Welcome to mirror list, hosted at ThFree Co, Russian Federation.

ImageCodec.jvm.cs « System.Drawing.Imaging « System.Drawing « class « mcs - github.com/mono/mono.git - Unnamed repository; edit this file 'description' to name the repository.
summaryrefslogtreecommitdiff
blob: 2eff947138a3e543eb60a9fcdf6d0aaa667ed8b6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
using System;
using System.Configuration;
using System.Collections;
using System.Collections.Specialized;
using System.Drawing.Imaging;
using System.Xml;
using Mainsoft.Drawing.Configuration;

using imageio = javax.imageio;
using stream = javax.imageio.stream;
using awt = java.awt;
using image = java.awt.image;
using spi = javax.imageio.spi;
using dom = org.w3c.dom;

namespace Mainsoft.Drawing.Imaging {
	/// <summary>
	/// Summary description for ImageCodec.
	/// </summary>
	public class ImageCodec : IDisposable {

		#region Members

		imageio.ImageReader _nativeReader = null;
		imageio.ImageWriter _nativeWriter = null;
		stream.ImageInputStream _nativeStream = null;

		ImageFormat _imageFormat = null;

		int _currentFrame = 0;

		#endregion

		#region Constructros

		protected ImageCodec() {
		}

		static ImageCodec() {
		}

		#endregion

		#region Internal properties

		internal imageio.ImageReader NativeReader {
			get { return _nativeReader; }
			set { 
				_nativeReader = value; 
				if (value == null)
					return;
				_imageFormat = MimeTypesToImageFormat( value.getOriginatingProvider().getMIMETypes() );
			}
		}
		internal imageio.ImageWriter NativeWriter {
			get { return _nativeWriter; }
			set { 
				_nativeWriter = value; 
				if (value == null)
					return;
				_imageFormat = MimeTypesToImageFormat( value.getOriginatingProvider().getMIMETypes() );
			}
		}

		internal stream.ImageInputStream NativeStream {
			get { return _nativeStream; }
			set {
				_nativeStream = value;
				if (value == null)
					return;

				if (NativeReader != null)
					NativeReader.setInput( value );

				if (NativeWriter != null)
					NativeWriter.setOutput( value );
			}
		}

		#endregion

		#region ImageCodec factory methods

		public static ImageCodec CreateReader(stream.ImageInputStream inputStream) {
			java.util.Iterator iter = imageio.ImageIO.getImageReaders( inputStream );
			return CreateReader(iter);
		}

		public static ImageCodec CreateReader(ImageFormat imageFormat) {
			return CreateReader( ImageFormatToClsid( imageFormat ) );
		}

		public static ImageCodec CreateReader(Guid clsid) {
			ImageCodec codec = null;
			try {
				ImageCodecInfo codecInfo = FindDecoder(clsid);
				java.util.Iterator iter = imageio.ImageIO.getImageReadersByMIMEType( codecInfo.MimeType );
				codec = CreateReader(iter);
			}
			catch {}

			if (codec == null) {
				ImageFormat format = ClsidToImageFormat(clsid);
				string name = (format != null) ? format.ToString() : clsid.ToString();
				throw new NotSupportedException(String.Format("The '{0}' format decoder is not installed.", name));
			}

			return codec;
		}

		private static ImageCodec CreateReader(java.util.Iterator iter) {
			if ( !iter.hasNext() )
				return null;

			ImageCodec imageCodec = new ImageCodec();
			imageCodec.NativeReader = (imageio.ImageReader) iter.next();
			return imageCodec;
		}

		public static ImageCodec CreateWriter(ImageFormat imageFormat) {
			return CreateWriter( ImageFormatToClsid( imageFormat ) );
		}

		public static ImageCodec CreateWriter(Guid clsid) {
			ImageCodec codec = null;
			try {
				ImageCodecInfo codecInfo = FindEncoder(clsid);
				java.util.Iterator iter = imageio.ImageIO.getImageWritersByMIMEType( codecInfo.MimeType );
				codec = CreateWriter(iter);
			}
			catch {}

			if (codec == null) {
				ImageFormat format = ClsidToImageFormat(clsid);
				string name = (format != null) ? format.ToString() : clsid.ToString();
				throw new NotSupportedException(String.Format("The '{0}' format encoder is not installed.", name));
			}

			return codec;
		}

		private static ImageCodec CreateWriter(java.util.Iterator iter) {
			if ( !iter.hasNext() )
				return null;
			
			ImageCodec imageCodec = new ImageCodec();
			imageCodec.NativeWriter = (imageio.ImageWriter) iter.next();
			return imageCodec;
		}

		#endregion

		#region Codec enumerations

		internal static Hashtable Decoders {
			get {
				const string MYNAME = "System.Drawing.Imaging.ImageCodecInfo.decoders";
				Hashtable o = (Hashtable) AppDomain.CurrentDomain.GetData (MYNAME);
				if (o != null)
					return o;
				o = new ReaderSpiIterator().Iterate();
				AppDomain.CurrentDomain.SetData(MYNAME, o);
				return o;
			}
		}

		internal static Hashtable Encoders {
			get {
				const string MYNAME = "System.Drawing.Imaging.ImageCodecInfo.encoders";
				Hashtable o = (Hashtable) AppDomain.CurrentDomain.GetData (MYNAME);
				if (o != null)
					return o;
				o = new WriterSpiIterator().Iterate();
				AppDomain.CurrentDomain.SetData(MYNAME, o);
				return o;
			}
		}

		internal static ImageCodecInfo FindEncoder (Guid clsid) {
			ImageCodecInfo codec = (ImageCodecInfo) Encoders[clsid];
			if (codec == null) {
				// .net saves in png if cannot find requested encoder. atc id 316563
				codec = (ImageCodecInfo) Encoders[ ImageCodec.PngClsid ];
			}
			return codec;
		}

		internal static ImageCodecInfo FindDecoder (Guid clsid) {
			ImageCodecInfo codec = (ImageCodecInfo) Decoders[clsid];
			if (codec == null) {
				ImageFormat format = ClsidToImageFormat(clsid);
				string name = (format != null) ? format.ToString() : clsid.ToString();
				throw new NotSupportedException(String.Format("The '{0}' format decoder is not installed.", name));
			}
			return codec;
		}

		#endregion

		#region SpiIterators

		abstract class BaseSpiIterator {
			protected abstract java.util.Iterator GetIterator (string mimeType);
			protected abstract spi.ImageReaderWriterSpi GetNext (java.util.Iterator iter);

			#region ProcessOneCodec
			private ImageCodecInfo ProcessOneCodec (Guid clsid, Guid formatID, string mimeType) {
				ImageCodecInfo ici = new ImageCodecInfo ();
				ici.Clsid = clsid;
				ici.FormatID = formatID;
				ici.MimeType = mimeType;
				java.util.Iterator iter = null;
				try {
					iter = GetIterator (mimeType);
				}
				catch(Exception) {
					return null;
				}
				while (iter.hasNext ()) {
					spi.ImageReaderWriterSpi rw = GetNext (iter);

					ici.CodecName = rw.getDescription (java.util.Locale.getDefault ());
					//ici.DllName = null;
					foreach (string suffix in rw.getFileSuffixes ()) {
						if (ici.FilenameExtension != null)
							ici.FilenameExtension += ";";
						ici.FilenameExtension += "*."+suffix;
					}
					ici.Flags = ImageCodecFlags.Builtin|ImageCodecFlags.SupportBitmap;
					if (rw is spi.ImageReaderSpi)
						ici.Flags |= ImageCodecFlags.Decoder;

					if (rw is spi.ImageWriterSpi)
						ici.Flags |= ImageCodecFlags.Encoder;

					ici.FormatDescription = string.Join(";",
						rw.getFormatNames());
					try {
						ici.Version = (int)Convert.ToDouble(rw.getVersion ());
					}
					catch (Exception) {
						ici.Version = 1;
					}
					break;
				}
				return ici;
			}
			#endregion

			internal Hashtable Iterate () {
				// TBD: Insert Exception handling here
				NameValueCollection nvc = (NameValueCollection) System.Configuration.ConfigurationSettings
					.GetConfig ("system.drawing/codecs");
				Hashtable codecs = new Hashtable (10);
			
				for (int i=0; i<nvc.Count; i++) {
					Guid clsid = new Guid (nvc.GetKey (i));
					ImageFormat format = ClsidToImageFormat (clsid);
					ImageCodecInfo codec = ProcessOneCodec (clsid, format.Guid, nvc[i]);
					if ((codec != null) && (codec.FilenameExtension != null))
						codecs [clsid] = codec;
				}
				return codecs;
			}
		}

		class ReaderSpiIterator: BaseSpiIterator {
			protected override java.util.Iterator GetIterator(string mimeType) {
				return imageio.ImageIO.getImageReadersByMIMEType (mimeType);
			}
			protected override javax.imageio.spi.ImageReaderWriterSpi GetNext(java.util.Iterator iter) {
				imageio.ImageReader r = (imageio.ImageReader) iter.next ();
				return r.getOriginatingProvider ();
			}
		}

		class WriterSpiIterator: BaseSpiIterator {
			protected override java.util.Iterator GetIterator(string mimeType) {
				return imageio.ImageIO.getImageWritersByMIMEType (mimeType);
			}
			protected override javax.imageio.spi.ImageReaderWriterSpi GetNext(java.util.Iterator iter) {
				imageio.ImageWriter w = (imageio.ImageWriter) iter.next ();
				return w.getOriginatingProvider ();
			}
		}
		#endregion

		#region Clsid and FormatID
		static Guid BmpClsid = new Guid ("557cf400-1a04-11d3-9a73-0000f81ef32e");
		static Guid JpegClsid = new Guid ("557cf401-1a04-11d3-9a73-0000f81ef32e");
		static Guid GifClsid = new Guid ("557cf402-1a04-11d3-9a73-0000f81ef32e");
		static Guid EmfClsid = new Guid ("557cf403-1a04-11d3-9a73-0000f81ef32e");
		static Guid WmfClsid = new Guid ("557cf404-1a04-11d3-9a73-0000f81ef32e");
		static Guid TiffClsid = new Guid ("557cf405-1a04-11d3-9a73-0000f81ef32e");
		static Guid PngClsid = new Guid ("557cf406-1a04-11d3-9a73-0000f81ef32e");
		static Guid IconClsid = new Guid ("557cf407-1a04-11d3-9a73-0000f81ef32e");

		private static ImageFormat MimeTypesToImageFormat (string [] mimeTypes) {
			foreach (ImageCodecInfo codec in Decoders.Values)
				for (int i=0; i<mimeTypes.Length; i++)
					if (codec.MimeType == mimeTypes [i])
						return new ImageFormat (codec.FormatID);
			return null;
		}

		internal static ImageFormat ClsidToImageFormat (Guid clsid) {
			if (clsid.Equals (BmpClsid))
				return ImageFormat.Bmp;
			else if (clsid.Equals (JpegClsid))
				return ImageFormat.Jpeg;
			else if (clsid.Equals (GifClsid))
				return ImageFormat.Gif;
			else if (clsid.Equals (EmfClsid))
				return ImageFormat.Emf;
			else if (clsid.Equals (WmfClsid))
				return ImageFormat.Wmf;
			else if (clsid.Equals (TiffClsid))
				return ImageFormat.Tiff;
			else if (clsid.Equals (PngClsid))
				return ImageFormat.Png;
			else if (clsid.Equals (IconClsid))
				return ImageFormat.Icon;
			else
				return null;
		}

		internal static Guid ImageFormatToClsid (ImageFormat format) {
			if (format == null)
				return Guid.Empty;

			if (format.Guid.Equals (ImageFormat.Bmp.Guid))
				return BmpClsid;
			else if (format.Guid.Equals (ImageFormat.Jpeg.Guid))
				return JpegClsid;
			else if (format.Guid.Equals (ImageFormat.Gif))
				return GifClsid;
			else if (format.Guid.Equals (ImageFormat.Emf.Guid))
				return EmfClsid;
			else if (format.Guid.Equals (ImageFormat.Wmf.Guid))
				return WmfClsid;
			else if (format.Guid.Equals (ImageFormat.Tiff.Guid))
				return TiffClsid;
			else if (format.Guid.Equals (ImageFormat.Png.Guid))
				return PngClsid;
			else if (format.Guid.Equals (ImageFormat.Icon.Guid))
				return IconClsid;
			else
				return Guid.Empty;
		}

		private FrameDimension FormatFrameDimesion {
			get {
				if (ImageFormat == null)
					return FrameDimension.Page;

				if (ImageFormat.Guid.Equals (ImageFormat.Bmp.Guid))
					return FrameDimension.Page;
				else if (ImageFormat.Guid.Equals (ImageFormat.Jpeg.Guid))
					return FrameDimension.Page;
				else if (ImageFormat.Guid.Equals (ImageFormat.Gif))
					return FrameDimension.Time;
				else if (ImageFormat.Guid.Equals (ImageFormat.Emf.Guid))
					return FrameDimension.Page;
				else if (ImageFormat.Guid.Equals (ImageFormat.Wmf.Guid))
					return FrameDimension.Page;
				else if (ImageFormat.Guid.Equals (ImageFormat.Tiff.Guid))
					return FrameDimension.Page;
				else if (ImageFormat.Guid.Equals (ImageFormat.Png.Guid))
					return FrameDimension.Page;
				else if (ImageFormat.Guid.Equals (ImageFormat.Icon.Guid))
					return FrameDimension.Resolution;
				else
					return FrameDimension.Page;
			}
		}

		#endregion
		
		#region Image read/write methods

		internal PlainImage ReadPlainImage() {
			awt.Image img = ReadImage( _currentFrame );
			if (img == null)
				return null;

			// its possible to fail to load thumbnails and metadata, but image is ok.
			awt.Image [] th = null;
#if THUMBNAIL_SUPPORTED
			try {
				th = ReadThumbnails( _currentFrame );
			}
			catch (Exception) {}
#endif
			
			XmlDocument md = null;
			imageio.metadata.IIOMetadata nativeMd = null;
			try {
				nativeMd = ReadImageMetadata( _currentFrame );
				md = ConvertImageMetadata( nativeMd );
			}
			catch (Exception) {}

			float [] resolution = GetResolution( md );

			PlainImage pi = new PlainImage( img, th, ImageFormat, resolution[0], resolution[1], FormatFrameDimesion );
			pi.NativeMetadata = nativeMd;
			return pi;
		}

		internal PlainImage ReadNextPlainImage() {
			_currentFrame++;
			return ReadPlainImage();
		}

		private awt.Image ReadImage(int frame) {
			if (NativeStream == null)
				throw new Exception("Input stream not specified");

			try {
				return NativeReader.read (frame);
			}
			catch (java.lang.IndexOutOfBoundsException) {
				return null;
			}
			catch (java.io.IOException ex) {
				throw new System.IO.IOException(ex.Message, ex);
			}
		}

#if THUMBNAIL_SUPPORTED
		private awt.Image [] ReadThumbnails(int frameIndex) {
			awt.Image [] thArray = null;

			try {
				if (NativeReader.readerSupportsThumbnails()) {
					int tmbNumber = NativeReader.getNumThumbnails(frameIndex);

					if (tmbNumber > 0) {
						thArray = new awt.Image[ tmbNumber ];

						for (int i = 0; i < tmbNumber; i++) {
							thArray[i] = NativeReader.readThumbnail(frameIndex, i);
						}
					}
				}
				return thArray;
			}
			catch (java.io.IOException ex) {
				throw new System.IO.IOException(ex.Message, ex);
			}
		}
#endif
		internal void WritePlainImage(PlainImageCollection pic) {
			if ((pic == null) || (pic.Count == 0))
				return;

			if (pic.Count == 1) {
				WritePlainImage( pic[0] );
				return;
			}

			try {
				if (NativeWriter.canWriteSequence ()) {
					NativeWriter.prepareWriteSequence (null);
					for (int i=0; i < pic.Count; i++) {
						imageio.IIOImage iio = GetIIOImageContainer( pic[i] );
						NativeWriter.writeToSequence (iio, null);
					}
					NativeWriter.endWriteSequence ();
				}
				else
					WritePlainImage( pic[0] );
			}
			catch (java.io.IOException ex) {
				throw new System.IO.IOException(ex.Message, ex);
			}
		}

		internal void WritePlainImage(PlainImage pi) {
			try {
				imageio.IIOImage iio = GetIIOImageContainer( pi );
				WriteImage( iio );
			}
			catch (java.io.IOException ex) {
				throw new System.IO.IOException(ex.Message, ex);
			}
		}

		private void WriteImage(imageio.IIOImage iio) {
			if (NativeStream == null)
				throw new Exception("Output stream not specified");

			NativeWriter.write( iio );
		}
		
		private imageio.IIOImage GetIIOImageContainer(PlainImage pi) {
			java.util.ArrayList al = null;
			
			// prepare thumbnails list
			if (pi.Thumbnails != null) {
				al = new java.util.ArrayList( pi.Thumbnails.Length );
				for (int i=0; i < pi.Thumbnails.Length; i++)
					al.add(pi.Thumbnails[i]);
			}

			// prepare IIOImage container
			if (pi.NativeImage is image.BufferedImage) {
				imageio.IIOImage iio = new javax.imageio.IIOImage(
					(image.BufferedImage)pi.NativeImage, al, null /*pi.NativeMetadata*/);
				return iio;
			}
			else
				// TBD: This codec is for raster formats only
				throw new NotSupportedException("Only raster formats are supported");
		}


		private imageio.metadata.IIOMetadata ReadImageMetadata(int frameIndex) {
			if (NativeStream == null)
				throw new Exception("Input stream not specified");

			try {
				imageio.metadata.IIOMetadata md = NativeReader.getImageMetadata( frameIndex );
				return md;
			}
			catch (java.io.IOException ex) {
				throw new System.IO.IOException(ex.Message, ex);
			}
		}

		#endregion

		#region Extra properties

		public ImageFormat ImageFormat {
			get { return _imageFormat; }
		}

		#endregion

		#region Metadata parse

		private float [] GetResolution(XmlDocument metaData) {
			if (metaData == null)
				return new float[]{0, 0};

			ResolutionConfigurationCollection rcc = 
				(ResolutionConfigurationCollection)
				ConfigurationSettings.GetConfig("system.drawing/codecsmetadata");

			if (rcc == null)
				throw new ConfigurationException("Configuration section codecsmetadata not found");

			ResolutionConfiguration rc = rcc[ ImageFormat.ToString() ];

			if (rc == null)
				return new float[]{0, 0};

			// Horizontal resolution
			string xResPath = rc.XResPath;
			string xRes;

			if (xResPath == string.Empty)
				xRes = rc.XResDefault;
			else
				xRes = GetValueFromMetadata(metaData, xResPath);

			if ((xRes == null) || (xRes == string.Empty))
				xRes = rc.XResDefault;

			// Vertical resolution
			string yResPath = rc.YResPath;
			string yRes;

			if (yResPath == string.Empty)
				yRes = rc.YResDefault;
			else
				yRes = GetValueFromMetadata(metaData, yResPath);

			if ((yRes == null) || (yRes == string.Empty))
				yRes = rc.YResDefault;

			// Resolution units
			string resUnitsPath = rc.UnitsTypePath;
			string resUnitsType;

			if (resUnitsPath == string.Empty)
				resUnitsType = rc.UnitsTypeDefault;
			else
				resUnitsType = GetValueFromMetadata(metaData, resUnitsPath);

			if (resUnitsType == null)
				resUnitsType = rc.UnitsTypeDefault;

			// Unit scale
			string unitScale = rc.UnitsScale[resUnitsType].ToString();

			// Adjust resolution to its units
			float [] res = new float[2];
			res[0] = ParseFloatValue(xRes) * ParseFloatValue(unitScale);
			res[1] = ParseFloatValue(yRes) * ParseFloatValue(unitScale);

			return res;
		}

		private string GetValueFromMetadata(XmlDocument metaData, string path) {
			XmlNode n = metaData.SelectSingleNode(path);
			if (n == null)
				return null;

			return n.InnerText;
		}

		private XmlDocument ConvertImageMetadata(imageio.metadata.IIOMetadata metaData) {
			string [] formatNames = metaData.getMetadataFormatNames();
			dom.Element rootNode = (dom.Element) metaData.getAsTree(formatNames[0]);

			XmlDocument _metadataDocument = new XmlDocument();
			XmlConvert(rootNode, _metadataDocument);

			return _metadataDocument;
		}

		private void XmlConvert(dom.Node jNode, XmlNode nNode) {
			XmlDocument document = nNode.OwnerDocument;
			if (document == null)
				document = (XmlDocument)nNode;

			XmlNode n = null;
			switch (jNode.getNodeType()) {
				case 1 :
					n = document.CreateNode(XmlNodeType.Element, jNode.getNodeName(), jNode.getNamespaceURI());
					break;

				case 4 :
					n = document.CreateNode(XmlNodeType.CDATA, jNode.getNodeName(), jNode.getNamespaceURI());
					break;

				default:
					return;
			}
			//set value
			n.InnerText = jNode.getNodeValue();
			nNode.AppendChild( n );

			//copy attributes
			org.w3c.dom.NamedNodeMap nm = jNode.getAttributes();
			for (int i=0; i<nm.getLength(); i++) {
				XmlAttribute a = document.CreateAttribute( nm.item(i).getNodeName() );
				a.Value = nm.item(i).getNodeValue();
				n.Attributes.Append( a );
			}

			//copy childs
			org.w3c.dom.NodeList nl = jNode.getChildNodes();
			for (int i=0; i<nl.getLength(); i++) {
				XmlConvert(nl.item(i), n);
			}
		}

		protected virtual float ParseFloatValue(string strValue) {
			try {
				if ((strValue != null) && (strValue != "")) {
					int dividerPos = strValue.IndexOf("/");
				
					if (dividerPos < 0) {
						return float.Parse(strValue);
					} 
					else {
						return float.Parse(strValue.Substring( 0, dividerPos )) /
							float.Parse(strValue.Substring( dividerPos + 1 ));
					}
				}
				return float.NaN;
			}
			catch (Exception) {
				return float.NaN;
			}
		}

		#endregion

		#region IDisposable members

		public void Dispose() {
			if (NativeReader != null) {
				NativeReader.dispose();
				NativeReader = null;
			}

			if (NativeWriter != null) {
				NativeWriter.dispose();
				NativeWriter = null;
			}
		}

		#endregion

	}
}