SDL project leaves trail

I have a sdl project. It is very fun. It doesn't work. The picture leaves a trail. Here is my Main(). I am leaving out the function prototypes to conserve space.

Code:

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int main(int argc, char * argv[]) {
       
char keyCode;
        Uint8 *keys;
        keys = SDL_GetKeyState(NULL);
        if(SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO) < 0) {
                printf("Cannot initialize Audio and/or Video%\n", SDL_GetError());
                exit(1);
        }
        atexit(SDL_Quit);
        screen = SDL_SetVideoMode(640, 480, 32, SDL_DOUBLEBUF|SDL_HWSURFACE); //HWwhat?
        if(screen == NULL) {
                printf("Unable to set 640 by 480 resolution%\n", SDL_GetError());
                exit(1);
        }

        InitImages();
        DrawBG();

        bool done = false;
        int xslope = 2;
        int yslope = 2;

        int speed = 1;
        while(done == false)
        {{{{{
               
                if( kbhit() ) {
                        keyCode = getch();
                        if(keyCode = 27)
                                exit(1);
                }
                //90 degree counter clockwise: (x,y) -> (-y, x)
                //90 degree clockwise: (x, y) -> (y, -x)
               
                int xopp = xslope * 2;
                int yopp = yslope * 2;

                //for vertical movement need to turn yslope into opposite reciprocal
                //(speed % 5 == 0)? (xpos = (xslope += (speed / 5))): xpos + xslope;
                //(speed % 5 == 0)? (ypos = (yslope += (speed / 5))): ypos + yslope;
                //xpos += (speed % 5 == 0)? (xslope + (speed / 5)) : xslope;
                //ypos += (speed % 5 == 0)? (yslope + (speed / 5)) : yslope;
       
                ypos += yslope;
                xpos +=xslope;
               
                if(ypos < 0) {
                        ypos = 0;
                        yslope = ( yslope - yopp );
                        yslope < 0? yslope-- : yslope++;
                }
       
                if(ypos >= (480 - 66)) {
                        ypos = (480 - 66);
                        yslope = ( yslope - yopp );
                        yslope < 0? xslope-- : xslope++;
                }

                if(xpos < 0) {
                        xpos = 0;
                        xslope = ( xslope - xopp );
                        xslope < 0? xslope-- : xslope++;
                       
                }

                if(xpos >= 581) {
                        xpos = 581;
                        xslope = (xslope - xopp );
                        xslope < 0? xslope-- : xslope++;                       
                       
                }
               

                DrawScene();

        }}}}}

                return 0;
}

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seriously though, if you can see anything wrong PLEASE tell me.
I will be greatly indebted

You are way more advanced than me but no one will be able to completely help you if you do not include the whole source.

anyone who knows SDL only needs to see this source.

SDL != Easy for me...

I dont understand it...
But im sure Prelude or Bubba would help...

I'd need to see your DrawScene() code but my guess is that you're not clearing the screen each frame.

- SDL_HWSURFACE tells SDL to create the surface in video memory rather than system memory.

Code:

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void DrawScene() {
        Slock(screen);
        DrawIMG(background, xpos - 2, ypos - 2, 63, 70, xpos - 2, ypos - 2);
        DrawIMG(ball, xpos, ypos);
        SDL_Flip(screen); //switches the buffer
        Sulock(screen);
}

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Now I thought the SDL_Flip function refreshed the screen so that this wouldn't happen.

Now I think I should clear something up. When the ball is moving at a constant speed it doesn't leave the trail. But I want it so that whenever it hits the out boundries it speeds up. This i what is causing the trail.