Each well-formed SVG image has the following structure:
SVG element
- Definitions element
- Root group
- Other group 1
- ...
- Other group n
This patch factors out initialization code into a private method in such
as way that the creation of this structure is clear from the code. The
root group is the replacement for the parent group from before. We need
this group as we cannot apply the viewport transform on the SVG element
itself (this caused issues in Chrome). If other code appends groups to
the SVG image, in reality it is appending those groups to the root
group, but this detail is abstracted away by this patch.
This patch ensures that we only create transformation groups when it is
actually required and that we re-use transform groups as much as possible.
It reduces the number of transform groups for the Tracemonkey paper from
2790 to 1271, thereby making the DOM much lighter and rendering/scrolling
smoother. Moreover, it simplifies the code and prevents duplication.
Finally, we issue a warning when an unimplemented graphic state is
encountered. Before, this was ignored silently, making debugging harder.
This patch:
- resolves a warning in the console about missing character encoding;
- makes the viewer use the same background color and PDF file as the
regular viewer;
- simplifies the example to bring it more in line with the other
examples.
Let `Parser_makeFilter` pass in the `DecodeParms` data to various image `Stream`s, instead of re-fetching it in various `[...]Stream.prototype.ensureBuffer` methods
In `Parser_filter` the `DecodeParms` data is fetched and passed to `Parser_makeFilter`, where we also make sure that a `Ref` is resolved to a direct object.
We can thus pass this along to the various image `Stream` constructors, to avoid the current situation where we lookup/resolve data that is already available.
Note also that we currently do *not* handle the case where `DecodeParms` is an Array entirely correct in the various image `Stream`s, and this patch fixes that for free.
While the array argument to TJ should only contain strings and numbers, other
unfortunate items are found in PDFs in the wild, e.g.:
[(Grandes) 0.0 Tc
-250.0 (Client\350les,) 0.0 Tc
-250.0 (Financements) 0.0 Tc
-250.0 (et) 0.0 Tc
-250.0 (March\351s) ] TJ
getOperatorList already properly ignores any non-string, non-numeric values in
TJ arrays; without this patch to getTextContent, returned text items can have
NaN widths due to calculations being applied to those non-numeric values.
For PDF files with multiple `/Filter`s, where the `/Length` entry is zero, we fail to render the file correctly. The reason is that `maybeLength` is `null` for the every filter except the first, and `!maybeLength` is thus truthy.
Hence it seems that we should completely ignore the `/Length` entry and also explicitly check `maybeLength === 0`.
Note that I've not (yet) come across a PDF file with this issue in the wild, but given all the stupid things PDF generators do I wouldn't be surprised if such a file actually exists. In order to prevent a possible future bug, I'm submitting this patch which includes a hand-edited PDF file that we currently cannot render correctly (but e.g. Adobe Reader can).
