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1 .\" $Id: TIFFWriteScanline.3tiff,v 1.2 2005/11/02 11:07:18 dron Exp $
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25 .if n .po 0
26 .TH TIFFWriteScanline 3TIFF "December 16, 1991" "libtiff"
27 .SH NAME
28 TIFFWriteScanline \- write a scanline to an open
29 .SM TIFF
30 file
31 .SH SYNOPSIS
32 .B "#include <tiffio.h>"
33 .sp
34 .BI "int TIFFWriteScanline(TIFF *" tif ", tdata_t " buf ", uint32 " row ", tsample_t " sample ")"
35 .SH DESCRIPTION
36 Write data to a file at the specified row. The
37 .I sample
38 parameter is used only if data are organized in separate planes (\c
39 .IR PlanarConfiguration =2).
40 The data are assumed to be uncompressed and in the native bit- and byte-order
41 of the host machine. The data written to the file is compressed according to
42 the compression scheme of the current
43 .SM TIFF
44 directory (see further below). If the current scanline is past the end of the
45 current subfile, the
46 .I ImageLength
47 field is automatically increased to include the scanline (except
48 for
49 .IR PlanarConfiguration =2,
50 where the
51 .I ImageLength
52 cannot be changed once the first data are written). If the
53 .I ImageLength
54 is increased, the
55 .I StripOffsets
56 and
57 .I StripByteCounts
58 fields are similarly enlarged to reflect data written past the previous end of
59 image.
60 .SH NOTES
61 The library writes encoded data using the native machine byte order. Correctly
62 implemented
63 .SM TIFF
64 readers are expected to do any necessary byte-swapping to correctly process
65 image data with BitsPerSample greater than 8. The library attempts to hide
66 bit-ordering differences between the image and the native machine by
67 converting data from the native machine order.
68 .PP
69 In C++ the
70 .I sample
71 parameter defaults to 0.
72 .PP
73 Once data are written to a file for the current directory, the values of
74 certain tags may not be altered; see
75 .IR TIFFSetField (3TIFF)
76 for more information.
77 .PP
78 It is not possible to write scanlines to a file that uses a tiled
79 organization. The routine
80 .IR TIFFIsTiled
81 can be used to determine if the file is organized as tiles or strips.
82 .SH "RETURN VALUES"
83 .IR TIFFWriteScanline
84 returns \-1 if it immediately detects an error and 1 for a successful write.
85 .SH DIAGNOSTICS
86 All error messages are directed to the
87 .IR TIFFError (3TIFF)
88 routine.
89 .PP
90 .BR "%s: File not open for writing .
91 The file was opened for reading, not writing.
92 .PP
93 .BR "Can not write scanlines to a tiled image" .
94 An attempt was made to write a scanline to a tiled image. The image is assumed
95 to be organized in tiles because the
96 .I TileWidth
97 and
98 .I TileLength
99 tags have been set with
100 .IR TIFFSetField (3TIFF).
101 .PP
102 .BR "Compression algorithm does not support random access" .
103 Data was written in a non-sequential order to a file that uses a compression
104 algorithm and that has
105 .I RowsPerStrip
106 greater than one. That is, data in the image is to be stored in a compressed
107 form, and with multiple rows packed into a strip. In this case, the library
108 does not support random access to the data. The data should either be written
109 as entire strips, sequentially by rows, or the value of
110 .I RowsPerStrip
111 should be set to one.
112 .PP
113 \fB%s: Must set "ImageWidth" before writing data\fP.
114 The image's width has not be set before the first write.
115 See
116 .BR TIFFSetField (3TIFF)
117 for information on how to do this.
118 .PP
119 \fB%s: Must set "PlanarConfiguration" before writing data\fP.
120 The organization of data has not be defined before the first write.
121 See
122 .BR TIFFSetField (3TIFF)
123 for information on how to do this.
124 .PP
125 \fBCan not change "ImageLength" when using separate planes\fP. Separate image
126 planes are being used (\c
127 .IR PlanarConfiguration =2),
128 but the number of rows has not been specified before the first write. The
129 library supports the dynamic growth of an image only when data are organized
130 in a contiguous manner (\c
131 .IR PlanarConfiguration =1).
132 .PP
133 .BR "%d: Sample out of range, max %d" .
134 The
135 .I sample
136 parameter was greater than the value of the SamplesPerPixel tag.
137 .PP
138 .BR "%s: No space for strip arrays .
139 There was not enough space for the arrays that hold strip offsets and byte
140 counts.
141 .SH BUGS
142 Writing subsampled YCbCR data does not work correctly because, for
143 .IR PlanarConfiguration =2
144 the size of a scanline is not calculated on a per-sample basis, and for
145 .IR PlanarConfiguration =1
146 the library does not pack the block-interleaved samples.
147 .SH "SEE ALSO"
148 .BR TIFFOpen (3TIFF),
149 .BR TIFFWriteEncodedStrip (3TIFF),
150 .BR TIFFWriteRawStrip (3TIFF),
151 .BR libtiff (3TIFF)
152 .PP
153 Libtiff library home page:
154 .BR http://www.remotesensing.org/libtiff/