we add a try/catch to the direct object finder's tryget method so it returns false rather than throwing.
if we have an acro-form reference in the catalog but no corresponding object in the document we instead scan all objects in the document to find form fields and reconstruct the acro-form dictionary.
previously we checked the offset was not inside the table (correct thing to check), however this is only a special case of the more general issue (cross reference offsets are wrong). we move handling for this into the pdf token scanner. if we attempt to read an object at an offset and it fails we brute force the entire file to find correct offsets. we also needed to add handling to make sure we don't attempt to use stream length tokens if we're brute-forcing since we can't look up indirect references for length.
when brute force searching for the start of the cross-reference table (xref) we read 5 byte buffers, previously if the 'x' of 'xref' was the first character of the buffer we skipped it. this checks when 'x' is the first character of the buffer.
fixes the recorded offset when an endimage is recovered from the first time. it was off by one so if the subsequent end image was also the wrong tag then the second attempt at recovery failed.
also allows recovery when other tags appear after an endimage as long as they're not block ending operations (end text, perhaps pop/push in future).
the brute force searcher offsets were off by one. this change means the offset returned is now aligned with the object number in the object number/generation/operator triple.
if we are reading a cross reference offset which contains a number we assumed it was a stream object. if it's not we now brute-force the entire file looking for an 'xref' token. this should be combined with a search for cross-reference streams and should run when we read neither the numeric token or an 'xref' token but for now this fixes the observed issue.
also adds number of images to the page api to prevent consumers needing to enumerate.
if the %pdf version header comment is offset from the start of the file the cross reference offsets will also be wrong by that amount. this change updates the cross reference location logic to use the offset from the located version header.
some files seem to have the format header preceded by large amounts of junk but this appears to be valid for chrome and acrobat reader. this change ups the amount of nonsense to be read prior to the version header.
also makes parsing of the version header culture invariant which may be related to #85.
since inline image data may contain the end image "ei" token inside the data stream there's no reliable way to actually determine if we've read all the data. for this reason if we end up with an invalid state parsing operations after we've read the end image token we try to recover by reading from the previous token to the next end image token if any. we supply log information to let the consumer know this is what we're doing. it's still not bullet-proof but it should be good enough.
also support negative page rotation values by adding them to a 360 degree rotation so -90 degrees clockwise is 270 degrees clockwise.
an arrray of 4 items representing a rectangle may define its values as indirect references. when converting to a rectangle we pass a pdf token scanner to resolve any indirect references.
since an inline image's data stream may contain the characters 'ei' as a result of compression it's possible to read an end image operator mid-data, this results in the next operator also being end image and the content stream being in an invalid state. to recover from this when we detect this situation we remove the previous operator, read to the current operator and replace the operator and data bytes in the list of operations.
since pdfbox defaults to us letter if the mediabox is missing rather than throwing we remove the behaviour where uselenientparsing is false which used to throw, now we log an error. throwing didn't provide any benefit to consumers.
if the font descriptor uses the fromsubtype flag the actual type of the font can differ from that specified in the font dictionary. in this case a truetype font actually contains a type1c, compact font format, font. in this case we fall back to using the type1 parser.
also handles a closesubpath command appearing without any path construction operators.
if the previous cross-reference location points to an offset outside the file size we skip it.
also makes cid font factory more resilient by skipping missing descriptors.
an %%eof for a pdf file may appear further back than the last 1024 bytes. this change doubles the search range. it also handles an empty differences array being defined for a font encoding.
we also remove the old approach to dependency injection from the code since we are now favouring static classes where possible.
the 3 font types mentioned are moved to the new fonts project, any referenced types are moved to the core project. most truetype classes are made public #8.
to make the project more useful and expose more usable classes we're rearchitecting in the following way. code used to read fonts from external file formats like truetype, adobe font metrics (afm) and adobe type 1 fonts are moving to a new project which doesn't reference most of the pdf logic. the shared logic is moving to a new flat-structured project called core. this is a sort-of onion type architecture, with core being the... core, fonts being the next layer of the onion, pdfpig itself the next. this will then support additional libraries/projects as outer layers of the onion as well as releasing standalone version of the font library as pdfbox does with fontbox.
previously the only way to test if a password was correct was to supply a single password and throw if the value was incorrect. this was slow. now parsing options supports a list of passwords as well as a single password option (which is equivalent to a list with a single item). these passwords are all tested at the same time and an exception is only thrown once all passwords are tested.
* cid cff fonts have multiple sub-fonts and multiple private dictionaries, in addition to a top level font and private dictionary. this fix uses the specific sub-dictionary when getting local subroutines on a per-glyph basis.
* chinese, japanese or korean fonts can use a ucs-2 encoding cmap for retrieving unicode values.
* add support for the additional glyph list for unicode values in true type fonts. adds nonmarkingreturn mapping to carriage return.
* makes font parsing classes static where there's no reason for them to be per-instance.
resources such as fonts are linked to page content operations using name labels, e.g. "/F1", these resource labels can be reassigned on different pages or inside form xobjects. we now clear the entire resource state for each page which is parsed and after form xobject operations which use resource dictionaries.
a single cross-reference stream may contain multiple disjoint runs of object numbers, previously we only took the first now we load all objects.
adds indexer to array token for ease-of-use.
adds page number and bounds information to all form fields.
support both xobject and inline images. adds unsupported filters so that exceptions are only thrown when accessing lazily evaluated image.bytes property rather than when opening the page.
treat all warnings as errors.
package license url is deprecated in favour of package license expression but nuget doesn't seem to support expressions properly for published packages yet so we'll keep the deprecated url for the time being. having both url and expression causes the build to fail.
small obvious performance improvements for file header passing and getting the encoding information using the existing reverse name to code map.
an inline image in a pdf content stream starts with the bi tag, then id declares the start of image data and ei the end. attempting to parse the bytes after the id tag as usual resulted in errors. this change adds special case handling for inline images.
- begin adding support for extended graphics state (the 'gs' operator) including setting the font #39.
- apply page level rotation to the glyph bounding box and width to get correct glyph sizes #41.
- wrap page rotation in a value type to ensure the value is restricted to right angle rotations and provide convenience members #42.
- fix bug where system font finder never worked for truetype fonts because it began reading the file from the wrong offset.
we need to apply rotation to the crop and media box and therefore find the correct width and height. but for now correctly deriving the rotation from the page tree should help consumers.
previously if the cross reference did not exist at exactly the provided offset we'd immediately throw, now we assume we can read a few more tokens to find the xref table or stream start. this won't work in the case where the provided offset is past the start of the table or nowhere near the table but in those cases there's not much we can do. there's some more work to do to provide a fallback xref parser which finds the xref tables and streams using a brute-force scan of the whole document.
