/// <summary>
/// Gets the PLTE chunk of the parent image and throws an exception if it is not present.
/// </summary>
/// <returns>The PLTE chunk of the parent image.</returns>
/// <exception cref="ChunkNotFoundException" />
protected PLTEChunk GetAssertPLTEChunk()
{
PLTEChunk chunk = _image.Chunks["PLTE"] as PLTEChunk;
if (chunk == null)
{
throw new ChunkNotFoundException("PLTE chunk not found.");
}
return(chunk);
}
public Color GetEffectiveBackgroundColor()
{
IHDRChunk hdr = this.GetAssertIHDRChunk();
switch (hdr.ColorType)
{
case ColorType.Grayscale:
case ColorType.GrayscaleWithAlpha:
if (hdr.BitDepth == 1)
{
return(Utils.MakeGray((_backgroundColor.Gray & 0x1) * 255));
}
else if (hdr.BitDepth == 2)
{
return(Utils.MakeGray((_backgroundColor.Gray & 0x3) * 255 / 3));
}
else if (hdr.BitDepth == 4)
{
return(Utils.MakeGray((_backgroundColor.Gray & 0xf) * 255 / 15));
}
else if (hdr.BitDepth == 8)
{
return(Utils.MakeGray(_backgroundColor.Gray & 0xff));
}
else if (hdr.BitDepth == 16)
{
return(Utils.MakeGray(_backgroundColor.Gray * 255 / 65535));
}
else
{
throw new InvalidChunkDataException("Invalid bit depth.");
}
case ColorType.Truecolor:
case ColorType.TruecolorWithAlpha:
if (hdr.BitDepth == 8)
{
return(Color.FromArgb(
_backgroundColor.Red & 0xff,
_backgroundColor.Green & 0xff,
_backgroundColor.Blue & 0xff));
}
else if (hdr.BitDepth == 16)
{
return(Color.FromArgb(
_backgroundColor.Red * 255 / 65535,
_backgroundColor.Green * 255 / 65535,
_backgroundColor.Blue * 255 / 65535));
}
else
{
throw new InvalidChunkDataException("Invalid bit depth.");
}
case ColorType.IndexedColor:
PLTEChunk plte = this.GetAssertPLTEChunk();
return(plte.Entries[_backgroundColor.Index]);
default:
throw new InvalidChunkDataException("Invalid color type.");
}
}
/// <summary>
/// Reads the image pixels and stores them in Bitmap.
/// </summary>
/// <param name="data">The image bytes.</param>
private void Read(byte[] data)
{
// optimized for speed (it's very slow already)
IHDRChunk hdr = _image.Chunks["IHDR"] as IHDRChunk;
int width = (int)hdr.Width;
int height = (int)hdr.Height;
byte bitDepth = hdr.BitDepth;
_bitmap = CreateBitmap(hdr.ColorType, hdr.BitDepth, width, height);
_scanlineLength = Utils.IntCeilDiv(Utils.GetBitsPerPixel(hdr.ColorType, hdr.BitDepth) * width, 8) + 1;
_bpp = Utils.GetBytesPerPixel(hdr.ColorType, hdr.BitDepth); // bytes per pixel
byte[] decoded = null;
// palette
PLTEChunk palette = _image.Chunks["PLTE"] as PLTEChunk;
#region tRNS Chunk
tRNSChunk trns = _image.Chunks["tRNS"] as tRNSChunk;
int tGray1 = -1;
int tGray2 = -1;
int tGray4 = -1;
int tGray8 = -1;
int tGray16 = -1;
Color tRgb8 = Color.FromArgb(0, 0, 0, 0);
Color tRgb16 = Color.FromArgb(0, 0, 0, 0);
int[] tPalette = null;
if (trns != null)
{
tGray1 = trns.Gray & 0x1;
tGray2 = trns.Gray & 0x3;
tGray4 = trns.Gray & 0xf;
tGray8 = trns.Gray & 0xff;
tGray16 = trns.Gray;
tRgb8 = Color.FromArgb(trns.Red & 0xff, trns.Green & 0xff, trns.Blue & 0xff);
tRgb16 = Color.FromArgb(trns.Red * 255 / 65535, trns.Green * 255 / 65535, trns.Blue * 255 / 65535);
if (palette != null)
{
tPalette = new int[palette.Entries.Length];
for (int i = 0; i < tPalette.Length; i++)
{
if (i < trns.PaletteAlpha.Length)
{
tPalette[i] = trns.PaletteAlpha[i];
}
else
{
tPalette[i] = 255;
}
}
}
}
else
{
if (palette != null)
{
tPalette = new int[palette.Entries.Length];
for (int i = 0; i < tPalette.Length; i++)
{
tPalette[i] = 255;
}
}
}
#endregion
if (hdr.InterlaceMethod == InterlaceMethod.Adam7)
{
#region Adam7
for (int pass = 0; pass < _adam7.Length; pass++)
{
}
#endregion
}
else
{
#region Normal
for (int line = 0; line < data.Length / _scanlineLength; line++)
{
decoded = this.Defilter(data, line, decoded);
switch (hdr.ColorType)
{
case ColorType.Grayscale:
if (bitDepth == 1)
{
for (int i = 0; i < Utils.IntCeilDiv(width, 8); i++)
{
int[] pixels = new int[8];
for (int j = 0; j < 8; j++)
{
pixels[j] = (decoded[i] >> (7 - j)) & 0x1;
}
for (int j = 0; j < 8; j++)
{
if (i * 8 + j < hdr.Width)
{
_bitmap.SetPixel(i * 8 + j, line,
Utils.MakeGray(pixels[j] == tGray1 ? 0 : 255, pixels[j] * 255));
}
}
}
}
else if (bitDepth == 2)
{
for (int i = 0; i < Utils.IntCeilDiv(width, 4); i++)
{
int[] pixels = new int[4];
for (int j = 0; j < 4; j++)
{
pixels[j] = (decoded[i] >> ((3 - j) * 2)) & 0x3;
}
for (int j = 0; j < 4; j++)
{
if (i * 4 + j < hdr.Width)
{
_bitmap.SetPixel(i * 4 + j, line,
Utils.MakeGray(pixels[j] == tGray2 ? 0 : 255, pixels[j] * 255 / 3));
}
}
}
}
else if (bitDepth == 4)
{
for (int i = 0; i < Utils.IntCeilDiv(width, 2); i++)
{
int pixel1 = decoded[i] >> 4; // upper four bits
int pixel2 = decoded[i] & 0xf; // lower two bits
_bitmap.SetPixel(i * 2, line, Utils.MakeGray(
pixel1 == tGray4 ? 0 : 255, pixel1 * 255 / 15));
if (i * 2 + 1 < hdr.Width)
{
_bitmap.SetPixel(i * 2 + 1, line, Utils.MakeGray(
pixel2 == tGray4 ? 0 : 255, pixel2 * 255 / 15));
}
}
}
else if (bitDepth == 8)
{
for (int i = 0; i < hdr.Width; i++)
{
_bitmap.SetPixel(i, line,
Utils.MakeGray(decoded[i] == tGray8 ? 0 : 255, decoded[i]));
}
}
else if (bitDepth == 16)
{
for (int i = 0; i < hdr.Width; i++)
{
int value = Utils.BytesToUShort(decoded, i * 2, Utils.Endianness.Big);
_bitmap.SetPixel(i, line, Utils.MakeGray(
value == tGray16 ? 0 : 255, value * 255 / 65535));
}
}
break;
case ColorType.GrayscaleWithAlpha:
if (bitDepth == 8)
{
for (int i = 0; i < hdr.Width; i++)
{
_bitmap.SetPixel(i, line, Color.FromArgb(
decoded[i * 2 + 1],
decoded[i * 2], decoded[i * 2], decoded[i * 2]
));
}
}
else if (bitDepth == 16)
{
for (int i = 0; i < hdr.Width; i++)
{
_bitmap.SetPixel(i, line, Color.FromArgb(
Utils.BytesToUShort(decoded, i * 4 + 2, Utils.Endianness.Big) * 255 / 65535,
Utils.BytesToUShort(decoded, i * 4, Utils.Endianness.Big) * 255 / 65535,
Utils.BytesToUShort(decoded, i * 4, Utils.Endianness.Big) * 255 / 65535,
Utils.BytesToUShort(decoded, i * 4, Utils.Endianness.Big) * 255 / 65535
));
}
}
break;
case ColorType.IndexedColor:
if (bitDepth == 1)
{
for (int i = 0; i < Utils.IntCeilDiv(width, 8); i++)
{
int[] pixels = new int[8];
for (int j = 0; j < 8; j++)
{
pixels[j] = (decoded[i] >> (7 - j)) & 0x1;
}
for (int j = 0; j < 8; j++)
{
if (i * 8 + j < hdr.Width)
{
_bitmap.SetPixel(i * 8 + j, line,
Color.FromArgb(tPalette[pixels[j]], palette.Entries[pixels[j]]));
}
}
}
}
else if (bitDepth == 2)
{
for (int i = 0; i < Utils.IntCeilDiv(width, 4); i++)
{
int[] pixels = new int[4];
for (int j = 0; j < 4; j++)
{
pixels[j] = (decoded[i] >> ((3 - j) * 2)) & 0x3;
}
for (int j = 0; j < 4; j++)
{
if (i * 4 + j < hdr.Width)
{
_bitmap.SetPixel(i * 4 + j, line,
Color.FromArgb(tPalette[pixels[j]], palette.Entries[pixels[j]]));
}
}
}
}
else if (bitDepth == 4)
{
for (int i = 0; i < Utils.IntCeilDiv(width, 2); i++)
{
int pixel1 = decoded[i] >> 4; // upper four bits
int pixel2 = decoded[i] & 0xf; // lower two bits
_bitmap.SetPixel(i * 2, line,
Color.FromArgb(tPalette[pixel1], palette.Entries[pixel1]));
if (i * 2 + 1 < hdr.Width)
{
_bitmap.SetPixel(i * 2 + 1, line,
Color.FromArgb(tPalette[pixel2], palette.Entries[pixel2]));
}
}
}
else if (bitDepth == 8)
{
for (int i = 0; i < hdr.Width; i++)
{
_bitmap.SetPixel(i, line,
Color.FromArgb(tPalette[decoded[i]], palette.Entries[decoded[i]]));
}
}
break;
case ColorType.Truecolor:
if (bitDepth == 8)
{
for (int i = 0; i < hdr.Width; i++)
{
Color c = Color.FromArgb(
decoded[i * 3],
decoded[i * 3 + 1],
decoded[i * 3 + 2]
);
_bitmap.SetPixel(i, line, Color.FromArgb(
Utils.ColorsEqual(c, tRgb8) ? 0 : 255, c));
}
}
else if (bitDepth == 16)
{
// .NET doesn't support 16-bit bit depths
for (int i = 0; i < hdr.Width; i++)
{
Color c = Color.FromArgb(
Utils.BytesToUShort(decoded, i * 6, Utils.Endianness.Big) * 255 / 65535,
Utils.BytesToUShort(decoded, i * 6 + 2, Utils.Endianness.Big) * 255 / 65535,
Utils.BytesToUShort(decoded, i * 6 + 4, Utils.Endianness.Big) * 255 / 65535
);
_bitmap.SetPixel(i, line, Color.FromArgb(
Utils.ColorsEqual(c, tRgb16) ? 0 : 255, c));
}
}
break;
case ColorType.TruecolorWithAlpha:
if (bitDepth == 8)
{
for (int i = 0; i < hdr.Width; i++)
{
_bitmap.SetPixel(i, line, Color.FromArgb(
decoded[i * 4 + 3],
decoded[i * 4],
decoded[i * 4 + 1],
decoded[i * 4 + 2]));
}
}
else if (bitDepth == 16)
{
for (int i = 0; i < hdr.Width; i++)
{
_bitmap.SetPixel(i, line, Color.FromArgb(
Utils.BytesToUShort(decoded, i * 8 + 6, Utils.Endianness.Big) * 255 / 65535,
Utils.BytesToUShort(decoded, i * 8, Utils.Endianness.Big) * 255 / 65535,
Utils.BytesToUShort(decoded, i * 8 + 2, Utils.Endianness.Big) * 255 / 65535,
Utils.BytesToUShort(decoded, i * 8 + 4, Utils.Endianness.Big) * 255 / 65535
));
}
}
break;
default:
throw new Exception("Invalid color type.");
}
}
#endregion
}
}
