private bool TestColorFormatHeader(StreamReaderHelper stream, ImportedImage ii)
{
// The SOS header (start of scan).
if (stream.GetWord(0, true) == 0xffda)
{
int components = stream.GetByte(4);
if (components < 1 || components > 4 || components == 2)
{
return(false);
}
// 1 for grayscale, 3 for RGB, 4 for CMYK.
int blockLength = stream.GetWord(2, true);
// Integrity check: correct size?
if (blockLength != 6 + 2 * components)
{
return(false);
}
// Eventually do more tests here.
// Magic: we assume that all JPEG files with 4 components are RGBW (inverted CMYK) and not CMYK.
// We add a test to tell CMYK from RGBW when we encounter a test file in CMYK format.
ii.Information.ImageFormat = components == 3 ? ImageInformation.ImageFormats.JPEG :
(components == 1 ? ImageInformation.ImageFormats.JPEGGRAY : ImageInformation.ImageFormats.JPEGRGBW);
return(true);
}
return(false);
}
private bool MoveToNextHeader(StreamReaderHelper stream)
{
int blockLength = stream.GetWord(2, true);
int headerMagic = stream.GetByte(0);
int headerType = stream.GetByte(1);
if (headerMagic == 0xff)
{
// EOI: last header.
if (headerType == 0xd9)
{
return(false);
}
// Check for standalone markers.
if (headerType == 0x01 || headerType >= 0xd0 && headerType <= 0xd7)
{
stream.CurrentOffset += 2;
return(true);
}
// Now assume header with block size.
stream.CurrentOffset += 2 + blockLength;
return(true);
}
return(false);
}
private bool TestJfifHeader(StreamReaderHelper stream, ImportedImage ii)
{
// The App0 header should be the first header in every JFIF file.
if (stream.GetWord(0, true) == 0xffe0)
{
// Now check for text "JFIF".
if (stream.GetDWord(4, true) == 0x4a464946)
{
int blockLength = stream.GetWord(2, true);
if (blockLength >= 16)
{
int version = stream.GetWord(9, true);
int units = stream.GetByte(11);
int densityX = stream.GetWord(12, true);
int densityY = stream.GetWord(14, true);
switch (units)
{
case 0: // Aspect ratio only.
ii.Information.HorizontalAspectRatio = densityX;
ii.Information.VerticalAspectRatio = densityY;
break;
case 1: // DPI.
ii.Information.HorizontalDPI = densityX;
ii.Information.VerticalDPI = densityY;
break;
case 2: // DPCM.
ii.Information.HorizontalDPM = densityX * 100;
ii.Information.VerticalDPM = densityY * 100;
break;
}
// More information here? More tests?
return(true);
}
}
}
return(false);
}
private bool TestInfoHeader(StreamReaderHelper stream, ImportedImage ii)
{
// The SOF header (start of frame).
int header = stream.GetWord(0, true);
if (header >= 0xffc0 && header <= 0xffc3 ||
header >= 0xffc9 && header <= 0xffcb)
{
// Lines in image.
int sizeY = stream.GetWord(5, true);
// Samples per line.
int sizeX = stream.GetWord(7, true);
// $THHO TODO: Check if we always get useful information here.
ii.Information.Width = (uint)sizeX;
ii.Information.Height = (uint)sizeY;
return(true);
}
return(false);
}
private bool TestBitmapFileHeader(StreamReaderHelper stream, out int offset)
{
offset = 0;
// File must start with "BM".
if (stream.GetWord(0, true) == 0x424d)
{
int filesize = (int)stream.GetDWord(2, false);
// Integrity check: filesize set in BM header should match size of the stream.
// We test "<" instead of "!=" to allow extra bytes at the end of the stream.
if (filesize < stream.Length)
return false;
offset = (int)stream.GetDWord(10, false);
stream.CurrentOffset += 14;
return true;
}
return false;
}
private bool TestBitmapFileHeader(StreamReaderHelper stream, out int offset)
{
offset = 0;
// File must start with "BM".
if (stream.GetWord(0, true) == 0x424d)
{
int filesize = (int)stream.GetDWord(2, false);
// Integrity check: filesize set in BM header should match size of the stream.
// We test "<" instead of "!=" to allow extra bytes at the end of the stream.
if (filesize < stream.Length)
{
return(false);
}
offset = (int)stream.GetDWord(10, false);
stream.CurrentOffset += 14;
return(true);
}
return(false);
}
private bool TestFileHeader(StreamReaderHelper stream)
{
// File must start with 0xffd8.
return(stream.GetWord(0, true) == 0xffd8);
}
private bool TestBitmapInfoHeader(StreamReaderHelper stream, ImportedImage ii, int offset)
{
int size = (int)stream.GetDWord(0, false);
if (size == 40 || size == 108 || size == 124) // sizeof BITMAPINFOHEADER == 40, sizeof BITMAPV4HEADER == 108, sizeof BITMAPV5HEADER == 124
{
uint width = stream.GetDWord(4, false);
int height = (int)stream.GetDWord(8, false);
int planes = stream.GetWord(12, false);
int bitcount = stream.GetWord(14, false);
int compression = (int)stream.GetDWord(16, false);
int sizeImage = (int)stream.GetDWord(20, false);
int xPelsPerMeter = (int)stream.GetDWord(24, false);
int yPelsPerMeter = (int)stream.GetDWord(28, false);
uint colorsUsed = stream.GetDWord(32, false);
uint colorsImportant = stream.GetDWord(36, false);
// TODO Integrity and plausibility checks.
if (sizeImage != 0 && sizeImage + offset > stream.Length)
{
return(false);
}
ImagePrivateDataBitmap privateData = (ImagePrivateDataBitmap)ii.Data;
// Return true only for supported formats.
if (compression == 0 || compression == 3) // BI_RGB == 0, BI_BITFIELDS == 3
{
((ImagePrivateDataBitmap)ii.Data).Offset = offset;
((ImagePrivateDataBitmap)ii.Data).ColorPaletteOffset = stream.CurrentOffset + size;
ii.Information.Width = width;
ii.Information.Height = (uint)Math.Abs(height);
ii.Information.HorizontalDPM = xPelsPerMeter;
ii.Information.VerticalDPM = yPelsPerMeter;
privateData.FlippedImage = height < 0;
if (planes == 1 && bitcount == 24)
{
// RGB24
ii.Information.ImageFormat = ImageInformation.ImageFormats.RGB24;
// TODO: Verify Mask if size >= 108 && compression == 3.
return(true);
}
if (planes == 1 && bitcount == 32)
{
// ARGB32
//ii.Information.ImageFormat = ImageInformation.ImageFormats.ARGB32;
ii.Information.ImageFormat = compression == 0 ?
ImageInformation.ImageFormats.RGB24 :
ImageInformation.ImageFormats.ARGB32;
// TODO: tell RGB from ARGB. Idea: assume RGB if alpha is always 0.
// TODO: Verify Mask if size >= 108 && compression == 3.
return(true);
}
if (planes == 1 && bitcount == 8)
{
// Palette8
ii.Information.ImageFormat = ImageInformation.ImageFormats.Palette8;
ii.Information.ColorsUsed = colorsUsed;
return(true);
}
if (planes == 1 && bitcount == 4)
{
// Palette8
ii.Information.ImageFormat = ImageInformation.ImageFormats.Palette4;
ii.Information.ColorsUsed = colorsUsed;
return(true);
}
if (planes == 1 && bitcount == 1)
{
// Palette8
ii.Information.ImageFormat = ImageInformation.ImageFormats.Palette1;
ii.Information.ColorsUsed = colorsUsed;
return(true);
}
// TODO Implement more formats!
}
}
return(false);
}
private bool TestJfifHeader(StreamReaderHelper stream, ImportedImage ii)
{
// The App0 header should be the first header in every JFIF file.
if (stream.GetWord(0, true) == 0xffe0)
{
// Now check for text "JFIF".
if (stream.GetDWord(4, true) == 0x4a464946)
{
int blockLength = stream.GetWord(2, true);
if (blockLength >= 16)
{
int version = stream.GetWord(9, true);
int units = stream.GetByte(11);
int densityX = stream.GetWord(12, true);
int densityY = stream.GetWord(14, true);
switch (units)
{
case 0: // Aspect ratio only.
ii.Information.HorizontalAspectRatio = densityX;
ii.Information.VerticalAspectRatio = densityY;
break;
case 1: // DPI.
ii.Information.HorizontalDPI = densityX;
ii.Information.VerticalDPI = densityY;
break;
case 2: // DPCM.
ii.Information.HorizontalDPM = densityX * 100;
ii.Information.VerticalDPM = densityY * 100;
break;
}
// More information here? More tests?
return true;
}
}
}
return false;
}
private bool TestFileHeader(StreamReaderHelper stream)
{
// File must start with 0xffd8.
return stream.GetWord(0, true) == 0xffd8;
}
private bool MoveToNextHeader(StreamReaderHelper stream)
{
int blockLength = stream.GetWord(2, true);
int headerMagic = stream.GetByte(0);
int headerType = stream.GetByte(1);
if (headerMagic == 0xff)
{
// EOI: last header.
if (headerType == 0xd9)
return false;
// Check for standalone markers.
if (headerType == 0x01 || headerType >= 0xd0 && headerType <= 0xd7)
{
stream.CurrentOffset += 2;
return true;
}
// Now assume header with block size.
stream.CurrentOffset += 2 + blockLength;
return true;
}
return false;
}
private bool TestInfoHeader(StreamReaderHelper stream, ImportedImage ii)
{
// The SOF header (start of frame).
int header = stream.GetWord(0, true);
if (header >= 0xffc0 && header <= 0xffc3 ||
header >= 0xffc9 && header <= 0xffcb)
{
// Lines in image.
int sizeY = stream.GetWord(5, true);
// Samples per line.
int sizeX = stream.GetWord(7, true);
// $THHO TODO: Check if we always get useful information here.
ii.Information.Width = (uint)sizeX;
ii.Information.Height = (uint)sizeY;
return true;
}
return false;
}
private bool TestColorFormatHeader(StreamReaderHelper stream, ImportedImage ii)
{
// The SOS header (start of scan).
if (stream.GetWord(0, true) == 0xffda)
{
int components = stream.GetByte(4);
if (components < 1 || components > 4 || components == 2)
return false;
// 1 for grayscale, 3 for RGB, 4 for CMYK.
int blockLength = stream.GetWord(2, true);
// Integrity check: correct size?
if (blockLength != 6 + 2 * components)
return false;
// Eventually do more tests here.
// Magic: we assume that all JPEG files with 4 components are RGBW (inverted CMYK) and not CMYK.
// We add a test to tell CMYK from RGBW when we encounter a test file in CMYK format.
ii.Information.ImageFormat = components == 3 ? ImageInformation.ImageFormats.JPEG :
(components == 1 ? ImageInformation.ImageFormats.JPEGGRAY : ImageInformation.ImageFormats.JPEGRGBW);
return true;
}
return false;
}
private bool TestBitmapInfoHeader(StreamReaderHelper stream, ImportedImage ii, int offset)
{
int size = (int)stream.GetDWord(0, false);
if (size == 40 || size == 108 || size == 124) // sizeof BITMAPINFOHEADER == 40, sizeof BITMAPV4HEADER == 108, sizeof BITMAPV5HEADER == 124
{
uint width = stream.GetDWord(4, false);
int height = (int)stream.GetDWord(8, false);
int planes = stream.GetWord(12, false);
int bitcount = stream.GetWord(14, false);
int compression = (int)stream.GetDWord(16, false);
int sizeImage = (int)stream.GetDWord(20, false);
int xPelsPerMeter = (int)stream.GetDWord(24, false);
int yPelsPerMeter = (int)stream.GetDWord(28, false);
uint colorsUsed = stream.GetDWord(32, false);
uint colorsImportant = stream.GetDWord(36, false);
// TODO Integrity and plausibility checks.
if (sizeImage != 0 && sizeImage + offset > stream.Length)
return false;
ImagePrivateDataBitmap privateData = (ImagePrivateDataBitmap)ii.Data;
// Return true only for supported formats.
if (compression == 0 || compression == 3) // BI_RGB == 0, BI_BITFIELDS == 3
{
((ImagePrivateDataBitmap)ii.Data).Offset = offset;
((ImagePrivateDataBitmap)ii.Data).ColorPaletteOffset = stream.CurrentOffset + size;
ii.Information.Width = width;
ii.Information.Height = (uint)Math.Abs(height);
ii.Information.HorizontalDPM = xPelsPerMeter;
ii.Information.VerticalDPM = yPelsPerMeter;
privateData.FlippedImage = height < 0;
if (planes == 1 && bitcount == 24)
{
// RGB24
ii.Information.ImageFormat = ImageInformation.ImageFormats.RGB24;
// TODO: Verify Mask if size >= 108 && compression == 3.
return true;
}
if (planes == 1 && bitcount == 32)
{
// ARGB32
//ii.Information.ImageFormat = ImageInformation.ImageFormats.ARGB32;
ii.Information.ImageFormat = compression == 0 ?
ImageInformation.ImageFormats.RGB24 :
ImageInformation.ImageFormats.ARGB32;
// TODO: tell RGB from ARGB. Idea: assume RGB if alpha is always 0.
// TODO: Verify Mask if size >= 108 && compression == 3.
return true;
}
if (planes == 1 && bitcount == 8)
{
// Palette8
ii.Information.ImageFormat = ImageInformation.ImageFormats.Palette8;
ii.Information.ColorsUsed = colorsUsed;
return true;
}
if (planes == 1 && bitcount == 4)
{
// Palette8
ii.Information.ImageFormat = ImageInformation.ImageFormats.Palette4;
ii.Information.ColorsUsed = colorsUsed;
return true;
}
if (planes == 1 && bitcount == 1)
{
// Palette8
ii.Information.ImageFormat = ImageInformation.ImageFormats.Palette1;
ii.Information.ColorsUsed = colorsUsed;
return true;
}
// TODO Implement more formats!
}
}
return false;
}
private bool TestFileHeader(StreamReaderHelper stream) => // File must start with 0xffd8. stream.GetWord(0, true) == 0xffd8;