mirror of
https://git.code.sf.net/p/libpng/code.git
synced 2025-07-10 18:04:09 +02:00
chore: Fix and update the libpng manual
Fix various typos and whitespace errors, and clean up obsolete formulations such as `(png_infopp)NULL`. Bring all URLs up to date.
This commit is contained in:
Cosmin Truta
parent
ac944e2b36
commit
537c66660e
@ -385,8 +385,7 @@ create the structure, so your application should check for that.
|
||||
|
||||
if (!info_ptr)
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr,
|
||||
(png_infopp)NULL, (png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, NULL, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -419,14 +418,13 @@ free any memory.
|
||||
|
||||
if (setjmp(png_jmpbuf(png_ptr)))
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
&end_info);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
|
||||
fclose(fp);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
Pass (png_infopp)NULL instead of &end_info if you didn't create
|
||||
an end_info structure.
|
||||
Pass NULL instead of &end_info if you didn't create an end_info
|
||||
structure.
|
||||
|
||||
If you would rather avoid the complexity of setjmp/longjmp issues,
|
||||
you can compile libpng with PNG_NO_SETJMP, in which case
|
||||
@ -496,7 +494,7 @@ You can set up a callback function to handle any unknown chunks in the
|
||||
input stream. You must supply the function
|
||||
|
||||
read_chunk_callback(png_structp png_ptr,
|
||||
png_unknown_chunkp chunk);
|
||||
png_unknown_chunkp chunk)
|
||||
{
|
||||
/* The unknown chunk structure contains your
|
||||
chunk data, along with similar data for any other
|
||||
@ -547,7 +545,7 @@ a progress meter or the like. It's demonstrated in pngtest.c.
|
||||
You must supply a function
|
||||
|
||||
void read_row_callback(png_structp png_ptr,
|
||||
png_uint_32 row, int pass);
|
||||
png_uint_32 row, int pass)
|
||||
{
|
||||
/* put your code here */
|
||||
}
|
||||
@ -1181,21 +1179,21 @@ If you know your image size and pixel size ahead of time, you can allocate
|
||||
row_pointers prior to calling png_read_png() with
|
||||
|
||||
if (height > PNG_UINT_32_MAX/(sizeof (png_byte)))
|
||||
png_error (png_ptr,
|
||||
png_error(png_ptr,
|
||||
"Image is too tall to process in memory");
|
||||
|
||||
if (width > PNG_UINT_32_MAX/pixel_size)
|
||||
png_error (png_ptr,
|
||||
png_error(png_ptr,
|
||||
"Image is too wide to process in memory");
|
||||
|
||||
row_pointers = png_malloc(png_ptr,
|
||||
height*(sizeof (png_bytep)));
|
||||
|
||||
for (int i=0; i<height, i++)
|
||||
row_pointers[i]=NULL; /* security precaution */
|
||||
for (int i = 0; i < height, i++)
|
||||
row_pointers[i] = NULL; /* security precaution */
|
||||
|
||||
for (int i=0; i<height, i++)
|
||||
row_pointers[i]=png_malloc(png_ptr,
|
||||
for (int i = 0; i < height, i++)
|
||||
row_pointers[i] = png_malloc(png_ptr,
|
||||
width*pixel_size);
|
||||
|
||||
png_set_rows(png_ptr, info_ptr, &row_pointers);
|
||||
@ -1205,14 +1203,14 @@ row_pointers[i] to point into the proper places in your block, but first
|
||||
be sure that your platform is able to allocate such a large buffer:
|
||||
|
||||
/* Guard against integer overflow */
|
||||
if (height > PNG_SIZE_MAX/(width*pixel_size)) {
|
||||
png_error(png_ptr,"image_data buffer would be too large");
|
||||
}
|
||||
if (height > PNG_SIZE_MAX/(width*pixel_size))
|
||||
png_error(png_ptr, "image_data buffer would be too large");
|
||||
|
||||
png_bytep buffer=png_malloc(png_ptr,height*width*pixel_size);
|
||||
png_bytep buffer = png_malloc(png_ptr,
|
||||
height*width*pixel_size);
|
||||
|
||||
for (int i=0; i<height, i++)
|
||||
row_pointers[i]=buffer+i*width*pixel_size;
|
||||
for (int i = 0; i < height, i++)
|
||||
row_pointers[i] = buffer + i*width*pixel_size;
|
||||
|
||||
png_set_rows(png_ptr, info_ptr, &row_pointers);
|
||||
|
||||
@ -1465,25 +1463,24 @@ png_set_rgb_to_gray()).
|
||||
non-paletted images (PNG_INFO_tRNS)
|
||||
|
||||
png_get_eXIf_1(png_ptr, info_ptr, &num_exif, &exif);
|
||||
(PNG_INFO_eXIf)
|
||||
|
||||
exif - Exif profile (array of png_byte)
|
||||
(PNG_INFO_eXIf)
|
||||
|
||||
png_get_hIST(png_ptr, info_ptr, &hist);
|
||||
(PNG_INFO_hIST)
|
||||
|
||||
hist - histogram of palette (array of
|
||||
png_uint_16)
|
||||
png_uint_16) (PNG_INFO_hIST)
|
||||
|
||||
png_get_tIME(png_ptr, info_ptr, &mod_time);
|
||||
|
||||
mod_time - time image was last modified
|
||||
(PNG_VALID_tIME)
|
||||
(PNG_INFO_tIME)
|
||||
|
||||
png_get_bKGD(png_ptr, info_ptr, &background);
|
||||
|
||||
background - background color (of type
|
||||
png_color_16p) (PNG_VALID_bKGD)
|
||||
png_color_16p) (PNG_INFO_bKGD)
|
||||
valid 16-bit red, green and blue
|
||||
values, regardless of color_type
|
||||
|
||||
@ -1745,11 +1742,11 @@ viewing application that wishes to treat all images in the same way.
|
||||
if (color_type == PNG_COLOR_TYPE_PALETTE)
|
||||
png_set_palette_to_rgb(png_ptr);
|
||||
|
||||
if (png_get_valid(png_ptr, info_ptr,
|
||||
PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
|
||||
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
|
||||
png_set_tRNS_to_alpha(png_ptr);
|
||||
|
||||
if (color_type == PNG_COLOR_TYPE_GRAY &&
|
||||
bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
|
||||
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
|
||||
png_set_expand_gray_1_2_4_to_8(png_ptr);
|
||||
|
||||
The first two functions are actually aliases for png_set_expand(), added
|
||||
in libpng version 1.0.4, with the function names expanded to improve code
|
||||
@ -1771,11 +1768,13 @@ PNG can have files with 16 bits per channel. If you only can handle
|
||||
8 bits per channel, this will strip the pixels down to 8-bit.
|
||||
|
||||
if (bit_depth == 16)
|
||||
{
|
||||
#if PNG_LIBPNG_VER >= 10504
|
||||
png_set_scale_16(png_ptr);
|
||||
#else
|
||||
png_set_strip_16(png_ptr);
|
||||
#endif
|
||||
}
|
||||
|
||||
(The more accurate "png_set_scale_16()" API became available in libpng version
|
||||
1.5.4).
|
||||
@ -1926,7 +1925,7 @@ with alpha.
|
||||
if (color_type == PNG_COLOR_TYPE_RGB ||
|
||||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)
|
||||
png_set_rgb_to_gray(png_ptr, error_action,
|
||||
double red_weight, double green_weight);
|
||||
(double)red_weight, (double)green_weight);
|
||||
|
||||
error_action = 1: silently do the conversion
|
||||
|
||||
@ -1949,8 +1948,8 @@ In the corresponding fixed point API the red_weight and green_weight values are
|
||||
simply scaled by 100,000:
|
||||
|
||||
png_set_rgb_to_gray(png_ptr, error_action,
|
||||
png_fixed_point red_weight,
|
||||
png_fixed_point green_weight);
|
||||
(png_fixed_point)red_weight,
|
||||
(png_fixed_point)green_weight);
|
||||
|
||||
If you have set error_action = 1 or 2, you can
|
||||
later check whether the image really was gray, after processing
|
||||
@ -2186,9 +2185,8 @@ do your own check for number_of_rows*width*pixel_size if you are using
|
||||
a multiple-row buffer:
|
||||
|
||||
/* Guard against integer overflow */
|
||||
if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size)) {
|
||||
png_error(png_ptr,"image_data buffer would be too large");
|
||||
}
|
||||
if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size))
|
||||
png_error(png_ptr, "image_data buffer would be too large");
|
||||
|
||||
Remember: Before you call png_read_update_info(), the png_get_*()
|
||||
functions return the values corresponding to the original PNG image.
|
||||
@ -2408,8 +2406,7 @@ separate.
|
||||
|
||||
if (!end_info)
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -2421,7 +2418,7 @@ If you do this, libpng will not process any chunks after IDAT other than
|
||||
skipping over them and perhaps (depending on whether you have called
|
||||
png_set_crc_action) checking their CRCs while looking for the IEND chunk.
|
||||
|
||||
png_read_end(png_ptr, (png_infop)NULL);
|
||||
png_read_end(png_ptr, NULL);
|
||||
|
||||
If you don't call png_read_end(), then your file pointer will be
|
||||
left pointing to the first chunk after the last IDAT, which is probably
|
||||
@ -2430,13 +2427,11 @@ the PNG datastream.
|
||||
|
||||
When you are done, you can free all memory allocated by libpng like this:
|
||||
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
&end_info);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
|
||||
|
||||
or, if you didn't create an end_info structure,
|
||||
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
|
||||
It is also possible to individually free the info_ptr members that
|
||||
point to libpng-allocated storage with the following function:
|
||||
@ -2556,15 +2551,13 @@ png_infop info_ptr;
|
||||
|
||||
if (!info_ptr)
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr,
|
||||
(png_infopp)NULL, (png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, NULL, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
if (setjmp(png_jmpbuf(png_ptr)))
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -2597,8 +2590,7 @@ png_infop info_ptr;
|
||||
{
|
||||
if (setjmp(png_jmpbuf(png_ptr)))
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -2763,8 +2755,7 @@ both "png_ptr"; you can call them anything you like, such as
|
||||
png_infop info_ptr = png_create_info_struct(png_ptr);
|
||||
if (!info_ptr)
|
||||
{
|
||||
png_destroy_write_struct(&png_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_write_struct(&png_ptr, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -2844,7 +2835,7 @@ a progress meter or the like. It's demonstrated in pngtest.c.
|
||||
You must supply a function
|
||||
|
||||
void write_row_callback(png_structp png_ptr, png_uint_32 row,
|
||||
int pass);
|
||||
int pass)
|
||||
{
|
||||
/* put your code here */
|
||||
}
|
||||
@ -3116,8 +3107,8 @@ width, height, bit_depth, and color_type must be the same in each call.
|
||||
|
||||
png_set_eXIf_1(png_ptr, info_ptr, num_exif, exif);
|
||||
|
||||
exif - Exif profile (array of
|
||||
png_byte) (PNG_INFO_eXIf)
|
||||
exif - Exif profile (array of png_byte)
|
||||
(PNG_INFO_eXIf)
|
||||
|
||||
png_set_hIST(png_ptr, info_ptr, hist);
|
||||
|
||||
@ -3127,12 +3118,12 @@ width, height, bit_depth, and color_type must be the same in each call.
|
||||
png_set_tIME(png_ptr, info_ptr, mod_time);
|
||||
|
||||
mod_time - time image was last modified
|
||||
(PNG_VALID_tIME)
|
||||
(PNG_INFO_tIME)
|
||||
|
||||
png_set_bKGD(png_ptr, info_ptr, background);
|
||||
|
||||
background - background color (of type
|
||||
png_color_16p) (PNG_VALID_bKGD)
|
||||
png_color_16p) (PNG_INFO_bKGD)
|
||||
|
||||
png_set_text(png_ptr, info_ptr, text_ptr, num_text);
|
||||
|
||||
@ -4218,7 +4209,7 @@ png_create_read_struct_2() or png_create_write_struct_2() to register your
|
||||
own functions as described above. These functions also provide a void
|
||||
pointer that can be retrieved via
|
||||
|
||||
mem_ptr=png_get_mem_ptr(png_ptr);
|
||||
mem_ptr = png_get_mem_ptr(png_ptr);
|
||||
|
||||
Your replacement memory functions must have prototypes as follows:
|
||||
|
||||
@ -4515,7 +4506,7 @@ When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
|
||||
can still use PNG_DEBUG to control your own debugging:
|
||||
|
||||
#ifdef PNG_DEBUG
|
||||
fprintf(stderr, ...
|
||||
fprintf(stderr, ...);
|
||||
#endif
|
||||
|
||||
When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
|
||||
@ -5239,7 +5230,7 @@ changed, and is unaffected by conditional compilation macros. It is the
|
||||
best choice for use in configure scripts for detecting the presence of any
|
||||
libpng version since 0.88. In an autoconf "configure.in" you could use
|
||||
|
||||
AC_CHECK_LIB(png, png_get_io_ptr, ...
|
||||
AC_CHECK_LIB(png, png_get_io_ptr, ...)
|
||||
|
||||
XV. Source code repository
|
||||
|
||||
@ -5248,12 +5239,12 @@ control. The git repository was built from old libpng-x.y.z.tar.gz files
|
||||
going back to version 0.70. You can access the git repository (read only)
|
||||
at
|
||||
|
||||
https://github.com/glennrp/libpng or
|
||||
https://github.com/pnggroup/libpng or
|
||||
https://git.code.sf.net/p/libpng/code.git
|
||||
|
||||
or you can browse it with a web browser at
|
||||
|
||||
https://github.com/glennrp/libpng or
|
||||
https://github.com/pnggroup/libpng or
|
||||
https://sourceforge.net/p/libpng/code/ci/libpng16/tree/
|
||||
|
||||
Patches can be sent to png-mng-implement at lists.sourceforge.net or
|
||||
@ -5263,7 +5254,7 @@ uploaded to the libpng bug tracker at
|
||||
|
||||
or as a "pull request" to
|
||||
|
||||
https://github.com/glennrp/libpng/pulls
|
||||
https://github.com/pnggroup/libpng/pulls
|
||||
|
||||
We also accept patches built from the tar or zip distributions, and
|
||||
simple verbal descriptions of bug fixes, reported either to the
|
||||
|
||||
113
libpng.3
113
libpng.3
@ -904,8 +904,7 @@ create the structure, so your application should check for that.
|
||||
|
||||
if (!info_ptr)
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr,
|
||||
(png_infopp)NULL, (png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, NULL, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -938,14 +937,13 @@ free any memory.
|
||||
|
||||
if (setjmp(png_jmpbuf(png_ptr)))
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
&end_info);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
|
||||
fclose(fp);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
Pass (png_infopp)NULL instead of &end_info if you didn't create
|
||||
an end_info structure.
|
||||
Pass NULL instead of &end_info if you didn't create an end_info
|
||||
structure.
|
||||
|
||||
If you would rather avoid the complexity of setjmp/longjmp issues,
|
||||
you can compile libpng with PNG_NO_SETJMP, in which case
|
||||
@ -1015,7 +1013,7 @@ You can set up a callback function to handle any unknown chunks in the
|
||||
input stream. You must supply the function
|
||||
|
||||
read_chunk_callback(png_structp png_ptr,
|
||||
png_unknown_chunkp chunk);
|
||||
png_unknown_chunkp chunk)
|
||||
{
|
||||
/* The unknown chunk structure contains your
|
||||
chunk data, along with similar data for any other
|
||||
@ -1066,7 +1064,7 @@ a progress meter or the like. It's demonstrated in pngtest.c.
|
||||
You must supply a function
|
||||
|
||||
void read_row_callback(png_structp png_ptr,
|
||||
png_uint_32 row, int pass);
|
||||
png_uint_32 row, int pass)
|
||||
{
|
||||
/* put your code here */
|
||||
}
|
||||
@ -1700,21 +1698,21 @@ If you know your image size and pixel size ahead of time, you can allocate
|
||||
row_pointers prior to calling png_read_png() with
|
||||
|
||||
if (height > PNG_UINT_32_MAX/(sizeof (png_byte)))
|
||||
png_error (png_ptr,
|
||||
png_error(png_ptr,
|
||||
"Image is too tall to process in memory");
|
||||
|
||||
if (width > PNG_UINT_32_MAX/pixel_size)
|
||||
png_error (png_ptr,
|
||||
png_error(png_ptr,
|
||||
"Image is too wide to process in memory");
|
||||
|
||||
row_pointers = png_malloc(png_ptr,
|
||||
height*(sizeof (png_bytep)));
|
||||
|
||||
for (int i=0; i<height, i++)
|
||||
row_pointers[i]=NULL; /* security precaution */
|
||||
for (int i = 0; i < height, i++)
|
||||
row_pointers[i] = NULL; /* security precaution */
|
||||
|
||||
for (int i=0; i<height, i++)
|
||||
row_pointers[i]=png_malloc(png_ptr,
|
||||
for (int i = 0; i < height, i++)
|
||||
row_pointers[i] = png_malloc(png_ptr,
|
||||
width*pixel_size);
|
||||
|
||||
png_set_rows(png_ptr, info_ptr, &row_pointers);
|
||||
@ -1724,14 +1722,14 @@ row_pointers[i] to point into the proper places in your block, but first
|
||||
be sure that your platform is able to allocate such a large buffer:
|
||||
|
||||
/* Guard against integer overflow */
|
||||
if (height > PNG_SIZE_MAX/(width*pixel_size)) {
|
||||
png_error(png_ptr,"image_data buffer would be too large");
|
||||
}
|
||||
if (height > PNG_SIZE_MAX/(width*pixel_size))
|
||||
png_error(png_ptr, "image_data buffer would be too large");
|
||||
|
||||
png_bytep buffer=png_malloc(png_ptr,height*width*pixel_size);
|
||||
png_bytep buffer = png_malloc(png_ptr,
|
||||
height*width*pixel_size);
|
||||
|
||||
for (int i=0; i<height, i++)
|
||||
row_pointers[i]=buffer+i*width*pixel_size;
|
||||
for (int i = 0; i < height, i++)
|
||||
row_pointers[i] = buffer + i*width*pixel_size;
|
||||
|
||||
png_set_rows(png_ptr, info_ptr, &row_pointers);
|
||||
|
||||
@ -1984,25 +1982,24 @@ png_set_rgb_to_gray()).
|
||||
non-paletted images (PNG_INFO_tRNS)
|
||||
|
||||
png_get_eXIf_1(png_ptr, info_ptr, &num_exif, &exif);
|
||||
(PNG_INFO_eXIf)
|
||||
|
||||
exif - Exif profile (array of png_byte)
|
||||
(PNG_INFO_eXIf)
|
||||
|
||||
png_get_hIST(png_ptr, info_ptr, &hist);
|
||||
(PNG_INFO_hIST)
|
||||
|
||||
hist - histogram of palette (array of
|
||||
png_uint_16)
|
||||
png_uint_16) (PNG_INFO_hIST)
|
||||
|
||||
png_get_tIME(png_ptr, info_ptr, &mod_time);
|
||||
|
||||
mod_time - time image was last modified
|
||||
(PNG_VALID_tIME)
|
||||
(PNG_INFO_tIME)
|
||||
|
||||
png_get_bKGD(png_ptr, info_ptr, &background);
|
||||
|
||||
background - background color (of type
|
||||
png_color_16p) (PNG_VALID_bKGD)
|
||||
png_color_16p) (PNG_INFO_bKGD)
|
||||
valid 16-bit red, green and blue
|
||||
values, regardless of color_type
|
||||
|
||||
@ -2264,11 +2261,11 @@ viewing application that wishes to treat all images in the same way.
|
||||
if (color_type == PNG_COLOR_TYPE_PALETTE)
|
||||
png_set_palette_to_rgb(png_ptr);
|
||||
|
||||
if (png_get_valid(png_ptr, info_ptr,
|
||||
PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
|
||||
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
|
||||
png_set_tRNS_to_alpha(png_ptr);
|
||||
|
||||
if (color_type == PNG_COLOR_TYPE_GRAY &&
|
||||
bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
|
||||
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
|
||||
png_set_expand_gray_1_2_4_to_8(png_ptr);
|
||||
|
||||
The first two functions are actually aliases for png_set_expand(), added
|
||||
in libpng version 1.0.4, with the function names expanded to improve code
|
||||
@ -2290,11 +2287,13 @@ PNG can have files with 16 bits per channel. If you only can handle
|
||||
8 bits per channel, this will strip the pixels down to 8-bit.
|
||||
|
||||
if (bit_depth == 16)
|
||||
{
|
||||
#if PNG_LIBPNG_VER >= 10504
|
||||
png_set_scale_16(png_ptr);
|
||||
#else
|
||||
png_set_strip_16(png_ptr);
|
||||
#endif
|
||||
}
|
||||
|
||||
(The more accurate "png_set_scale_16()" API became available in libpng version
|
||||
1.5.4).
|
||||
@ -2445,7 +2444,7 @@ with alpha.
|
||||
if (color_type == PNG_COLOR_TYPE_RGB ||
|
||||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)
|
||||
png_set_rgb_to_gray(png_ptr, error_action,
|
||||
double red_weight, double green_weight);
|
||||
(double)red_weight, (double)green_weight);
|
||||
|
||||
error_action = 1: silently do the conversion
|
||||
|
||||
@ -2468,8 +2467,8 @@ In the corresponding fixed point API the red_weight and green_weight values are
|
||||
simply scaled by 100,000:
|
||||
|
||||
png_set_rgb_to_gray(png_ptr, error_action,
|
||||
png_fixed_point red_weight,
|
||||
png_fixed_point green_weight);
|
||||
(png_fixed_point)red_weight,
|
||||
(png_fixed_point)green_weight);
|
||||
|
||||
If you have set error_action = 1 or 2, you can
|
||||
later check whether the image really was gray, after processing
|
||||
@ -2705,9 +2704,8 @@ do your own check for number_of_rows*width*pixel_size if you are using
|
||||
a multiple-row buffer:
|
||||
|
||||
/* Guard against integer overflow */
|
||||
if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size)) {
|
||||
png_error(png_ptr,"image_data buffer would be too large");
|
||||
}
|
||||
if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size))
|
||||
png_error(png_ptr, "image_data buffer would be too large");
|
||||
|
||||
Remember: Before you call png_read_update_info(), the png_get_*()
|
||||
functions return the values corresponding to the original PNG image.
|
||||
@ -2927,8 +2925,7 @@ separate.
|
||||
|
||||
if (!end_info)
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -2940,7 +2937,7 @@ If you do this, libpng will not process any chunks after IDAT other than
|
||||
skipping over them and perhaps (depending on whether you have called
|
||||
png_set_crc_action) checking their CRCs while looking for the IEND chunk.
|
||||
|
||||
png_read_end(png_ptr, (png_infop)NULL);
|
||||
png_read_end(png_ptr, NULL);
|
||||
|
||||
If you don't call png_read_end(), then your file pointer will be
|
||||
left pointing to the first chunk after the last IDAT, which is probably
|
||||
@ -2949,13 +2946,11 @@ the PNG datastream.
|
||||
|
||||
When you are done, you can free all memory allocated by libpng like this:
|
||||
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
&end_info);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
|
||||
|
||||
or, if you didn't create an end_info structure,
|
||||
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
|
||||
It is also possible to individually free the info_ptr members that
|
||||
point to libpng-allocated storage with the following function:
|
||||
@ -3075,15 +3070,13 @@ png_infop info_ptr;
|
||||
|
||||
if (!info_ptr)
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr,
|
||||
(png_infopp)NULL, (png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, NULL, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
if (setjmp(png_jmpbuf(png_ptr)))
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -3116,8 +3109,7 @@ png_infop info_ptr;
|
||||
{
|
||||
if (setjmp(png_jmpbuf(png_ptr)))
|
||||
{
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -3282,8 +3274,7 @@ both "png_ptr"; you can call them anything you like, such as
|
||||
png_infop info_ptr = png_create_info_struct(png_ptr);
|
||||
if (!info_ptr)
|
||||
{
|
||||
png_destroy_write_struct(&png_ptr,
|
||||
(png_infopp)NULL);
|
||||
png_destroy_write_struct(&png_ptr, NULL);
|
||||
return ERROR;
|
||||
}
|
||||
|
||||
@ -3363,7 +3354,7 @@ a progress meter or the like. It's demonstrated in pngtest.c.
|
||||
You must supply a function
|
||||
|
||||
void write_row_callback(png_structp png_ptr, png_uint_32 row,
|
||||
int pass);
|
||||
int pass)
|
||||
{
|
||||
/* put your code here */
|
||||
}
|
||||
@ -3635,8 +3626,8 @@ width, height, bit_depth, and color_type must be the same in each call.
|
||||
|
||||
png_set_eXIf_1(png_ptr, info_ptr, num_exif, exif);
|
||||
|
||||
exif - Exif profile (array of
|
||||
png_byte) (PNG_INFO_eXIf)
|
||||
exif - Exif profile (array of png_byte)
|
||||
(PNG_INFO_eXIf)
|
||||
|
||||
png_set_hIST(png_ptr, info_ptr, hist);
|
||||
|
||||
@ -3646,12 +3637,12 @@ width, height, bit_depth, and color_type must be the same in each call.
|
||||
png_set_tIME(png_ptr, info_ptr, mod_time);
|
||||
|
||||
mod_time - time image was last modified
|
||||
(PNG_VALID_tIME)
|
||||
(PNG_INFO_tIME)
|
||||
|
||||
png_set_bKGD(png_ptr, info_ptr, background);
|
||||
|
||||
background - background color (of type
|
||||
png_color_16p) (PNG_VALID_bKGD)
|
||||
png_color_16p) (PNG_INFO_bKGD)
|
||||
|
||||
png_set_text(png_ptr, info_ptr, text_ptr, num_text);
|
||||
|
||||
@ -4737,7 +4728,7 @@ png_create_read_struct_2() or png_create_write_struct_2() to register your
|
||||
own functions as described above. These functions also provide a void
|
||||
pointer that can be retrieved via
|
||||
|
||||
mem_ptr=png_get_mem_ptr(png_ptr);
|
||||
mem_ptr = png_get_mem_ptr(png_ptr);
|
||||
|
||||
Your replacement memory functions must have prototypes as follows:
|
||||
|
||||
@ -5034,7 +5025,7 @@ When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
|
||||
can still use PNG_DEBUG to control your own debugging:
|
||||
|
||||
#ifdef PNG_DEBUG
|
||||
fprintf(stderr, ...
|
||||
fprintf(stderr, ...);
|
||||
#endif
|
||||
|
||||
When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
|
||||
@ -5758,7 +5749,7 @@ changed, and is unaffected by conditional compilation macros. It is the
|
||||
best choice for use in configure scripts for detecting the presence of any
|
||||
libpng version since 0.88. In an autoconf "configure.in" you could use
|
||||
|
||||
AC_CHECK_LIB(png, png_get_io_ptr, ...
|
||||
AC_CHECK_LIB(png, png_get_io_ptr, ...)
|
||||
|
||||
.SH XV. Source code repository
|
||||
|
||||
@ -5767,12 +5758,12 @@ control. The git repository was built from old libpng-x.y.z.tar.gz files
|
||||
going back to version 0.70. You can access the git repository (read only)
|
||||
at
|
||||
|
||||
https://github.com/glennrp/libpng or
|
||||
https://github.com/pnggroup/libpng or
|
||||
https://git.code.sf.net/p/libpng/code.git
|
||||
|
||||
or you can browse it with a web browser at
|
||||
|
||||
https://github.com/glennrp/libpng or
|
||||
https://github.com/pnggroup/libpng or
|
||||
https://sourceforge.net/p/libpng/code/ci/libpng16/tree/
|
||||
|
||||
Patches can be sent to png-mng-implement at lists.sourceforge.net or
|
||||
@ -5782,7 +5773,7 @@ uploaded to the libpng bug tracker at
|
||||
|
||||
or as a "pull request" to
|
||||
|
||||
https://github.com/glennrp/libpng/pulls
|
||||
https://github.com/pnggroup/libpng/pulls
|
||||
|
||||
We also accept patches built from the tar or zip distributions, and
|
||||
simple verbal descriptions of bug fixes, reported either to the
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user