SdlSandbox/sdl1/mirrorImage/retourner.cpp

#include "retourner.h"

SDL_Surface* retournement(SDL_Surface* originale, int nbQuarts)
{
    //Création de la seconde surface
    SDL_Surface* pivot(0);
    if (nbQuarts%2)
        pivot=SDL_CreateRGBSurface(SDL_HWSURFACE,originale->h,originale->w,32,0,0,0,0);
    else
        pivot=SDL_CreateRGBSurface(SDL_HWSURFACE,originale->w,originale->h,32,0,0,0,0);

    //Photocopie quart de tour
    SDL_Rect fromPos={0,0,1,1};
    SDL_Rect toPos={0,0,0,0};
    for (fromPos.x = 0; fromPos.x < originale->w; fromPos.x++)
        for (fromPos.y = 0; fromPos.y < originale->h; fromPos.y++)
        {
            if (nbQuarts%4 == 0)
            {
                toPos.x=fromPos.x;
                toPos.y=fromPos.y;
            }
            if (nbQuarts%4 == 1)
            {
                toPos.x=originale->h-fromPos.y;
                toPos.y=fromPos.x;
            }
            if (nbQuarts%4 == 2)
            {
                toPos.x=originale->w-fromPos.x;
                toPos.y=originale->h-fromPos.y;
            }
            if (nbQuarts%4 == 3)
            {
                toPos.x=fromPos.y;
                toPos.y=originale->w-fromPos.x;
            }
            SDL_BlitSurface(originale,&fromPos,pivot,&toPos);
        }

    return pivot;
}