Thread: GDI sprite (Win32 API)

Please help... how can I make sprite (simple picture moving when pressed arrows)

I thought something like this:
when arrow pressed, then
1) delete previous picture from screen
2) calculate new coordinates
3) show picture using BitBlt()

I have done step 2 and step 3 (it works), put how can I do step 1 -> "delete" previous picture from screen? Or is there any better way making sprite?

I have tried to delete previous picture using rectangle ->
FillRect(..., ..., GetStockObject(WHITE_BRUSH)); but thats no solution what if the background is a image?... and using this the picture starts to blink.

Here's my code and I' am using DevC++ compilator:

Code:

#include <string>
#include <iostream>
#include <sstream>
#include <math.h>
#include <windows.h>
#define KEYSTATE(vknum) ((GetAsyncKeyState(vknum) & 0x8000) ? TRUE : FALSE)
using namespace std;

HINSTANCE hInst;
LRESULT CALLBACK WindProcedure(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam);

double x = 50;
double y = 50;
double speed = 0.05;

int max_x = 400;
int max_y = 200;
int min_x = 0;
int min_y = 0;


HWND hWnd;
HDC hDC, MemDCExercising;
HANDLE bmpExercising;  
    

INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX  WndCls;
    static char szAppName[] = "BitmapIntro";
    MSG         Msg;
    
	hInst       = hInstance;
    WndCls.cbSize        = sizeof(WndCls);
    WndCls.style         = CS_OWNDC | CS_VREDRAW | CS_HREDRAW;
    WndCls.lpfnWndProc   = WindProcedure;
    WndCls.cbClsExtra    = 0;
    WndCls.cbWndExtra    = 0;
    WndCls.hInstance     = hInst;
    WndCls.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    WndCls.hCursor       = LoadCursor(NULL, IDC_ARROW);
    WndCls.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    WndCls.lpszMenuName  = NULL;
    WndCls.lpszClassName = szAppName;
    WndCls.hIconSm       = LoadIcon(hInstance, IDI_APPLICATION);
    RegisterClassEx(&WndCls);

    hWnd = CreateWindowEx(WS_EX_OVERLAPPEDWINDOW,
                          szAppName,
                          "Sprite",
                          WS_OVERLAPPEDWINDOW | WS_VISIBLE,
                          CW_USEDEFAULT,
                          CW_USEDEFAULT,
                          CW_USEDEFAULT,
                          CW_USEDEFAULT,
                          NULL,
                          NULL,
                          hInstance,
                          NULL);

 
                  
        hDC = GetDC(hWnd);
           
	    bmpExercising = LoadImage(hInst, "C:\\mypic.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
	    // Create a memory device compatible with the above DC variable
	    MemDCExercising = CreateCompatibleDC(hDC);
             // Select the new bitmap
     SelectObject(MemDCExercising, bmpExercising);


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

    return static_cast<int>(Msg.wParam);
}


void point (HWND hWnd)
{
            
           int xC =  (int) round(x);
           int yC =  (int) round(y);           
           
           if(xC>max_x){ xC=max_x; x=max_x; }
           if(yC>max_y){ yC=max_y; y=max_y; }
           if(xC<min_x){ xC=min_x; x=min_x; }
           if(yC<min_y){ yC=min_y; y=min_y; }

	     
//////////////////////////////////////////////////////////////////////////
/* THIS IS THE PLACE WHERE DELETE PREVOIUS IMAGE */
////////////////////////////////////////////////////////////////////////



	    BitBlt(hDC, xC, yC, 400, 400, MemDCExercising, 0, 0, SRCCOPY);
	      
	      
	    CancelDC(hDC);
        ReleaseDC(hWnd, hDC);
           
}

LRESULT CALLBACK WindProcedure(HWND hWnd, UINT Msg,
			   WPARAM wParam, LPARAM lParam)
{

        if(KEYSTATE(VK_UP)){  y-=speed;  point(hWnd); }
        if(KEYSTATE(VK_DOWN)){  y+=speed;  point(hWnd); }
        if(KEYSTATE(VK_LEFT)){  x-=speed;  point(hWnd); }
        if(KEYSTATE(VK_RIGHT)){  x+=speed;  point(hWnd); }

        
    switch(Msg)
    {
                       
        
	case WM_DESTROY:
	    PostQuitMessage(WM_QUIT);
	    break;
	    case WM_PAINT:

	    break;

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

Thank you!

thank you for a reply.

Originally Posted by Stan100

Redraw the background picture?

Draw the background picture again (it will draw over the old picture), then draw your new image.

that's it... but if there is another moving picture then redrawing the background will delete it (I guess, I just have to redraw another picture also)
Is this a normal technlogy to show a simple animation in window. Is there an another(better) way to get the old picture deleted (after using BitBlt())?

Originally Posted by Stan100

You'll also want to look up buffering to help stop the flicker. You draw the scene on an unseen screen, and then replace the old screen with the new re-drawn screen.

How? Little example, please

Originally Posted by Stan100

Erm, if you find yourself getting deep into animation win win32 GUI, you may want to start looking at OpenGL or DirectX. They're MUCH faster than the win32 GUI

Not yet... but soon.

Originally Posted by Stan100

*Edit*
BTW, it's not a "compilator", it's called a "compiler"

and I wondered why this word (compilator) looks so strange

Originally Posted by Stan100

*Edit Again*
You have an odd way of checking the keystate, why don't you put it inside your message handler's switch statement?

WM_KEYPRESS message?


Actually I am very grateful, if someone can give me a working code (or link) for something similary... I have searched so many days from Google and MSDN. Best way to learn is to examine working code.