1<!-- Creator : groff version 1.18.1 --> 2<!-- CreationDate: Sat Feb 24 18:37:17 2007 --> 3<html> 4<head> 5<meta name="generator" content="groff -Thtml, see www.gnu.org"> 6<meta name="Content-Style" content="text/css"> 7<title>TIFFReadScanline</title> 8</head> 9<body> 10 11<h1 align=center>TIFFReadScanline</h1> 12<a href="#NAME">NAME</a><br> 13<a href="#SYNOPSIS">SYNOPSIS</a><br> 14<a href="#DESCRIPTION">DESCRIPTION</a><br> 15<a href="#NOTES">NOTES</a><br> 16<a href="#RETURN VALUES">RETURN VALUES</a><br> 17<a href="#DIAGNOSTICS">DIAGNOSTICS</a><br> 18<a href="#BUGS">BUGS</a><br> 19<a href="#SEE ALSO">SEE ALSO</a><br> 20 21<hr> 22<a name="NAME"></a> 23<h2>NAME</h2> 24<!-- INDENTATION --> 25<table width="100%" border=0 rules="none" frame="void" 26 cols="2" cellspacing="0" cellpadding="0"> 27<tr valign="top" align="left"> 28<td width="8%"></td> 29<td width="91%"> 30<p>TIFFReadScanline − read and decode a scanline of 31data from an open <small>TIFF</small> file</p> 32</td> 33</table> 34<a name="SYNOPSIS"></a> 35<h2>SYNOPSIS</h2> 36<!-- INDENTATION --> 37<table width="100%" border=0 rules="none" frame="void" 38 cols="2" cellspacing="0" cellpadding="0"> 39<tr valign="top" align="left"> 40<td width="8%"></td> 41<td width="91%"> 42<p><b>#include <tiffio.h></b></p> 43<!-- INDENTATION --> 44<p><b>int TIFFReadScanline(TIFF *</b><i>tif</i><b>, 45tdata_t</b> <i>buf</i><b>, uint32</b> <i>row</i><b>, 46tsample_t</b> <i>sample</i><b>)</b></p> 47</td> 48</table> 49<a name="DESCRIPTION"></a> 50<h2>DESCRIPTION</h2> 51<!-- INDENTATION --> 52<table width="100%" border=0 rules="none" frame="void" 53 cols="2" cellspacing="0" cellpadding="0"> 54<tr valign="top" align="left"> 55<td width="8%"></td> 56<td width="91%"> 57<p>Read the data for the specified row into the (user 58supplied) data buffer <i>buf</i>. The data are returned 59decompressed and, in the native byte- and bit-ordering, but 60are otherwise packed (see further below). The buffer must be 61large enough to hold an entire scanline of data. 62Applications should call the routine <i>TIFFScanlineSize</i> 63to find out the size (in bytes) of a scanline buffer. The 64<i>row</i> parameter is always used by 65<i>TIFFReadScanline</i>; the <i>sample</i> parameter is used 66only if data are organized in separate planes 67(<i>PlanarConfiguration</i>=2).</p> 68</td> 69</table> 70<a name="NOTES"></a> 71<h2>NOTES</h2> 72<!-- INDENTATION --> 73<table width="100%" border=0 rules="none" frame="void" 74 cols="2" cellspacing="0" cellpadding="0"> 75<tr valign="top" align="left"> 76<td width="8%"></td> 77<td width="91%"> 78<p>The library attempts to hide bit- and byte-ordering 79differences between the image and the native machine by 80converting data to the native machine order. Bit reversal is 81done if the <i>FillOrder</i> tag is opposite to the native 82machine bit order. 16- and 32-bit samples are automatically 83byte-swapped if the file was written with a byte order 84opposite to the native machine byte order,</p> 85<!-- INDENTATION --> 86<p>In C++ the <i>sample</i> parameter defaults to 0.</p> 87</td> 88</table> 89<a name="RETURN VALUES"></a> 90<h2>RETURN VALUES</h2> 91<!-- INDENTATION --> 92<table width="100%" border=0 rules="none" frame="void" 93 cols="2" cellspacing="0" cellpadding="0"> 94<tr valign="top" align="left"> 95<td width="8%"></td> 96<td width="91%"> 97<p><i>TIFFReadScanline</i> returns −1 if it detects an 98error; otherwise 1 is returned.</p> 99</td> 100</table> 101<a name="DIAGNOSTICS"></a> 102<h2>DIAGNOSTICS</h2> 103<!-- INDENTATION --> 104<table width="100%" border=0 rules="none" frame="void" 105 cols="2" cellspacing="0" cellpadding="0"> 106<tr valign="top" align="left"> 107<td width="8%"></td> 108<td width="91%"> 109<p>All error messages are directed to the 110<i>TIFFError</i>(3TIFF) routine.</p> 111<!-- INDENTATION --> 112<p><b>Compression algorithm does not support random 113access</b>. Data was requested in a non-sequential order 114from a file that uses a compression algorithm and that has 115<i>RowsPerStrip</i> greater than one. That is, data in the 116image is stored in a compressed form, and with multiple rows 117packed into a strip. In this case, the library does not 118support random access to the data. The data should either be 119accessed sequentially, or the file should be converted so 120that each strip is made up of one row of data.</p> 121</td> 122</table> 123<a name="BUGS"></a> 124<h2>BUGS</h2> 125<!-- INDENTATION --> 126<table width="100%" border=0 rules="none" frame="void" 127 cols="2" cellspacing="0" cellpadding="0"> 128<tr valign="top" align="left"> 129<td width="8%"></td> 130<td width="91%"> 131<p>Reading subsampled YCbCR data does not work correctly 132because, for <i>PlanarConfiguration</i>=2 the size of a 133scanline is not calculated on a per-sample basis, and for 134<i>PlanarConfiguration</i>=1 the library does not unpack the 135block-interleaved samples; use the strip- and tile-based 136interfaces to read these formats.</p> 137</td> 138</table> 139<a name="SEE ALSO"></a> 140<h2>SEE ALSO</h2> 141<!-- INDENTATION --> 142<table width="100%" border=0 rules="none" frame="void" 143 cols="2" cellspacing="0" cellpadding="0"> 144<tr valign="top" align="left"> 145<td width="8%"></td> 146<td width="91%"> 147<p><b>TIFFOpen</b>(3TIFF), 148<b>TIFFReadEncodedStrip</b>(3TIFF), 149<b>TIFFReadRawStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p> 150<!-- INDENTATION --> 151<p>Libtiff library home page: 152<b>http://www.simplesystems.org/libtiff/</b></p> 153</td> 154</table> 155<hr> 156</body> 157</html> 158