/* pngwtran.c - transforms the data in a row for PNG writers * * Last changed in libpng 1.6.18 [(PENDING RELEASE)] * Copyright (c) 1998-2015 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.) * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h */ #include "pngpriv.h" #ifdef PNG_WRITE_SUPPORTED #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED #ifdef 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). */ static void png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth) { png_debug(1, "in png_do_pack"); if (row_info->bit_depth == 8 && 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; } default: break; } row_info->bit_depth = (png_byte)bit_depth; row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels); row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width); } } #endif #ifdef 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. */ static void png_do_shift(png_row_infop row_info, png_bytep row, png_const_color_8p bit_depth) { png_debug(1, "in png_do_shift"); if (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) != 0) { 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) != 0) { 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_size_t i; unsigned int mask; png_size_t 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++) { int j; unsigned int v, out; v = *bp; out = 0; for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0]) { if (j > 0) out |= v << j; else out |= (v >> (-j)) & mask; } *bp = (png_byte)(out & 0xff); } } else if (row_info->bit_depth == 8) { png_bytep bp = row; png_uint_32 i; png_uint_32 istop = channels * row_info->width; for (i = 0; i < istop; i++, bp++) { const unsigned int c = i%channels; int j; unsigned int v, out; v = *bp; out = 0; for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c]) { if (j > 0) out |= v << j; else out |= v >> (-j); } *bp = (png_byte)(out & 0xff); } } else { png_bytep bp; png_uint_32 i; png_uint_32 istop = channels * row_info->width; for (bp = row, i = 0; i < istop; i++) { const unsigned int c = i%channels; int j; unsigned int value, v; v = png_get_uint_16(bp); value = 0; for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c]) { if (j > 0) value |= v << j; else value |= v >> (-j); } *bp++ = (png_byte)((value >> 8) & 0xff); *bp++ = (png_byte)(value & 0xff); } } } } #endif #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED static void png_do_write_swap_alpha(png_row_infop row_info, png_bytep row) { png_debug(1, "in png_do_write_swap_alpha"); { if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) { if (row_info->bit_depth == 8) { /* This converts from ARGB to RGBA */ png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width = row_info->width; for (i = 0, sp = dp = row; i < row_width; i++) { png_byte save = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = save; } } #ifdef PNG_WRITE_16BIT_SUPPORTED else { /* This converts from AARRGGBB to RRGGBBAA */ png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width = row_info->width; for (i = 0, sp = dp = row; i < row_width; i++) { png_byte save[2]; save[0] = *(sp++); save[1] = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = save[0]; *(dp++) = save[1]; } } #endif /* WRITE_16BIT */ } else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) { if (row_info->bit_depth == 8) { /* This converts from AG to GA */ png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width = row_info->width; for (i = 0, sp = dp = row; i < row_width; i++) { png_byte save = *(sp++); *(dp++) = *(sp++); *(dp++) = save; } } #ifdef PNG_WRITE_16BIT_SUPPORTED else { /* This converts from AAGG to GGAA */ png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width = row_info->width; for (i = 0, sp = dp = row; i < row_width; i++) { png_byte save[2]; save[0] = *(sp++); save[1] = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = save[0]; *(dp++) = save[1]; } } #endif /* WRITE_16BIT */ } } } #endif #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED static void png_do_write_invert_alpha(png_row_infop row_info, png_bytep row) { png_debug(1, "in png_do_write_invert_alpha"); { if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) { if (row_info->bit_depth == 8) { /* This inverts the alpha channel in RGBA */ png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width = row_info->width; for (i = 0, sp = dp = row; i < row_width; i++) { /* Does nothing *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); */ sp+=3; dp = sp; *dp = (png_byte)(255 - *(sp++)); } } #ifdef PNG_WRITE_16BIT_SUPPORTED else { /* This inverts the alpha channel in RRGGBBAA */ png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width = row_info->width; for (i = 0, sp = dp = row; i < row_width; i++) { /* Does nothing *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); *(dp++) = *(sp++); */ sp+=6; dp = sp; *(dp++) = (png_byte)(255 - *(sp++)); *dp = (png_byte)(255 - *(sp++)); } } #endif /* WRITE_16BIT */ } else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) { if (row_info->bit_depth == 8) { /* This inverts the alpha channel in GA */ png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width = row_info->width; for (i = 0, sp = dp = row; i < row_width; i++) { *(dp++) = *(sp++); *(dp++) = (png_byte)(255 - *(sp++)); } } #ifdef PNG_WRITE_16BIT_SUPPORTED else { /* This inverts the alpha channel in GGAA */ png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width = row_info->width; for (i = 0, sp = dp = row; i < row_width; i++) { /* Does nothing *(dp++) = *(sp++); *(dp++) = *(sp++); */ sp+=2; dp = sp; *(dp++) = (png_byte)(255 - *(sp++)); *dp = (png_byte)(255 - *(sp++)); } } #endif /* WRITE_16BIT */ } } } #endif /* Transform the data according to the user's wishes. The order of * transformations is significant. */ void /* PRIVATE */ png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info) { png_debug(1, "in png_do_write_transformations"); if (png_ptr == NULL) return; #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0) if (png_ptr->write_user_transform_fn != NULL) (*(png_ptr->write_user_transform_fn)) /* User write transform function */ (png_ptr, /* png_ptr */ row_info, /* row_info: */ /* png_uint_32 width; width of row */ /* png_size_t 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 #ifdef PNG_WRITE_FILLER_SUPPORTED if ((png_ptr->transformations & PNG_FILLER) != 0) png_do_strip_channel(row_info, png_ptr->row_buf + 1, !(png_ptr->flags & PNG_FLAG_FILLER_AFTER)); #endif #ifdef PNG_WRITE_PACKSWAP_SUPPORTED if ((png_ptr->transformations & PNG_PACKSWAP) != 0) png_do_packswap(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_WRITE_PACK_SUPPORTED if ((png_ptr->transformations & PNG_PACK) != 0) png_do_pack(row_info, png_ptr->row_buf + 1, (png_uint_32)png_ptr->bit_depth); #endif #ifdef PNG_WRITE_SWAP_SUPPORTED # ifdef PNG_16BIT_SUPPORTED if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) png_do_swap(row_info, png_ptr->row_buf + 1); # endif #endif #ifdef PNG_WRITE_SHIFT_SUPPORTED if ((png_ptr->transformations & PNG_SHIFT) != 0) png_do_shift(row_info, png_ptr->row_buf + 1, &(png_ptr->shift)); #endif #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0) png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0) png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_WRITE_BGR_SUPPORTED if ((png_ptr->transformations & PNG_BGR) != 0) png_do_bgr(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_WRITE_INVERT_SUPPORTED if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) png_do_invert(row_info, png_ptr->row_buf + 1); #endif } #endif /* WRITE_TRANSFORMS */ #endif /* WRITE */