src/glpng.c

   1 /*
   2  * PNG loader library for OpenGL v1.45 (10/07/00)
   3  * by Ben Wyatt ben@wyatt100.freeserve.co.uk
   4  * Using LibPNG 1.0.2 and ZLib 1.1.3
   5  *
   6  * This software is provided 'as-is', without any express or implied warranty.
   7  * In no event will the author be held liable for any damages arising from the
   8  * use of this software.
   9  *
  10  * Permission is hereby granted to use, copy, modify, and distribute this
  11  * source code, or portions hereof, for any purpose, without fee, subject to
  12  * the following restrictions:
  13  *
  14  * 1. The origin of this source code must not be misrepresented. You must not
  15  *    claim that you wrote the original software. If you use this software in
  16  *    a product, an acknowledgment in the product documentation would be
  17  *    appreciated but is not required.
  18  * 2. Altered versions must be plainly marked as such and must not be
  19  *    misrepresented as being the original source.
  20  * 3. This notice must not be removed or altered from any source distribution.
  21  */
  22
  23 #ifdef _WIN32 /* Stupid Windows needs to include windows.h before gl.h */
  24         #undef FAR
  25         #include <windows.h>
  26 #endif
  27
  28 #define GL_GLEXT_PROTOTYPES
  29
  30 #include <GL/glpng.h>
  31 #include <GL/gl.h>
  32 #include <GL/glext.h>
  33 #include <stdlib.h>
  34 #include <stdint.h>
  35 #include <string.h>
  36 #include <math.h>
  37 #include <png.h>
  38
  39 /* Used to decide if GL/gl.h supports the paletted extension */
  40 #ifdef GL_COLOR_INDEX1_EXT
  41 #define SUPPORTS_PALETTE_EXT
  42 #endif
  43
  44 static unsigned char DefaultAlphaCallback(unsigned char red, unsigned char green, unsigned char blue) {
  45         return 255;
  46 }
  47
  48 static unsigned char StencilRed = 0, StencilGreen = 0, StencilBlue = 0;
  49 static unsigned char (*AlphaCallback)(unsigned char red, unsigned char green, unsigned char blue) = DefaultAlphaCallback;
  50 static int StandardOrientation = 0;
  51
  52 #ifdef SUPPORTS_PALETTE_EXT
  53 #ifdef _WIN32
  54 static PFNGLCOLORTABLEEXTPROC glColorTableEXT = NULL;
  55 #endif
  56 #endif
  57
  58 static int PalettedTextures = -1;
  59 static GLint MaxTextureSize = 0;
  60
  61 /* screenGamma = displayGamma/viewingGamma
  62  * displayGamma = CRT has gamma of ~2.2
  63  * viewingGamma depends on platform. PC is 1.0, Mac is 1.45, SGI defaults
  64  * to 1.7, but this can be checked and changed w/ /usr/sbin/gamma command.
  65  * If the environment variable VIEWING_GAMMA is set, adjust gamma per this value.
  66  */
  67 #ifdef _MAC
  68         static double screenGamma = 2.2 / 1.45;
  69 #elif SGI
  70         static double screenGamma = 2.2 / 1.7;
  71 #else /* PC/default */
  72         static double screenGamma = 2.2 / 1.0;
  73 #endif
  74
  75 static char gammaExplicit = 0;  /*if  */
  76
  77 static void checkForGammaEnv()
  78 {
  79         double viewingGamma;
  80         char *gammaEnv = getenv("VIEWING_GAMMA");
  81
  82         if(gammaEnv && !gammaExplicit)
  83         {
  84                 sscanf(gammaEnv, "%lf", &viewingGamma);
  85                 screenGamma = 2.2/viewingGamma;
  86         }
  87 }
  88
  89 /* Returns a safe texture size to use (ie a power of 2), based on the current texture size "i" */
  90 static int SafeSize(int i) {
  91         int p;
  92
  93         if (i > MaxTextureSize) return MaxTextureSize;
  94
  95         for (p = 0; p < 24; p++)
  96                 if (i <= (1<<p))
  97                         return 1<<p;
  98
  99         return MaxTextureSize;
 100 }
 101
 102 /* Resize the texture since gluScaleImage doesn't work on everything */
 103 static void Resize(int components, const png_bytep d1, int w1, int h1, png_bytep d2, int w2, int h2) {
 104         const float sx = (float) w1/w2, sy = (float) h1/h2;
 105         int x, y, xx, yy, c;
 106         png_bytep d;
 107
 108         for (y = 0; y < h2; y++) {
 109                 yy = (int) (y*sy)*w1;
 110
 111                 for (x = 0; x < w2; x++) {
 112                         xx = (int) (x*sx);
 113                         d = d1 + (yy+xx)*components;
 114
 115                         for (c = 0; c < components; c++)
 116                                 *d2++ = *d++;
 117                 }
 118         }
 119 }
 120
 121 #ifdef _WIN32
 122 static int ExtSupported(const char *x) {
 123         static const GLubyte *ext = NULL;
 124         const char *c;
 125         int xlen = strlen(x);
 126
 127         if (ext == NULL) ext = glGetString(GL_EXTENSIONS);
 128
 129         c = (const char*)ext;
 130
 131         while (*c != '\0') {
 132                 if (strcmp(c, x) == 0 && (c[xlen] == '\0' || c[xlen] == ' ')) return 1;
 133                 c++;
 134         }
 135
 136         return 0;
 137 }
 138 #endif
 139
 140 #define GET(o) ((int)*(data + (o)))
 141
 142 static int HalfSize(GLint components, GLint width, GLint height, const unsigned char *data, unsigned char *d, int filter) {
 143         int x, y, c;
 144         int line = width*components;
 145
 146         if (width > 1 && height > 1) {
 147                 if (filter)
 148                         for (y = 0; y < height; y += 2) {
 149                                 for (x = 0; x < width; x += 2) {
 150                                         for (c = 0; c < components; c++) {
 151                                                 *d++ = (GET(0)+GET(components)+GET(line)+GET(line+components)) / 4;
 152                                                 data++;
 153                                         }
 154                                         data += components;
 155                                 }
 156                                 data += line;
 157                         }
 158                 else
 159                         for (y = 0; y < height; y += 2) {
 160                                 for (x = 0; x < width; x += 2) {
 161                                         for (c = 0; c < components; c++) {
 162                                                 *d++ = GET(0);
 163                                                 data++;
 164                                         }
 165                                         data += components;
 166                                 }
 167                                 data += line;
 168                         }
 169         }
 170         else if (width > 1 && height == 1) {
 171                 if (filter)
 172                         for (y = 0; y < height; y += 1) {
 173                                 for (x = 0; x < width; x += 2) {
 174                                         for (c = 0; c < components; c++) {
 175                                                 *d++ = (GET(0)+GET(components)) / 2;
 176                                                 data++;
 177                                         }
 178                                         data += components;
 179                                 }
 180                         }
 181                 else
 182                         for (y = 0; y < height; y += 1) {
 183                                 for (x = 0; x < width; x += 2) {
 184                                         for (c = 0; c < components; c++) {
 185                                                 *d++ = GET(0);
 186                                                 data++;
 187                                         }
 188                                         data += components;
 189                                 }
 190                         }
 191         }
 192         else if (width == 1 && height > 1) {
 193                 if (filter)
 194                         for (y = 0; y < height; y += 2) {
 195                                 for (x = 0; x < width; x += 1) {
 196                                         for (c = 0; c < components; c++) {
 197                                                 *d++ = (GET(0)+GET(line)) / 2;
 198                                                 data++;
 199                                         }
 200                                 }
 201                                 data += line;
 202                         }
 203                 else
 204                         for (y = 0; y < height; y += 2) {
 205                                 for (x = 0; x < width; x += 1) {
 206                                         for (c = 0; c < components; c++) {
 207                                                 *d++ = GET(0);
 208                                                 data++;
 209                                         }
 210                                 }
 211                                 data += line;
 212                         }
 213         }
 214         else {
 215                 return 0;
 216         }
 217
 218         return 1;
 219 }
 220
 221 #undef GET
 222
 223 /* Replacement for gluBuild2DMipmaps so GLU isn't needed */
 224 static void Build2DMipmaps(GLint components, GLint width, GLint height, GLenum format, const unsigned char *data, int filter) {
 225         int level = 0;
 226         unsigned char *d = (unsigned char *) malloc((width/2)*(height/2)*components+4);
 227         const unsigned char *last = data;
 228
 229         glTexImage2D(GL_TEXTURE_2D, level, components, width, height, 0, format, GL_UNSIGNED_BYTE, data);
 230         level++;
 231
 232         while (HalfSize(components, width, height, last, d, filter)) {
 233                 if (width  > 1) width  /= 2;
 234                 if (height > 1) height /= 2;
 235
 236                 glTexImage2D(GL_TEXTURE_2D, level, components, width, height, 0, format, GL_UNSIGNED_BYTE, d);
 237                 level++;
 238                 last = d;
 239         }
 240
 241         free(d);
 242 }
 243
 244 int APIENTRY pngLoadRaw(const char *filename, pngRawInfo *pinfo) {
 245         int result;
 246         FILE *fp = fopen(filename, "rb");
 247         if (fp == NULL) return 0;
 248
 249         result = pngLoadRawF(fp, pinfo);
 250
 251         if (fclose(fp) != 0) {
 252                 if (result) {
 253                         free(pinfo->Data);
 254                         free(pinfo->Palette);
 255                 }
 256                 return 0;
 257         }
 258
 259         return result;
 260 }
 261
 262 int APIENTRY pngLoadRawF(FILE *fp, pngRawInfo *pinfo) {
 263         unsigned char header[8];
 264         png_structp png;
 265         png_infop   info;
 266         png_infop   endinfo;
 267         double      fileGamma;
 268
 269         png_uint_32 width, height, i;
 270         int depth, color;
 271
 272         png_bytep data = NULL;
 273         png_bytep *row_p = NULL;
 274
 275         if (pinfo == NULL) return 0;
 276
 277         fread(header, 1, 8, fp);
 278         if (!png_check_sig(header, 8)) return 0;
 279
 280         png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 281         if (!png) return 0;
 282         info = png_create_info_struct(png);
 283         if (!info) return 0;
 284         endinfo = png_create_info_struct(png);
 285         if (!endinfo) return 0;
 286
 287         if (setjmp(png_jmpbuf(png)))
 288                 goto error;
 289
 290         png_init_io(png, fp);
 291         png_set_sig_bytes(png, 8);
 292         png_read_info(png, info);
 293         png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);
 294
 295         pinfo->Width  = width;
 296         pinfo->Height = height;
 297         pinfo->Depth  = depth;
 298
 299         /*--GAMMA--*/
 300         checkForGammaEnv();
 301         if (png_get_gAMA(png, info, &fileGamma))
 302                 png_set_gamma(png, screenGamma, fileGamma);
 303         else
 304                 png_set_gamma(png, screenGamma, 1.0/2.2);
 305
 306         png_read_update_info(png, info);
 307
 308         /* HDG: We allocate all the png data in one linear array, thus
 309            height * png_get_rowbytes() may not be > PNG_UINT_32_MAX !
 310            This check fixes CVE-2010-1519. */
 311         if ((uint64_t)height * png_get_rowbytes(png, info) > PNG_UINT_32_MAX)
 312                 goto error;
 313
 314         data = (png_bytep) malloc(png_get_rowbytes(png, info)*height);
 315         row_p = (png_bytep *) malloc(sizeof(png_bytep)*height);
 316         if (!data || !row_p)
 317                 goto error;
 318
 319         for (i = 0; i < height; i++) {
 320                 if (StandardOrientation)
 321                         row_p[height - 1 - i] = &data[png_get_rowbytes(png, info)*i];
 322                 else
 323                         row_p[i] = &data[png_get_rowbytes(png, info)*i];
 324         }
 325
 326         png_read_image(png, row_p);
 327         free(row_p);
 328         row_p = NULL;
 329
 330         if (color == PNG_COLOR_TYPE_PALETTE) {
 331                 int cols;
 332                 png_get_PLTE(png, info, (png_colorp *) &pinfo->Palette, &cols);
 333         }
 334         else {
 335                 pinfo->Palette = NULL;
 336         }
 337
 338         if (color&PNG_COLOR_MASK_ALPHA) {
 339                 if (color&PNG_COLOR_MASK_PALETTE || color == PNG_COLOR_TYPE_GRAY_ALPHA)
 340                         pinfo->Components = 2;
 341                 else
 342                         pinfo->Components = 4;
 343                 pinfo->Alpha = 8;
 344         }
 345         else {
 346                 if (color&PNG_COLOR_MASK_PALETTE || color == PNG_COLOR_TYPE_GRAY)
 347                         pinfo->Components = 1;
 348                 else
 349                         pinfo->Components = 3;
 350                 pinfo->Alpha = 0;
 351         }
 352
 353         pinfo->Data = data;
 354
 355         png_read_end(png, endinfo);
 356         png_destroy_read_struct(&png, &info, &endinfo);
 357         return 1;
 358
 359 error:
 360         png_destroy_read_struct(&png, &info, &endinfo);
 361         free(data);
 362         free(row_p);
 363         return 0;
 364 }
 365
 366 static int pngLoadCommon(int mipmap, int trans, pngInfo *pinfo, png_structp png, png_infop info, png_infop endinfo) {
 367         GLint pack, unpack;
 368         double fileGamma;
 369
 370         png_uint_32 width, height, rw, rh, i;
 371         int depth, color;
 372
 373         png_bytep data = NULL, data2 = NULL;
 374         png_bytep *row_p = NULL;
 375
 376         int ret = 0;
 377
 378         png_set_sig_bytes(png, 8);
 379         png_read_info(png, info);
 380         png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);
 381
 382         if (pinfo != NULL) {
 383                 pinfo->Width  = width;
 384                 pinfo->Height = height;
 385                 pinfo->Depth  = depth;
 386         }
 387
 388         if (MaxTextureSize == 0)
 389                 glGetIntegerv(GL_MAX_TEXTURE_SIZE, &MaxTextureSize);
 390
 391         #ifdef SUPPORTS_PALETTE_EXT
 392         #ifdef _WIN32
 393                 if (PalettedTextures == -1)
 394                         PalettedTextures = ExtSupported("GL_EXT_paletted_texture") && (strstr((const char *) glGetString(GL_VERSION), "1.1.0 3Dfx Beta") == NULL);
 395
 396                 if (PalettedTextures) {
 397                         if (glColorTableEXT == NULL) {
 398                                 glColorTableEXT = (PFNGLCOLORTABLEEXTPROC) wglGetProcAddress("glColorTableEXT");
 399                                 if (glColorTableEXT == NULL)
 400                                         PalettedTextures = 0;
 401                         }
 402                 }
 403         #endif
 404         #endif
 405
 406         if (PalettedTextures == -1)
 407                 PalettedTextures = 0;
 408
 409         if (color == PNG_COLOR_TYPE_GRAY || color == PNG_COLOR_TYPE_GRAY_ALPHA)
 410                 png_set_gray_to_rgb(png);
 411
 412         if (color&PNG_COLOR_MASK_ALPHA && trans != PNG_ALPHA) {
 413                 png_set_strip_alpha(png);
 414                 color &= ~PNG_COLOR_MASK_ALPHA;
 415         }
 416
 417         if (!(PalettedTextures && mipmap >= 0 && trans == PNG_SOLID))
 418                 if (color == PNG_COLOR_TYPE_PALETTE)
 419                         png_set_expand(png);
 420
 421         /*--GAMMA--*/
 422         checkForGammaEnv();
 423         if (png_get_gAMA(png, info, &fileGamma))
 424                 png_set_gamma(png, screenGamma, fileGamma);
 425         else
 426                 png_set_gamma(png, screenGamma, 1.0/2.2);
 427
 428         png_read_update_info(png, info);
 429
 430         /* HDG: We allocate all the png data in one linear array, thus
 431            height * png_get_rowbytes() may not be > PNG_UINT_32_MAX !
 432            This check fixes CVE-2010-1519. */
 433         if ((uint64_t)height * png_get_rowbytes(png, info) > PNG_UINT_32_MAX)
 434                 goto finish;
 435
 436         data = (png_bytep) malloc(png_get_rowbytes(png, info)*height);
 437         row_p = (png_bytep *) malloc(sizeof(png_bytep)*height);
 438         if (!data || !row_p)
 439                 goto finish;
 440
 441         for (i = 0; i < height; i++) {
 442                 if (StandardOrientation)
 443                         row_p[height - 1 - i] = &data[png_get_rowbytes(png, info)*i];
 444                 else
 445                         row_p[i] = &data[png_get_rowbytes(png, info)*i];
 446         }
 447
 448         png_read_image(png, row_p);
 449         free(row_p);
 450         row_p = NULL;
 451
 452         rw = SafeSize(width), rh = SafeSize(height);
 453
 454         if (rw != width || rh != height) {
 455                 const int channels = png_get_rowbytes(png, info)/width;
 456
 457                 data2 = (png_bytep) malloc(rw*rh*channels);
 458                 if (!data2)
 459                         goto finish;
 460
 461                 /* Doesn't work on certain sizes */
 462 /*              if (gluScaleImage(glformat, width, height, GL_UNSIGNED_BYTE, data, rw, rh, GL_UNSIGNED_BYTE, data2) != 0)
 463                         goto finish;
 464 */
 465                 Resize(channels, data, width, height, data2, rw, rh);
 466
 467                 width = rw, height = rh;
 468                 free(data);
 469                 data = data2;
 470                 data2 = NULL;
 471         }
 472
 473         { /* OpenGL stuff */
 474                 glGetIntegerv(GL_PACK_ALIGNMENT, &pack);
 475                 glGetIntegerv(GL_UNPACK_ALIGNMENT, &unpack);
 476                 glPixelStorei(GL_PACK_ALIGNMENT, 1);
 477                 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 478
 479                 #ifdef SUPPORTS_PALETTE_EXT
 480                 if (PalettedTextures && mipmap >= 0 && trans == PNG_SOLID && color == PNG_COLOR_TYPE_PALETTE) {
 481                         png_colorp pal;
 482                         int cols;
 483                         GLint intf;
 484
 485                         if (pinfo != NULL) pinfo->Alpha = 0;
 486                         png_get_PLTE(png, info, &pal, &cols);
 487
 488                         switch (cols) {
 489                                 case 1<<1:  intf = GL_COLOR_INDEX1_EXT;  break;
 490                                 case 1<<2:  intf = GL_COLOR_INDEX2_EXT;  break;
 491                                 case 1<<4:  intf = GL_COLOR_INDEX4_EXT;  break;
 492                                 case 1<<8:  intf = GL_COLOR_INDEX8_EXT;  break;
 493                                 case 1<<12: intf = GL_COLOR_INDEX12_EXT; break;
 494                                 case 1<<16: intf = GL_COLOR_INDEX16_EXT; break;
 495                                 default:
 496                                         /*printf("Warning: Colour depth %i not recognised\n", cols);*/
 497                                         goto finish;
 498                         }
 499                         glColorTableEXT(GL_TEXTURE_2D, GL_RGB8, cols, GL_RGB, GL_UNSIGNED_BYTE, pal);
 500                         glTexImage2D(GL_TEXTURE_2D, mipmap, intf, width, height, 0, GL_COLOR_INDEX, GL_UNSIGNED_BYTE, data);
 501                 }
 502                 else
 503                 #endif
 504                 if (trans == PNG_SOLID || trans == PNG_ALPHA || color == PNG_COLOR_TYPE_RGB_ALPHA || color == PNG_COLOR_TYPE_GRAY_ALPHA) {
 505                         GLenum glformat;
 506                         GLint glcomponent;
 507
 508                         switch (color) {
 509                                 case PNG_COLOR_TYPE_GRAY:
 510                                 case PNG_COLOR_TYPE_RGB:
 511                                 case PNG_COLOR_TYPE_PALETTE:
 512                                         glformat = GL_RGB;
 513                                         glcomponent = 3;
 514                                         if (pinfo != NULL) pinfo->Alpha = 0;
 515                                         break;
 516
 517                                 case PNG_COLOR_TYPE_GRAY_ALPHA:
 518                                 case PNG_COLOR_TYPE_RGB_ALPHA:
 519                                         glformat = GL_RGBA;
 520                                         glcomponent = 4;
 521                                         if (pinfo != NULL) pinfo->Alpha = 8;
 522                                         break;
 523
 524                                 default:
 525                                         /*puts("glformat not set");*/
 526                                         goto finish;
 527                         }
 528
 529                         if (mipmap == PNG_BUILDMIPMAPS)
 530                                 Build2DMipmaps(glcomponent, width, height, glformat, data, 1);
 531                         else if (mipmap == PNG_SIMPLEMIPMAPS)
 532                                 Build2DMipmaps(glcomponent, width, height, glformat, data, 0);
 533                         else
 534                                 glTexImage2D(GL_TEXTURE_2D, mipmap, glcomponent, width, height, 0, glformat, GL_UNSIGNED_BYTE, data);
 535                 }
 536                 else {
 537                         png_bytep p, endp, q;
 538                         int r, g, b, a;
 539
 540                         /* HDG another potential 32 bit address overflow, the
 541                            original png had 3 channels and we are going to
 542                            4 channels now! */
 543                         if ((uint64_t)width * height > (PNG_UINT_32_MAX >> 2))
 544                                 goto finish;
 545
 546                         p = data, endp = p+width*height*3;
 547                         q = data2 = (png_bytep) malloc(sizeof(png_byte)*width*height*4);
 548
 549                         if (pinfo != NULL) pinfo->Alpha = 8;
 550
 551                         #define FORSTART \
 552                                 do { \
 553                                         r = *p++; /*red  */ \
 554                                         g = *p++; /*green*/ \
 555                                         b = *p++; /*blue */ \
 556                                         *q++ = r; \
 557                                         *q++ = g; \
 558                                         *q++ = b;
 559
 560                         #define FOREND \
 561                                         q++; \
 562                                 } while (p != endp);
 563
 564                         #define ALPHA *q
 565
 566                         switch (trans) {
 567                                 case PNG_CALLBACKT:
 568                                         FORSTART
 569                                                 ALPHA = AlphaCallback((unsigned char) r, (unsigned char) g, (unsigned char) b);
 570                                         FOREND
 571                                         break;
 572
 573                                 case PNG_STENCIL:
 574                                         FORSTART
 575                                                 if (r == StencilRed && g == StencilGreen && b == StencilBlue)
 576                                                         ALPHA = 0;
 577                                                 else
 578                                                         ALPHA = 255;
 579                                         FOREND
 580                                         break;
 581
 582                                 case PNG_BLEND1:
 583                                         FORSTART
 584                                                 a = r+g+b;
 585                                                 if (a > 255) ALPHA = 255; else ALPHA = a;
 586                                         FOREND
 587                                         break;
 588
 589                                 case PNG_BLEND2:
 590                                         FORSTART
 591                                                 a = r+g+b;
 592                                                 if (a > 255*2) ALPHA = 255; else ALPHA = a/2;
 593                                         FOREND
 594                                         break;
 595
 596                                 case PNG_BLEND3:
 597                                         FORSTART
 598                                                 ALPHA = (r+g+b)/3;
 599                                         FOREND
 600                                         break;
 601
 602                                 case PNG_BLEND4:
 603                                         FORSTART
 604                                                 a = r*r+g*g+b*b;
 605                                                 if (a > 255) ALPHA = 255; else ALPHA = a;
 606                                         FOREND
 607                                         break;
 608
 609                                 case PNG_BLEND5:
 610                                         FORSTART
 611                                                 a = r*r+g*g+b*b;
 612                                                 if (a > 255*2) ALPHA = 255; else ALPHA = a/2;
 613                                         FOREND
 614                                         break;
 615
 616                                 case PNG_BLEND6:
 617                                         FORSTART
 618                                                 a = r*r+g*g+b*b;
 619                                                 if (a > 255*3) ALPHA = 255; else ALPHA = a/3;
 620                                         FOREND
 621                                         break;
 622
 623                                 case PNG_BLEND7:
 624                                         FORSTART
 625                                                 a = r*r+g*g+b*b;
 626                                                 if (a > 255*255) ALPHA = 255; else ALPHA = (int) sqrt(a);
 627                                         FOREND
 628                                         break;
 629                         }
 630
 631                         #undef FORSTART
 632                         #undef FOREND
 633                         #undef ALPHA
 634
 635                         if (mipmap == PNG_BUILDMIPMAPS)
 636                                 Build2DMipmaps(4, width, height, GL_RGBA, data2, 1);
 637                         else if (mipmap == PNG_SIMPLEMIPMAPS)
 638                                 Build2DMipmaps(4, width, height, GL_RGBA, data2, 0);
 639                         else
 640                                 glTexImage2D(GL_TEXTURE_2D, mipmap, 4, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data2);
 641
 642                 }
 643
 644                 glPixelStorei(GL_PACK_ALIGNMENT, pack);
 645                 glPixelStorei(GL_UNPACK_ALIGNMENT, unpack);
 646         } /* OpenGL end */
 647
 648         png_read_end(png, endinfo);
 649         ret = 1;
 650
 651 finish:
 652         free(data);
 653         free(data2);
 654         free(row_p);
 655         return ret;
 656 }
 657
 658 int APIENTRY pngLoad(const char *filename, int mipmap, int trans, pngInfo *pinfo) {
 659         int result;
 660         FILE *fp = fopen(filename, "rb");
 661         if (fp == NULL) return 0;
 662
 663         result = pngLoadF(fp, mipmap, trans, pinfo);
 664
 665         if (fclose(fp) != 0) return 0;
 666
 667         return result;
 668 }
 669
 670 int APIENTRY pngLoadF(FILE *fp, int mipmap, int trans, pngInfo *pinfo) {
 671         unsigned char header[8];
 672         png_structp png;
 673         png_infop info;
 674         png_infop endinfo;
 675
 676         int ret = 0;
 677
 678         fread(header, 1, 8, fp);
 679         if (!png_check_sig(header, 8)) return 0;
 680
 681         png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 682         if (!png) return 0;
 683         info = png_create_info_struct(png);
 684         if (!info) return 0;
 685         endinfo = png_create_info_struct(png);
 686         if (!endinfo) return 0;
 687
 688         if (!setjmp(png_jmpbuf(png))) {
 689                 png_init_io(png, fp);
 690                 ret = pngLoadCommon(mipmap, trans, pinfo, png, info, endinfo);
 691         }
 692
 693         png_destroy_read_struct(&png, &info, &endinfo);
 694         return ret;
 695 }
 696
 697 typedef struct glpng_memread_struct {
 698         png_bytep mem;
 699         png_size_t rpos;
 700 } glpng_memread;
 701
 702 static void glpng_read_mem(png_structp png, png_bytep dst, png_size_t size) {
 703         glpng_memread *mr = (glpng_memread*) png_get_io_ptr(png);
 704         memcpy(dst, mr->mem + mr->rpos, size);
 705         mr->rpos += size;
 706 }
 707
 708 int APIENTRY pngLoadMem(const char *mem, int size, int mipmap, int trans, pngInfo *pinfo) {
 709         unsigned char header[8];
 710         png_structp png;
 711         png_infop info;
 712         png_infop endinfo;
 713         glpng_memread memread;
 714
 715         int ret = 0;
 716
 717         if (size < 8)
 718                 return 0; // error
 719
 720         memcpy(header, mem, 8);
 721         if (!png_check_sig(header, 8)) return 0;
 722
 723         png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 724         if (!png) return 0;
 725         info = png_create_info_struct(png);
 726         if (!info) return 0;
 727         endinfo = png_create_info_struct(png);
 728         if (!endinfo) return 0;
 729
 730         if (!setjmp(png_jmpbuf(png))) {
 731                 memread.rpos = 0;
 732                 memread.mem = ((png_bytep) mem) + 8;
 733                 png_set_read_fn(png, &memread, glpng_read_mem);
 734                 ret = pngLoadCommon(mipmap, trans, pinfo, png, info, endinfo);
 735         }
 736
 737         png_destroy_read_struct(&png, &info, &endinfo);
 738         return ret;
 739 }
 740
 741 static unsigned int SetParams(int wrapst, int magfilter, int minfilter) {
 742         unsigned int id;
 743
 744         glGenTextures(1, &id);
 745         glBindTexture(GL_TEXTURE_2D, id);
 746
 747         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrapst);
 748         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrapst);
 749
 750         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magfilter);
 751         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minfilter);
 752
 753         return id;
 754 }
 755
 756 unsigned int APIENTRY pngBind(const char *filename, int mipmap, int trans, pngInfo *info, int wrapst, int minfilter, int magfilter) {
 757         unsigned int id = SetParams(wrapst, magfilter, minfilter);
 758
 759         if (id != 0 && pngLoad(filename, mipmap, trans, info))
 760                 return id;
 761         return 0;
 762 }
 763
 764 unsigned int APIENTRY pngBindF(FILE *file, int mipmap, int trans, pngInfo *info, int wrapst, int minfilter, int magfilter) {
 765         unsigned int id = SetParams(wrapst, magfilter, minfilter);
 766
 767         if (id != 0 && pngLoadF(file, mipmap, trans, info))
 768                 return id;
 769         return 0;
 770 }
 771
 772 unsigned int APIENTRY pngBindMem(const char *mem, int size, int mipmap, int trans, pngInfo *info, int wrapst, int minfilter, int magfilter) {
 773         unsigned int id = SetParams(wrapst, magfilter, minfilter);
 774
 775         if (id != 0 && pngLoadMem(mem, size, mipmap, trans, info))
 776                 return id;
 777         return 0;
 778 }
 779
 780 void APIENTRY pngSetStencil(unsigned char red, unsigned char green, unsigned char blue) {
 781         StencilRed = red, StencilGreen = green, StencilBlue = blue;
 782 }
 783
 784 void APIENTRY pngSetAlphaCallback(unsigned char (*callback)(unsigned char red, unsigned char green, unsigned char blue)) {
 785         if (callback == NULL)
 786                 AlphaCallback = DefaultAlphaCallback;
 787         else
 788                 AlphaCallback = callback;
 789 }
 790
 791 void APIENTRY pngSetViewingGamma(double viewingGamma) {
 792         if(viewingGamma > 0) {
 793                 gammaExplicit = 1;
 794                 screenGamma = 2.2/viewingGamma;
 795         }
 796         else {
 797                 gammaExplicit = 0;
 798                 screenGamma = 2.2;
 799         }
 800 }
 801
 802 void APIENTRY pngSetStandardOrientation(int standardorientation) {
 803         StandardOrientation = standardorientation;
 804 }