#include #include #include #include #include #include #include #include "read_png.h" #include "bez.h" char **row_ptr; SDL_Surface *png_data=0; /* alpha blend routine */ unsigned int AlphaBlend(const unsigned int bg, const unsigned int src) { unsigned int a = src >> 24; /* alpha */ /* If source pixel is transparent, just return the background */ if (0 == a) return bg; /* alpha blending the source and background colors */ unsigned int rb = (((src & 0x00ff00ff) * a) + ((bg & 0x00ff00ff) * (0xff - a))) & 0xff00ff00; unsigned int g = (((src & 0x0000ff00) * a) + ((bg & 0x0000ff00) * (0xff - a))) & 0x00ff0000; return (src & 0xff000000) | ((rb | g) >> 8); } void putpixel(SDL_Surface *surface, int x, int y, Uint32 pixel) { if ( x<0 || y<0 ) return ; int bpp = surface->format->BytesPerPixel; /* Here p is the address to the pixel we want to set */ Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp; //if (*((Uint32*) p)) //printf("%x %x\n", *((Uint32*) p), pixel ); pixel = AlphaBlend ( *((Uint32*) p), pixel ); switch(bpp) { case 1: *p = pixel; break; case 2: *(Uint16 *)p = pixel; break; case 3: if(SDL_BYTEORDER == SDL_BIG_ENDIAN) { p[0] = (pixel >> 16) & 0xff; p[1] = (pixel >> 8) & 0xff; p[2] = pixel & 0xff; } else { p[0] = pixel & 0xff; p[1] = (pixel >> 8) & 0xff; p[2] = (pixel >> 16) & 0xff; } break; case 4: *(Uint32 *)p = pixel; break; } } void anti_alias ( int direction, float p1, float p2, SDL_Surface *s ) { float frac; int shift; frac = p1 - floorf(p1); if (frac > 0.5) shift=1; else shift=-1; frac = fabsf(0.5-frac); if (!direction) { putpixel ( s, p2, p1, (int) ((1-frac)*255) << 24 | 0xffff00 ); putpixel ( s, p2, p1+shift, (int) (frac*255) << 24 | 0xffff00 ); } else { putpixel ( s, p1, p2, (int) ((1-frac)*255) << 24 | 0xffdd22 ); putpixel ( s, p1+shift, p2, (int) (frac*255) << 24 | 0xffdd22 ); } } void draw_line ( float x1, float y1, float x2, float y2, SDL_Surface *s) { static SDL_Surface* surface; surface = s?s:surface; // default to last non-null surface if (!surface) { printf("Error no surface to draw to\n"); exit ( 99 ); } if ( x1<0 || y1<0 || x2<0 || y2<0 || x1>=640 || x2 >= 640 || y1 >= 480 || y2 >= 480 ) { printf("Error, attempted to draw off screen.\n"); return ; } float sx, sy; sx = x2 - x1; sy = y2 - y1; // printf ("p1 %d,%d p2 %d,%d s1 %d,%d a %d\n",x1,y1, x2,y2, sx,sy, abs(sx)); // // XXX: For partial pixels we need to add transparency proportional to where // the line was started. if (fabsf(sx) > fabsf(sy)) for (float f=0; f <= fabsf (sx) ; f++) anti_alias ( 0, y1+f/fabsf(sx)*sy, x1+(sx/fabsf(sx)*f), surface ); else for (float f=0; f <= fabsf (sy) ; f++) anti_alias ( 1, x1+f/fabsf(sy)*sx, y1+(sy/fabsf(sy)*f), surface ); } int do_sdl () { int done=0, draw=0, i,j; SDL_Surface *screen; SDL_Event s_event; if ( (screen=SDL_SetVideoMode(640,480,0,SDL_HWSURFACE|SDL_NOFRAME|SDL_ASYNCBLIT)) == NULL ) { fprintf(stderr, "Failed to set video mode: %s\n", SDL_GetError()); return(2); } if (png_data) { SDL_BlitSurface( png_data, NULL ,screen, NULL); SDL_UpdateRect(screen, 0, 0, 0, 0); } SDL_LockSurface(screen); draw_line ( 10, 10, 400, 100, screen ); /*draw_line ( 10, 10, 100, 400, screen ); draw_line ( 100, 400, 500, 475, screen ); draw_line ( 500, 475, 400, 100, screen ); draw_line ( 100, 400, 400, 100, screen ); draw_line ( 500, 475, 10, 10, screen ); draw_line ( 10, 10, 475, 10, screen ); draw_line ( 475, 10, 475, 475, screen ); draw_line ( 475, 475, 10, 475, screen ); draw_line ( 10, 475, 10, 10, screen ); draw_line ( 10, 10, 475, 475, screen ); draw_line ( 10, 475, 475, 10, screen ); */ point p[15]; p[0].x = 50; p[0].y = 50; p[1].x = 150; p[1].y = 200; p[2].x = 400; p[2].y = 300; p[3].x = 600; p[3].y = 50; p[4].x = 625; p[4].y = 450; p[5].x = 600; p[5].y = 400; draw_envelope ( (point*) &p,5, (void*) draw_line ); draw_bez ( (point*) &p , 5, 6, (void*) draw_line ); p[0].x = 600; p[0].y = 400; p[1].x = 20; p[1].y = 20; p[2].x = 11; p[2].y = 469; p[3].x = 420; p[3].y = 400; p[4].x = 300; p[4].y = 100; p[5].x = 50; p[5].y = 50; draw_envelope ( (point*) &p,5, (void*) draw_line ); draw_bez ( (point*) &p , 5, 6, (void*) draw_line ); /* for (float t=0; t < 2*3.1415; t = t+3.1415926535897932385/64) draw_line ( 225, 475, 200+200*sinf(t), 200+200*cosf(t), screen); for (float t=0; t < 2*3.1415; t = t+3.1415926535897932385/64) draw_line ( 25, 450, 200+200*sinf(t), 200+200*cosf(t), screen); */ SDL_UnlockSurface(screen); SDL_UpdateRect(screen, 0, 0, 0, 0); while ( !done && SDL_WaitEvent(&s_event) ) switch (s_event.type) { case SDL_MOUSEBUTTONDOWN: draw=1; case SDL_MOUSEMOTION: if ( draw ) { SDL_LockSurface(screen); putpixel( screen, s_event.button.x, s_event.button.y, 0x1fffff00 ); SDL_UnlockSurface(screen); SDL_UpdateRect(screen, s_event.button.x, s_event.button.y, 1, 1); } break; case SDL_MOUSEBUTTONUP: draw=0; break; case SDL_KEYDOWN: { done=1; } } } int read_png (char* file_name) { FILE* png_file; char png_header[8]; printf("Using PNG %s\n", PNG_LIBPNG_VER_STRING); png_file = fopen(file_name, "r"); if (!png_file) { printf("Error opening file\n"); return 0; } fread(&png_header, 1, 8, png_file); if (png_sig_cmp(png_header, 0, 8)) { printf("Error reading PNG\n"); return 0; } png_structp png_ptr = png_create_read_struct ( PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); png_infop info_ptr= png_create_info_struct (png_ptr); if (!png_ptr || !info_ptr) { printf("PNG ERROR"); return 0; } png_set_sig_bytes(png_ptr, 8); png_init_io(png_ptr, png_file); png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL); row_ptr = (char**) png_get_rows(png_ptr, info_ptr); //printf(" W=%4d H=%4d\n", info_ptr->width, info_ptr->height ); png_data=SDL_CreateRGBSurface(SDL_SWSURFACE,info_ptr->width, info_ptr->height,24,0xff,0xff00,0xff0000,0); for (int i=0; i < info_ptr->height; i++) memcpy ( png_data->pixels + png_data->pitch*i, row_ptr[i], info_ptr->width*3 ); png_destroy_read_struct(&png_ptr, &info_ptr, NULL); }