private static void TestPngEncoderCore <TPixel>(
TestImageProvider <TPixel> provider,
PngColorType pngColorType,
PngFilterMethod pngFilterMethod,
PngBitDepth bitDepth,
PngInterlaceMode interlaceMode,
PngCompressionLevel compressionLevel = PngCompressionLevel.DefaultCompression,
int paletteSize = 255,
bool appendPngColorType = false,
bool appendPngFilterMethod = false,
bool appendPixelType = false,
bool appendCompressionLevel = false,
bool appendPaletteSize = false,
bool appendPngBitDepth = false,
PngChunkFilter optimizeMethod = PngChunkFilter.None)
where TPixel : unmanaged, IPixel <TPixel>
{
using (Image <TPixel> image = provider.GetImage())
{
var encoder = new PngEncoder
{
ColorType = pngColorType,
FilterMethod = pngFilterMethod,
CompressionLevel = compressionLevel,
BitDepth = bitDepth,
Quantizer = new WuQuantizer(new QuantizerOptions {
MaxColors = paletteSize
}),
InterlaceMethod = interlaceMode,
ChunkFilter = optimizeMethod,
};
string pngColorTypeInfo = appendPngColorType ? pngColorType.ToString() : string.Empty;
string pngFilterMethodInfo = appendPngFilterMethod ? pngFilterMethod.ToString() : string.Empty;
string compressionLevelInfo = appendCompressionLevel ? $"_C{compressionLevel}" : string.Empty;
string paletteSizeInfo = appendPaletteSize ? $"_PaletteSize-{paletteSize}" : string.Empty;
string pngBitDepthInfo = appendPngBitDepth ? bitDepth.ToString() : string.Empty;
string pngInterlaceModeInfo = interlaceMode != PngInterlaceMode.None ? $"_{interlaceMode}" : string.Empty;
string debugInfo = $"{pngColorTypeInfo}{pngFilterMethodInfo}{compressionLevelInfo}{paletteSizeInfo}{pngBitDepthInfo}{pngInterlaceModeInfo}";
string actualOutputFile = provider.Utility.SaveTestOutputFile(image, "png", encoder, debugInfo, appendPixelType);
// Compare to the Magick reference decoder.
IImageDecoder referenceDecoder = TestEnvironment.GetReferenceDecoder(actualOutputFile);
// We compare using both our decoder and the reference decoder as pixel transformation
// occurs within the encoder itself leaving the input image unaffected.
// This means we are benefiting from testing our decoder also.
using (var imageSharpImage = Image.Load <TPixel>(actualOutputFile, new PngDecoder()))
using (var referenceImage = Image.Load <TPixel>(actualOutputFile, referenceDecoder))
{
ImageComparer.Exact.VerifySimilarity(referenceImage, imageSharpImage);
}
}
}
/// <summary>
/// Initializes a new instance of the <see cref="ZlibDeflateStream"/> class.
/// </summary>
/// <param name="memoryAllocator">The memory allocator to use for buffer allocations.</param>
/// <param name="stream">The stream to compress.</param>
/// <param name="level">The compression level.</param>
public ZlibDeflateStream(MemoryAllocator memoryAllocator, Stream stream, PngCompressionLevel level)
{
int compressionLevel = (int)level;
this.rawStream = stream;
// Write the zlib header : http://tools.ietf.org/html/rfc1950
// CMF(Compression Method and flags)
// This byte is divided into a 4 - bit compression method and a
// 4-bit information field depending on the compression method.
// bits 0 to 3 CM Compression method
// bits 4 to 7 CINFO Compression info
//
// 0 1
// +---+---+
// |CMF|FLG|
// +---+---+
const int Cmf = 0x78;
int flg = 218;
// http://stackoverflow.com/a/2331025/277304
if (compressionLevel >= 5 && compressionLevel <= 6)
{
flg = 156;
}
else if (compressionLevel >= 3 && compressionLevel <= 4)
{
flg = 94;
}
else if (compressionLevel <= 2)
{
flg = 1;
}
// Just in case
flg -= ((Cmf * 256) + flg) % 31;
if (flg < 0)
{
flg += 31;
}
this.rawStream.WriteByte(Cmf);
this.rawStream.WriteByte((byte)flg);
this.deflateStream = new DeflaterOutputStream(memoryAllocator, this.rawStream, compressionLevel);
}
public void WorksWithAllCompressionLevels <TPixel>(TestImageProvider <TPixel> provider, PngCompressionLevel compressionLevel)
where TPixel : unmanaged, IPixel <TPixel>
{
foreach (PngInterlaceMode interlaceMode in InterlaceMode)
{
TestPngEncoderCore(
provider,
PngColorType.RgbWithAlpha,
PngFilterMethod.Adaptive,
PngBitDepth.Bit8,
interlaceMode,
compressionLevel,
appendCompressionLevel: true);
}
}
