though a form dictionary should always contain fields (as required by the spec) it is possible for this entry to be missing. in this case we return false for trygetform.
though required by the spec an adobe type 1 font may be missing all width data. in this case we default to empty values and treat it like a normal adobe type 1 font.
now that rectangle constructor uses the order [ llx, lly, urx, ury ] and does not apply correction for points constructor parameters must be passed in the correct order. this change fixes the hyperlink factory which was passing them in the wrong order.
in addition the pdfpath bounding box was using left, right, top and bottom to calculate the minimum bounding box. this produced incorrect values now individual path operator bounding boxes are rotated, since for a rotated rectangle top may be less than bottom.
the performance seems to have taken a hit due to these changes however.
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.
an encoding array in an adobe type 1 font may be missing its declaration ending in 'for', if we encounter 'dup' while looking for the 'for' token we have a special case to go straight into reading the encoding.
also handles a case where the page content stream contains a path-closing operator without any path being active.
fonts can appear as dicitionary objects rather than indirect references in the resource dictionary for a page. if we encounter this we parse and store the font by name for retrieval during content parsing.
in order to recreate the valid bytes for use in decryption it is necessary to know which encoding was used to read a string token. this is because utf16-be encoding has a byte-order marker which should be included in the resulting bytes.
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.
if no widths array entry exists for the character and no font program is present for a true type simple font then use the 0 index glyph width if present in the widths array.
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.
when a marked content region contains an image we load it eagerly since we won't have access to the necessary classes at evaluation time. we also default image colorspace to the active graphics state colorspace if the dictionary doesn't contain a valid entry.
since the properties in marked content may be indirect references or belong to the page resources array, the value should be calculated during content processing. this change tidies up the marked content classes so they do not expose mutable data and uses the pdf token scanner overloads to load dictionary data.
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 font uses a named encoding which is not recognised, use the corresponding encoding based on the base font name, or fall back to windows ansi encoding.
some documents declare stream objects without an endobj marker at the end of the stream. if a new obj token is encountered after reading a stream we reset the scanner to the object number token and return the stream.
don't cache objects parsed if their offset doesn't match the cross-reference offset, unless the object was parsed by a brute-force search operation. this is because 1 object may lie in 2 streams, 1 valid and 1 invalid. If the invalid stream is parsed first for another object then the valid stream will never be read.
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.
some objects may be defined in more than one stream. parsing both streams would overwrite the object in the cache. to prevent this we avoid overwriting the existing object in the cache if it has the expected offset from the cross reference table.
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.
