2 /* pngwtran.c - transforms the data in a row for PNG writers
4 * Last changed in libpng 1.6.9 [February 6, 2014]
5 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
16 #ifdef PNG_WRITE_SUPPORTED
17 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
19 #ifdef PNG_WRITE_PACK_SUPPORTED
20 /* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
21 * row_info bit depth should be 8 (one pixel per byte). The channels
22 * should be 1 (this only happens on grayscale and paletted images).
25 png_do_pack(png_row_infop row_info
, png_bytep row
, png_uint_32 bit_depth
)
27 png_debug(1, "in png_do_pack");
29 if (row_info
->bit_depth
== 8 &&
30 row_info
->channels
== 1)
32 switch ((int)bit_depth
)
39 png_uint_32 row_width
= row_info
->width
;
46 for (i
= 0; i
< row_width
; i
++)
76 png_uint_32 row_width
= row_info
->width
;
83 for (i
= 0; i
< row_width
; i
++)
87 value
= (png_byte
)(*sp
& 0x03);
88 v
|= (value
<< shift
);
115 png_uint_32 row_width
= row_info
->width
;
122 for (i
= 0; i
< row_width
; i
++)
126 value
= (png_byte
)(*sp
& 0x0f);
127 v
|= (value
<< shift
);
153 row_info
->bit_depth
= (png_byte
)bit_depth
;
154 row_info
->pixel_depth
= (png_byte
)(bit_depth
* row_info
->channels
);
155 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
,
161 #ifdef PNG_WRITE_SHIFT_SUPPORTED
162 /* Shift pixel values to take advantage of whole range. Pass the
163 * true number of bits in bit_depth. The row should be packed
164 * according to row_info->bit_depth. Thus, if you had a row of
165 * bit depth 4, but the pixels only had values from 0 to 7, you
166 * would pass 3 as bit_depth, and this routine would translate the
170 png_do_shift(png_row_infop row_info
, png_bytep row
,
171 png_const_color_8p bit_depth
)
173 png_debug(1, "in png_do_shift");
175 if (row_info
->color_type
!= PNG_COLOR_TYPE_PALETTE
)
177 int shift_start
[4], shift_dec
[4];
180 if (row_info
->color_type
& PNG_COLOR_MASK_COLOR
)
182 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->red
;
183 shift_dec
[channels
] = bit_depth
->red
;
186 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->green
;
187 shift_dec
[channels
] = bit_depth
->green
;
190 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->blue
;
191 shift_dec
[channels
] = bit_depth
->blue
;
197 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->gray
;
198 shift_dec
[channels
] = bit_depth
->gray
;
202 if (row_info
->color_type
& PNG_COLOR_MASK_ALPHA
)
204 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->alpha
;
205 shift_dec
[channels
] = bit_depth
->alpha
;
209 /* With low row depths, could only be grayscale, so one channel */
210 if (row_info
->bit_depth
< 8)
215 png_size_t row_bytes
= row_info
->rowbytes
;
217 if (bit_depth
->gray
== 1 && row_info
->bit_depth
== 2)
220 else if (row_info
->bit_depth
== 4 && bit_depth
->gray
== 3)
226 for (i
= 0; i
< row_bytes
; i
++, bp
++)
234 for (j
= shift_start
[0]; j
> -shift_dec
[0]; j
-= shift_dec
[0])
240 out
|= (v
>> (-j
)) & mask
;
243 *bp
= (png_byte
)(out
& 0xff);
247 else if (row_info
->bit_depth
== 8)
251 png_uint_32 istop
= channels
* row_info
->width
;
253 for (i
= 0; i
< istop
; i
++, bp
++)
256 const unsigned int c
= i
%channels
;
263 for (j
= shift_start
[c
]; j
> -shift_dec
[c
]; j
-= shift_dec
[c
])
272 *bp
= (png_byte
)(out
& 0xff);
280 png_uint_32 istop
= channels
* row_info
->width
;
282 for (bp
= row
, i
= 0; i
< istop
; i
++)
284 const unsigned int c
= i
%channels
;
286 unsigned int value
, v
;
288 v
= png_get_uint_16(bp
);
291 for (j
= shift_start
[c
]; j
> -shift_dec
[c
]; j
-= shift_dec
[c
])
299 *bp
++ = (png_byte
)((value
>> 8) & 0xff);
300 *bp
++ = (png_byte
)(value
& 0xff);
307 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
309 png_do_write_swap_alpha(png_row_infop row_info
, png_bytep row
)
311 png_debug(1, "in png_do_write_swap_alpha");
314 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
316 if (row_info
->bit_depth
== 8)
318 /* This converts from ARGB to RGBA */
321 png_uint_32 row_width
= row_info
->width
;
323 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
325 png_byte save
= *(sp
++);
333 #ifdef PNG_WRITE_16BIT_SUPPORTED
336 /* This converts from AARRGGBB to RRGGBBAA */
339 png_uint_32 row_width
= row_info
->width
;
341 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
356 #endif /* PNG_WRITE_16BIT_SUPPORTED */
359 else if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
)
361 if (row_info
->bit_depth
== 8)
363 /* This converts from AG to GA */
366 png_uint_32 row_width
= row_info
->width
;
368 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
370 png_byte save
= *(sp
++);
376 #ifdef PNG_WRITE_16BIT_SUPPORTED
379 /* This converts from AAGG to GGAA */
382 png_uint_32 row_width
= row_info
->width
;
384 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
395 #endif /* PNG_WRITE_16BIT_SUPPORTED */
401 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
403 png_do_write_invert_alpha(png_row_infop row_info
, png_bytep row
)
405 png_debug(1, "in png_do_write_invert_alpha");
408 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
410 if (row_info
->bit_depth
== 8)
412 /* This inverts the alpha channel in RGBA */
415 png_uint_32 row_width
= row_info
->width
;
417 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
425 *(dp
++) = (png_byte
)(255 - *(sp
++));
429 #ifdef PNG_WRITE_16BIT_SUPPORTED
432 /* This inverts the alpha channel in RRGGBBAA */
435 png_uint_32 row_width
= row_info
->width
;
437 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
448 *(dp
++) = (png_byte
)(255 - *(sp
++));
449 *(dp
++) = (png_byte
)(255 - *(sp
++));
452 #endif /* PNG_WRITE_16BIT_SUPPORTED */
455 else if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
)
457 if (row_info
->bit_depth
== 8)
459 /* This inverts the alpha channel in GA */
462 png_uint_32 row_width
= row_info
->width
;
464 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
467 *(dp
++) = (png_byte
)(255 - *(sp
++));
471 #ifdef PNG_WRITE_16BIT_SUPPORTED
474 /* This inverts the alpha channel in GGAA */
477 png_uint_32 row_width
= row_info
->width
;
479 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
486 *(dp
++) = (png_byte
)(255 - *(sp
++));
487 *(dp
++) = (png_byte
)(255 - *(sp
++));
490 #endif /* PNG_WRITE_16BIT_SUPPORTED */
496 /* Transform the data according to the user's wishes. The order of
497 * transformations is significant.
500 png_do_write_transformations(png_structrp png_ptr
, png_row_infop row_info
)
502 png_debug(1, "in png_do_write_transformations");
507 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
508 if (png_ptr
->transformations
& PNG_USER_TRANSFORM
)
509 if (png_ptr
->write_user_transform_fn
!= NULL
)
510 (*(png_ptr
->write_user_transform_fn
)) /* User write transform
512 (png_ptr
, /* png_ptr */
513 row_info
, /* row_info: */
514 /* png_uint_32 width; width of row */
515 /* png_size_t rowbytes; number of bytes in row */
516 /* png_byte color_type; color type of pixels */
517 /* png_byte bit_depth; bit depth of samples */
518 /* png_byte channels; number of channels (1-4) */
519 /* png_byte pixel_depth; bits per pixel (depth*channels) */
520 png_ptr
->row_buf
+ 1); /* start of pixel data for row */
523 #ifdef PNG_WRITE_FILLER_SUPPORTED
524 if (png_ptr
->transformations
& PNG_FILLER
)
525 png_do_strip_channel(row_info
, png_ptr
->row_buf
+ 1,
526 !(png_ptr
->flags
& PNG_FLAG_FILLER_AFTER
));
529 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
530 if (png_ptr
->transformations
& PNG_PACKSWAP
)
531 png_do_packswap(row_info
, png_ptr
->row_buf
+ 1);
534 #ifdef PNG_WRITE_PACK_SUPPORTED
535 if (png_ptr
->transformations
& PNG_PACK
)
536 png_do_pack(row_info
, png_ptr
->row_buf
+ 1,
537 (png_uint_32
)png_ptr
->bit_depth
);
540 #ifdef PNG_WRITE_SWAP_SUPPORTED
541 if (png_ptr
->transformations
& PNG_SWAP_BYTES
)
542 png_do_swap(row_info
, png_ptr
->row_buf
+ 1);
545 #ifdef PNG_WRITE_SHIFT_SUPPORTED
546 if (png_ptr
->transformations
& PNG_SHIFT
)
547 png_do_shift(row_info
, png_ptr
->row_buf
+ 1,
551 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
552 if (png_ptr
->transformations
& PNG_SWAP_ALPHA
)
553 png_do_write_swap_alpha(row_info
, png_ptr
->row_buf
+ 1);
556 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
557 if (png_ptr
->transformations
& PNG_INVERT_ALPHA
)
558 png_do_write_invert_alpha(row_info
, png_ptr
->row_buf
+ 1);
561 #ifdef PNG_WRITE_BGR_SUPPORTED
562 if (png_ptr
->transformations
& PNG_BGR
)
563 png_do_bgr(row_info
, png_ptr
->row_buf
+ 1);
566 #ifdef PNG_WRITE_INVERT_SUPPORTED
567 if (png_ptr
->transformations
& PNG_INVERT_MONO
)
568 png_do_invert(row_info
, png_ptr
->row_buf
+ 1);
571 #endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
572 #endif /* PNG_WRITE_SUPPORTED */