Read/write gif format from/to file and memory. More...

#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include "allheaders.h"
#include "gif_lib.h"

Functions
static PIX *	pixInterlaceGIF (PIX *pixs)
PIX *	pixReadStreamGif (FILE *fp)
l_int32	pixWriteStreamGif (FILE fp, PIX pix)
PIX *	pixReadMemGif (const l_uint8 *cdata, size_t size)
l_int32	pixWriteMemGif (l_uint8 *pdata, size_t psize, PIX *pix)
Variables
static const l_int32	InterlacedOffset [] = {0, 4, 2, 1}
static const l_int32	InterlacedJumps [] = {8, 8, 4, 2}

Detailed Description

Read/write gif format from/to file and memory.

  Read gif from file
        PIX        *pixReadStreamGif()
        static PIX *pixInterlaceGIF()

  Write gif to file
        l_int32     pixWriteStreamGif()

  Read/write from/to memory (see warning)
        PIX        *pixReadMemGif()
        l_int32     pixWriteMemGif()
   
  This uses the gif library, version 4.1.6.  Do not use 4.1.4.

  This module was generously contribued by Antony Dovgal.
  He can be contacted at:  tony *AT* daylessday.org

Definition in file gifio.c.

Function Documentation

static PIX * pixInterlaceGIF ( PIX * pixs ) [static]

Definition at line 195 of file gifio.c.

References ERROR_PTR, InterlacedJumps, InterlacedOffset, NULL, pixCreateTemplate(), pixGetData(), pixGetDimensions(), pixGetWpl(), and PROCNAME.

Referenced by pixReadStreamGif().

PIX* pixReadStreamGif ( FILE * fp )

pixReadStreamGif()

Input: stream Return: pix, or null on error

Definition at line 71 of file gifio.c.

References ERROR_PTR, NULL, pixcmapAddColor(), pixcmapCreate(), pixcmapDestroy(), pixCreate(), pixGetData(), pixGetWpl(), pixInterlaceGIF(), pixSetColormap(), pixTransferAllData(), PROCNAME, SET_DATA_BIT, SET_DATA_BYTE, SET_DATA_DIBIT, and SET_DATA_QBIT.

Referenced by pixReadStream().

l_int32 pixWriteStreamGif	(	FILE *	fp,
		PIX *	pix
	)

pixWriteStreamGif()

Input: stream pix (1, 2, 4, 8, 16 or 32 bpp) Return: 0 if OK, 1 on error

Notes: (1) All output gif have colormaps. If the pix is 32 bpp rgb, this quantizes the colors and writes out 8 bpp. If the pix is 16 bpp grayscale, it converts to 8 bpp first. (2) We can't write to memory using open_memstream() because the gif functions write through a file descriptor, not a file stream.

Definition at line 244 of file gifio.c.

References CALLOC, ERROR_INT, FALSE, FREE, GET_DATA_BIT, GET_DATA_BYTE, GET_DATA_DIBIT, GET_DATA_QBIT, L_WARNING, NULL, pixClone(), pixcmapAddColor(), pixcmapCreate(), pixcmapGetColor(), pixcmapGetCount(), pixConvertRGBToColormap(), pixConvertTo8(), pixDestroy(), pixGetColormap(), pixGetData(), pixGetDepth(), pixGetDimensions(), pixGetText(), pixGetWpl(), pixSetColormap(), PROCNAME, and TRUE.

Referenced by pixWriteStream().

PIX* pixReadMemGif	(	const l_uint8 *	cdata,
		size_t	size
	)

pixReadMemGif()

Input: data (const; gif-encoded) size (of data) Return: pix, or null on error

Notes: (1) Of course, we are cheating here -- writing the data out to file and then reading it back in as a gif format. (2) This should not be assumed to be safe from a sophisticated attack, even though we have attempted to make the filename difficult to guess by embedding the process number and the current time in microseconds. The best way to handle temporary files is to use file descriptors (capabilities) or file handles. However, I know of no way to do this for gif files because of the way that libgif handles the file descriptors. The canonical approach would be to do this: char templ[] = "hiddenfilenameXXXXXX"; l_int32 fd = mkstemp(templ); FILE *fp = fdopen(fd, "w+b"); fwrite(data, 1, size, fp); rewind(fp); Pix *pix = pixReadStreamGif(fp); but this fails because fp is in a bad state after writing.

Definition at line 441 of file gifio.c.

References ERROR_PTR, FREE, genTempFilename(), l_binaryWrite(), NULL, pixRead(), and PROCNAME.

Referenced by pixReadHeaderMem(), and pixReadMem().