/// <summary>
/// The make image end chunk.
/// </summary>
private void MakeImageEndChunk()
{
this.m_iendChunk = new PngChunk(PngChunkIend);
}
/// <summary>
/// Initializes a new instance of the <see cref="PngStream"/> class.
/// Builds a PNG stream around a set of chunks.
/// </summary>
/// <param name="chunks">
/// The chunks that make up this PNG image.
/// </param>
/// <remarks>
/// See http://www.w3.org/TR/PNG/ for more detail on all
/// this stuff.
/// </remarks>
public PngStream(PngChunk[] chunks)
{
this.m_chunks = chunks;
}
/// <summary>
/// The make image end chunk.
/// </summary>
private void MakeImageEndChunk()
{
this.m_iendChunk = new PngChunk(PngChunkIend);
}
/// <summary>
/// The make image header chunk.
/// </summary>
private void MakeImageHeaderChunk()
{
this.m_ihdrChunk = new PngChunk(PngChunkIhdr);
var ihdrData = new byte[13];
NetworkOrderBitConverter.GetBytes((uint)this.m_imageWidth, ihdrData, 0);
NetworkOrderBitConverter.GetBytes((uint)this.m_imageHeight, ihdrData, 4);
ihdrData[8] = 8; // Bits per channel
ihdrData[9] = 2; // Colour model - RGB
this.m_ihdrChunk.SetData(ihdrData);
}
/// <summary>
/// The make image data chunk.
/// </summary>
private void MakeImageDataChunk()
{
this.m_idatChunk = new PngChunk(PngChunkIdat);
int preDeflateImageDataSize = (this.m_imageWidth * 3 + 1) * this.m_imageHeight;
int pngDataSize = MapPixelDataOffset(preDeflateImageDataSize);
this.pngPixelData = new byte[pngDataSize + 4]; // Extra 4 bytes for ADLER-32
this.pngPixelData[0] = 0x78;
this.pngPixelData[1] = 1;
// Block headers are all 0 except for last one, which is 1.
for (int blockStart = 0; blockStart < preDeflateImageDataSize - 0xffff; blockStart += 0xffff)
{
int blockOffset = MapPixelDataOffset(blockStart);
this.pngPixelData[blockOffset - 4] = 0xff;
this.pngPixelData[blockOffset - 3] = 0xff;
// Next two bytes two's complement - already initialized to 0
}
int lastBlock = MapPixelDataOffset((preDeflateImageDataSize / 0xffff) * 0xffff);
int lastBlockSize = preDeflateImageDataSize % 0xffff;
this.pngPixelData[lastBlock - 5] = 1;
this.pngPixelData[lastBlock - 4] = (byte)(lastBlockSize & 0xff);
this.pngPixelData[lastBlock - 3] = (byte)((lastBlockSize >> 8) & 0xff);
lastBlockSize = ~lastBlockSize;
this.pngPixelData[lastBlock - 2] = (byte)(lastBlockSize & 0xff);
this.pngPixelData[lastBlock - 1] = (byte)((lastBlockSize >> 8) & 0xff);
}
