/*
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% %
% %
% %
% S i g n a t u r e I m a g e %
% %
% %
% %
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%
% SignatureImage() computes a message digest from an image pixel stream with
% an implementation of the NIST SHA-256 Message Digest algorithm. This
% signature uniquely identifies the image and is convenient for determining
% if an image has been modified or whether two images are identical.
%
% The format of the SignatureImage method is:
%
% MagickBooleanType SignatureImage(Image *image,ExceptionInfo *exception)
%
% A description of each parameter follows:
%
% o image: the image.
%
% o exception: return any errors or warnings in this structure.
%
*/
MagickExport MagickBooleanType SignatureImage(Image *image,
ExceptionInfo *exception)
{
CacheView
*image_view;
char
*hex_signature;
double
pixel;
register const Quantum
*p;
SignatureInfo
*signature_info;
ssize_t
y;
StringInfo
*signature;
unsigned char
*pixels;
/*
Compute image digital signature.
*/
assert(image != (Image *) NULL);
assert(image->signature == MagickSignature);
if (image->debug != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
signature_info=AcquireSignatureInfo();
signature=AcquireStringInfo(image->columns*GetPixelChannels(image)*
sizeof(pixel));
image_view=AcquireVirtualCacheView(image,exception);
for (y=0; y < (ssize_t) image->rows; y++)
{
register ssize_t
x;
register unsigned char
*q;
p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
if (p == (const Quantum *) NULL)
break;
SetStringInfoLength(signature,image->columns*GetPixelChannels(image)*
sizeof(pixel));
pixels=GetStringInfoDatum(signature);
q=pixels;
for (x=0; x < (ssize_t) image->columns; x++)
{
register ssize_t
i;
if (GetPixelReadMask(image,p) == 0)
{
p+=GetPixelChannels(image);
continue;
}
for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
{
register ssize_t
j;
PixelChannel channel=GetPixelChannelChannel(image,i);
PixelTrait traits=GetPixelChannelTraits(image,channel);
if (traits == UndefinedPixelTrait)
continue;
pixel=QuantumScale*p[i];
for (j=0; j < (ssize_t) sizeof(pixel); j++)
*q++=(unsigned char) ((unsigned char *) &pixel)[j];
}
p+=GetPixelChannels(image);
}
SetStringInfoLength(signature,(size_t) (q-pixels));
UpdateSignature(signature_info,signature);
}
image_view=DestroyCacheView(image_view);
FinalizeSignature(signature_info);
hex_signature=StringInfoToHexString(GetSignatureDigest(signature_info));
(void) DeleteImageProperty(image,"signature");
(void) SetImageProperty(image,"signature",hex_signature,exception);
/*
Free resources.
*/
hex_signature=DestroyString(hex_signature);
signature=DestroyStringInfo(signature);
signature_info=DestroySignatureInfo(signature_info);
return(MagickTrue);
}
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% %
% S i g n a t u r e I m a g e %
% %
% %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% SignatureImage() computes a message digest from an image pixel stream with
% an implementation of the NIST SHA-256 Message Digest algorithm. This
% signature uniquely identifies the image and is convenient for determining
% if an image has been modified or whether two images are identical.
%
% The format of the SignatureImage method is:
%
% MagickBooleanType SignatureImage(Image *image)
%
% A description of each parameter follows:
%
% o image: the image.
%
*/
MagickExport MagickBooleanType SignatureImage(Image *image)
{
CacheView
*image_view;
char
*hex_signature;
ExceptionInfo
*exception;
QuantumInfo
*quantum_info;
QuantumType
quantum_type;
register const PixelPacket
*p;
SignatureInfo
*signature_info;
size_t
length;
ssize_t
y;
StringInfo
*signature;
unsigned char
*pixels;
/*
Compute image digital signature.
*/
assert(image != (Image *) NULL);
assert(image->signature == MagickSignature);
if (image->debug != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
quantum_info=AcquireQuantumInfo((const ImageInfo *) NULL,image);
if (quantum_info == (QuantumInfo *) NULL)
ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
image->filename);
quantum_type=RGBQuantum;
if (image->matte != MagickFalse)
quantum_type=RGBAQuantum;
if (image->colorspace == CMYKColorspace)
{
quantum_type=CMYKQuantum;
if (image->matte != MagickFalse)
quantum_type=CMYKAQuantum;
}
signature_info=AcquireSignatureInfo();
signature=AcquireStringInfo(quantum_info->extent);
pixels=GetQuantumPixels(quantum_info);
exception=(&image->exception);
image_view=AcquireCacheView(image);
for (y=0; y < (ssize_t) image->rows; y++)
{
p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
if (p == (const PixelPacket *) NULL)
break;
length=ExportQuantumPixels(image,image_view,quantum_info,quantum_type,
pixels,&image->exception);
SetStringInfoLength(signature,length);
SetStringInfoDatum(signature,pixels);
UpdateSignature(signature_info,signature);
}
image_view=DestroyCacheView(image_view);
quantum_info=DestroyQuantumInfo(quantum_info);
FinalizeSignature(signature_info);
hex_signature=StringInfoToHexString(GetSignatureDigest(signature_info));
(void) DeleteImageProperty(image,"signature");
(void) SetImageProperty(image,"signature",hex_signature);
/*
Free resources.
*/
hex_signature=DestroyString(hex_signature);
signature=DestroyStringInfo(signature);
signature_info=DestroySignatureInfo(signature_info);
return(MagickTrue);
}
