| |
| /* pngwtran.c - transforms the data in a row for png writers |
| |
| libpng 1.0 beta 1 - version 0.71 |
| For conditions of distribution and use, see copyright notice in png.h |
| Copyright (c) 1995 Guy Eric Schalnat, Group 42, Inc. |
| June 26, 1995 |
| */ |
| |
| #define PNG_INTERNAL |
| #include "png.h" |
| |
| /* transform the data according to the users wishes. The order of |
| transformations is significant. */ |
| void |
| png_do_write_transformations(png_struct *png_ptr) |
| { |
| if (png_ptr->transformations & PNG_RGBA) |
| png_do_write_rgbx(&(png_ptr->row_info), png_ptr->row_buf + 1); |
| if (png_ptr->transformations & PNG_XRGB) |
| png_do_write_xrgb(&(png_ptr->row_info), png_ptr->row_buf + 1); |
| if (png_ptr->transformations & PNG_PACK) |
| png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1, |
| png_ptr->bit_depth); |
| if (png_ptr->transformations & PNG_SHIFT) |
| png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1, |
| &(png_ptr->shift)); |
| if (png_ptr->transformations & PNG_SWAP_BYTES) |
| png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1); |
| if (png_ptr->transformations & PNG_BGR) |
| png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1); |
| if (png_ptr->transformations & PNG_INVERT_MONO) |
| png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1); |
| } |
| |
| /* 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 |
| png_do_pack(png_row_info *row_info, png_byte *row, png_byte bit_depth) |
| { |
| if (row_info && row && row_info->bit_depth == 8 && |
| row_info->channels == 1) |
| { |
| switch (bit_depth) |
| { |
| case 1: |
| { |
| png_byte *sp; |
| png_byte *dp; |
| int mask; |
| png_int_32 i; |
| int v; |
| |
| sp = row; |
| dp = row; |
| mask = 0x80; |
| v = 0; |
| for (i = 0; i < row_info->width; i++) |
| { |
| if (*sp) |
| v |= mask; |
| sp++; |
| if (mask > 1) |
| mask >>= 1; |
| else |
| { |
| mask = 0x80; |
| *dp = v; |
| dp++; |
| v = 0; |
| } |
| } |
| if (mask != 0x80) |
| *dp = v; |
| break; |
| } |
| case 2: |
| { |
| png_byte *sp; |
| png_byte *dp; |
| int shift; |
| png_int_32 i; |
| int v; |
| png_byte value; |
| |
| sp = row; |
| dp = row; |
| shift = 6; |
| v = 0; |
| for (i = 0; i < row_info->width; i++) |
| { |
| value = *sp & 0x3; |
| v |= (value << shift); |
| if (shift == 0) |
| { |
| shift = 6; |
| *dp = v; |
| dp++; |
| v = 0; |
| } |
| else |
| shift -= 2; |
| sp++; |
| } |
| if (shift != 6) |
| *dp = v; |
| break; |
| } |
| case 4: |
| { |
| png_byte *sp; |
| png_byte *dp; |
| int shift; |
| png_int_32 i; |
| int v; |
| png_byte value; |
| |
| sp = row; |
| dp = row; |
| shift = 4; |
| v = 0; |
| for (i = 0; i < row_info->width; i++) |
| { |
| value = *sp & 0xf; |
| v |= (value << shift); |
| |
| if (shift == 0) |
| { |
| shift = 4; |
| *dp = v; |
| dp++; |
| v = 0; |
| } |
| else |
| shift -= 4; |
| |
| sp++; |
| } |
| if (shift != 4) |
| *dp = v; |
| break; |
| } |
| } |
| row_info->bit_depth = bit_depth; |
| row_info->pixel_depth = bit_depth * row_info->channels; |
| row_info->rowbytes = |
| ((row_info->width * row_info->pixel_depth + 7) >> 3); |
| } |
| } |
| |
| /* 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 |
| png_do_shift(png_row_info *row_info, png_byte *row, png_color_8 *bit_depth) |
| { |
| if (row && row_info && |
| row_info->color_type != PNG_COLOR_TYPE_PALETTE) |
| { |
| int shift_start[4], shift_dec[4]; |
| int channels; |
| |
| 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 dephts, could only be grayscale, so one channel */ |
| if (row_info->bit_depth < 8) |
| { |
| png_byte *bp; |
| png_uint_32 i; |
| int j; |
| png_byte mask; |
| |
| 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 (bp = row, i = 0; i < row_info->rowbytes; i++, bp++) |
| { |
| int v; |
| |
| 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) |
| { |
| png_byte *bp; |
| png_uint_32 i; |
| int j; |
| |
| for (bp = row, i = 0; i < row_info->width; i++) |
| { |
| int c; |
| |
| for (c = 0; c < channels; c++, bp++) |
| { |
| int v; |
| |
| v = *bp; |
| *bp = 0; |
| for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c]) |
| { |
| if (j > 0) |
| *bp |= (png_byte)((v << j) & 0xff); |
| else |
| *bp |= (png_byte)((v >> (-j)) & 0xff); |
| } |
| } |
| } |
| } |
| else |
| { |
| png_byte *bp; |
| png_uint_32 i; |
| int j; |
| |
| for (bp = row, i = 0; |
| i < row_info->width * row_info->channels; |
| i++) |
| { |
| int c; |
| |
| for (c = 0; c < channels; c++, bp += 2) |
| { |
| png_uint_16 value, v; |
| |
| v = ((png_uint_16)(*bp) << 8) + (png_uint_16)(*(bp + 1)); |
| value = 0; |
| for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c]) |
| { |
| if (j > 0) |
| value |= (png_uint_16)((v << j) & (png_uint_16)0xffff); |
| else |
| value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff); |
| } |
| *bp = value >> 8; |
| *(bp + 1) = value & 0xff; |
| } |
| } |
| } |
| } |
| } |
| |
| /* remove filler byte after rgb */ |
| void |
| png_do_write_rgbx(png_row_info *row_info, png_byte *row) |
| { |
| if (row && row_info && row_info->color_type == PNG_COLOR_TYPE_RGB && |
| row_info->bit_depth == 8) |
| { |
| png_byte *sp, *dp; |
| png_uint_32 i; |
| |
| for (i = 1, sp = row + 4, dp = row + 3; |
| i < row_info->width; |
| i++) |
| { |
| *dp++ = *sp++; |
| *dp++ = *sp++; |
| *dp++ = *sp++; |
| sp++; |
| } |
| row_info->channels = 3; |
| row_info->pixel_depth = 24; |
| row_info->rowbytes = row_info->width * 3; |
| } |
| } |
| |
| /* remove filler byte before rgb */ |
| void |
| png_do_write_xrgb(png_row_info *row_info, png_byte *row) |
| { |
| if (row && row_info && row_info->color_type == PNG_COLOR_TYPE_RGB && |
| row_info->bit_depth == 8) |
| { |
| png_byte *sp, *dp; |
| png_uint_32 i; |
| |
| for (i = 0, sp = row, dp = row; |
| i < row_info->width; |
| i++) |
| { |
| sp++; |
| *dp++ = *sp++; |
| *dp++ = *sp++; |
| *dp++ = *sp++; |
| } |
| row_info->channels = 3; |
| row_info->pixel_depth = 24; |
| row_info->rowbytes = row_info->width * 3; |
| } |
| } |
| |
