| |
| /* pngwtran.c - transforms the data in a row for PNG writers |
| * |
| * Last changed in libpng 1.6.17 [(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" |
| #define PNG_SRC_FILE PNG_SRC_FILE_pngwtran |
| |
| #ifdef PNG_WRITE_SUPPORTED |
| #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED |
| |
| #ifdef PNG_WRITE_PACK_SUPPORTED |
| /* Pack pixels into bytes. Get the true bit depth from png_ptr. 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_transform_controlp row_info, png_bytep row) |
| { |
| png_debug(1, "in png_do_pack"); |
| |
| # define png_ptr row_info->png_ptr |
| |
| /* The comment suggests the following must be true. |
| * TODO: test this. |
| */ |
| affirm(row_info->bit_depth == 8 && row_info->channels == 1); |
| |
| { |
| switch (png_ptr->bit_depth) |
| { |
| case 1: |
| { |
| png_const_bytep ep = row + png_transform_rowbytes(row_info); |
| png_bytep dp = row; |
| unsigned int mask = 0x80, v = 0; |
| |
| while (row < ep) |
| { |
| if (*row++ != 0) |
| v |= mask; |
| |
| mask >>= 1; |
| |
| if (mask == 0) |
| { |
| mask = 0x80; |
| *dp++ = (png_byte)/*SAFE*/v; |
| v = 0; |
| } |
| } |
| |
| if (mask != 0x80) |
| *dp++ = (png_byte)/*SAFE*/v; |
| |
| row_info->bit_depth = 1; |
| break; |
| } |
| |
| case 2: |
| { |
| png_const_bytep ep = row + png_transform_rowbytes(row_info); |
| png_bytep dp = row; |
| unsigned int shift = 8, v = 0; |
| |
| while (row < ep) |
| { |
| shift -= 2; |
| v |= (*row++ & 0x3) << shift; |
| |
| if (shift == 0) |
| { |
| shift = 8; |
| *dp++ = png_check_byte(png_ptr, v); |
| v = 0; |
| } |
| } |
| |
| if (shift != 8) |
| *dp++ = png_check_byte(png_ptr, v); |
| |
| row_info->bit_depth = 2; |
| break; |
| } |
| |
| case 4: |
| { |
| png_const_bytep ep = row + png_transform_rowbytes(row_info); |
| png_bytep dp = row; |
| unsigned int shift = 8, v = 0; |
| |
| while (row < ep) |
| { |
| shift -= 4; |
| v |= ((*row++ & 0xf) << shift); |
| |
| if (shift == 0) |
| { |
| shift = 8; |
| *dp++ = png_check_byte(png_ptr, v); |
| v = 0; |
| } |
| } |
| |
| if (shift != 8) |
| *dp++ = png_check_byte(png_ptr, v); |
| |
| row_info->bit_depth = 4; |
| break; |
| } |
| |
| default: |
| break; |
| } |
| } |
| # undef png_ptr |
| } |
| #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. |
| * |
| * NOTE: this is horrible complexity for no value. Once people suggested they |
| * were selling 16-bit displays with 5:6:5 bits spread R:G:B but so far as I |
| * could determine these displays produced intermediate grey (uncolored) colors, |
| * which is impossible with a true 5:6:5, so most likely 5:6:5 was marketing. |
| */ |
| static void |
| png_do_shift(png_transform_controlp row_info, png_bytep row) |
| { |
| png_debug(1, "in png_do_shift"); |
| |
| # define png_ptr row_info->png_ptr |
| |
| if (!(row_info->flags & PNG_INDEXED) && (row_info->channels-1) <= 3) |
| { |
| png_const_color_8p bit_depth = &png_ptr->shift; |
| int shift_start[4], shift_dec[4]; |
| int channels = 0; |
| |
| if (row_info->channels == 3 || row_info->channels == 4) |
| { |
| 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 /* 1 or 2 channels */ |
| { |
| shift_start[channels] = row_info->bit_depth - bit_depth->gray; |
| shift_dec[channels] = bit_depth->gray; |
| channels++; |
| } |
| |
| if (row_info->channels == 2 || row_info->channels == 4) |
| { |
| shift_start[channels] = row_info->bit_depth - bit_depth->alpha; |
| shift_dec[channels] = bit_depth->alpha; |
| channels++; |
| } |
| |
| /* With low res 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; |
| size_t row_bytes = png_transform_rowbytes(row_info); |
| |
| affirm(row_info->channels == 1); |
| |
| 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_check_byte(png_ptr, out); |
| } |
| } |
| |
| 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_check_byte(png_ptr, out); |
| } |
| } |
| |
| 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_check_byte(png_ptr, value >> 8); |
| *bp++ = PNG_BYTE(value); |
| } |
| } |
| } |
| |
| # undef png_ptr |
| } |
| #endif |
| |
| #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED |
| static void |
| png_do_write_swap_alpha(png_transform_controlp row_info, png_bytep row) |
| { |
| png_debug(1, "in png_do_write_swap_alpha"); |
| |
| # define png_ptr row_info->png_ptr |
| { |
| if (row_info->channels == 4) |
| { |
| if (row_info->bit_depth == 8) |
| { |
| png_const_bytep ep = row + png_transform_rowbytes(row_info) - 4; |
| |
| /* This converts from ARGB to RGBA */ |
| while (row <= ep) |
| { |
| png_byte save = row[0]; |
| row[0] = row[1]; |
| row[1] = row[2]; |
| row[2] = row[3]; |
| row[3] = save; |
| row += 4; |
| } |
| |
| debug(row == ep+4); |
| } |
| |
| #ifdef PNG_WRITE_16BIT_SUPPORTED |
| else if (row_info->bit_depth == 16) |
| { |
| /* This converts from AARRGGBB to RRGGBBAA */ |
| png_const_bytep ep = row + png_transform_rowbytes(row_info) - 8; |
| |
| while (row <= ep) |
| { |
| png_byte s0 = row[0]; |
| png_byte s1 = row[1]; |
| memmove(row, row+2, 6); |
| row[6] = s0; |
| row[7] = s1; |
| row += 8; |
| } |
| |
| debug(row == ep+8); |
| } |
| #endif /* WRITE_16BIT */ |
| } |
| |
| else if (row_info->channels == 2) |
| { |
| if (row_info->bit_depth == 8) |
| { |
| /* This converts from AG to GA */ |
| png_const_bytep ep = row + png_transform_rowbytes(row_info) - 2; |
| |
| /* This converts from ARGB to RGBA */ |
| while (row <= ep) |
| { |
| png_byte save = *row; |
| *row = row[1], ++row; |
| *row++ = save; |
| } |
| |
| debug(row == ep+2); |
| } |
| |
| #ifdef PNG_WRITE_16BIT_SUPPORTED |
| else |
| { |
| /* This converts from AAGG to GGAA */ |
| png_const_bytep ep = row + png_transform_rowbytes(row_info) - 4; |
| |
| while (row <= ep) |
| { |
| png_byte save = row[0]; |
| row[0] = row[2]; |
| row[2] = save; |
| |
| save = row[1]; |
| row[1] = row[3]; |
| row[3] = save; |
| |
| row += 4; |
| } |
| |
| debug(row == ep+4); |
| } |
| #endif /* WRITE_16BIT */ |
| } |
| } |
| |
| # undef png_ptr |
| } |
| #endif |
| |
| #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED |
| static void |
| png_do_write_invert_alpha(png_transform_controlp row_info, png_bytep row) |
| { |
| png_debug(1, "in png_do_write_invert_alpha"); |
| |
| # define png_ptr row_info->png_ptr |
| { |
| if (row_info->channels == 4) |
| { |
| if (row_info->bit_depth == 8) |
| { |
| /* This inverts the alpha channel in RGBA */ |
| png_const_bytep ep = row + png_transform_rowbytes(row_info) - 1; |
| |
| row += 3; /* alpha channel */ |
| while (row <= ep) |
| *row ^= 0xff, row += 4; |
| } |
| |
| #ifdef PNG_WRITE_16BIT_SUPPORTED |
| else if (row_info->bit_depth == 16) |
| { |
| /* This inverts the alpha channel in RRGGBBAA */ |
| png_const_bytep ep = row + png_transform_rowbytes(row_info) - 2; |
| |
| row += 6; |
| |
| while (row <= ep) |
| row[0] ^= 0xff, row[1] ^= 0xff, row += 8; |
| } |
| #endif /* WRITE_16BIT */ |
| } |
| |
| else if (row_info->channels == 2) |
| { |
| if (row_info->bit_depth == 8) |
| { |
| /* This inverts the alpha channel in GA */ |
| png_const_bytep ep = row + png_transform_rowbytes(row_info) - 1; |
| |
| ++row; |
| |
| while (row <= ep) |
| *row ^= 0xff, row += 2; |
| } |
| |
| #ifdef PNG_WRITE_16BIT_SUPPORTED |
| else |
| { |
| /* This inverts the alpha channel in GGAA */ |
| png_const_bytep ep = row + png_transform_rowbytes(row_info) - 2; |
| |
| row += 2; |
| |
| while (row <= ep) |
| row[0] ^= 0xff, row[1] ^= 0xff, row += 4; |
| } |
| #endif /* WRITE_16BIT */ |
| } |
| } |
| # undef png_ptr |
| } |
| #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_in) |
| { |
| png_transform_control display; |
| |
| 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_in, /* 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 |
| |
| png_init_transform_control(png_ptr, &display, row_info_in); |
| |
| #ifdef PNG_WRITE_FILLER_SUPPORTED |
| if ((png_ptr->transformations & PNG_FILLER) != 0) |
| png_do_strip_channel(&display, 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(&display, png_ptr->row_buf + 1); |
| #endif |
| |
| #ifdef PNG_WRITE_PACK_SUPPORTED |
| if ((png_ptr->transformations & PNG_PACK) != 0) |
| png_do_pack(&display, png_ptr->row_buf + 1); |
| #endif |
| |
| #ifdef PNG_WRITE_SWAP_SUPPORTED |
| # ifdef PNG_16BIT_SUPPORTED |
| if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) |
| png_do_swap(&display, png_ptr->row_buf + 1); |
| # endif |
| #endif |
| |
| #ifdef PNG_WRITE_SHIFT_SUPPORTED |
| if ((png_ptr->transformations & PNG_SHIFT) != 0) |
| png_do_shift(&display, png_ptr->row_buf + 1); |
| #endif |
| |
| #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED |
| if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0) |
| png_do_write_swap_alpha(&display, 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(&display, png_ptr->row_buf + 1); |
| #endif |
| |
| #ifdef PNG_WRITE_BGR_SUPPORTED |
| if ((png_ptr->transformations & PNG_BGR) != 0) |
| png_do_bgr(&display, png_ptr->row_buf + 1); |
| #endif |
| |
| #ifdef PNG_WRITE_INVERT_SUPPORTED |
| if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) |
| png_do_invert(&display, png_ptr->row_buf + 1); |
| #endif |
| |
| /* Clear the flags; they are irrelevant because the write code is |
| * reversing transformations to get PNG data but the shared transformation |
| * code assumes input PNG data. Only PNG_INDEXED is required. |
| */ |
| if ((display.flags & PNG_BAD_INDEX) != 0) |
| png_error(png_ptr, "palette data has out of range index"); |
| |
| display.flags &= PNG_INDEXED; |
| png_end_transform_control(row_info_in, &display); |
| } |
| #endif /* WRITE_TRANSFORMS */ |
| #endif /* WRITE */ |
