/// <summary>
/// Constructor.
/// </summary>
/// <param name="applicationExtension">
/// The application extension to build the Netscape extension from.
/// </param>
public NetscapeExtension( ApplicationExtension applicationExtension )
: base( applicationExtension.IdentificationBlock,
applicationExtension.ApplicationData )
{
#region guard against application extensions which are not Netscape extensions
string message;
if( applicationExtension.ApplicationIdentifier != "NETSCAPE" )
{
message = "The application identifier is not 'NETSCAPE' "
+ "therefore this application extension is not a "
+ "Netscape extension. Application identifier: "
+ applicationExtension.ApplicationIdentifier;
throw new ArgumentException( message, "applicationExtension" );
}
if( applicationExtension.ApplicationAuthenticationCode != "2.0" )
{
message = "The application authentication code is not '2.0' "
+ "therefore this application extension is not a "
+ "Netscape extension. Application authentication code: "
+ applicationExtension.ApplicationAuthenticationCode;
throw new ArgumentException( message, "applicationExtension" );
}
#endregion
foreach( DataBlock block in ApplicationData )
{
if( block.ActualBlockSize == 0 )
{
// then we've found the block terminator
break;
}
// The first byte in a Netscape application extension data
// block should be 1. Ignore if anything else.
if( block.ActualBlockSize > 2 && block[0] == 1 )
{
// The loop count is held in the second and third bytes
// of the data block, least significant byte first.
int byte1 = ( (int) block[1] ) & 0xff;
int byte2 = ( (int) block[2] ) & 0xff;
// String the two bytes together to make an integer,
// with byte 2 coming first.
_loopCount = (byte2 << 8) | byte1;
}
}
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="applicationExtension">
/// The application extension to build the Netscape extension from.
/// </param>
public NetscapeExtension(ApplicationExtension applicationExtension)
: base(applicationExtension.IdentificationBlock,
applicationExtension.ApplicationData)
{
#region guard against application extensions which are not Netscape extensions
string message;
if (applicationExtension.ApplicationIdentifier != "NETSCAPE")
{
message = "The application identifier is not 'NETSCAPE' "
+ "therefore this application extension is not a "
+ "Netscape extension. Application identifier: "
+ applicationExtension.ApplicationIdentifier;
throw new ArgumentException(message, "applicationExtension");
}
if (applicationExtension.ApplicationAuthenticationCode != "2.0")
{
message = "The application authentication code is not '2.0' "
+ "therefore this application extension is not a "
+ "Netscape extension. Application authentication code: "
+ applicationExtension.ApplicationAuthenticationCode;
throw new ArgumentException(message, "applicationExtension");
}
#endregion
foreach (DataBlock block in ApplicationData)
{
if (block.ActualBlockSize == 0)
{
// then we've found the block terminator
break;
}
// The first byte in a Netscape application extension data
// block should be 1. Ignore if anything else.
if (block.ActualBlockSize > 2 && block[0] == 1)
{
// The loop count is held in the second and third bytes
// of the data block, least significant byte first.
int byte1 = ((int)block[1]) & 0xff;
int byte2 = ((int)block[2]) & 0xff;
// String the two bytes together to make an integer,
// with byte 2 coming first.
_loopCount = (byte2 << 8) | byte1;
}
}
}
/// <summary>
/// Main file parser. Reads GIF content blocks.
/// </summary>
/// <param name="inputStream">
/// Input stream from which the GIF data is to be read.
/// </param>
private void ReadContents( Stream inputStream )
{
// read GIF file content blocks
bool done = false;
GraphicControlExtension lastGce = null;
string message; // for error conditions
while( !done && ConsolidatedState == ErrorState.Ok )
{
int code = Read( inputStream );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
WriteCodeToDebugXml( code );
switch( code )
{
case CodeImageSeparator:
WriteDebugXmlComment( "0x2C - image separator" );
AddFrame( inputStream, lastGce );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
break;
case CodeExtensionIntroducer:
WriteDebugXmlComment( "0x21 - extension introducer" );
code = Read( inputStream );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
WriteCodeToDebugXml( code );
switch( code )
{
case CodePlaintextLabel:
// FEATURE: handle plain text extension
WriteDebugXmlComment( "0x01 - plain text extension" );
SkipBlocks( inputStream );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
break;
case CodeGraphicControlLabel:
WriteDebugXmlComment( "0xF9 - graphic control label" );
lastGce = new GraphicControlExtension( inputStream,
XmlDebugging );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
WriteDebugXmlNode( lastGce.DebugXmlReader );
break;
case CodeCommentLabel:
// FEATURE: handle comment extension
WriteDebugXmlComment( "0xFE - comment extension" );
SkipBlocks( inputStream );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
break;
case CodeApplicationExtensionLabel:
WriteDebugXmlComment( "0xFF - application extension label" );
ApplicationExtension ext
= new ApplicationExtension( inputStream,
XmlDebugging );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
WriteDebugXmlNode( ext.DebugXmlReader );
if( ext.ApplicationIdentifier == "NETSCAPE"
&& ext.ApplicationAuthenticationCode == "2.0" )
{
_netscapeExtension = new NetscapeExtension( ext );
}
else
{
// TESTME: ReadContents - non-Netscape application extension
_applicationExtensions.Add( ext );
}
break;
default : // uninteresting extension
// TESTME: ReadContents - uninteresting extension
WriteDebugXmlComment( "Ignoring this extension" );
SkipBlocks( inputStream );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
break;
}
break;
case CodeTrailer:
// We've reached an explicit end-of-data marker, so stop
// processing the stream.
WriteDebugXmlComment( "0x3B - end of data" );
done = true;
break;
case 0x00 : // bad byte, but keep going and see what happens
WriteDebugXmlComment( "0x00 - unexpected code" );
message
= "Unexpected block terminator encountered at "
+ "position " + inputStream.Position
+ " after reading " + _frames.Count + " frames.";
SetStatus( ErrorState.UnexpectedBlockTerminator,
message );
break;
case -1: // reached the end of the input stream
WriteDebugXmlComment( "-1 - end of input stream" );
message
= "Reached the end of the input stream without "
+ "encountering trailer 0x3b";
SetStatus( ErrorState.EndOfInputStream, message );
break;
default :
WriteDebugXmlComment( "Not a recognised code" );
message
= "Bad data block introducer: 0x"
+ code.ToString( "X", CultureInfo.InvariantCulture ).PadLeft( 2, '0' )
+ " (" + code + ") at position " + inputStream.Position
+ " ("
+ inputStream.Position.ToString( "X",
CultureInfo.InvariantCulture )
+ " hex) after reading "
+ _frames.Count + " frames.";
SetStatus( ErrorState.BadDataBlockIntroducer, message );
break;
}
}
}
public void ConstructorTest()
{
byte[] idData = new byte[]
{
(byte) 'N',
(byte) 'E',
(byte) 'T',
(byte) 'S',
(byte) 'C',
(byte) 'A',
(byte) 'P',
(byte) 'E',
(byte) '2',
(byte) '.',
(byte) '0',
};
DataBlock idBlock = new DataBlock( 11, idData );
Collection<DataBlock> appData = new Collection<DataBlock>();
// First byte in the data block is always 1 for a netscape extension
// Second and third bytes are the loop count, lsb first
byte[] loopCount = new byte[] { 1, 4, 0 };
appData.Add( new DataBlock( 3, loopCount ) );
// Add the block terminator
appData.Add( new DataBlock( 0, new byte[0] ) );
ApplicationExtension appExt
= new ApplicationExtension( idBlock, appData );
_ne = new NetscapeExtension( appExt );
Assert.AreEqual( 4, _ne.LoopCount );
Assert.AreEqual( "NETSCAPE", _ne.ApplicationIdentifier );
Assert.AreEqual( "2.0", _ne.ApplicationAuthenticationCode );
Assert.AreEqual( ErrorState.Ok, _ne.ConsolidatedState );
}
public void ConstructorTestNotNetscape()
{
byte[] idData = new byte[]
{
(byte) 'B',
(byte) 'I',
(byte) 'G',
(byte) 'P',
(byte) 'A',
(byte) 'N',
(byte) 'T',
(byte) 'S',
(byte) '2',
(byte) '.',
(byte) '0',
};
DataBlock idBlock = new DataBlock( 11, idData );
ApplicationExtension appExt
= new ApplicationExtension( idBlock, new Collection<DataBlock>() );
try
{
_ne = new NetscapeExtension( appExt );
}
catch( ArgumentException ex )
{
string message
= "The application identifier is not 'NETSCAPE' "
+ "therefore this application extension is not a "
+ "Netscape extension. Application identifier: BIGPANTS";
StringAssert.Contains( message, ex.Message );
Assert.AreEqual( "applicationExtension", ex.ParamName );
throw;
}
}
public void ConstructorTestNot2Point0()
{
byte[] idData = new byte[]
{
(byte) 'N',
(byte) 'E',
(byte) 'T',
(byte) 'S',
(byte) 'C',
(byte) 'A',
(byte) 'P',
(byte) 'E',
(byte) '3',
(byte) '.',
(byte) '0',
};
DataBlock idBlock = new DataBlock( 11, idData );
ApplicationExtension appExt
= new ApplicationExtension( idBlock, new Collection<DataBlock>() );
try
{
_ne = new NetscapeExtension( appExt );
}
catch( ArgumentException ex )
{
string message
= "The application authentication code is not '2.0' "
+ "therefore this application extension is not a "
+ "Netscape extension. Application authentication code: 3.0";
StringAssert.Contains( message, ex.Message );
Assert.AreEqual( "applicationExtension", ex.ParamName );
throw;
}
}
private static void CheckNetscapeExtension( Stream s, int loopCount )
{
// check netscape extension
ApplicationExtension ae = new ApplicationExtension( s );
Assert.AreEqual( ErrorState.Ok, ae.ConsolidatedState );
NetscapeExtension ne = new NetscapeExtension( ae );
Assert.AreEqual( ErrorState.Ok, ne.ConsolidatedState );
Assert.AreEqual( loopCount, ne.LoopCount );
}
public void WikipediaExampleTest()
{
ReportStart();
_e = new AnimatedGifEncoder();
GifFrame frame = new GifFrame( WikipediaExample.ExpectedBitmap );
frame.Delay = WikipediaExample.DelayTime;
_e.AddFrame( frame );
// TODO: some way of creating/testing a UseLocal version of WikipediaExample
string fileName = "WikipediaExampleUseGlobal.gif";
_e.WriteToFile( fileName );
Stream s = File.OpenRead( fileName );
int code;
// check GIF header
GifHeader gh = new GifHeader( s );
Assert.AreEqual( ErrorState.Ok, gh.ConsolidatedState );
// check logical screen descriptor
LogicalScreenDescriptor lsd = new LogicalScreenDescriptor( s );
Assert.AreEqual( ErrorState.Ok, lsd.ConsolidatedState );
WikipediaExample.CheckLogicalScreenDescriptor( lsd );
// read global colour table
ColourTable gct
= new ColourTable( s, WikipediaExample.GlobalColourTableSize );
Assert.AreEqual( ErrorState.Ok, gct.ConsolidatedState );
// cannot compare global colour table as different encoders will
// produce difference colour tables.
// WikipediaExample.CheckGlobalColourTable( gct );
// check for extension introducer
code = ExampleComponent.CallRead( s );
Assert.AreEqual( GifComponent.CodeExtensionIntroducer, code );
// check for app extension label
code = ExampleComponent.CallRead( s );
Assert.AreEqual( GifComponent.CodeApplicationExtensionLabel, code );
// check netscape extension
ApplicationExtension ae = new ApplicationExtension( s );
Assert.AreEqual( ErrorState.Ok, ae.ConsolidatedState );
NetscapeExtension ne = new NetscapeExtension( ae );
Assert.AreEqual( ErrorState.Ok, ne.ConsolidatedState );
Assert.AreEqual( 0, ne.LoopCount );
// check for extension introducer
code = ExampleComponent.CallRead( s );
Assert.AreEqual( GifComponent.CodeExtensionIntroducer, code );
// check for gce label
code = ExampleComponent.CallRead( s );
Assert.AreEqual( GifComponent.CodeGraphicControlLabel, code );
// check graphic control extension
GraphicControlExtension gce = new GraphicControlExtension( s );
Assert.AreEqual( ErrorState.Ok, gce.ConsolidatedState );
WikipediaExample.CheckGraphicControlExtension( gce );
// check for image separator
code = ExampleComponent.CallRead( s );
Assert.AreEqual( GifComponent.CodeImageSeparator, code );
// check for image descriptor
ImageDescriptor id = new ImageDescriptor( s );
Assert.AreEqual( ErrorState.Ok, id.ConsolidatedState );
WikipediaExample.CheckImageDescriptor( id );
// read, decode and check image data
// Cannot compare encoded LZW data directly as different encoders
// will create different colour tables, so even if the bitmaps are
// identical, the colour indices will be different
int pixelCount = WikipediaExample.FrameSize.Width
* WikipediaExample.FrameSize.Height;
TableBasedImageData tbid = new TableBasedImageData( s, pixelCount );
for( int y = 0; y < WikipediaExample.LogicalScreenSize.Height; y++ )
{
for( int x = 0; x < WikipediaExample.LogicalScreenSize.Width; x++ )
{
int i = (y * WikipediaExample.LogicalScreenSize.Width) + x;
Assert.AreEqual( WikipediaExample.ExpectedBitmap.GetPixel( x, y ),
gct[tbid.Pixels[i]],
"X: " + x + ", Y: " + y );
}
}
// Check for block terminator after image data
code = ExampleComponent.CallRead( s );
Assert.AreEqual( 0x00, code );
// check for GIF trailer
code = ExampleComponent.CallRead( s );
Assert.AreEqual( GifComponent.CodeTrailer, code );
// check we're at the end of the stream
code = ExampleComponent.CallRead( s );
Assert.AreEqual( -1, code );
s.Close();
_d = new GifDecoder( fileName );
_d.Decode();
Assert.AreEqual( ErrorState.Ok, _d.ConsolidatedState );
BitmapAssert.AreEqual( WikipediaExample.ExpectedBitmap,
(Bitmap) _d.Frames[0].TheImage,
"" );
ReportEnd();
}
