2 /* pngwtran.c - transforms the data in a row for PNG writers
4 * Last changed in libpng 1.5.13 [September 27, 2012]
5 * Copyright (c) 1998-2012 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
18 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
19 /* Transform the data according to the user's wishes. The order of
20 * transformations is significant.
23 png_do_write_transformations(png_structp png_ptr
, png_row_infop row_info
)
25 png_debug(1, "in png_do_write_transformations");
30 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
31 if (png_ptr
->transformations
& PNG_USER_TRANSFORM
)
32 if (png_ptr
->write_user_transform_fn
!= NULL
)
33 (*(png_ptr
->write_user_transform_fn
)) /* User write transform
35 (png_ptr
, /* png_ptr */
36 row_info
, /* row_info: */
37 /* png_uint_32 width; width of row */
38 /* png_size_t rowbytes; number of bytes in row */
39 /* png_byte color_type; color type of pixels */
40 /* png_byte bit_depth; bit depth of samples */
41 /* png_byte channels; number of channels (1-4) */
42 /* png_byte pixel_depth; bits per pixel (depth*channels) */
43 png_ptr
->row_buf
+ 1); /* start of pixel data for row */
46 #ifdef PNG_WRITE_FILLER_SUPPORTED
47 if (png_ptr
->transformations
& PNG_FILLER
)
49 if (png_ptr
->color_type
& (PNG_COLOR_MASK_ALPHA
|PNG_COLOR_MASK_PALETTE
))
51 /* GA, RGBA or palette; in any of these cases libpng will not do the
52 * the correct thing (whatever that might be).
54 png_warning(png_ptr
, "incorrect png_set_filler call ignored");
55 png_ptr
->transformations
&= ~PNG_FILLER
;
59 png_do_strip_channel(row_info
, png_ptr
->row_buf
+ 1,
60 !(png_ptr
->flags
& PNG_FLAG_FILLER_AFTER
));
64 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
65 if (png_ptr
->transformations
& PNG_PACKSWAP
)
66 png_do_packswap(row_info
, png_ptr
->row_buf
+ 1);
69 #ifdef PNG_WRITE_PACK_SUPPORTED
70 if (png_ptr
->transformations
& PNG_PACK
)
71 png_do_pack(row_info
, png_ptr
->row_buf
+ 1,
72 (png_uint_32
)png_ptr
->bit_depth
);
75 #ifdef PNG_WRITE_SWAP_SUPPORTED
76 if (png_ptr
->transformations
& PNG_SWAP_BYTES
)
77 png_do_swap(row_info
, png_ptr
->row_buf
+ 1);
80 #ifdef PNG_WRITE_SHIFT_SUPPORTED
81 if (png_ptr
->transformations
& PNG_SHIFT
)
82 png_do_shift(row_info
, png_ptr
->row_buf
+ 1,
86 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
87 if (png_ptr
->transformations
& PNG_SWAP_ALPHA
)
88 png_do_write_swap_alpha(row_info
, png_ptr
->row_buf
+ 1);
91 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
92 if (png_ptr
->transformations
& PNG_INVERT_ALPHA
)
93 png_do_write_invert_alpha(row_info
, png_ptr
->row_buf
+ 1);
96 #ifdef PNG_WRITE_BGR_SUPPORTED
97 if (png_ptr
->transformations
& PNG_BGR
)
98 png_do_bgr(row_info
, png_ptr
->row_buf
+ 1);
101 #ifdef PNG_WRITE_INVERT_SUPPORTED
102 if (png_ptr
->transformations
& PNG_INVERT_MONO
)
103 png_do_invert(row_info
, png_ptr
->row_buf
+ 1);
107 #ifdef PNG_WRITE_PACK_SUPPORTED
108 /* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
109 * row_info bit depth should be 8 (one pixel per byte). The channels
110 * should be 1 (this only happens on grayscale and paletted images).
113 png_do_pack(png_row_infop row_info
, png_bytep row
, png_uint_32 bit_depth
)
115 png_debug(1, "in png_do_pack");
117 if (row_info
->bit_depth
== 8 &&
118 row_info
->channels
== 1)
120 switch ((int)bit_depth
)
127 png_uint_32 row_width
= row_info
->width
;
134 for (i
= 0; i
< row_width
; i
++)
164 png_uint_32 row_width
= row_info
->width
;
171 for (i
= 0; i
< row_width
; i
++)
175 value
= (png_byte
)(*sp
& 0x03);
176 v
|= (value
<< shift
);
203 png_uint_32 row_width
= row_info
->width
;
210 for (i
= 0; i
< row_width
; i
++)
214 value
= (png_byte
)(*sp
& 0x0f);
215 v
|= (value
<< shift
);
241 row_info
->bit_depth
= (png_byte
)bit_depth
;
242 row_info
->pixel_depth
= (png_byte
)(bit_depth
* row_info
->channels
);
243 row_info
->rowbytes
= PNG_ROWBYTES(row_info
->pixel_depth
,
249 #ifdef PNG_WRITE_SHIFT_SUPPORTED
250 /* Shift pixel values to take advantage of whole range. Pass the
251 * true number of bits in bit_depth. The row should be packed
252 * according to row_info->bit_depth. Thus, if you had a row of
253 * bit depth 4, but the pixels only had values from 0 to 7, you
254 * would pass 3 as bit_depth, and this routine would translate the
258 png_do_shift(png_row_infop row_info
, png_bytep row
,
259 png_const_color_8p bit_depth
)
261 png_debug(1, "in png_do_shift");
263 if (row_info
->color_type
!= PNG_COLOR_TYPE_PALETTE
)
265 int shift_start
[4], shift_dec
[4];
268 if (row_info
->color_type
& PNG_COLOR_MASK_COLOR
)
270 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->red
;
271 shift_dec
[channels
] = bit_depth
->red
;
274 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->green
;
275 shift_dec
[channels
] = bit_depth
->green
;
278 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->blue
;
279 shift_dec
[channels
] = bit_depth
->blue
;
285 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->gray
;
286 shift_dec
[channels
] = bit_depth
->gray
;
290 if (row_info
->color_type
& PNG_COLOR_MASK_ALPHA
)
292 shift_start
[channels
] = row_info
->bit_depth
- bit_depth
->alpha
;
293 shift_dec
[channels
] = bit_depth
->alpha
;
297 /* With low row depths, could only be grayscale, so one channel */
298 if (row_info
->bit_depth
< 8)
303 png_size_t row_bytes
= row_info
->rowbytes
;
305 if (bit_depth
->gray
== 1 && row_info
->bit_depth
== 2)
308 else if (row_info
->bit_depth
== 4 && bit_depth
->gray
== 3)
314 for (i
= 0; i
< row_bytes
; i
++, bp
++)
322 for (j
= shift_start
[0]; j
> -shift_dec
[0]; j
-= shift_dec
[0])
325 *bp
|= (png_byte
)((v
<< j
) & 0xff);
328 *bp
|= (png_byte
)((v
>> (-j
)) & mask
);
333 else if (row_info
->bit_depth
== 8)
337 png_uint_32 istop
= channels
* row_info
->width
;
339 for (i
= 0; i
< istop
; i
++, bp
++)
344 int c
= (int)(i
%channels
);
349 for (j
= shift_start
[c
]; j
> -shift_dec
[c
]; j
-= shift_dec
[c
])
352 *bp
|= (png_byte
)((v
<< j
) & 0xff);
355 *bp
|= (png_byte
)((v
>> (-j
)) & 0xff);
364 png_uint_32 istop
= channels
* row_info
->width
;
366 for (bp
= row
, i
= 0; i
< istop
; i
++)
368 int c
= (int)(i
%channels
);
369 png_uint_16 value
, v
;
372 v
= (png_uint_16
)(((png_uint_16
)(*bp
) << 8) + *(bp
+ 1));
375 for (j
= shift_start
[c
]; j
> -shift_dec
[c
]; j
-= shift_dec
[c
])
378 value
|= (png_uint_16
)((v
<< j
) & (png_uint_16
)0xffff);
381 value
|= (png_uint_16
)((v
>> (-j
)) & (png_uint_16
)0xffff);
383 *bp
++ = (png_byte
)(value
>> 8);
384 *bp
++ = (png_byte
)(value
& 0xff);
391 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
393 png_do_write_swap_alpha(png_row_infop row_info
, png_bytep row
)
395 png_debug(1, "in png_do_write_swap_alpha");
398 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
400 if (row_info
->bit_depth
== 8)
402 /* This converts from ARGB to RGBA */
405 png_uint_32 row_width
= row_info
->width
;
407 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
409 png_byte save
= *(sp
++);
417 #ifdef PNG_WRITE_16BIT_SUPPORTED
420 /* This converts from AARRGGBB to RRGGBBAA */
423 png_uint_32 row_width
= row_info
->width
;
425 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
440 #endif /* PNG_WRITE_16BIT_SUPPORTED */
443 else if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
)
445 if (row_info
->bit_depth
== 8)
447 /* This converts from AG to GA */
450 png_uint_32 row_width
= row_info
->width
;
452 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
454 png_byte save
= *(sp
++);
460 #ifdef PNG_WRITE_16BIT_SUPPORTED
463 /* This converts from AAGG to GGAA */
466 png_uint_32 row_width
= row_info
->width
;
468 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
479 #endif /* PNG_WRITE_16BIT_SUPPORTED */
485 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
487 png_do_write_invert_alpha(png_row_infop row_info
, png_bytep row
)
489 png_debug(1, "in png_do_write_invert_alpha");
492 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
494 if (row_info
->bit_depth
== 8)
496 /* This inverts the alpha channel in RGBA */
499 png_uint_32 row_width
= row_info
->width
;
501 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
509 *(dp
++) = (png_byte
)(255 - *(sp
++));
513 #ifdef PNG_WRITE_16BIT_SUPPORTED
516 /* This inverts the alpha channel in RRGGBBAA */
519 png_uint_32 row_width
= row_info
->width
;
521 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
532 *(dp
++) = (png_byte
)(255 - *(sp
++));
533 *(dp
++) = (png_byte
)(255 - *(sp
++));
536 #endif /* PNG_WRITE_16BIT_SUPPORTED */
539 else if (row_info
->color_type
== PNG_COLOR_TYPE_GRAY_ALPHA
)
541 if (row_info
->bit_depth
== 8)
543 /* This inverts the alpha channel in GA */
546 png_uint_32 row_width
= row_info
->width
;
548 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
551 *(dp
++) = (png_byte
)(255 - *(sp
++));
555 #ifdef PNG_WRITE_16BIT_SUPPORTED
558 /* This inverts the alpha channel in GGAA */
561 png_uint_32 row_width
= row_info
->width
;
563 for (i
= 0, sp
= dp
= row
; i
< row_width
; i
++)
570 *(dp
++) = (png_byte
)(255 - *(sp
++));
571 *(dp
++) = (png_byte
)(255 - *(sp
++));
574 #endif /* PNG_WRITE_16BIT_SUPPORTED */
579 #endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
581 #ifdef PNG_MNG_FEATURES_SUPPORTED
582 /* Undoes intrapixel differencing */
584 png_do_write_intrapixel(png_row_infop row_info
, png_bytep row
)
586 png_debug(1, "in png_do_write_intrapixel");
588 if ((row_info
->color_type
& PNG_COLOR_MASK_COLOR
))
591 png_uint_32 row_width
= row_info
->width
;
592 if (row_info
->bit_depth
== 8)
597 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB
)
600 else if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
606 for (i
= 0, rp
= row
; i
< row_width
; i
++, rp
+= bytes_per_pixel
)
608 *(rp
) = (png_byte
)((*rp
- *(rp
+ 1)) & 0xff);
609 *(rp
+ 2) = (png_byte
)((*(rp
+ 2) - *(rp
+ 1)) & 0xff);
613 #ifdef PNG_WRITE_16BIT_SUPPORTED
614 else if (row_info
->bit_depth
== 16)
619 if (row_info
->color_type
== PNG_COLOR_TYPE_RGB
)
622 else if (row_info
->color_type
== PNG_COLOR_TYPE_RGB_ALPHA
)
628 for (i
= 0, rp
= row
; i
< row_width
; i
++, rp
+= bytes_per_pixel
)
630 png_uint_32 s0
= (*(rp
) << 8) | *(rp
+ 1);
631 png_uint_32 s1
= (*(rp
+ 2) << 8) | *(rp
+ 3);
632 png_uint_32 s2
= (*(rp
+ 4) << 8) | *(rp
+ 5);
633 png_uint_32 red
= (png_uint_32
)((s0
- s1
) & 0xffffL
);
634 png_uint_32 blue
= (png_uint_32
)((s2
- s1
) & 0xffffL
);
635 *(rp
) = (png_byte
)((red
>> 8) & 0xff);
636 *(rp
+ 1) = (png_byte
)(red
& 0xff);
637 *(rp
+ 4) = (png_byte
)((blue
>> 8) & 0xff);
638 *(rp
+ 5) = (png_byte
)(blue
& 0xff);
641 #endif /* PNG_WRITE_16BIT_SUPPORTED */
644 #endif /* PNG_MNG_FEATURES_SUPPORTED */
645 #endif /* PNG_WRITE_SUPPORTED */