Implement JPEG image object support.

This commit is contained in:
Michael R Sweet 2021-05-25 16:31:32 -04:00
parent eb4477ce9b
commit 128d5f0d42
No known key found for this signature in database
GPG Key ID: 999559A027815955
2 changed files with 282 additions and 6 deletions

View File

@ -12,13 +12,24 @@
//
#include "pdfio-content.h"
#include "pdfio-private.h"
#include <math.h>
//
// Local types...
//
typedef pdfio_obj_t *(*image_func_t)(pdfio_dict_t *dict, int fd);
//
// Local functions...
//
static pdfio_obj_t *copy_gif(pdfio_dict_t *dict, int fd);
static pdfio_obj_t *copy_jpeg(pdfio_dict_t *dict, int fd);
static pdfio_obj_t *copy_png(pdfio_dict_t *dict, int fd);
static bool write_string(pdfio_stream_t *st, const char *s);
@ -859,6 +870,8 @@ pdfioFileCreateICCProfileObject(
//
// 'pdfioFileCreateImageObject()' - Add an image object to a PDF file.
//
// Currently only GIF, JPEG, and PNG files are supported.
//
pdfio_obj_t * // O - Object
pdfioFileCreateImageObject(
@ -866,10 +879,230 @@ pdfioFileCreateImageObject(
const char *filename, // I - Filename
bool interpolate) // I - Interpolate image data?
{
(void)pdf;
(void)filename;
(void)interpolate;
pdfio_dict_t *dict; // Image dictionary
pdfio_obj_t *obj; // Image object
int fd; // File
unsigned char buffer[32]; // Read buffer
image_func_t copy_func = NULL; // Image copy function
// Range check input...
if (!pdf || !filename)
return (NULL);
// Try opening the file...
if ((fd = open(filename, O_RDONLY | O_BINARY)) < 0)
{
_pdfioFileError(pdf, "Unable to open image file '%s': %s", filename, strerror(errno));
return (NULL);
}
// Read the file header to determine the file format...
if (read(fd, buffer, sizeof(buffer)) < (ssize_t)sizeof(buffer))
{
_pdfioFileError(pdf, "Unable to read header from image file '%s'.", filename);
close(fd);
return (NULL);
}
lseek(fd, 0, SEEK_SET);
if (!memcmp(buffer, "\211PNG\015\012\032\012\000\000\000\015IHDR", 16))
{
// PNG image...
copy_func = copy_png;
}
else if (!memcmp(buffer, "GIF87a", 6) || !memcmp(buffer, "GIF89a", 6))
{
// GIF image...
copy_func = copy_gif;
}
else if (!memcmp(buffer, "\377\330\377", 3))
{
// JPEG image...
copy_func = copy_jpeg;
}
else
{
// Something else that isn't supported...
_pdfioFileError(pdf, "Unsupported image file '%s'.", filename);
close(fd);
return (NULL);
}
// Create the base image dictionary the copy the file into an object...
if ((dict = pdfioDictCreate(pdf)) == NULL)
{
close(fd);
return (NULL);
}
pdfioDictSetName(dict, "Type", "XObject");
pdfioDictSetName(dict, "SubType", "Image");
pdfioDictSetBoolean(dict, "Interpolate", interpolate);
obj = (copy_func)(dict, fd);
// Close the file and return the object...
close(fd);
return (obj);
}
//
// 'copy_gif()' - Copy a GIF image.
//
static pdfio_obj_t * // O - Object or `NULL` on error
copy_gif(pdfio_dict_t *dict, // I - Dictionary
int fd) // I - File descriptor
{
// TODO: Implement copy_gif
(void)dict;
(void)fd;
return (NULL);
}
//
// 'copy_jpeg()' - Copy a JPEG image.
//
static pdfio_obj_t * // O - Object or `NULL` on error
copy_jpeg(pdfio_dict_t *dict, // I - Dictionary
int fd) // I - File descriptor
{
pdfio_obj_t *obj; // Object
pdfio_stream_t *st; // Stream for JPEG data
ssize_t bytes; // Bytes read
unsigned char buffer[16384], // Read buffer
*bufptr, // Pointer into buffer
*bufend; // End of buffer
size_t length; // Length of chunk
unsigned width = 0, // Width in columns
height = 0, // Height in lines
num_colors = 0; // Number of colors
// Scan the file for a SOFn marker, then we can get the dimensions...
bytes = read(fd, buffer, sizeof(buffer));
for (bufptr = buffer + 2, bufend = buffer + bytes; bufptr < bufend;)
{
if (*bufptr == 0xff)
{
bufptr ++;
if (bufptr >= bufend)
{
/*
* If we are at the end of the current buffer, re-fill and continue...
*/
if ((bytes = read(fd, buffer, sizeof(buffer))) <= 0)
break;
bufptr = buffer;
bufend = buffer + bytes;
}
if (*bufptr == 0xff)
continue;
if ((bufptr + 16) >= bufend)
{
/*
* Read more of the marker...
*/
bytes = bufend - bufptr;
memmove(buffer, bufptr, (size_t)bytes);
bufptr = buffer;
bufend = buffer + bytes;
if ((bytes = read(fd, bufend, sizeof(buffer) - (size_t)bytes)) <= 0)
break;
bufend += bytes;
}
length = (size_t)((bufptr[1] << 8) | bufptr[2]);
PDFIO_DEBUG("copy_jpeg: JPEG X'FF%02X' (length %u)\n", *bufptr, (unsigned)length);
if ((*bufptr >= 0xc0 && *bufptr <= 0xc3) || (*bufptr >= 0xc5 && *bufptr <= 0xc7) || (*bufptr >= 0xc9 && *bufptr <= 0xcb) || (*bufptr >= 0xcd && *bufptr <= 0xcf))
{
// SOFn marker, look for dimensions...
width = (unsigned)((bufptr[6] << 8) | bufptr[7]);
height = (unsigned)((bufptr[4] << 8) | bufptr[5]);
num_colors = bufptr[8];
break;
}
// Skip past this marker...
bufptr ++;
bytes = bufend - bufptr;
while (length >= (size_t)bytes)
{
length -= (size_t)bytes;
if ((bytes = read(fd, buffer, sizeof(buffer))) <= 0)
break;
bufptr = buffer;
bufend = buffer + bytes;
}
if (length > (size_t)bytes)
break;
bufptr += length;
}
}
if (width == 0 || height == 0 || (num_colors != 1 && num_colors != 3))
return (NULL);
// Create the image object...
pdfioDictSetNumber(dict, "Width", width);
pdfioDictSetNumber(dict, "Height", height);
pdfioDictSetNumber(dict, "BitsPerComponent", 8);
pdfioDictSetName(dict, "ColorSpace", num_colors == 3 ? "CalRGB" : "CalGray");
pdfioDictSetName(dict, "Filter", "DCTDecode");
obj = pdfioFileCreateObject(dict->pdf, dict);
st = pdfioObjCreateStream(obj, PDFIO_FILTER_NONE);
// Copy the file to a stream...
lseek(fd, 0, SEEK_SET);
while ((bytes = read(fd, buffer, sizeof(buffer))) > 0)
{
if (!pdfioStreamWrite(st, buffer, (size_t)bytes))
return (NULL);
}
if (!pdfioStreamClose(st))
return (NULL);
return (obj);
}
//
// 'copy_png()' - Copy a PNG image.
//
static pdfio_obj_t * // O - Object or `NULL` on error
copy_png(pdfio_dict_t *dict, // I - Dictionary
int fd) // I - File descriptor
{
// TODO: Implement copy_png
(void)dict;
(void)fd;
return (NULL);
}

View File

@ -18,8 +18,51 @@
# include <stdarg.h>
# include <errno.h>
# include <inttypes.h>
# ifdef _WIN32
# include <io.h>
# include <direct.h>
/*
* Microsoft renames the POSIX functions to _name, and introduces
* a broken compatibility layer using the original names. As a result,
* random crashes can occur when, for example, strdup() allocates memory
* from a different heap than used by malloc() and free().
*
* To avoid moronic problems like this, we #define the POSIX function
* names to the corresponding non-standard Microsoft names.
*/
# define access _access
# define close _close
# define fileno _fileno
# define lseek _lseek
# define mkdir(d,p) _mkdir(d)
# define open _open
# define read _read
# define rmdir _rmdir
# define snprintf _snprintf
# define strdup _strdup
# define unlink _unlink
# define vsnprintf _vsnprintf
# define write _write
/*
* Map various parameters for POSIX...
*/
# define F_OK 00
# define W_OK 02
# define R_OK 04
# define O_RDONLY _O_RDONLY
# define O_WRONLY _O_WRONLY
# define O_CREAT _O_CREAT
# define O_TRUNC _O_TRUNC
# define O_BINARY _O_BINARY
# else // !_WIN32
# include <fcntl.h>
# include <unistd.h>
# define O_BINARY 0
# endif // _WIN32
# include <string.h>
# include <ctype.h>
# include <zlib.h>