wrlib/scale.c

   1 /* scale.c - image scaling
   2  *
   3  * Raster graphics library
   4  *
   5  * Copyright (c) 1997-2003 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., 51 Franklin St, Fifth Floor, Boston,
  20  *  MA 02110-1301, USA.
  21  */
  22
  23 #include <config.h>
  24
  25 #include <stdlib.h>
  26 #include <stdio.h>
  27 #include <string.h>
  28 #include <X11/Xlib.h>
  29 #include <math.h>
  30
  31 #ifndef PI
  32 #define PI 3.14159265358979323846
  33 #endif
  34
  35 #include <assert.h>
  36
  37 #include "wraster.h"
  38
  39 /*
  40  *----------------------------------------------------------------------
  41  * RScaleImage--
  42  *      Creates a scaled copy of an image.
  43  *
  44  * Returns:
  45  *      The new scaled image.
  46  *
  47  *----------------------------------------------------------------------
  48  */
  49 RImage *RScaleImage(RImage * image, unsigned new_width, unsigned new_height)
  50 {
  51         int ox;
  52         int px, py;
  53         register int x, y, t;
  54         int dx, dy;
  55         unsigned char *s;
  56         unsigned char *d;
  57         RImage *img;
  58
  59         if (new_width == image->width && new_height == image->height)
  60                 return RCloneImage(image);
  61
  62         img = RCreateImage(new_width, new_height, image->format == RRGBAFormat);
  63
  64         if (!img)
  65                 return NULL;
  66
  67         /* fixed point math idea taken from Imlib by
  68          * Carsten Haitzler (Rasterman) */
  69         dx = (image->width << 16) / new_width;
  70         dy = (image->height << 16) / new_height;
  71
  72         py = 0;
  73
  74         d = img->data;
  75
  76         if (image->format == RRGBAFormat) {
  77                 for (y = 0; y < new_height; y++) {
  78                         t = image->width * (py >> 16);
  79
  80                         s = image->data + (t << 2);     /* image->data+t*4 */
  81
  82                         ox = 0;
  83                         px = 0;
  84                         for (x = 0; x < new_width; x++) {
  85                                 px += dx;
  86
  87                                 *(d++) = *(s);
  88                                 *(d++) = *(s + 1);
  89                                 *(d++) = *(s + 2);
  90                                 *(d++) = *(s + 3);
  91
  92                                 t = (px - ox) >> 16;
  93                                 ox += t << 16;
  94
  95                                 s += t << 2;    /* t*4 */
  96                         }
  97                         py += dy;
  98                 }
  99         } else {
 100                 for (y = 0; y < new_height; y++) {
 101                         t = image->width * (py >> 16);
 102
 103                         s = image->data + (t << 1) + t; /* image->data+t*3 */
 104
 105                         ox = 0;
 106                         px = 0;
 107                         for (x = 0; x < new_width; x++) {
 108                                 px += dx;
 109
 110                                 *(d++) = *(s);
 111                                 *(d++) = *(s + 1);
 112                                 *(d++) = *(s + 2);
 113
 114                                 t = (px - ox) >> 16;
 115                                 ox += t << 16;
 116
 117                                 s += (t << 1) + t;      /* t*3 */
 118                         }
 119                         py += dy;
 120                 }
 121         }
 122
 123         return img;
 124 }
 125
 126 /*
 127  * Filtered Image Rescaling code copy/pasted from
 128  * Graphics Gems III
 129  * Public Domain 1991 by Dale Schumacher
 130  */
 131
 132 /*
 133  *      filter function definitions
 134  */
 135 #define box_support             (0.5)
 136
 137 static double box_filter(double t)
 138 {
 139         if ((t > -0.5) && (t <= 0.5))
 140                 return (1.0);
 141         return (0.0);
 142 }
 143
 144 #define triangle_support        (1.0)
 145
 146 static double triangle_filter(double t)
 147 {
 148         if (t < 0.0)
 149                 t = -t;
 150         if (t < 1.0)
 151                 return (1.0 - t);
 152         return (0.0);
 153 }
 154
 155 #define bell_support            (1.5)
 156
 157 static double bell_filter(double t)  /* box (*) box (*) box */
 158 {
 159         if (t < 0)
 160                 t = -t;
 161         if (t < .5)
 162                 return (.75 - (t * t));
 163         if (t < 1.5) {
 164                 t = (t - 1.5);
 165                 return (.5 * (t * t));
 166         }
 167         return (0.0);
 168 }
 169
 170 #define B_spline_support        (2.0)
 171
 172 static double B_spline_filter(double t)   /* box (*) box (*) box (*) box */
 173 {
 174         double tt;
 175
 176         if (t < 0)
 177                 t = -t;
 178         if (t < 1) {
 179                 tt = t * t;
 180                 return ((.5 * tt * t) - tt + (2.0 / 3.0));
 181         } else if (t < 2) {
 182                 t = 2 - t;
 183                 return ((1.0 / 6.0) * (t * t * t));
 184         }
 185         return (0.0);
 186 }
 187
 188 static double sinc(double x)
 189 {
 190         x *= PI;
 191         if (x != 0)
 192                 return (sin(x) / x);
 193         return (1.0);
 194 }
 195
 196 #define Lanczos3_support        (3.0)
 197
 198 static double Lanczos3_filter(double t)
 199 {
 200         if (t < 0)
 201                 t = -t;
 202         if (t < 3.0)
 203                 return (sinc(t) * sinc(t / 3.0));
 204         return (0.0);
 205 }
 206
 207 #define Mitchell_support        (2.0)
 208
 209 #define B       (1.0 / 3.0)
 210 #define C       (1.0 / 3.0)
 211
 212 static double Mitchell_filter(double t)
 213 {
 214         double tt;
 215
 216         tt = t * t;
 217         if (t < 0)
 218                 t = -t;
 219         if (t < 1.0) {
 220                 t = (((12.0 - 9.0 * B - 6.0 * C) * (t * tt))
 221                      + ((-18.0 + 12.0 * B + 6.0 * C) * tt)
 222                      + (6.0 - 2 * B));
 223                 return (t / 6.0);
 224         } else if (t < 2.0) {
 225                 t = (((-1.0 * B - 6.0 * C) * (t * tt))
 226                      + ((6.0 * B + 30.0 * C) * tt)
 227                      + ((-12.0 * B - 48.0 * C) * t)
 228                      + (8.0 * B + 24 * C));
 229                 return (t / 6.0);
 230         }
 231         return (0.0);
 232 }
 233
 234 static double (*filterf)(double) = Mitchell_filter;
 235 static double fwidth = Mitchell_support;
 236
 237 void _wraster_change_filter(int type)
 238 {
 239         switch (type) {
 240         case RBoxFilter:
 241                 filterf = box_filter;
 242                 fwidth = box_support;
 243                 break;
 244         case RTriangleFilter:
 245                 filterf = triangle_filter;
 246                 fwidth = triangle_support;
 247                 break;
 248         case RBellFilter:
 249                 filterf = bell_filter;
 250                 fwidth = bell_support;
 251                 break;
 252         case RBSplineFilter:
 253                 filterf = B_spline_filter;
 254                 fwidth = B_spline_support;
 255                 break;
 256         case RLanczos3Filter:
 257                 filterf = Lanczos3_filter;
 258                 fwidth = Lanczos3_support;
 259                 break;
 260         default:
 261         case RMitchellFilter:
 262                 filterf = Mitchell_filter;
 263                 fwidth = Mitchell_support;
 264                 break;
 265         }
 266 }
 267
 268 /*
 269  *      image rescaling routine
 270  */
 271
 272 typedef struct {
 273         int pixel;
 274         double weight;
 275 } CONTRIB;
 276
 277 typedef struct {
 278         int n;                  /* number of contributors */
 279         CONTRIB *p;             /* pointer to list of contributions */
 280 } CLIST;
 281
 282 /* clamp the input to the specified range */
 283 #define CLAMP(v,l,h)    ((v)<(l) ? (l) : (v) > (h) ? (h) : v)
 284
 285 /* return of calloc is not checked if NULL in the function below! */
 286 RImage *RSmoothScaleImage(RImage * src, unsigned new_width, unsigned new_height)
 287 {
 288         CLIST *contrib;                 /* array of contribution lists */
 289         RImage *tmp;            /* intermediate image */
 290         double xscale, yscale;  /* zoom scale factors */
 291         int i, j, k;            /* loop variables */
 292         int n;                  /* pixel number */
 293         double center, left, right;     /* filter calculation variables */
 294         double width, fscale;   /* filter calculation variables */
 295         double rweight, gweight, bweight;
 296         RImage *dst;
 297         unsigned char *p;
 298         unsigned char *sp;
 299         int sch = src->format == RRGBAFormat ? 4 : 3;
 300
 301         dst = RCreateImage(new_width, new_height, False);
 302
 303         /* create intermediate image to hold horizontal zoom */
 304         tmp = RCreateImage(dst->width, src->height, False);
 305         xscale = (double)new_width / (double)src->width;
 306         yscale = (double)new_height / (double)src->height;
 307
 308         /* pre-calculate filter contributions for a row */
 309         contrib = (CLIST *) calloc(new_width, sizeof(CLIST));
 310         if (xscale < 1.0) {
 311                 width = fwidth / xscale;
 312                 fscale = 1.0 / xscale;
 313                 for (i = 0; i < new_width; ++i) {
 314                         contrib[i].n = 0;
 315                         contrib[i].p = (CONTRIB *) calloc((int) ceil(width * 2 + 1), sizeof(CONTRIB));
 316                         center = (double)i / xscale;
 317                         left = ceil(center - width);
 318                         right = floor(center + width);
 319                         for (j = left; j <= right; ++j) {
 320                                 rweight = center - (double)j;
 321                                 rweight = (*filterf) (rweight / fscale) / fscale;
 322                                 if (j < 0) {
 323                                         n = -j;
 324                                 } else if (j >= src->width) {
 325                                         n = (src->width - j) + src->width - 1;
 326                                 } else {
 327                                         n = j;
 328                                 }
 329                                 k = contrib[i].n++;
 330                                 contrib[i].p[k].pixel = n * sch;
 331                                 contrib[i].p[k].weight = rweight;
 332                         }
 333                 }
 334         } else {
 335
 336                 for (i = 0; i < new_width; ++i) {
 337                         contrib[i].n = 0;
 338                         contrib[i].p = (CONTRIB *) calloc((int) ceil(fwidth * 2 + 1), sizeof(CONTRIB));
 339                         center = (double)i / xscale;
 340                         left = ceil(center - fwidth);
 341                         right = floor(center + fwidth);
 342                         for (j = left; j <= right; ++j) {
 343                                 rweight = center - (double)j;
 344                                 rweight = (*filterf) (rweight);
 345                                 if (j < 0) {
 346                                         n = -j;
 347                                 } else if (j >= src->width) {
 348                                         n = (src->width - j) + src->width - 1;
 349                                 } else {
 350                                         n = j;
 351                                 }
 352                                 k = contrib[i].n++;
 353                                 contrib[i].p[k].pixel = n * sch;
 354                                 contrib[i].p[k].weight = rweight;
 355                         }
 356                 }
 357         }
 358
 359         /* apply filter to zoom horizontally from src to tmp */
 360         p = tmp->data;
 361
 362         for (k = 0; k < tmp->height; ++k) {
 363                 CONTRIB *pp;
 364
 365                 sp = src->data + src->width * k * sch;
 366
 367                 for (i = 0; i < tmp->width; ++i) {
 368                         rweight = gweight = bweight = 0.0;
 369
 370                         pp = contrib[i].p;
 371
 372                         for (j = 0; j < contrib[i].n; ++j) {
 373                                 rweight += sp[pp[j].pixel] * pp[j].weight;
 374                                 gweight += sp[pp[j].pixel + 1] * pp[j].weight;
 375                                 bweight += sp[pp[j].pixel + 2] * pp[j].weight;
 376                         }
 377                         *p++ = CLAMP(rweight, 0, 255);
 378                         *p++ = CLAMP(gweight, 0, 255);
 379                         *p++ = CLAMP(bweight, 0, 255);
 380                 }
 381         }
 382
 383         /* free the memory allocated for horizontal filter weights */
 384         for (i = 0; i < new_width; ++i) {
 385                 free(contrib[i].p);
 386         }
 387         free(contrib);
 388
 389         /* pre-calculate filter contributions for a column */
 390         contrib = (CLIST *) calloc(dst->height, sizeof(CLIST));
 391         if (yscale < 1.0) {
 392                 width = fwidth / yscale;
 393                 fscale = 1.0 / yscale;
 394                 for (i = 0; i < dst->height; ++i) {
 395                         contrib[i].n = 0;
 396                         contrib[i].p = (CONTRIB *) calloc((int) ceil(width * 2 + 1), sizeof(CONTRIB));
 397                         center = (double)i / yscale;
 398                         left = ceil(center - width);
 399                         right = floor(center + width);
 400                         for (j = left; j <= right; ++j) {
 401                                 rweight = center - (double)j;
 402                                 rweight = (*filterf) (rweight / fscale) / fscale;
 403                                 if (j < 0) {
 404                                         n = -j;
 405                                 } else if (j >= tmp->height) {
 406                                         n = (tmp->height - j) + tmp->height - 1;
 407                                 } else {
 408                                         n = j;
 409                                 }
 410                                 k = contrib[i].n++;
 411                                 contrib[i].p[k].pixel = n * 3;
 412                                 contrib[i].p[k].weight = rweight;
 413                         }
 414                 }
 415         } else {
 416                 for (i = 0; i < dst->height; ++i) {
 417                         contrib[i].n = 0;
 418                         contrib[i].p = (CONTRIB *) calloc((int) ceil(fwidth * 2 + 1), sizeof(CONTRIB));
 419                         center = (double)i / yscale;
 420                         left = ceil(center - fwidth);
 421                         right = floor(center + fwidth);
 422                         for (j = left; j <= right; ++j) {
 423                                 rweight = center - (double)j;
 424                                 rweight = (*filterf) (rweight);
 425                                 if (j < 0) {
 426                                         n = -j;
 427                                 } else if (j >= tmp->height) {
 428                                         n = (tmp->height - j) + tmp->height - 1;
 429                                 } else {
 430                                         n = j;
 431                                 }
 432                                 k = contrib[i].n++;
 433                                 contrib[i].p[k].pixel = n * 3;
 434                                 contrib[i].p[k].weight = rweight;
 435                         }
 436                 }
 437         }
 438
 439         /* apply filter to zoom vertically from tmp to dst */
 440         sp = malloc(tmp->height * 3);
 441
 442         for (k = 0; k < new_width; ++k) {
 443                 CONTRIB *pp;
 444
 445                 p = dst->data + k * 3;
 446
 447                 /* copy a column into a row */
 448                 {
 449                         int i;
 450                         unsigned char *p, *d;
 451
 452                         d = sp;
 453                         for (i = tmp->height, p = tmp->data + k * 3; i-- > 0; p += tmp->width * 3) {
 454                                 *d++ = *p;
 455                                 *d++ = *(p + 1);
 456                                 *d++ = *(p + 2);
 457                         }
 458                 }
 459                 for (i = 0; i < new_height; ++i) {
 460                         rweight = gweight = bweight = 0.0;
 461
 462                         pp = contrib[i].p;
 463
 464                         for (j = 0; j < contrib[i].n; ++j) {
 465                                 rweight += sp[pp[j].pixel] * pp[j].weight;
 466                                 gweight += sp[pp[j].pixel + 1] * pp[j].weight;
 467                                 bweight += sp[pp[j].pixel + 2] * pp[j].weight;
 468                         }
 469                         *p = CLAMP(rweight, 0, 255);
 470                         *(p + 1) = CLAMP(gweight, 0, 255);
 471                         *(p + 2) = CLAMP(bweight, 0, 255);
 472                         p += new_width * 3;
 473                 }
 474         }
 475         free(sp);
 476
 477         /* free the memory allocated for vertical filter weights */
 478         for (i = 0; i < dst->height; ++i) {
 479                 free(contrib[i].p);
 480         }
 481         free(contrib);
 482
 483         RReleaseImage(tmp);
 484
 485         return dst;
 486 }