include/loaders/GP_PNG.h

   1 /*****************************************************************************
   2  * This file is part of gfxprim library.                                     *
   3  *                                                                           *
   4  * Gfxprim is free software; you can redistribute it and/or                  *
   5  * modify it under the terms of the GNU Lesser General Public                *
   6  * License as published by the Free Software Foundation; either              *
   7  * version 2.1 of the License, or (at your option) any later version.        *
   8  *                                                                           *
   9  * Gfxprim is distributed in the hope that it will be useful,                *
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU         *
  12  * Lesser General Public License for more details.                           *
  13  *                                                                           *
  14  * You should have received a copy of the GNU Lesser General Public          *
  15  * License along with gfxprim; if not, write to the Free Software            *
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,                        *
  17  * Boston, MA  02110-1301  USA                                               *
  18  *                                                                           *
  19  * Copyright (C) 2009-2012 Cyril Hrubis <metan@ucw.cz>                       *
  20  *                                                                           *
  21  *****************************************************************************/
  22
  23  /*
  24
  25    PNG support using libpng library.
  26
  27   */
  28
  29 #ifndef LOADERS_GP_PNG_H
  30 #define LOADERS_GP_PNG_H
  31
  32 #include "core/GP_ProgressCallback.h"
  33 #include "core/GP_Context.h"
  34
  35 #include "GP_MetaData.h"
  36
  37 /*
  38  * The possible errno values:
  39  *
  40  * - Anything FILE operation may return (fopen(), fclose(), fseek(), ...).
  41  * - EIO for png_read()/png_write() failure
  42  * - ENOSYS for not implemented bitmap format
  43  * - ENOMEM from malloc()
  44  * - EILSEQ for wrong image signature/data
  45  * - ECANCELED when call was aborted from callback
  46  */
  47
  48 /*
  49  * Opens up file and checks signature. Upon successful return (zero is
  50  * returned) the file possition would be set to eight bytes (exactly after the
  51  * PNG signature).
  52  */
  53 int GP_OpenPNG(const char *src_path, FILE **f);
  54
  55 /*
  56  * Reads PNG from an open FILE. Expects the file possition set after the eight
  57  * bytes PNG signature.
  58  *
  59  * Upon succesfull return pointer to newly allocated context is returned.
  60  * Otherwise NULL is returned and errno is filled.
  61  */
  62 GP_Context *GP_ReadPNG(FILE *f, GP_ProgressCallback *callback);
  63
  64 /*
  65  * Does both GP_OpenPNG and GP_ReadPNG at once.
  66  */
  67 GP_Context *GP_LoadPNG(const char *src_path, GP_ProgressCallback *callback);
  68
  69 /*
  70  * Loads png meta-data.
  71  */
  72 int GP_ReadPNGMetaData(FILE *f, GP_MetaData *data);
  73 int GP_LoadPNGMetaData(const char *src_path, GP_MetaData *data);
  74
  75 /*
  76  * Saves PNG to a file. Zero is returned on succes. Upon failure non-zero is
  77  * returned and errno is filled accordingly.
  78  */
  79 int GP_SavePNG(const GP_Context *src, const char *dst_path,
  80                GP_ProgressCallback *callback);
  81
  82 #endif /* LOADERS_GP_PNG_H */