/// <summary>
/// Sets the pixels of the decoded image.
/// </summary>
/// <param name="imageData">
/// Table based image data containing the indices within the active
/// colour table of the colours of the pixels in this frame.
/// </param>
/// <param name="lsd">
/// The logical screen descriptor for the GIF stream.
/// </param>
/// <param name="id">
/// The image descriptor for this frame.
/// </param>
/// <param name="activeColourTable">
/// The colour table to use with this frame - either the global colour
/// table or a local colour table.
/// </param>
/// <param name="gce">
/// The graphic control extension, if any, which precedes this image in
/// the input stream.
/// </param>
/// <param name="previousFrame">
/// The frame which precedes this one in the GIF stream, if present.
/// </param>
/// <param name="previousFrameBut1">
/// The frame which precedes the frame before this one in the GIF stream,
/// if present.
/// </param>
/// <param name="status">
/// GifComponentStatus containing any errors which occurred during the
/// creation of the bitmap.
/// </param>
private static Bitmap CreateBitmap( TableBasedImageData imageData,
LogicalScreenDescriptor lsd,
ImageDescriptor id,
ColourTable activeColourTable,
GraphicControlExtension gce,
GifFrame previousFrame,
GifFrame previousFrameBut1,
out GifComponentStatus status )
{
status = new GifComponentStatus( ErrorState.Ok, "" );
Color[] pixelsForThisFrame = new Color[lsd.LogicalScreenSize.Width
* lsd.LogicalScreenSize.Height];
Bitmap baseImage = GetBaseImage( previousFrame,
previousFrameBut1,
lsd,
gce,
activeColourTable );
// copy each source line to the appropriate place in the destination
int pass = 1;
int interlaceRowIncrement = 8;
int interlaceRowNumber = 0; // the row of pixels we're currently
// setting in an interlaced image.
for( int i = 0; i < id.Size.Height; i++)
{
int pixelRowNumber = i;
if( id.IsInterlaced )
{
#region work out the pixel row we're setting for an interlaced image
if( interlaceRowNumber >= id.Size.Height )
{
pass++;
switch( pass )
{
case 2 :
interlaceRowNumber = 4;
break;
case 3 :
interlaceRowNumber = 2;
interlaceRowIncrement = 4;
break;
case 4 :
interlaceRowNumber = 1;
interlaceRowIncrement = 2;
break;
}
}
#endregion
pixelRowNumber = interlaceRowNumber;
interlaceRowNumber += interlaceRowIncrement;
}
// Colour in the pixels for this row
pixelRowNumber += id.Position.Y;
if( pixelRowNumber < lsd.LogicalScreenSize.Height )
{
int k = pixelRowNumber * lsd.LogicalScreenSize.Width;
int dx = k + id.Position.X; // start of line in dest
int dlim = dx + id.Size.Width; // end of dest line
if( (k + lsd.LogicalScreenSize.Width) < dlim )
{
// TESTME: CreateBitmap - past dest edge
dlim = k + lsd.LogicalScreenSize.Width; // past dest edge
}
int sx = i * id.Size.Width; // start of line in source
while (dx < dlim)
{
// map color and insert in destination
int indexInColourTable = (int) imageData.Pixels[sx++];
// Set this pixel's colour if its index isn't the
// transparent colour index, or if this frame doesn't
// have a transparent colour.
Color c;
if( gce.HasTransparentColour && indexInColourTable == gce.TransparentColourIndex )
{
c = Color.Empty; // transparent pixel
}
else
{
if( indexInColourTable < activeColourTable.Length )
{
c = activeColourTable[indexInColourTable];
}
else
{
// TESTME: CreateBitmap - BadColourIndex
c = Color.Black;
string message
= "Colour index: "
+ indexInColourTable
+ ", colour table length: "
+ activeColourTable.Length
+ " (" + dx + "," + pixelRowNumber + ")";
status = new GifComponentStatus( ErrorState.BadColourIndex,
message );
}
}
pixelsForThisFrame[dx] = c;
dx++;
}
}
}
return CreateBitmap( baseImage, pixelsForThisFrame );
}
internal static void CheckImageDescriptor( ImageDescriptor id )
{
Assert.AreEqual( HasLocalColourTable, id.HasLocalColourTable,
"HasLocalColourTable" );
Assert.AreEqual( IsInterlaced, id.IsInterlaced, "IsInterlaced" );
Assert.AreEqual( LocalColourTableIsSorted, id.IsSorted,
"LocalColourTableIsSorted" );
Assert.AreEqual( Math.Pow( 2, LocalColourTableSizeBits + 1 ),
id.LocalColourTableSize, "LocalColourTableSize" );
Assert.AreEqual( FramePosition, id.Position, "Position" );
Assert.AreEqual( FrameSize, id.Size, "Size" );
}
private static ImageDescriptor CheckImageDescriptor( Stream s,
bool shouldHaveLocalColourTable,
int localColourTableSizeBits)
{
// check for image descriptor
ImageDescriptor id = new ImageDescriptor( s );
Assert.AreEqual( ErrorState.Ok,
id.ConsolidatedState,
"Image descriptor consolidated state" );
Assert.AreEqual( shouldHaveLocalColourTable,
id.HasLocalColourTable,
"Should have local colour table" );
Assert.AreEqual( false, id.IsInterlaced, "Is interlaced" );
Assert.AreEqual( false, id.IsSorted, "Local colour table is sorted" );
Assert.AreEqual( localColourTableSizeBits,
id.LocalColourTableSizeBits,
"Local colour table size (bits)" );
Assert.AreEqual( 1 << (localColourTableSizeBits + 1),
id.LocalColourTableSize,
"Local colour table size");
Assert.AreEqual( new Size( 2, 2 ), id.Size, "Image descriptor size" );
Assert.AreEqual( new Point( 0, 0 ),
id.Position,
"Image descriptor position" );
return id;
}
public GifFrame( Stream inputStream,
LogicalScreenDescriptor lsd,
ColourTable gct,
GraphicControlExtension gce,
GifFrame previousFrame,
GifFrame previousFrameBut1,
bool xmlDebugging )
: base( xmlDebugging )
{
#region guard against null arguments
if( lsd == null )
{
throw new ArgumentNullException( "lsd" );
}
if( gce == null )
{
SetStatus( ErrorState.NoGraphicControlExtension, "" );
// use a default GCE
gce = new GraphicControlExtension( GraphicControlExtension.ExpectedBlockSize,
DisposalMethod.NotSpecified,
false,
false,
100,
0 );
}
#endregion
int transparentColourIndex = gce.TransparentColourIndex;
ImageDescriptor imageDescriptor = new ImageDescriptor( inputStream,
XmlDebugging );
WriteDebugXmlNode( imageDescriptor.DebugXmlReader );
#region determine the colour table to use for this frame
Color backgroundColour = Color.FromArgb( 0 ); // TODO: is this the right background colour?
// TODO: use backgroundColourIndex from the logical screen descriptor?
ColourTable activeColourTable;
if( imageDescriptor.HasLocalColourTable )
{
_localColourTable
= new ColourTable( inputStream,
imageDescriptor.LocalColourTableSize,
XmlDebugging );
WriteDebugXmlNode( _localColourTable.DebugXmlReader );
activeColourTable = _localColourTable; // make local table active
}
else
{
if( gct == null )
{
// We have neither local nor global colour table, so we
// won't be able to decode this frame.
Bitmap emptyBitmap = new Bitmap( lsd.LogicalScreenSize.Width,
lsd.LogicalScreenSize.Height );
_image = emptyBitmap;
_delay = gce.DelayTime;
SetStatus( ErrorState.FrameHasNoColourTable, "" );
return;
}
activeColourTable = gct; // make global table active
if( lsd.BackgroundColourIndex == transparentColourIndex )
{
backgroundColour = Color.FromArgb( 0 );
}
}
#endregion
// decode pixel data
int pixelCount = imageDescriptor.Size.Width * imageDescriptor.Size.Height;
TableBasedImageData indexedPixels
= new TableBasedImageData( inputStream, pixelCount, XmlDebugging );
WriteDebugXmlNode( indexedPixels.DebugXmlReader );
if( indexedPixels.Pixels.Count == 0 )
{
// TESTME: constructor - indexedPixels.Pixels.Count == 0
Bitmap emptyBitmap = new Bitmap( lsd.LogicalScreenSize.Width,
lsd.LogicalScreenSize.Height );
_image = emptyBitmap;
_delay = gce.DelayTime;
SetStatus( ErrorState.FrameHasNoImageData, "" );
WriteDebugXmlFinish();
return;
}
// Skip any remaining blocks up to the next block terminator (in
// case there is any surplus data before the next frame)
SkipBlocks( inputStream );
_indexedPixels = indexedPixels;
_extension = gce;
if( gce != null )
{
_delay = gce.DelayTime;
}
_imageDescriptor = imageDescriptor;
_backgroundColour = backgroundColour;
GifComponentStatus status;
_image = CreateBitmap( indexedPixels,
lsd,
imageDescriptor,
activeColourTable,
gce,
previousFrame,
previousFrameBut1,
out status );
WriteDebugXmlFinish();
}
private static void CheckImageData( Stream s,
ColourTable act,
ImageDescriptor id,
Bitmap expectedBitmap)
{
// 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 = id.Size.Width * id.Size.Height;
TableBasedImageData tbid = new TableBasedImageData( s, pixelCount );
Assert.AreEqual( ErrorState.Ok, tbid.ConsolidatedState );
for( int y = 0; y < id.Size.Height; y++ )
{
for( int x = 0; x < id.Size.Width; x++ )
{
int i = (y * id.Size.Width) + x;
Assert.AreEqual( expectedBitmap.GetPixel( x, y ),
act[tbid.Pixels[i]],
"X: " + x + ", Y: " + y );
}
}
}
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();
}
/// <summary>
/// Sets the pixels of the decoded image.
/// </summary>
/// <param name="imageData">
/// Table based image data containing the indices within the active
/// colour table of the colours of the pixels in this frame.
/// </param>
/// <param name="lsd">
/// The logical screen descriptor for the GIF stream.
/// </param>
/// <param name="id">
/// The image descriptor for this frame.
/// </param>
/// <param name="activeColourTable">
/// The colour table to use with this frame - either the global colour
/// table or a local colour table.
/// </param>
/// <param name="gce">
/// The graphic control extension, if any, which precedes this image in
/// the input stream.
/// </param>
/// <param name="previousFrame">
/// The frame which precedes this one in the GIF stream, if present.
/// </param>
/// <param name="previousFrameBut1">
/// The frame which precedes the frame before this one in the GIF stream,
/// if present.
/// </param>
/// <param name="status">
/// GifComponentStatus containing any errors which occurred during the
/// creation of the bitmap.
/// </param>
private static Bitmap CreateBitmap(TableBasedImageData imageData,
LogicalScreenDescriptor lsd,
ImageDescriptor id,
ColourTable activeColourTable,
GraphicControlExtension gce,
GifFrame previousFrame,
GifFrame previousFrameBut1,
out GifComponentStatus status)
{
status = new GifComponentStatus(ErrorState.Ok, "");
Color[] pixelsForThisFrame = new Color[lsd.LogicalScreenSize.Width
* lsd.LogicalScreenSize.Height];
Bitmap baseImage = GetBaseImage(previousFrame,
previousFrameBut1,
lsd,
gce,
activeColourTable);
// copy each source line to the appropriate place in the destination
int pass = 1;
int interlaceRowIncrement = 8;
int interlaceRowNumber = 0; // the row of pixels we're currently
// setting in an interlaced image.
for (int i = 0; i < id.Size.Height; i++)
{
int pixelRowNumber = i;
if (id.IsInterlaced)
{
#region work out the pixel row we're setting for an interlaced image
if (interlaceRowNumber >= id.Size.Height)
{
pass++;
switch (pass)
{
case 2:
interlaceRowNumber = 4;
break;
case 3:
interlaceRowNumber = 2;
interlaceRowIncrement = 4;
break;
case 4:
interlaceRowNumber = 1;
interlaceRowIncrement = 2;
break;
}
}
#endregion
pixelRowNumber = interlaceRowNumber;
interlaceRowNumber += interlaceRowIncrement;
}
// Colour in the pixels for this row
pixelRowNumber += id.Position.Y;
if (pixelRowNumber < lsd.LogicalScreenSize.Height)
{
int k = pixelRowNumber * lsd.LogicalScreenSize.Width;
int dx = k + id.Position.X; // start of line in dest
int dlim = dx + id.Size.Width; // end of dest line
if ((k + lsd.LogicalScreenSize.Width) < dlim)
{
// TESTME: CreateBitmap - past dest edge
dlim = k + lsd.LogicalScreenSize.Width; // past dest edge
}
int sx = i * id.Size.Width; // start of line in source
while (dx < dlim)
{
// map color and insert in destination
int indexInColourTable = (int)imageData.Pixels[sx++];
// Set this pixel's colour if its index isn't the
// transparent colour index, or if this frame doesn't
// have a transparent colour.
Color c;
if (gce.HasTransparentColour && indexInColourTable == gce.TransparentColourIndex)
{
c = Color.Empty; // transparent pixel
}
else
{
if (indexInColourTable < activeColourTable.Length)
{
c = activeColourTable[indexInColourTable];
}
else
{
// TESTME: CreateBitmap - BadColourIndex
c = Color.Black;
string message
= "Colour index: "
+ indexInColourTable
+ ", colour table length: "
+ activeColourTable.Length
+ " (" + dx + "," + pixelRowNumber + ")";
status = new GifComponentStatus(ErrorState.BadColourIndex,
message);
}
}
pixelsForThisFrame[dx] = c;
dx++;
}
}
}
return(CreateBitmap(baseImage, pixelsForThisFrame));
}
public GifFrame(Stream inputStream,
LogicalScreenDescriptor lsd,
ColourTable gct,
GraphicControlExtension gce,
GifFrame previousFrame,
GifFrame previousFrameBut1,
bool xmlDebugging)
: base(xmlDebugging)
{
#region guard against null arguments
if (lsd == null)
{
throw new ArgumentNullException("lsd");
}
if (gce == null)
{
SetStatus(ErrorState.NoGraphicControlExtension, "");
// use a default GCE
gce = new GraphicControlExtension(GraphicControlExtension.ExpectedBlockSize,
DisposalMethod.NotSpecified,
false,
false,
100,
0);
}
#endregion
int transparentColourIndex = gce.TransparentColourIndex;
ImageDescriptor imageDescriptor = new ImageDescriptor(inputStream,
XmlDebugging);
WriteDebugXmlNode(imageDescriptor.DebugXmlReader);
#region determine the colour table to use for this frame
Color backgroundColour = Color.FromArgb(0); // TODO: is this the right background colour?
// TODO: use backgroundColourIndex from the logical screen descriptor?
ColourTable activeColourTable;
if (imageDescriptor.HasLocalColourTable)
{
_localColourTable
= new ColourTable(inputStream,
imageDescriptor.LocalColourTableSize,
XmlDebugging);
WriteDebugXmlNode(_localColourTable.DebugXmlReader);
activeColourTable = _localColourTable; // make local table active
}
else
{
if (gct == null)
{
// We have neither local nor global colour table, so we
// won't be able to decode this frame.
Bitmap emptyBitmap = new Bitmap(lsd.LogicalScreenSize.Width,
lsd.LogicalScreenSize.Height);
_image = emptyBitmap;
_delay = gce.DelayTime;
SetStatus(ErrorState.FrameHasNoColourTable, "");
return;
}
activeColourTable = gct; // make global table active
if (lsd.BackgroundColourIndex == transparentColourIndex)
{
backgroundColour = Color.FromArgb(0);
}
}
#endregion
// decode pixel data
int pixelCount = imageDescriptor.Size.Width * imageDescriptor.Size.Height;
TableBasedImageData indexedPixels
= new TableBasedImageData(inputStream, pixelCount, XmlDebugging);
WriteDebugXmlNode(indexedPixels.DebugXmlReader);
if (indexedPixels.Pixels.Count == 0)
{
// TESTME: constructor - indexedPixels.Pixels.Count == 0
Bitmap emptyBitmap = new Bitmap(lsd.LogicalScreenSize.Width,
lsd.LogicalScreenSize.Height);
_image = emptyBitmap;
_delay = gce.DelayTime;
SetStatus(ErrorState.FrameHasNoImageData, "");
WriteDebugXmlFinish();
return;
}
// Skip any remaining blocks up to the next block terminator (in
// case there is any surplus data before the next frame)
SkipBlocks(inputStream);
_indexedPixels = indexedPixels;
_extension = gce;
if (gce != null)
{
_delay = gce.DelayTime;
}
_imageDescriptor = imageDescriptor;
_backgroundColour = backgroundColour;
GifComponentStatus status;
_image = CreateBitmap(indexedPixels,
lsd,
imageDescriptor,
activeColourTable,
gce,
previousFrame,
previousFrameBut1,
out status);
WriteDebugXmlFinish();
}
/// <summary>
/// Writes an image descriptor to the supplied stream.
/// </summary>
/// <param name="imageSize">
/// The size, in pixels, of the image in this frame.
/// </param>
/// <param name="position">
/// The position of this image within the logical screen.
/// </param>
/// <param name="localColourTable">
/// The local colour table for this frame.
/// Supply null if the global colour table is to be used for this frame.
/// </param>
/// <param name="outputStream">
/// The stream to write to.
/// </param>
private static void WriteImageDescriptor( Size imageSize,
Point position,
ColourTable localColourTable,
Stream outputStream )
{
bool hasLocalColourTable;
int localColourTableSize;
if( localColourTable == null )
{
hasLocalColourTable = false;
localColourTableSize = 0;
}
else
{
hasLocalColourTable = true;
localColourTableSize = localColourTable.SizeBits;
}
bool isInterlaced = false; // encoding of interlaced images not currently supported
bool localColourTableIsSorted = false; // sorting of colour tables not currently supported
ImageDescriptor id = new ImageDescriptor( position,
imageSize,
hasLocalColourTable,
isInterlaced,
localColourTableIsSorted,
localColourTableSize );
outputStream.WriteByte( GifComponent.CodeImageSeparator );
id.WriteToStream( outputStream );
}
