Функции
	FF_PAD_STRUCTURE (AVBPrint, 1024, char str;unsigned len;unsigned size;unsigned size_max;char reserved_internal_buffer[1];) void av_bprint_init(AVBPrint buf

void	av_bprint_init_for_buffer (AVBPrint buf, char buffer, unsigned size)

void	av_bprintf (AVBPrint buf, const char fmt,...) av_printf_format(2

void void	av_vbprintf (AVBPrint buf, const char fmt, va_list vl_arg)

void	av_bprint_chars (AVBPrint *buf, char c, unsigned n)

void	av_bprint_append_data (AVBPrint buf, const char data, unsigned size)

void	av_bprint_strftime (AVBPrint buf, const char fmt, const struct tm *tm)

void	av_bprint_get_buffer (AVBPrint buf, unsigned size, unsigned char mem, unsigned actual_size)

void	av_bprint_clear (AVBPrint *buf)

static int	av_bprint_is_complete (const AVBPrint *buf)

int	av_bprint_finalize (AVBPrint buf, char *ret_str)

void	av_bprint_escape (AVBPrint dstbuf, const char src, const char *special_chars, enum AVEscapeMode mode, int flags)

Переменные
unsigned	size_init

unsigned unsigned	size_max

Функции

◆ FF_PAD_STRUCTURE()

FF_PAD_STRUCTURE	(	AVBPrint	,
		1024	,
		char *str;unsigned len;unsigned size;unsigned size_max;char reserved_internal_buffer;	[1]
	)

Buffer to print data progressively

The string buffer grows as necessary and is always 0-terminated. The content of the string is never accessed, and thus is encoding-agnostic and can even hold binary data.

Small buffers are kept in the structure itself, and thus require no memory allocation at all (unless the contents of the buffer is needed after the structure goes out of scope). This is almost as lightweight as declaring a local "char buf[512]".

The length of the string can go beyond the allocated size: the buffer is then truncated, but the functions still keep account of the actual total length.

In other words, buf->len can be greater than buf->size and records the total length of what would have been to the buffer if there had been enough memory.

Append operations do not need to be tested for failure: if a memory allocation fails, data stop being appended to the buffer, but the length is still updated. This situation can be tested with av_bprint_is_complete().

The size_max field determines several possible behaviours:

size_max = -1 (= UINT_MAX) or any large value will let the buffer be reallocated as necessary, with an amortized linear cost.

size_max = 0 prevents writing anything to the buffer: only the total length is computed. The write operations can then possibly be repeated in a buffer with exactly the necessary size (using size_init = size_max = len + 1).

size_max = 1 is automatically replaced by the exact size available in the structure itself, thus ensuring no dynamic memory allocation. The internal buffer is large enough to hold a reasonable paragraph of text, such as the current paragraph. Convenience macros for special values for av_bprint_init() size_max parameter. Init a print buffer.

Аргументы

buf	buffer to init
size_init	initial size (including the final 0)
size_max	maximum size; 0 means do not write anything, just count the length; 1 is replaced by the maximum value for automatic storage; any large value means that the internal buffer will be reallocated as needed up to that limit; -1 is converted to UINT_MAX, the largest limit possible. Check also AV_BPRINT_SIZE_* macros.

◆ av_bprint_init_for_buffer()

void av_bprint_init_for_buffer	(	AVBPrint *	buf,
		char *	buffer,
		unsigned	size
	)

Init a print buffer using a pre-existing buffer.

The buffer will not be reallocated.

Аргументы

buf	buffer structure to init
buffer	byte buffer to use for the string data
size	size of buffer

◆ av_bprintf()

void av_bprintf	(	AVBPrint *	buf,
		const char *	fmt,
			...
	)

Append a formatted string to a print buffer.

◆ av_vbprintf()

void void av_vbprintf	(	AVBPrint *	buf,
		const char *	fmt,
		va_list	vl_arg
	)

Append a formatted string to a print buffer.

◆ av_bprint_chars()

void av_bprint_chars	(	AVBPrint *	buf,
		char	c,
		unsigned	n
	)

Append char c n times to a print buffer.

◆ av_bprint_append_data()

void av_bprint_append_data	(	AVBPrint *	buf,
		const char *	data,
		unsigned	size
	)

Append data to a print buffer.

param buf bprint buffer to use param data pointer to data param size size of data

◆ av_bprint_strftime()

void av_bprint_strftime	(	AVBPrint *	buf,
		const char *	fmt,
		const struct tm *	tm
	)

Append a formatted date and time to a print buffer.

param buf bprint buffer to use param fmt date and time format string, see strftime() param tm broken-down time structure to translate

Заметки: due to poor design of the standard strftime function, it may produce poor results if the format string expands to a very long text and the bprint buffer is near the limit stated by the size_max option.

◆ av_bprint_get_buffer()

void av_bprint_get_buffer	(	AVBPrint *	buf,
		unsigned	size,
		unsigned char **	mem,
		unsigned *	actual_size
	)

Allocate bytes in the buffer for external use.

Аргументы

[in]	buf	buffer structure
[in]	size	required size
[out]	mem	pointer to the memory area
[out]	actual_size	size of the memory area after allocation; can be larger or smaller than size

◆ av_bprint_clear()

void av_bprint_clear ( AVBPrint * buf )

Reset the string to "" but keep internal allocated data.

◆ av_bprint_is_complete()

static int av_bprint_is_complete ( const AVBPrint * buf )

inlinestatic

Test if the print buffer is complete (not truncated).

It may have been truncated due to a memory allocation failure or the size_max limit (compare size and size_max if necessary).

См. определение в файле bprint.h строка 185

 {
     return buf->len < buf->size;
 }

◆ av_bprint_finalize()

int av_bprint_finalize	(	AVBPrint *	buf,
		char **	ret_str
	)

Finalize a print buffer.

The print buffer can no longer be used afterwards, but the len and size fields are still valid.

[out] ret_str if not NULL, used to return a permanent copy of the buffer contents, or NULL if memory allocation fails; if NULL, the buffer is discarded and freed
Возвращает
0 for success or error code (probably AVERROR(ENOMEM))

◆ av_bprint_escape()

void av_bprint_escape	(	AVBPrint *	dstbuf,
		const char *	src,
		const char *	special_chars,
		enum AVEscapeMode	mode,
		int	flags
	)

Escape the content in src and append it to dstbuf.

Аргументы

dstbuf	already inited destination bprint buffer
src	string containing the text to escape
special_chars	string containing the special characters which need to be escaped, can be NULL
mode	escape mode to employ, see AV_ESCAPE_MODE_* macros. Any unknown value for mode will be considered equivalent to AV_ESCAPE_MODE_BACKSLASH, but this behaviour can change without notice.
flags	flags which control how to escape, see AV_ESCAPE_FLAG_* macros

Переменные

◆ size_init

unsigned size_init

См. определение в файле bprint.h строка 111

◆ size_max

unsigned unsigned size_max

См. определение в файле bprint.h строка 111