(*

 * Hedgewars, a free turn based strategy game

 * Copyright (c) 2004-2015 Andrey Korotaev <unC0Rr@gmail.com>

 *

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

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

 * the Free Software Foundation; version 2 of the License

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

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

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

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 *)

{$INCLUDE "options.inc"}

unit PNGh;

interface

uses png;

{$IFDEF DARWIN}

    {$linklib png}

{$ENDIF}

const

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

    // We actually do not need all of them.

    // These describe the color_type field in png_info.

    // color type masks

    PNG_COLOR_MASK_PALETTE = 1;

    PNG_COLOR_MASK_COLOR   = 2;

    PNG_COLOR_MASK_ALPHA   = 4;

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

    PNG_COLOR_TYPE_GRAY       = 0;

    PNG_COLOR_TYPE_PALETTE    = PNG_COLOR_MASK_COLOR or PNG_COLOR_MASK_PALETTE;

    PNG_COLOR_TYPE_RGB        = PNG_COLOR_MASK_COLOR;

    PNG_COLOR_TYPE_RGB_ALPHA  = PNG_COLOR_MASK_COLOR or PNG_COLOR_MASK_ALPHA;

    PNG_COLOR_TYPE_GRAY_ALPHA = PNG_COLOR_MASK_ALPHA;

    // aliases

    PNG_COLOR_TYPE_RGBA = PNG_COLOR_TYPE_RGB_ALPHA;

    PNG_COLOR_TYPE_GA   = PNG_COLOR_TYPE_GRAY_ALPHA;

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

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

    PNG_COMPRESSION_TYPE_DEFAULT = PNG_COMPRESSION_TYPE_BASE;

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

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

    PNG_INTRAPIXEL_DIFFERENCING = 64; // Used only in MNG datastreams

    PNG_FILTER_TYPE_DEFAULT     = PNG_FILTER_TYPE_BASE;

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

    PNG_INTERLACE_NONE  = 0; // Non-interlaced image

    PNG_INTERLACE_ADAM7 = 1; // Adam7 interlacing

    PNG_INTERLACE_LAST  = 2; // Not a valid value

type

    // where is better place for this definition?

    PFile = ^file;

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

implementation

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

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

begin

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

end;

procedure PngFlushData(png_ptr: png_structp); cdecl;

begin

    png_ptr:= png_ptr;

end;

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

begin

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

end;

end.