[Worldforge-all-lists] Re: [WF-Cpptraining] SDL: Previous assignment?

[Gabriel C. <gab...@da...>]

On Sun, 1 Apr 2001, Wuzzeb wrote:

> Anyone completed the assignment?  It was moving a
> picture around the screen.  If no one posts a
> solution, I will post one in a couple of days.
> 
> Wuzzeb

Yeah, I have, here goes:
( This expects a file named sdl.bmp to live in the directory you run
it from. )

------ cut here ------

#include <stdio.h>
#include <stdlib.h>

#include "SDL.h"

#define MSTEP        4
#define FILETOOPEN   "sdl.bmp"


struct Ipos_t {
    SDL_Rect pos; 
    SDL_Surface *bitmap;
    };

int main( void ) {
    SDL_Surface *window = NULL;
    int win_w, win_h;
    struct Ipos_t image;
    Uint32 cBlack;
    bool done = false;
    int updown = 0;
    
    SDL_Surface *buffer;

    SDL_Event event;

        if( SDL_Init( SDL_INIT_VIDEO ) < 0 ) {
            fprintf(stderr, "Unable to init SDL: %s\n", 
            SDL_GetError() );
            exit(1);
            }

    window = SDL_SetVideoMode( 640, 480, 16, SDL_SWSURFACE  );

    if( !window ) {
        fprintf(stderr,"Unable to open a surface. Bye.\n");
        exit(1);
        }
    
    buffer = SDL_CreateRGBSurface( SDL_SWSURFACE, 640, 480, 16, 0, 0, 0, 0);
    if( !buffer ) {
        fprintf( stderr, "Unable to create double buffer.  Bye.\n");
        exit(1);
        }

    image.bitmap = SDL_LoadBMP( FILETOOPEN );
    if( ! image.bitmap ) {
        fprintf(stderr, "Unable to load sdl.bmp.  Bye bye.\n");
        exit(1);
        }

    image.pos.w = image.bitmap->w;
    image.pos.h = image.bitmap->h;
    image.pos.x = image.pos.y = 0;

    win_w = window->w;
    win_h = window->h;

    cBlack = SDL_MapRGB( window->format, 0, 0, 0 );

    fprintf(stderr, "Controls:  Left arrow moves it left, "
	"moves it right.  Up = up, down = down.  Q = quit.\n");

    while( !done ) {
        // do Event Polling
        while( SDL_PollEvent( &event )) {
            switch( event.type ) {
                case SDL_KEYDOWN: updown=1;
                case SDL_KEYUP: {

                    switch( event.key.keysym.sym ) {
                        case SDLK_q: 
                            done = true;
                            break;
                        case SDLK_UP:
                            if( updown ) { 
                                if( image.pos.y > 0+MSTEP  )
                                    image.pos.y -= MSTEP;
                                }
                            break;
                        case SDLK_DOWN:
                            if( updown ) {
                                if( image.pos.y < (win_h - image.pos.h -MSTEP)) 
                                    image.pos.y += MSTEP;
                                }
                            break;

                        case SDLK_LEFT:
                            if( updown ) {
                                if( image.pos.x > 0+MSTEP )
                                    image.pos.x -=MSTEP;
                                }
                            break;

                        case SDLK_RIGHT:
                            if( updown ) {
                                if( image.pos.x < (win_w - image.pos.w -MSTEP))
                                    image.pos.x += MSTEP;
                                }
                            break;

                        default:
                            // printf("Key was %d\n", 
                            //    event.key.keysym.sym );
                            break;    
                        }

                    } updown = 0; break;
                case SDL_QUIT:
                    done = true;
                    break;
                }
            }

        SDL_FillRect( buffer, NULL, cBlack );
        SDL_BlitSurface( image.bitmap, 0, buffer, &image.pos );

        SDL_UpdateRect( buffer, 0, 0, 0, 0 );

        SDL_BlitSurface( buffer, 0, window, 0 );

        SDL_UpdateRect( window, 0, 0, 0, 0 );
        }

    SDL_FreeSurface( image.bitmap );
    return 0;
    }




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