WM_START:{
    		GameOver = 0;
    		Misek = Tezavnost*5;
    		GameDevelopment = 1;
    		InitializeAnimals(hwnd);
    	    InvalidateRect(hwnd, NULL, TRUE);
    		break;
    	}
        case WM_CREATE:{
    		AddMenus(hwnd);
    		SendMessage(hwnd, WM_START, 0, 0);
    	    break;
        }
    	case WM_KEYDOWN:{
    
    		if(!Vertical){
    		    Cat.prevX = Cat.X;
    		    Cat.prevY = Cat.Y;
    		}
    
            if(wParam == 0x57){
    		    if(Cat.Y-34 <= 0)
    				Beep(500,500);
    		    else
    			    Cat.Y -= 34;
    	    }
    		if(wParam == 0x41){
    		    if(Cat.X-34 <= 0)
    				Beep(500,500);
    		    else
    			    Cat.X -= 34;
    	    }
    		if(wParam == 0x53){
    		    if(Cat.Y+34 >= HEIGHT-150)
    				Beep(500,500);
    		    else
    			    Cat.Y += 34;
    	    }
    		if(wParam == 0x44){
    		    if(Cat.X+34 >= WIDTH-34)
    				Beep(500,500);
    		    else
    			    Cat.X += 34;
    	    }
    		CheckStatus(hwnd);
    		Vertical = 1;
    		InvalidateRect(hwnd, NULL, FALSE);
    	    break;
    	}
    	case WM_PAINT:{
    		 
    		Vertical = 0;
    		hdc = BeginPaint(hwnd, &ps);
    		
    		HBRUSH hFillBrush = GetSysColorBrush(COLOR_3DFACE);
    		HBRUSH hBrushOld = (HBRUSH)SelectObject(hdc, hFillBrush);
    		HPEN hLinePen = CreatePen(PS_NULL, 0, RGB(0, 0, 0));
    	    HPEN hPenOld = (HPEN)SelectObject(hdc, hLinePen);
    
    		Rectangle(hdc, Cat.prevX, Cat.prevY, Cat.prevX+34, Cat.prevY+34);
    
            hLinePen = CreatePen(PS_SOLID, 2, RGB(0, 0, 0));
    	    hPenOld = (HPEN)SelectObject(hdc, hLinePen);
    
    		if(GameDevelopment){
    			for(int i = 1;i<=WIDTH;i=i+34){
    			    MoveToEx(hdc, i, 0, NULL);
    				LineTo(hdc, i, HEIGHT-139);
    			}
    			for(int i = 1;i<=HEIGHT-139;i=i+34){
    			    MoveToEx(hdc, 0, i, NULL);
    				LineTo(hdc, WIDTH-17, i);
    			}
    
    			if(GameDevelopment == 1 || Resizing == 1){
    			    LoadAndBlitMice(hdc);
    				Resizing = 0;
    		    }
    			LoadAndBlitCat(hdc);
    			if(GameDevelopment == 1 || Resizing == 1){
    			    LoadAndBlitDogs(hdc);
    				Resizing = 0;
    		    }
    		}
    
    		SelectObject(hdc, hPenOld);
    	    DeleteObject(hLinePen);
    		SelectObject(hdc, hBrushOld);
    		DeleteObject(hFillBrush);
    		 
    		EndPaint(hwnd, &ps);
    
            break;
    	}
    	case WM_SIZE:{
    	    Resizing = 1;
    		break;
    	}
        case WM_DESTROY:
        {
            PostQuitMessage(0);
            break; 
        }
      }
      return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    
    void AddMenus(HWND hwnd){
      HMENU hMenubar;
      HMENU hMenu;
    
      hMenubar = CreateMenu();
      hMenu = CreateMenu();
    
      AppendMenu(hMenu, MF_STRING, IDM_FILE_NEW, TEXT("&New"));
      AppendMenu(hMenu, MF_STRING, IDM_FILE_REPLAY, TEXT("&Replay"));
      AppendMenu(hMenu, MF_STRING, IDM_FILE_DIFFICULTY, TEXT("&Difficutly"));
      AppendMenu(hMenu, MF_STRING, IDM_FILE_OPTIONS, TEXT("&Options"));
      AppendMenu(hMenu, MF_SEPARATOR, 0, NULL);
      AppendMenu(hMenu, MF_STRING, IDM_FILE_QUIT, TEXT("&Quit"));
    
      AppendMenu(hMenubar, MF_POPUP, (UINT_PTR)hMenu, TEXT("&File"));
      SetMenu(hwnd, hMenubar);
    }
    
    void LoadAndBlitCat(HDC hWinDC){
    	HBITMAP hBitmap;
        BITMAP qBitmap;
        HDC hLocalDC;
    
        hBitmap = (HBITMAP)LoadImage(NULL, TEXT("Cat.bmp"), IMAGE_BITMAP, 0, 0, 
                    LR_CREATEDIBSECTION | LR_DEFAULTSIZE | LR_LOADFROMFILE);
        hLocalDC = CreateCompatibleDC(hWinDC);
    
        GetObject((HGDIOBJ) hBitmap, sizeof(BITMAP), (LPVOID) &qBitmap);
    
        HBITMAP hOldBmp = (HBITMAP) SelectObject(hLocalDC, hBitmap);
    
    
        BitBlt(hWinDC, Cat.X, Cat.Y, qBitmap.bmWidth, qBitmap.bmHeight, hLocalDC, 0, 0, SRCCOPY);
        SelectObject(hLocalDC, hOldBmp);
    
    	DeleteDC(hLocalDC);
    	DeleteObject(hBitmap);
    }
    void LoadAndBlitMice(HDC hWinDC){
    	HBITMAP hBitmap;
        BITMAP qBitmap;
        HDC hLocalDC;
        
        hBitmap = (HBITMAP)LoadImage(NULL, TEXT("Mouse.bmp"), IMAGE_BITMAP, 0, 0, 
                    LR_CREATEDIBSECTION | LR_DEFAULTSIZE | LR_LOADFROMFILE);
        hLocalDC = CreateCompatibleDC(hWinDC);
    
        GetObject((HGDIOBJ) hBitmap, sizeof(BITMAP), (LPVOID) &qBitmap);
    
        HBITMAP hOldBmp = (HBITMAP) SelectObject(hLocalDC, hBitmap);
    
        for(int i=0;i<Tezavnost*5;i++)
    		if(Mouse[i].status != 'D')
                BitBlt(hWinDC, Mouse[i].X, Mouse[i].Y, qBitmap.bmWidth, qBitmap.bmHeight, hLocalDC, 0, 0, SRCCOPY);
    		
    
        SelectObject(hLocalDC, hOldBmp);
    
    	DeleteDC(hLocalDC);
    	DeleteObject(hBitmap);
    }
    void LoadAndBlitDogs(HDC hWinDC){
    	HBITMAP hBitmap;
        BITMAP qBitmap;
        HDC hLocalDC;
        
        hBitmap = (HBITMAP)LoadImage(NULL, TEXT("Batman.bmp"), IMAGE_BITMAP, 0, 0, 
                    LR_CREATEDIBSECTION | LR_DEFAULTSIZE | LR_LOADFROMFILE);
        hLocalDC = CreateCompatibleDC(hWinDC);
    
        GetObject((HGDIOBJ) hBitmap, sizeof(BITMAP), (LPVOID) &qBitmap);
    
        HBITMAP hOldBmp = (HBITMAP) SelectObject(hLocalDC, hBitmap);
    
        for(int i=0;i<Tezavnost*50;i++)
            BitBlt(hWinDC, Dog[i].X, Dog[i].Y, qBitmap.bmWidth, qBitmap.bmHeight, hLocalDC, 0, 0, SRCCOPY);
    	
        SelectObject(hLocalDC, hOldBmp);
    
    	DeleteDC(hLocalDC);
    	DeleteObject(hBitmap);
    }
    
    void InitializeAnimals(HWND hwnd){
    	int i, j, si;
    	Cat.X =2;
    	Cat.Y=2;
    
    	srand(time(NULL));
    
    	for(i=0;i<Tezavnost*5;i++)
    		Mouse[i].status = 'A';
    
    	for(i=0;i<Tezavnost*5;i++){//Misi XY
    	    do{
    		    si=0;
    		    Mouse[i].X = (rand()%40*34)+2;
    		    Mouse[i].Y = (rand()%20*34)+2;
    	        for(j=0;i>j;j++)
    			    if((Mouse[i].Y == Mouse[j].Y && Mouse[i].X == Mouse[i].X) || 
                                    (Mouse[i].Y == Cat.Y && Mouse[i].X == Cat.X))
    				    si=1;
    		}while(si);
    	}
    
    	for(i=0;i<Tezavnost*50;i++){//Psi XY
    	    do{
    		    si=0;
    		    Dog[i].X = (rand()%40*34)+2;
    		    Dog[i].Y = (rand()%20*34)+2;
    			for(j=0;i>j;j++)
    			    if((Dog[i].X == Cat.X && Dog[i].Y == Cat.Y) || (
                                    Dog[i].X == Dog[j].X && Dog[i].Y == Dog[j].Y) || 
                                    (Dog[i].X == Mouse[j].X && Dog[i].Y == Mouse[j].Y))
    				    si=1;
    			if(Dog[i].X == Mouse[j].X && Dog[i].Y == Mouse[j].Y)
    				si=1;
    		}while(si);
    	}
    }
    
    void CheckStatus(HWND hwnd){
    	int i;
        for(i=0;i<Tezavnost*5;i++){
    	    if(Mouse[i].Y == Cat.Y && Mouse[i].X == Cat.X){
    		    Mouse[i].status = 'D';
    			    if(--Misek == 0){
    				    if(MessageBox(hwnd, TEXT("YOU WIN"), TEXT("MessageBox"), MB_YESNO) == IDYES)
    					    SendMessage(hwnd, WM_START, 0, 0);
    					else
    					    SendMessage(hwnd, WM_CLOSE, 0, 0);
    				}
    				i=1000;
    	        }
    	}
    	for(i=0;i<Tezavnost*50;i++){
    	    if(Dog[i].Y == Cat.Y && Dog[i].X == Cat.X){
    			if(MessageBox(hwnd, TEXT("YOU LOST"), TEXT("MessageBox"), MB_YESNO) == IDYES)
    			    SendMessage(hwnd, WM_START, 0, 0);
    		    else
    				SendMessage(hwnd, WM_CLOSE, 0, 0);
    			i=1000;
    			}
    	}
    }
    This is the code the works but if I would put CheckStatus at the end of WM_PAINT it doesn't restart properly.
    Last edited by Sevko; 01-01-2011 at 06:51 AM.

  2. #2
    and the hat of int overfl Salem's Avatar
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    Moved to windows forum.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  3. #3
    Jack of many languages Dino's Avatar
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    I'm pretty sure paint is NOT where you want to check for status changes / actions from the user. Why do you want it to be in the paint code?
    Mac and Windows cross platform programmer. Ruby lover.

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  4. #4
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    Because i you press W+A it sends 2 WM_KEYDOWN messages so first it goes up and the coordinates change by -34 then it goes left and it changes by -34 and if you hit something with the upward movment you loose. But if i were to check this in paint the coordinates are already - - so if nothing is there you don't loose. But for now I just disabled moving vertically.
    Last edited by Sevko; 01-01-2011 at 09:55 AM.

  5. #5
    and the Hat of Guessing tabstop's Avatar
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    Quote Originally Posted by Sevko View Post
    Because i you press W+A it sends 2 WM_KEYDOWN messages so first it goes up and the coordinates change by -34 then it goes left and it changes by -34 and if you hit something with the upward movment you loose. But if i were to check this in paint the coordinates are already - - so if nothing is there you don't loose. But for now I just disabled moving vertically.
    I don't really follow what you're saying here. All paint should do is draw what you want to draw. No checking for win/loss, no actual moving things, just drawing things.

    If what you're saying is "if they press W+A fast enough I want them to move northwest without worrying if they ran into something", then the answer is to make a different key for northwest.

  6. #6
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    Quote Originally Posted by Sevko View Post
    I have homework for school and we were instructed to write a game in plain c with conio2.h for graphical output. But I hvae decided to make it in WinApi.
    I would think your instructor gave you the assignment for a reason... like maybe he wants you to have a given programming experience...

    The game is not going to work proplerly with your status check in WM_PAINT because that's not what the WM_PAINT message is about... it is sent when a portion of a window is changed or occluded and needs to be re-drawn. You need to devise another way to know when your game is over... like sending a "Game Over" message and processing it in your windproc.

  7. #7
    Super Moderator VirtualAce's Avatar
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    As has been said Paint or OnPaint() is the wrong place to change the status of the game. If you follow a simple model-view-controller paradigm you will have a much better chance of success.

    The view or the painting in your case should never change the status of the application. If you are looking to make a game loop in Win32 the best way I know how is to use the WM_IDLE message in your WndProc and then do your updating and rendering/drawing in the block of code that intercepts the message. The view only renders the data it has been given access to. If the view changes you get a different view of the same data. If the data changes you get the same view but with different data.

  8. #8
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    A few observations.....

    Your paint will be very slow, with over 100 BitBlt() calls + LoadImage() + CreateDC() each time the screen is redrawn.
    I would consider double buffering (I have posted plenty of examples) as only the 'cat' moves, the 'mice' and 'dogs' could be drawn once to a mem DC when a game starts and this whole mem DC blitted once as a backgraound (instead of the 110 possible blits) each time the 'cat' moves [2 blits total; background and then cat].

    Your paint should ONLY call one BitBlt() using the PAINTSTRUCT's HDC and RECT. WM_PAINT is often generated outside your app and so should be as quick as possible (and never modify the 'state' as pointed out).

    To call for a quicker paint, use InvalidateRect() followed by an UpdateWindow().
    This bypasses the OS msg queue and posts the paint directly to the callback. [WM_PAINT msgs are also generated outside your app and are the lowest priority in the OS msg queue. Multiple WM_PAINT msgs are concatinated in the msg queue, which may cause issues ie jerky updates, shearing, flicker etc).

    You have a GDI leak in your paint.
    The hLinePen is allocated memory and selected into the DC (the default is in hPenOld).
    A new GDI object is allocated over hLinePen and selected into the DC (probably the original hLinePen is now in hPenOld and the original / default pen is lost).
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