wrlib/rotate.c

   1 /* rotate.c - image rotation
   2  *
   3  * Raster graphics library
   4  *
   5  * Copyright (c) 2000-2003 Alfredo K. Kojima
   6  *
   7  *  This library is free software; you can redistribute it and/or
   8  *  modify it under the terms of the GNU Library General Public
   9  *  License as published by the Free Software Foundation; either
  10  *  version 2 of the License, or (at your option) any later version.
  11  *
  12  *  This library is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  *  Library General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU Library General Public
  18  *  License along with this library; if not, write to the Free
  19  *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #include <config.h>
  23
  24 #include <stdlib.h>
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <X11/Xlib.h>
  28 #include "wraster.h"
  29
  30 #include <math.h>
  31
  32 #ifndef PI
  33 #define PI 3.14159265358979323846
  34 #endif
  35
  36
  37 static RImage *rotateImage(RImage *image, float angle);
  38
  39
  40 RImage*
  41 RRotateImage(RImage *image, float angle)
  42 {
  43     RImage *img;
  44     int nwidth, nheight;
  45     int x, y;
  46     int bpp = image->format == RRGBAFormat ? 4 : 3;
  47
  48     angle = ((int)angle % 360) + (angle - (int)angle);
  49
  50     if (angle == 0.0) {
  51         return RCloneImage(image);
  52
  53     } else if (angle == 90.0) {
  54         nwidth = image->height;
  55         nheight = image->width;
  56
  57         img = RCreateImage(nwidth, nheight, True);
  58         if (!img) {
  59             return NULL;
  60         }
  61
  62         if (bpp == 3) {
  63             unsigned char *optr, *nptr;
  64             unsigned offs;
  65
  66
  67             offs = nwidth * 4;
  68
  69             optr = image->data;
  70             nptr = img->data;
  71
  72             for (x = 0; x < nwidth; x++) {
  73                 nptr = img->data + x*4;
  74                 for (y = nheight; y; y--) {
  75                     nptr[0] = *optr++;
  76                     nptr[1] = *optr++;
  77                     nptr[2] = *optr++;
  78                     nptr[3] = 255;
  79
  80                     nptr += offs;
  81                 }
  82             }
  83         } else {
  84             unsigned *optr, *nptr;
  85             unsigned *p;
  86
  87             optr = (unsigned*)image->data;
  88             p = (unsigned*)img->data;
  89             for (x = 0; x < nwidth; x++) {
  90                 nptr = p++;
  91                 for (y = nheight; y; y--) {
  92                     *nptr = *optr++;
  93                     nptr += nwidth;
  94                 }
  95             }
  96         }
  97     } else if (angle == 180.0) {
  98
  99         nwidth = image->width;
 100         nheight = image->height;
 101         img = RCreateImage(nwidth, nheight, True);
 102         if (!img) {
 103             return NULL;
 104         }
 105
 106         if (bpp == 3) {
 107             unsigned char *optr, *nptr;
 108
 109             optr = image->data;
 110             nptr = img->data + nwidth * nheight * 4 - 4;
 111
 112             for (y = 0; y < nheight; y++) {
 113                 for (x = 0; x < nwidth; x++) {
 114                     nptr[0] = optr[0];
 115                     nptr[1] = optr[1];
 116                     nptr[2] = optr[2];
 117                     nptr[3] = 255;
 118
 119                     optr += 3;
 120                     nptr -= 4;
 121                 }
 122             }
 123         } else {
 124             unsigned *optr, *nptr;
 125
 126             optr = (unsigned*)image->data;
 127             nptr = (unsigned*)img->data + nwidth * nheight - 1;
 128
 129             for (y = nheight*nwidth-1; y >= 0; y--) {
 130                 *nptr = *optr;
 131                 optr++;
 132                 nptr--;
 133             }
 134         }
 135     } else if (angle == 270.0) {
 136         nwidth = image->height;
 137         nheight = image->width;
 138
 139         img = RCreateImage(nwidth, nheight, True);
 140         if (!img) {
 141             return NULL;
 142         }
 143
 144         if (bpp == 3) {
 145             unsigned char *optr, *nptr;
 146             unsigned offs;
 147
 148
 149             offs = nwidth * 4;
 150
 151             optr = image->data;
 152             nptr = img->data;
 153
 154             for (x = 0; x < nwidth; x++) {
 155                 nptr = img->data + x*4;
 156                 for (y = nheight; y; y--) {
 157                     nptr[0] = *optr++;
 158                     nptr[1] = *optr++;
 159                     nptr[2] = *optr++;
 160                     nptr[3] = 255;
 161
 162                     nptr += offs;
 163                 }
 164             }
 165         } else {
 166             unsigned *optr, *nptr;
 167             unsigned *p;
 168
 169             optr = (unsigned*)image->data;
 170             p = (unsigned*)img->data + nwidth*nheight;
 171             for (x = 0; x < nwidth; x++) {
 172                 nptr = p--;
 173                 for (y = nheight; y; y--) {
 174                     *nptr = *optr++;
 175                     nptr -= nwidth;
 176                 }
 177             }
 178         }
 179     } else {
 180         img = rotateImage(image, angle);
 181     }
 182
 183     return img;
 184 }
 185
 186
 187
 188
 189 /*
 190  * Image rotation through Bresenham's line algorithm:
 191  *
 192  * If a square must be rotate by angle a, like in:
 193  *  _______
 194  * |    B  |
 195  * |   /4\ |
 196  * |  /3 8\|
 197  * | /2 7 /|
 198  * |A1 6 / |      A_______B
 199  * | \5 / a| <--- |1 2 3 4|
 200  * |__C/_)_|      |5 6 7 8|
 201  *                C-------
 202  *
 203  * for each point P1 in the line from C to A
 204  *      for each point P2 in the perpendicular line starting at P1
 205  *              get pixel from the source and plot at P2
 206  *              increment pixel location from source
 207  *
 208  */
 209
 210
 211 static void
 212 copyLine(int x1, int y1, int x2, int y2, int nwidth, int format,
 213          unsigned char *dst, unsigned char **src)
 214 {
 215     unsigned char *s = *src;
 216     int dx, dy;
 217     int xi, yi;
 218     int offset;
 219     int dpr, dpru, p;
 220
 221     dx = abs(x2 - x1);
 222     dy = abs(y2 - y1);
 223
 224     if (x1 > x2) xi = -1; else xi = 1;
 225     if (y1 > y2) yi = -1; else yi = 1;
 226
 227     if (dx >= dy) {
 228
 229         dpr = dy << 1;
 230         dpru = dpr - (dx << 1);
 231         p = dpr - dx;
 232
 233         while (dx-- >= 0) {
 234             /* fetch and draw the pixel */
 235             offset = (x1 + y1 * nwidth) << 2;
 236             dst[offset++] = *s++;
 237             dst[offset++] = *s++;
 238             dst[offset++] = *s++;
 239             if (format == RRGBAFormat)
 240                 dst[offset++] = *s++;
 241             else
 242                 dst[offset++] = 255;
 243
 244             /* calc next step */
 245             if (p > 0) {
 246                 x1 += xi;
 247                 y1 += yi;
 248                 p += dpru;
 249             } else {
 250                 x1 += xi;
 251                 p += dpr;
 252             }
 253         }
 254     } else {
 255
 256         dpr = dx << 1;
 257         dpru = dpr - (dy << 1);
 258         p = dpr - dy;
 259
 260         while (dy-- >= 0) {
 261             /* fetch and draw the pixel */
 262             offset = (x1 + y1 * nwidth) << 2;
 263             dst[offset++] = *s++;
 264             dst[offset++] = *s++;
 265             dst[offset++] = *s++;
 266             if (format == RRGBAFormat)
 267                 dst[offset++] = *s++;
 268             else
 269                 dst[offset++] = 255;
 270
 271             /* calc next step */
 272             if (p > 0) {
 273                 x1 += xi;
 274                 y1 += yi;
 275                 p += dpru;
 276             } else {
 277                 y1 += yi;
 278                 p += dpr;
 279             }
 280         }
 281     }
 282
 283
 284     *src = s;
 285 }
 286
 287
 288 static RImage*
 289 rotateImage(RImage *image, float angle)
 290 {
 291     RImage *img;
 292     int nwidth, nheight;
 293     int x1, y1;
 294     int x2, y2;
 295     int dx, dy;
 296     int xi, yi;
 297     int xx, yy;
 298     unsigned char *src, *dst;
 299     int dpr, dpru, p;
 300
 301     /* only 180o for now */
 302     if (angle > 180.0)
 303         angle -= 180.0;
 304
 305
 306     angle = (angle * PI) / 180.0;
 307
 308     nwidth = ceil(abs(cos(angle) * image->width))
 309         + ceil(abs(cos(PI/2 - angle) * image->width));
 310
 311     nheight = ceil(abs(sin(angle) * image->height))
 312         + ceil(abs(cos(PI/2 - angle) * image->height));
 313
 314     img = RCreateImage(nwidth, nheight, True);
 315     if (!img)
 316         return NULL;
 317
 318     src = image->data;
 319     dst = img->data;
 320
 321     x1 = floor(abs(cos(PI/2 - angle)*image->width));
 322     y1 = 0;
 323
 324     x2 = 0;
 325     y2 = floor(abs(sin(PI/2 - angle)*image->width));
 326
 327     xx = floor(abs(cos(angle)*image->height)) - 1;
 328     yy = nheight - 1;
 329
 330     printf("%ix%i, %i %i     %i %i %i\n",
 331            nwidth, nheight, x1, y1, x2, y2, (int)((angle*180.0)/PI));
 332
 333     dx = abs(x2 - x1);
 334     dy = abs(y2 - y1);
 335
 336     if (x1 > x2) xi = -1; else xi = 1;
 337     if (y1 > y2) yi = -1; else yi = 1;
 338
 339     if (dx >= dy) {
 340         dpr = dy << 1;
 341         dpru = dpr - (dx << 1);
 342         p = dpr - dx;
 343
 344         while (dx-- >= 0) {
 345
 346             copyLine(x1, y1, xx, yy, nwidth, image->format, dst, &src);
 347
 348             /* calc next step */
 349
 350             if (p > 0) {
 351                 x1 += xi;
 352                 y1 += yi;
 353                 xx += xi;
 354                 yy += yi;
 355                 p += dpru;
 356             } else {
 357                 x1 += xi;
 358                 xx += xi;
 359                 p += dpr;
 360             }
 361         }
 362     } else {
 363         puts("NOT IMPLEMTENED");
 364         return img;
 365         dpr = dx << 1;
 366         dpru = dpr - (dy << 1);
 367         p = dpr - dy;
 368
 369         while (dy-- >= 0) {
 370             xx = abs(x1*sin(angle*PI/180.0));
 371             yy = abs(y1*cos(angle*PI/180.0));
 372
 373             copyLine(x1, y1, xx, yy, nwidth, image->format, dst, &src);
 374
 375             /* calc next step*/
 376             if (p > 0) {
 377                 x1 += xi;
 378                 y1 += yi;
 379                 p += dpru;
 380             } else {
 381                 y1 += yi;
 382                 p += dpr;
 383             }
 384         }
 385     }
 386
 387     return img;
 388 }
 389