/// <summary> /// Writes a Logical Screen Descriptor to the supplied stream. /// Also writes a global colour table if required. /// </summary> /// <param name="outputStream"> /// The stream to write to. /// </param> private void WriteLogicalScreenDescriptor( Stream outputStream ) { bool hasGlobalColourTable = _strategy == ColourTableStrategy.UseGlobal; int colourResolution = 7; // TODO: parameterise colourResolution? bool globalColourTableIsSorted = false; // Sorting of colour tables is not currently supported int backgroundColorIndex = 0; // TODO: parameterise backgroundColourIndex? int pixelAspectRatio = 0; // TODO: parameterise pixelAspectRatio? if( _strategy == ColourTableStrategy.UseGlobal ) { if( _quantizerType == QuantizerType.UseSuppliedPalette ) { // use supplied palette _globalColourTable = new ColourTable(); string buildColourTableCounterText = "Building colour table from supplied palette"; AddCounter( buildColourTableCounterText, _palette.Count ); int paletteIndex = 0; foreach( Color c in _palette ) { _globalColourTable.Add( c ); MyProgressCounters[buildColourTableCounterText].Value = paletteIndex; paletteIndex++; } _globalColourTable.Pad(); RemoveCounter( buildColourTableCounterText ); } else { // Analyse the pixels in all the images to build the // global colour table. Collection<Image> images = new Collection<Image>(); foreach( GifFrame thisFrame in _frames ) { Image thisImage = thisFrame.TheImage; images.Add( thisImage ); } _pixelAnalysis = new PixelAnalysis( images ); _pixelAnalysis.ColourQuality = _quality; _pixelAnalysis.Analyse(); _globalColourTable = _pixelAnalysis.ColourTable; } LogicalScreenDescriptor lsd = new LogicalScreenDescriptor( _logicalScreenSize, hasGlobalColourTable, colourResolution, globalColourTableIsSorted, _globalColourTable.SizeBits, backgroundColorIndex, pixelAspectRatio ); lsd.WriteToStream( outputStream ); _globalColourTable.WriteToStream( outputStream ); } else { LogicalScreenDescriptor lsd = new LogicalScreenDescriptor( _logicalScreenSize, hasGlobalColourTable, colourResolution, globalColourTableIsSorted, 7, backgroundColorIndex, pixelAspectRatio ); lsd.WriteToStream( outputStream ); } }
/// <summary> /// Creates a colour table directly from the distinct colours in the /// supplied image(s). /// </summary> private void CreateDirectColourTable() { string buildColourTableCounterText = "Creating colour table from images"; AddCounter( buildColourTableCounterText, _distinctColours.Values.Count ); _colourTable = new ColourTable(); int distinctColourIndex = 0; foreach( Color c in _distinctColours.Values ) { MyProgressCounters[buildColourTableCounterText].Value = distinctColourIndex; _colourTable.Add( c ); distinctColourIndex++; } _colourTable.Pad(); RemoveCounter( buildColourTableCounterText ); }
private ColourTable SetActiveColourTable() { ColourTable act; // active colour table if( _strategy == ColourTableStrategy.UseLocal ) { if( _quantizerType == QuantizerType.UseSuppliedPalette ) { if( _frames[_encodingFrame].Palette == null ) { // TESTME: SetActiveColourTable - SetActiveColourTable, UseSuppliedPalette, no palette supplied string message = "You have opted to use a local colour table built " + "from a supplied palette, but frame " + _encodingFrame + "does not have a palette."; throw new InvalidOperationException( message ); } else { // Build local colour table from colours in the frame's // supplied palette. act = new ColourTable(); foreach( Color c in _frames[_encodingFrame].Palette ) { act.Add( c ); } act.Pad(); } } else { // Build local colour table based on colours in the image. Image thisImage = _frames[_encodingFrame].TheImage; _pixelAnalysis = new PixelAnalysis( thisImage, _quantizerType ); _pixelAnalysis.ColourQuality = _quality; _pixelAnalysis.Analyse(); // make local colour table active act = _pixelAnalysis.ColourTable; } } else { // make global colour table active act = _globalColourTable; } return act; }