/// <summary>
/// Does the remaining work to convert the byte[] containing the image into a Color[] containing colors
/// for each pixel. This operation is different for most individual combinations of ColorType and bitDepth
/// and currently only ColorType 2 is supported.
/// </summary>
/// <param name="image"></param>
/// <param name="header"></param>
/// <param name="palette"></param>
/// <returns></returns>
private static Color[] BuildPixels(byte[] image, ref HeaderInfo header, ref PaletteInfo palette)
{
//System.Diagnostics.Trace.WriteLine(String.Format("ColorType: {0}\tBitDepth: {1}", header.ColorType, header.BitDepth));
// System.Diagnostics.Trace.WriteLine(String.Format("Width: {0}\tHeight: {1}", header.Width, header.Height));
int totalPixels = (int)(header.Width * header.Height);
int currentIndex = 0;
if (totalPixels > mStaticPixels.Length)
{
mStaticPixels = new Color[totalPixels];
}
//MemoryStream imageStream = new MemoryStream(image);
int indexInImage = 0;
int filterByte;
switch ((int)header.ColorType)
{
//Each pixel is an R,G,B triple
case 2:
{
//This section of code containing conversion of 16-bit samples is currently untested.
if (header.BitDepth > 8)
{
int bps = (int)(header.Width * header.BitDepth * 3 + 1);
//int R = 0;
//int G = 0;
//int B = 0;
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
mStaticPixels[currentIndex].R = image[indexInImage++]; indexInImage++;
mStaticPixels[currentIndex].G = image[indexInImage++]; indexInImage++;
mStaticPixels[currentIndex].B = image[indexInImage++]; indexInImage++;
mStaticPixels[currentIndex].A = byte.MaxValue;
currentIndex++;
}
}
}
else
{
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
mStaticPixels[currentIndex].R = image[indexInImage++];
mStaticPixels[currentIndex].G = image[indexInImage++];
mStaticPixels[currentIndex].B = image[indexInImage++];
mStaticPixels[currentIndex].A = byte.MaxValue;
currentIndex++;
}
}
}
break;
}
//Each pixel is a grayscale sample
case 0:
{
if (header.BitDepth < 8)
{
byte sample;
int value;
float grayValue;
int numBits = 8 / header.BitDepth;
int mask = (255 >> (8 - header.BitDepth));
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width / numBits; ++i)
{
value = image[indexInImage++];
for (int j = 8 - header.BitDepth; j >= 0; j -= header.BitDepth)
{
grayValue = (float)((value & (mask << j)) >> j);
sample = (byte)((grayValue / ((1 << header.BitDepth) - 1)) * 255);
mStaticPixels[currentIndex].R = sample;
mStaticPixels[currentIndex].G = sample;
mStaticPixels[currentIndex].B = sample;
mStaticPixels[currentIndex].A = byte.MaxValue;
currentIndex++;
}
}
}
}
else if (header.BitDepth == 8)
{
byte sample;
float value;
//Get the filter byte out of the way
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
//Read the scanline
for (int i = 0; i < header.Width; ++i)
{
value = (float)(image[indexInImage++]);
sample = (byte)((value / ((1 << header.BitDepth) - 1)) * 255);
mStaticPixels[currentIndex].R = sample;
mStaticPixels[currentIndex].G = sample;
mStaticPixels[currentIndex].B = sample;
mStaticPixels[currentIndex].A = byte.MaxValue;
currentIndex++;
}
}
}
else
{
byte sample;
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
sample = image[indexInImage++]; indexInImage++;
mStaticPixels[currentIndex].R = sample;
mStaticPixels[currentIndex].G = sample;
mStaticPixels[currentIndex].B = sample;
mStaticPixels[currentIndex].A = byte.MaxValue;
currentIndex++;
}
}
}
break;
}
//Each pixel is a palette index
case 3:
{
RGB entry;
int value;
int numBits = 8 / header.BitDepth;
int mask = (255 >> (8 - header.BitDepth));
int index;
long headerWidthDividedByNumBits = header.Width / numBits;
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < headerWidthDividedByNumBits; ++i)
{
value = image[indexInImage++];
for (int j = 8 - header.BitDepth; j >= 0; j -= header.BitDepth)
{
index = (value & (mask << j)) >> j;
entry = palette.Entries[index];
mStaticPixels[currentIndex].R = entry.R;
mStaticPixels[currentIndex].G = entry.G;
mStaticPixels[currentIndex].B = entry.B;
//if (mMaxTransIndex >= index)
{
mStaticPixels[currentIndex].A = mTransparentEntries[index];
}
currentIndex++;
}
}
}
break;
}
//Each pixel is a grayscale sample, followed by an alpha sample
case 4:
{
switch ((int)header.BitDepth)
{
case 8:
{
//Open stream to image array
byte sample;
//Get the filter byte out of the way
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
//Read the scanline
for (int i = 0; i < header.Width; ++i)
{
sample = image[indexInImage++];
mStaticPixels[currentIndex].R = sample;
mStaticPixels[currentIndex].G = sample;
mStaticPixels[currentIndex].B = sample;
mStaticPixels[currentIndex].A = image[indexInImage++];
currentIndex++;
}
}
break;
}
case 16:
{
byte sample;
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
sample = image[indexInImage++]; indexInImage++;
mStaticPixels[currentIndex].R = sample;
mStaticPixels[currentIndex].G = sample;
mStaticPixels[currentIndex].B = sample;
mStaticPixels[currentIndex].A = image[indexInImage++];
indexInImage++;
currentIndex++;
}
}
break;
}
}
break;
}
//Each pixel is an R,G,B triple, followed by an alpha sample
case 6:
{
switch ((int)header.BitDepth)
{
case 8:
{
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
mStaticPixels[currentIndex].R = image[indexInImage++];
mStaticPixels[currentIndex].G = image[indexInImage++];
mStaticPixels[currentIndex].B = image[indexInImage++];
mStaticPixels[currentIndex].A = image[indexInImage++];
currentIndex++;
}
}
break;
}
case 16:
{
int bps = (int)(header.Width * header.BitDepth * 3 + 1);
//int R = 0;
//int G = 0;
//int B = 0;
//int A = 0;
while ((filterByte = image[indexInImage++]) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
mStaticPixels[currentIndex].R = image[indexInImage++]; indexInImage++;
mStaticPixels[currentIndex].G = image[indexInImage++]; indexInImage++;
mStaticPixels[currentIndex].B = image[indexInImage++]; indexInImage++;
mStaticPixels[currentIndex].A = image[indexInImage++]; indexInImage++;
currentIndex++;
}
}
break;
}
}
break;
}
}
//imageStream.Close();
return mStaticPixels;
}
/// <summary>
/// Takes a List of all of the Chunks in the .png image being loaded (after IHDR is loaded and removed)
/// and processes each Chunk appropriately before returning the compressed image. NOTE: Currently only
/// processes the required Chunks PLTE, IDAT and IEND. Ancillary chunks are currently unsupported.
/// </summary>
/// <param name="chunks">The List of chunks loaded from the .png image file</param>
/// <param name="header">The HeaderInfo loaded from the IHDR chunk</param>
/// <param name="palette">An unused PaletteInfo struct to load the PLTE chunk data into</param>
/// <returns>A byte[] containing the constructed and decompressed image</returns>
private static byte[] ProcessChunks(List<Chunk> chunks, HeaderInfo header, ref PaletteInfo palette)
{
int numberOfBytesRead = 0;
foreach (Chunk currentChunk in chunks)
{
switch (currentChunk.Type)
{
//Only one IHDR can exist, and it should have already been removed
case ChunkTypes.IHDR:
{
throw new Exception(String.Format("List<Chunk> chunks still contains IHDR chunk info."));
//break;
}
case ChunkTypes.PLTE:
{ //Check if a palette can even be used for this image's ColorType
if ((header.ColorType == 0) || (header.ColorType == 4))
throw new Exception(String.Format(
"The given ColorType, {0}, does not support the use of a Palette.", header.ColorType));
//if so, prepare the palette to hold the maximum number of colors for the given bitDepth
palette.Entries = new RGB[(1 << (header.BitDepth + 1)) - 1];
//Read the PLTE chunk into the given PaletteInfo
ReadPalette(currentChunk, ref palette);
break;
}
case ChunkTypes.IDAT:
{
//Read the IDAT chunk's data into the List for imageData
ReadImageData(currentChunk, ref sReadImageDataByteBuffer, ref numberOfBytesRead);
break;
}
case ChunkTypes.IEND:
{
//This should be the last chunk to be loaded, so it's safe now to decompress the image
//and do any extra processing caused by ancillary chunks.
//Check if there are any chunks after IEND
if (chunks.IndexOf(currentChunk) != chunks.Count - 1)
throw new Exception(String.Format(
"IEND chunk does not appear to be the last chunk in the image."));
//Load the compressed image into an InflaterInputStream to inflate(decompress) the image
MemoryStream streamForInflater = new MemoryStream(sReadImageDataByteBuffer, 0, numberOfBytesRead);
InflaterInputStream decompressionStream = new InflaterInputStream(streamForInflater);
//Read the decompressed image through the stream and into a byte[]
ReadStream(ref decompressionStream);
break;
}
case ChunkTypes.tRNS:
{
mMaxTransIndex = (int)currentChunk.Length - 1;
for (int i = 0; i < currentChunk.Length; ++i)
{
mTransparentEntries[i] = (byte)currentChunk.ChunkData.ReadByte();
}
break;
}
//Represents an ancillary chunk that isn't yet implemented or an unknown chunk type
case ChunkTypes.UNSUPPORTED:
{
break;
}
}
}
//Return the image
return sByteBuffer;
}
/// <summary>
/// Loads a .png image from the fileName given and returns an array of pixel colors.
/// </summary>
/// <param name="fileName">The name of the .png image to be loaded.</param>
/// <returns>
/// Returns a Microsoft.Xna.Framework.Graphics.Color[] containing one item(Color) for each pixel
/// in the image.</returns>
public static ImageData GetPixelData(string fileName)
{
for (int i = 0; i < ByteBufferSize; i++)
{
mTransparentEntries[i] = byte.MaxValue;
}
int bytesRead = LoadFile(fileName);
mMaxTransIndex = -1;
//Load the file into "byte stream"
Stream sourceStream = new MemoryStream(sByteBuffer, 0, bytesRead);
//Check the signature to verify this is an actual .png image
if (!CheckSignature(ref sourceStream))
throw new ArgumentException(
String.Format("Argument Stream {0} does not contain a valid PNG file.", sourceStream));
//Since all data in .png files is organized into categorized chunks, create a
//List to store them in so that they can be read and processed later.
List<Chunk> chunks = new List<Chunk>();
//Load each Chunk of data from the stream into the List of Chunks. Then
//close the stream.
while (GetNextChunk(ref sourceStream, ref chunks)) { }
sourceStream.Close();
//Read and store the information from the IHDR chunk, which contains
//general info for this image. Note: IHDR chunk is removed from List<Chunk> chunks.
HeaderInfo header = ReadHeader(ref chunks);
//Create an empty palette in case we need it
PaletteInfo palette = new PaletteInfo();
//Process the Chunks of data and obtain the decompressed bytes of the image
byte[] filteredImage = ProcessChunks(chunks, header, ref palette);
//Reverse the filtering that was done on the image before compression
byte[] defilteredImage = ReverseFiltering(filteredImage, header);
//Translate the un-filtered image bytes into Colors and store in the array to be returned.
Color[] pixelData = BuildPixels(defilteredImage, ref header, ref palette);
//System.Diagnostics.Trace.WriteLine(pixelData.Length);
ImageData imageData = new ImageData((int)header.Width, (int)header.Height, pixelData);
return imageData;
}
/// <summary>
/// Processes the PLTE chunk by reading in all of the indexed color values and storing them in
/// a PaletteInfo struct.
/// </summary>
/// <param name="plte">The Chunk containing the PLTE chunk from the file</param>
/// <param name="palette">An unused PaletteInfo struct to be filled by data from plte</param>
private static void ReadPalette(Chunk plte, ref PaletteInfo palette)
{
//The length of PLTE's data segment should be 3 * the number of entries
uint numEntries = (uint)plte.ChunkData.Length / 3;
//Checking for monkey-business???
if ((numEntries * 3) == plte.ChunkData.Length)
{
//Read in the values of the color entries and store them.
for (int i = 0; i < numEntries; ++i)
{
RGB value = new RGB();
value.R = (byte)plte.ChunkData.ReadByte(); //System.Diagnostics.Trace.WriteLine(value.R);
value.G = (byte)plte.ChunkData.ReadByte();// System.Diagnostics.Trace.WriteLine(value.G);
value.B = (byte)plte.ChunkData.ReadByte();// System.Diagnostics.Trace.WriteLine(value.B);
palette.Entries[i] = value;
}
}
}
private static Color[] OldMethod(byte[] image, ref HeaderInfo header, ref PaletteInfo palette)
{
int totalPixels = (int)(header.Width * header.Height);
int currentIndex = 0;
if (totalPixels > mStaticPixels.Length)
{
mStaticPixels = new Color[totalPixels];
}
MemoryStream imageStream = new MemoryStream(image);
int filterByte;
switch ((int)header.ColorType)
{
//Each pixel is an R,G,B triple
case 2:
{
//This section of code containing conversion of 16-bit samples is currently untested.
if (header.BitDepth > 8)
{
int bps = (int)(header.Width * header.BitDepth * 3 + 1);
int R = 0;
int G = 0;
int B = 0;
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
R = imageStream.ReadByte(); imageStream.ReadByte();
G = imageStream.ReadByte(); imageStream.ReadByte();
B = imageStream.ReadByte(); imageStream.ReadByte();
mStaticPixels[currentIndex] = (new Color((byte)R, (byte)G, (byte)B));
currentIndex++;
}
}
}
else
{
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
mStaticPixels[currentIndex] = (new Color(
(byte)imageStream.ReadByte(),
(byte)imageStream.ReadByte(),
(byte)imageStream.ReadByte()));
currentIndex++;
}
}
}
break;
}
//Each pixel is a grayscale sample
case 0:
{
if (header.BitDepth < 8)
{
byte sample;
int value;
float grayValue;
int numBits = 8 / header.BitDepth;
int mask = (255 >> (8 - header.BitDepth));
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width / numBits; ++i)
{
value = imageStream.ReadByte();
for (int j = 8 - header.BitDepth; j >= 0; j -= header.BitDepth)
{
grayValue = (float)((value & (mask << j)) >> j);
sample = (byte)((grayValue / ((1 << header.BitDepth) - 1)) * 255);
mStaticPixels[currentIndex] = (new Color(sample, sample, sample));
currentIndex++;
}
}
}
}
else if (header.BitDepth == 8)
{
byte sample;
float value;
//Get the filter byte out of the way
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
//Read the scanline
for (int i = 0; i < header.Width; ++i)
{
value = (float)(imageStream.ReadByte());
sample = (byte)((value / ((1 << header.BitDepth) - 1)) * 255);
mStaticPixels[currentIndex] = (new Color(sample, sample, sample));
currentIndex++;
}
}
}
else
{
byte sample;
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
sample = (byte)imageStream.ReadByte(); imageStream.ReadByte();
mStaticPixels[currentIndex] = (new Color(sample, sample, sample));
currentIndex++;
}
}
}
break;
}
//Each pixel is a palette index
case 3:
{
RGB entry;
int value;
int numBits = 8 / header.BitDepth;
int mask = (255 >> (8 - header.BitDepth));
int index;
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width / numBits; ++i)
{
value = imageStream.ReadByte();
for (int j = 8 - header.BitDepth; j >= 0; j -= header.BitDepth)
{
index = (value & (mask << j)) >> j;
entry = palette.Entries[index];
mStaticPixels[currentIndex] = (new Color((byte)entry.R, (byte)entry.G, (byte)entry.B));
if (mMaxTransIndex >= index)
{
mStaticPixels[currentIndex].A = mTransparentEntries[index];
}
currentIndex++;
}
}
}
break;
}
//Each pixel is a grayscale sample, followed by an alpha sample
case 4:
{
switch ((int)header.BitDepth)
{
case 8:
{
//Open stream to image array
byte sample;
//Get the filter byte out of the way
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
//Read the scanline
for (int i = 0; i < header.Width; ++i)
{
sample = (byte)(imageStream.ReadByte());
mStaticPixels[currentIndex] = (new Color(sample, sample, sample, (byte)imageStream.ReadByte()));
currentIndex++;
}
}
break;
}
case 16:
{
byte sample;
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
sample = (byte)imageStream.ReadByte(); imageStream.ReadByte();
mStaticPixels[currentIndex] = (new Color(sample, sample, sample, (byte)imageStream.ReadByte())); imageStream.ReadByte();
currentIndex++;
}
}
break;
}
}
break;
}
//Each pixel is an R,G,B triple, followed by an alpha sample
case 6:
{
switch ((int)header.BitDepth)
{
case 8:
{
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
mStaticPixels[currentIndex] = (new Color(
(byte)imageStream.ReadByte(),
(byte)imageStream.ReadByte(),
(byte)imageStream.ReadByte(),
(byte)imageStream.ReadByte()));
currentIndex++;
}
}
break;
}
case 16:
{
int bps = (int)(header.Width * header.BitDepth * 3 + 1);
int R = 0;
int G = 0;
int B = 0;
int A = 0;
while ((filterByte = imageStream.ReadByte()) > -1 && currentIndex < totalPixels)
{
for (int i = 0; i < header.Width; ++i)
{
R = imageStream.ReadByte(); imageStream.ReadByte();
G = imageStream.ReadByte(); imageStream.ReadByte();
B = imageStream.ReadByte(); imageStream.ReadByte();
A = imageStream.ReadByte(); imageStream.ReadByte();
mStaticPixels[currentIndex] = (new Color((byte)R, (byte)G, (byte)B, (byte)A));
currentIndex++;
}
}
break;
}
}
break;
}
}
imageStream.Close();
return mStaticPixels;
}
