1 (*

     2  * Hedgewars, a free turn based strategy game

     3  * Copyright (c) 2004-2012 Andrey Korotaev <unC0Rr@gmail.com>

     4  *

     5  * This program is free software; you can redistribute it and/or modify

     6  * it under the terms of the GNU General Public License as published by

     7  * the Free Software Foundation; version 2 of the License

     8  *

     9  * This program 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

    12  * GNU General Public License for more details.

    13  *

    14  * You should have received a copy of the GNU General Public License

    15  * along with this program; if not, write to the Free Software

    16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA

    17  *)

    18 

    19 {$INCLUDE "options.inc"}

    20 

    21 unit PNGh;

    22 interface

    23 

    24 uses png;

    25 

    26 {$IFDEF FPC}

    27     {$PACKRECORDS C}

    28 {$ELSE}

    29     {$DEFINE cdecl attribute(cdecl)}

    30 {$ENDIF}

    31 

    32 const

    33     // Constants for libpng, they are not defined in png unit.

    34     // We actually don't need all of them.

    35 

    36     // These describe the color_type field in png_info.

    37     // color type masks

    38     PNG_COLOR_MASK_PALETTE = 1;

    39     PNG_COLOR_MASK_COLOR   = 2;

    40     PNG_COLOR_MASK_ALPHA   = 4;

    41 

    42     // color types.  Note that not all combinations are legal

    43     PNG_COLOR_TYPE_GRAY       = 0;

    44     PNG_COLOR_TYPE_PALETTE    = (PNG_COLOR_MASK_COLOR or PNG_COLOR_MASK_PALETTE);

    45     PNG_COLOR_TYPE_RGB        = (PNG_COLOR_MASK_COLOR);

    46     PNG_COLOR_TYPE_RGB_ALPHA  = (PNG_COLOR_MASK_COLOR or PNG_COLOR_MASK_ALPHA);

    47     PNG_COLOR_TYPE_GRAY_ALPHA = (PNG_COLOR_MASK_ALPHA);

    48 

    49     // aliases

    50     PNG_COLOR_TYPE_RGBA = PNG_COLOR_TYPE_RGB_ALPHA;

    51     PNG_COLOR_TYPE_GA   = PNG_COLOR_TYPE_GRAY_ALPHA;

    52 

    53     // This is for compression type. PNG 1.0-1.2 only define the single type.

    54     PNG_COMPRESSION_TYPE_BASE    = 0; // Deflate method 8, 32K window

    55     PNG_COMPRESSION_TYPE_DEFAULT = PNG_COMPRESSION_TYPE_BASE;

    56 

    57     // This is for filter type. PNG 1.0-1.2 only define the single type.

    58     PNG_FILTER_TYPE_BASE        = 0;  // Single row per-byte filtering

    59     PNG_INTRAPIXEL_DIFFERENCING = 64; // Used only in MNG datastreams

    60     PNG_FILTER_TYPE_DEFAULT     = PNG_FILTER_TYPE_BASE;

    61 

    62     // These are for the interlacing type.  These values should NOT be changed.

    63     PNG_INTERLACE_NONE  = 0; // Non-interlaced image

    64     PNG_INTERLACE_ADAM7 = 1; // Adam7 interlacing

    65     PNG_INTERLACE_LAST  = 2; // Not a valid value

    66 

    67 type

    68     // where is better place for this definition?

    69     PFile = ^file;

    70 

    71 procedure png_init_pascal_io(png_ptr: png_structp; pf : PFile);

    72 

    73 implementation

    74 

    75 // We cannot get c-style FILE* pointer to pass it to libpng, so we implement our own writing functions

    76 procedure PngWriteData(png_ptr: png_structp; p: PByte; len: png_size_t); cdecl;

    77 begin

    78     BlockWrite( PFile(png_get_io_ptr(png_ptr))^, p^, len);

    79 end;

    80 

    81 procedure PngFlushData(png_ptr: png_structp); cdecl;

    82 begin

    83 end;

    84 

    85 procedure png_init_pascal_io(png_ptr: png_structp; pf : PFile);

    86 begin

    87     png_set_write_fn(png_ptr, pf, @PngWriteData, @PngFlushData);

    88 end;

    89 

    90 end.