/// <summary>
/// Reads GIF image from stream
/// </summary>
/// <param name="inputStream">
/// Stream containing GIF file.
/// </param>
/// <exception cref="ArgumentNullException">
/// The supplied stream is null.
/// </exception>
private void ReadStream( Stream inputStream )
{
_frames = new Collection<GifFrame>();
_applicationExtensions = new Collection<ApplicationExtension>();
_gct = null;
_readStreamCounterText = "Reading stream byte";
AddCounter( _readStreamCounterText, (int) inputStream.Length );
_header = new GifHeader( inputStream, XmlDebugging );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
WriteDebugXmlNode( _header.DebugXmlReader );
if( _header.ErrorState != ErrorState.Ok )
{
WriteDebugXmlFinish();
return;
}
_lsd = new LogicalScreenDescriptor( inputStream, XmlDebugging );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
WriteDebugXmlNode( _lsd.DebugXmlReader );
if( TestState( ErrorState.EndOfInputStream ) )
{
WriteDebugXmlFinish();
return;
}
if( _lsd.HasGlobalColourTable )
{
_gct = new ColourTable( inputStream,
_lsd.GlobalColourTableSize,
XmlDebugging );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
WriteDebugXmlNode( _gct.DebugXmlReader );
}
if( ConsolidatedState == ErrorState.Ok )
{
ReadContents( inputStream );
MyProgressCounters[_readStreamCounterText].Value
= (int) inputStream.Position;
}
inputStream.Close();
WriteDebugXmlFinish();
RemoveCounter( _readStreamCounterText );
}
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();
}
private static void CheckGifHeader( Stream s )
{
// check GIF header
GifHeader gh = new GifHeader( s );
Assert.AreEqual( ErrorState.Ok, gh.ConsolidatedState );
Assert.AreEqual( "GIF", gh.Signature );
Assert.AreEqual( "89a", gh.Version );
}
private static void WriteGifHeader( Stream outputStream )
{
GifHeader header = new GifHeader( "GIF", "89a" );
header.WriteToStream( outputStream );
}
