Comments (6)
hadasg
commented on July 20, 2024
Unintentionally I sent you the original code, below is the code after my changes:
EStatusCode JPEGImageParser::ReadPhotoshopData(JPEGImageInformation& outImageInformation,bool outPhotoshopDataOK)
{
EStatusCode status;
unsigned int intSkip;
unsigned long toSkip;
unsigned int nameSkip;
unsigned long dataLength;
bool resolutionBimNotFound = true;
do {
status = ReadIntValue(intSkip);
if(status != PDFHummus::eSuccess)
break;
toSkip = intSkip-2;
status = SkipTillChar(scEOS,toSkip);
if(status != PDFHummus::eSuccess)
break;
while(toSkip > 0 && resolutionBimNotFound)
{
if (toSkip < 4)
break;
status = ReadStreamToBuffer(4);
if(status !=PDFHummus::eSuccess)
break;
toSkip-=4;
if(0 != memcmp(mReadBuffer,sc8Bim,4))
break; // k. corrupt header. stop here and just skip the next
if (toSkip < 3)
break;
status = ReadStreamToBuffer(3);
if(status !=PDFHummus::eSuccess)
break;
toSkip-=3;
nameSkip = (int)mReadBuffer[2];
if(nameSkip % 2 == 0)
++nameSkip;
if (toSkip < nameSkip)
break;
SkipStream(nameSkip);
toSkip-=nameSkip;
resolutionBimNotFound = (0 != memcmp(mReadBuffer,scResolutionBIMID,2));
if (toSkip < 4)
break;
status = ReadLongValue(dataLength);
if(status != PDFHummus::eSuccess)
break;
toSkip-=4;
if(resolutionBimNotFound)
{
if(dataLength % 2 == 1)
++dataLength;
if (toSkip < dataLength)
break;
toSkip-=dataLength;
SkipStream(dataLength);
}
else
{
if (toSkip < 16)
break;
status = ReadStreamToBuffer(16);
if(status !=PDFHummus::eSuccess)
break;
toSkip-=16;
outImageInformation.PhotoshopInformationExists = true;
outImageInformation.PhotoshopXDensity = GetIntValue(mReadBuffer) + GetFractValue(mReadBuffer + 2);
outImageInformation.PhotoshopYDensity = GetIntValue(mReadBuffer + 8) + GetFractValue(mReadBuffer + 10);
}
}
if(PDFHummus::eSuccess == status)
SkipStream(toSkip);
}while(false);
outPhotoshopDataOK = !resolutionBimNotFound;
return status;
}
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galkahana
commented on July 20, 2024
Hi Hadas,
seems good. i'll take it.
Thanks.
Gal.
ps. mazel tov.
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hadasg
commented on July 20, 2024
Thanks :)
from pdf-writer.
hadasg
commented on July 20, 2024
Below is the final code - I changed the code to return false in the out parameter "outPhotoshopDataOK" in case of failure.
EStatusCode JPEGImageParser::ReadPhotoshopData(JPEGImageInformation& outImageInformation,bool outPhotoshopDataOK)
{
EStatusCode status;
unsigned int intSkip;
unsigned long toSkip;
unsigned int nameSkip;
unsigned long dataLength;
bool resolutionBimNotFound = true;
do {
status = ReadIntValue(intSkip);
if(status != PDFHummus::eSuccess)
break;
toSkip = intSkip-2;
status = SkipTillChar(scEOS,toSkip);
if(status != PDFHummus::eSuccess)
break;
while(toSkip > 0 && resolutionBimNotFound)
{
if (toSkip < 4)
break;
status = ReadStreamToBuffer(4);
if(status !=PDFHummus::eSuccess)
break;
toSkip-=4;
if(0 != memcmp(mReadBuffer,sc8Bim,4))
break; // k. corrupt header. stop here and just skip the next
if (toSkip < 3)
break;
status = ReadStreamToBuffer(3);
if(status !=PDFHummus::eSuccess)
break;
toSkip-=3;
nameSkip = (int)mReadBuffer[2];
if(nameSkip % 2 == 0)
++nameSkip;
if (toSkip < nameSkip)
break;
SkipStream(nameSkip);
toSkip-=nameSkip;
resolutionBimNotFound = (0 != memcmp(mReadBuffer,scResolutionBIMID,2));
if (toSkip < 4)
{
resolutionBimNotFound = true;
break;
}
status = ReadLongValue(dataLength);
if (status != PDFHummus::eSuccess)
{
resolutionBimNotFound = true;
break;
}
toSkip-=4;
if(resolutionBimNotFound)
{
if(dataLength % 2 == 1)
++dataLength;
if (toSkip < dataLength)
break;
toSkip-=dataLength;
SkipStream(dataLength);
}
else
{
if (toSkip < 16)
{
resolutionBimNotFound = true;
break;
}
status = ReadStreamToBuffer(16);
if(status !=PDFHummus::eSuccess)
{
resolutionBimNotFound = true;
break;
}
toSkip-=16;
outImageInformation.PhotoshopInformationExists = true;
outImageInformation.PhotoshopXDensity = GetIntValue(mReadBuffer) + GetFractValue(mReadBuffer + 2);
outImageInformation.PhotoshopYDensity = GetIntValue(mReadBuffer + 8) + GetFractValue(mReadBuffer + 10);
}
}
if(PDFHummus::eSuccess == status)
SkipStream(toSkip);
}while(false);
outPhotoshopDataOK = !resolutionBimNotFound;
return status;
}
from pdf-writer.
galkahana
commented on July 20, 2024
Hi Hadas,
well i figured that the code looks a little bit cluttered with all those checks. I figured the spirit of the solution has to be with - if there's a read error fail the whole process, if there's not enough to read than just ignore this photoshop data.
This led me to rewrite this method a bit. you can see the end result in what i checked in right now here:
https://github.com/galkahana/PDF-Writer/blob/master/PDFWriter/JPEGImageParser.cpp#L283
the code is refactored to let subroutines deal with checking whether there's enough to read, do the read and reduce the accumulated bytes to skip. The result is cleaner code, having the same amount of conditionals as the original.
I think it still maintains the same gist of things.
let me know what you think.
Gal.
from pdf-writer.
hadasg
commented on July 20, 2024
Hi Gal,
It's look good and cleaner.
Thanks,
Hadas
from pdf-writer.
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