/* pngwtran.c - transforms the data in a row for PNG writers * * libpng 1.0.9 - January 31, 2001 * For conditions of distribution and use, see copyright notice in png.h * Copyright (c) 1998-2001 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) */#define PNG_INTERNAL#include "png.h"/* Transform the data according to the user's wishes.  The order of * transformations is significant. */void /* PRIVATE */png_do_write_transformations(png_structp png_ptr){   png_debug(1, "in png_do_write_transformations\n");   if (png_ptr == NULL)      return;#if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)   if (png_ptr->transformations & PNG_USER_TRANSFORM)      if(png_ptr->write_user_transform_fn != NULL)        (*(png_ptr->write_user_transform_fn)) /* user write transform function */          (png_ptr,                    /* png_ptr */           &(png_ptr->row_info),       /* row_info:     */             /*  png_uint_32 width;          width of row */             /*  png_uint_32 rowbytes;       number of bytes in row */             /*  png_byte color_type;        color type of pixels */             /*  png_byte bit_depth;         bit depth of samples */             /*  png_byte channels;          number of channels (1-4) */             /*  png_byte pixel_depth;       bits per pixel (depth*channels) */           png_ptr->row_buf + 1);      /* start of pixel data for row */#endif#if defined(PNG_WRITE_FILLER_SUPPORTED)   if (png_ptr->transformations & PNG_FILLER)      png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,         png_ptr->flags);#endif#if defined(PNG_WRITE_PACKSWAP_SUPPORTED)   if (png_ptr->transformations & PNG_PACKSWAP)      png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);#endif#if defined(PNG_WRITE_PACK_SUPPORTED)   if (png_ptr->transformations & PNG_PACK)      png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,         (png_uint_32)png_ptr->bit_depth);#endif#if defined(PNG_WRITE_SWAP_SUPPORTED)   if (png_ptr->transformations & PNG_SWAP_BYTES)      png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);#endif#if defined(PNG_WRITE_SHIFT_SUPPORTED)   if (png_ptr->transformations & PNG_SHIFT)      png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,         &(png_ptr->shift));#endif#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)   if (png_ptr->transformations & PNG_INVERT_ALPHA)      png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);#endif#if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)   if (png_ptr->transformations & PNG_SWAP_ALPHA)      png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);#endif#if defined(PNG_WRITE_BGR_SUPPORTED)   if (png_ptr->transformations & PNG_BGR)      png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);#endif#if defined(PNG_WRITE_INVERT_SUPPORTED)   if (png_ptr->transformations & PNG_INVERT_MONO)      png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);#endif}#if defined(PNG_WRITE_PACK_SUPPORTED)/* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The * row_info bit depth should be 8 (one pixel per byte).  The channels * should be 1 (this only happens on grayscale and paletted images). */void /* PRIVATE */png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth){   png_debug(1, "in png_do_pack\n");   if (row_info->bit_depth == 8 &&#if defined(PNG_USELESS_TESTS_SUPPORTED)       row != NULL && row_info != NULL &&#endif      row_info->channels == 1)   {      switch ((int)bit_depth)      {         case 1:         {            png_bytep sp, dp;            int mask, v;            png_uint_32 i;            png_uint_32 row_width = row_info->width;            sp = row;            dp = row;            mask = 0x80;            v = 0;            for (i = 0; i < row_width; i++)            {               if (*sp != 0)                  v |= mask;               sp++;               if (mask > 1)                  mask >>= 1;               else               {                  mask = 0x80;                  *dp = (png_byte)v;                  dp++;                  v = 0;               }            }            if (mask != 0x80)               *dp = (png_byte)v;            break;         }         case 2:         {            png_bytep sp, dp;            int shift, v;            png_uint_32 i;            png_uint_32 row_width = row_info->width;            sp = row;            dp = row;            shift = 6;            v = 0;            for (i = 0; i < row_width; i++)            {               png_byte value;               value = (png_byte)(*sp & 0x03);               v |= (value << shift);               if (shift == 0)               {                  shift = 6;                  *dp = (png_byte)v;                  dp++;                  v = 0;               }               else                  shift -= 2;               sp++;            }            if (shift != 6)               *dp = (png_byte)v;            break;         }         case 4:         {            png_bytep sp, dp;            int shift, v;            png_uint_32 i;            png_uint_32 row_width = row_info->width;            sp = row;            dp = row;            shift = 4;            v = 0;            for (i = 0; i < row_width; i++)            {               png_byte value;               value = (png_byte)(*sp & 0x0f);               v |= (value << shift);               if (shift == 0)               {                  shift = 4;                  *dp = (png_byte)v;                  dp++;                  v = 0;               }               else                  shift -= 4;               sp++;            }            if (shift != 4)               *dp = (png_byte)v;            break;         }      }      row_info->bit_depth = (png_byte)bit_depth;      row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);      row_info->rowbytes =         ((row_info->width * row_info->pixel_depth + 7) >> 3);   }}#endif#if defined(PNG_WRITE_SHIFT_SUPPORTED)/* Shift pixel values to take advantage of whole range.  Pass the * true number of bits in bit_depth.  The row should be packed * according to row_info->bit_depth.  Thus, if you had a row of * bit depth 4, but the pixels only had values from 0 to 7, you * would pass 3 as bit_depth, and this routine would translate the * data to 0 to 15. */void /* PRIVATE */png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth){   png_debug(1, "in png_do_shift\n");#if defined(PNG_USELESS_TESTS_SUPPORTED)   if (row != NULL && row_info != NULL &&#else   if (#endif      row_info->color_type != PNG_COLOR_TYPE_PALETTE)   {      int shift_start[4], shift_dec[4];      int channels = 0;      if (row_info->color_type & PNG_COLOR_MASK_COLOR)      {         shift_start[channels] = row_info->bit_depth - bit_depth->red;         shift_dec[channels] = bit_depth->red;         channels++;         shift_start[channels] = row_info->bit_depth - bit_depth->green;         shift_dec[channels] = bit_depth->green;         channels++;         shift_start[channels] = row_info->bit_depth - bit_depth->blue;         shift_dec[channels] = bit_depth->blue;         channels++;      }      else      {         shift_start[channels] = row_info->bit_depth - bit_depth->gray;         shift_dec[channels] = bit_depth->gray;         channels++;      }      if (row_info->color_type & PNG_COLOR_MASK_ALPHA)      {         shift_start[channels] = row_info->bit_depth - bit_depth->alpha;         shift_dec[channels] = bit_depth->alpha;         channels++;      }      /* with low row depths, could only be grayscale, so one channel */      if (row_info->bit_depth < 8)      {         png_bytep bp = row;         png_uint_32 i;         png_byte mask;         png_uint_32 row_bytes = row_info->rowbytes;         if (bit_depth->gray == 1 && row_info->bit_depth == 2)            mask = 0x55;         else if (row_info->bit_depth == 4 && bit_depth->gray == 3)            mask = 0x11;         else            mask = 0xff;         for (i = 0; i < row_bytes; i++, bp++)         {            png_uint_16 v;            int j;            v = *bp;            *bp = 0;            for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])            {               if (j > 0)                  *bp |= (png_byte)((v << j) & 0xff);               else                  *bp |= (png_byte)((v >> (-j)) & mask);            }         }      }      else if (row_info->bit_depth == 8)