/*!
* freadHeaderPng()
*
* Input: stream
* &width (<return>)
* &height (<return>)
* &bps (<return>, bits/sample)
* &spp (<return>, samples/pixel)
* &iscmap (<optional return>; input NULL to ignore)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) If there is a colormap, iscmap is returned as 1; else 0.
*/
l_int32
freadHeaderPng(FILE *fp,
l_int32 *pwidth,
l_int32 *pheight,
l_int32 *pbps,
l_int32 *pspp,
l_int32 *piscmap)
{
l_int32 nbytes, ret;
l_uint8 *data;
PROCNAME("freadHeaderPng");
if (!fp)
return ERROR_INT("stream not defined", procName, 1);
if (!pwidth || !pheight || !pbps || !pspp)
return ERROR_INT("input ptr(s) not defined", procName, 1);
nbytes = fnbytesInFile(fp);
if (nbytes < 40)
return ERROR_INT("file too small to be png", procName, 1);
if ((data = (l_uint8 *)CALLOC(40, sizeof(l_uint8))) == NULL)
return ERROR_INT("CALLOC fail for data", procName, 1);
if (fread(data, 1, 40, fp) != 40)
return ERROR_INT("error reading data", procName, 1);
ret = sreadHeaderPng(data, pwidth, pheight, pbps, pspp, piscmap);
FREE(data);
return ret;
}
/*!
* findFileFormatStream()
*
* Input: fp (file stream)
* &format (<return>)
* Return: 0 if OK, 1 on error or if format is not recognized
*
* Notes:
* (1) Important: Side effect -- this resets fp to BOF.
*/
l_int32
findFileFormatStream(FILE *fp,
l_int32 *pformat)
{
l_uint8 firstbytes[12];
l_int32 format;
PROCNAME("findFileFormatStream");
if (!pformat)
return ERROR_INT("&format not defined", procName, 1);
*pformat = IFF_UNKNOWN;
if (!fp)
return ERROR_INT("stream not defined", procName, 1);
rewind(fp);
if (fnbytesInFile(fp) < 12)
return ERROR_INT("truncated file", procName, 1);
if (fread((char *)&firstbytes, 1, 12, fp) != 12)
return ERROR_INT("failed to read first 12 bytes of file", procName, 1);
rewind(fp);
findFileFormatBuffer(firstbytes, &format);
if (format == IFF_TIFF) {
findTiffCompression(fp, &format);
rewind(fp);
}
*pformat = format;
if (format == IFF_UNKNOWN)
return 1;
else
return 0;
}
