private ImageData ReadBitmapWithAlpha(IBinaryStream file, BmpMetaData info)
{
file.Position = info.ImageLength;
var alpha = new byte[info.Width * info.Height];
if (alpha.Length != file.Read(alpha, 0, alpha.Length))
{
throw new EndOfStreamException();
}
file.Position = info.ImageOffset;
int dst_stride = (int)info.Width * 4;
var pixels = new byte[(int)info.Height * dst_stride];
int a_src = 0;
for (int y = (int)info.Height - 1; y >= 0; --y)
{
int dst = dst_stride * y;
for (int x = 0; x < dst_stride; x += 4)
{
file.Read(pixels, dst + x, 3);
pixels[dst + x + 3] = alpha[a_src++];
}
}
return(ImageData.Create(info, PixelFormats.Bgra32, null, pixels, dst_stride));
}
public ImageData Read(IBinaryStream file, BmpMetaData info)
{
if (file.AsStream.CanSeek)
{
var width_x_height = info.Width * info.Height;
uint bmp_length = width_x_height * (uint)info.BPP / 8 + info.ImageOffset;
if (bmp_length == info.ImageLength || bmp_length + 2 == info.ImageLength)
{
if (0x20 == info.BPP)
{
return(ReadBitmapBGRA(file, info));
}
else if (0x18 == info.BPP)
{
uint length_with_alpha = info.ImageLength + width_x_height;
if (length_with_alpha == file.Length || length_with_alpha + info.Width == file.Length)
{
return(ReadBitmapWithAlpha(file, info));
}
}
}
else if (0x20 == info.BPP && (info.ImageLength - (width_x_height * 3 + info.ImageOffset)) <= 2)
{
return(ReadBitmapBGRA(file, info));
}
}
return(null);
}
private ImageData ReadBitmapBGRA(IBinaryStream file, BmpMetaData info)
{
file.Position = info.ImageOffset;
int stride = (int)info.Width * 4;
var pixels = new byte[(int)info.Height * stride];
bool has_alpha = false;
for (int y = (int)info.Height - 1; y >= 0; --y)
{
int dst = stride * y;
file.Read(pixels, dst, stride);
for (int x = 3; !has_alpha && x < stride; x += 4)
{
has_alpha = pixels[dst + x] != 0;
}
}
PixelFormat format = has_alpha ? PixelFormats.Bgra32 : PixelFormats.Bgr32;
return(ImageData.Create(info, format, null, pixels, stride));
}
private ImageData ReadBitmapWithAlpha(Stream file, BmpMetaData info)
{
file.Position = info.ImageLength;
var alpha = new byte[info.Width*info.Height];
if (alpha.Length != file.Read (alpha, 0, alpha.Length))
throw new EndOfStreamException();
file.Position = info.HeaderLength;
int dst_stride = (int)info.Width * 4;
var pixels = new byte[(int)info.Height * dst_stride];
int a_src = 0;
for (int y = (int)info.Height-1; y >= 0; --y)
{
int dst = dst_stride * y;
for (int x = 0; x < dst_stride; x += 4)
{
file.Read (pixels, dst+x, 3);
pixels[dst+x+3] = alpha[a_src++];
}
}
return ImageData.Create (info, PixelFormats.Bgra32, null, pixels, dst_stride);
}
private ImageData ReadBitmapBGRA(Stream file, BmpMetaData info)
{
file.Position = info.HeaderLength;
int stride = (int)info.Width * 4;
var pixels = new byte[(int)info.Height * stride];
bool has_alpha = false;
for (int y = (int)info.Height-1; y >= 0; --y)
{
int dst = stride * y;
file.Read (pixels, dst, stride);
for (int x = 3; !has_alpha && x < stride; x += 4)
has_alpha = pixels[dst+x] != 0;
}
PixelFormat format = has_alpha ? PixelFormats.Bgra32 : PixelFormats.Bgr32;
return ImageData.Create (info, format, null, pixels, stride);
}
