Am 20.03.2018 23:31 schrieb Leonard Rosenthol:
To be clear - AP's are optional in ISO 32000-1 (PDF 1.x) but are
required by ISO 32000-2 (PDF 2.x)
Ah, thanks, wasn't aware of that. Afaik poppler doesn't claim to support
PDF 2.x yet, but good to know anyway.
However, you are completely correct that drawing an AP (either
pre-generated or dynamically created) outside of the Rect is a bug.
The Rect is considered a clipping rect for the AP - this is defined in
32K somewhere...
Ok, then the bugfixing patches should get their own entry on bugzilla.
Such a change should be visible (actively announced?) to downstream
projects, because it's very likely some of them have adapted to the
buggy poppler behavior and would have to change accordingly. I'll cut
the patches out of my unrelated patch series therefore.
Cheers
Tobias
On 3/20/18, 6:22 PM, "poppler on behalf of Tobias Deiminger"
<[email protected] on behalf of
[email protected]> wrote:
I've stumbled upon the following issue several times, and it
affects a
patch series I'm currently doing. Please let me ask about it here.
Suppose we've got an annotation object like
<<
/Type /Annot
/Rect [0.00 0.00 10.00 10.00]
% ... other required stuff, omitted for readability ... %
% Important: There's no /AP %
>>
An annotation at position 0,0 with dimension 10x10 pts... There's
no AP
entry, i.e. no embedded appearance. That's fine, AP is optional in
ISO
32000. Poppler conforms and does its best to generate the missing
appearance at runtime.
But then poppler does something that seems buggy. In some cases it
ignores /Rect and draws the generated appearance with a new size
chosen
by poppler. The new size is not written back to /Rect, nor is it
reflected in public APIs (this puzzles Okular [0]). As an example
you'll
always get 24x24 pts icons for popup notes, even if /Rect says
10x10
pts.
My first question: Is ignoring /Rect for dynamically generated
appearances compliant with ISO 32000?
If not, then it's a poppler bug, and I'd prefer to fix the bug
instead
of building workarounds into my patch.
If I got it right, "Algorithm: Appearance streams" from ISO 32000
describes how to do it right. We shall transform AP BBox to match
with
Annot Rect. And we're almost there: Gfx::drawAnnot [1] sets up a
matrix
to transform AP BBox into a rectangle given by xMin, yMin, xMax,
yMax
arguments. It already works. We just have to use the original Rect
coordinates when calling Gfx::drawAnnot, instead of new ones. We
might
loose aspect ratio for popplers own appearances, but that's imho
better
than lying about the drawn size.
So my second question: Is calling Gfx::drawAnnot with original
/Rect
coordinates a valid approach for a fix?
[0]
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[1]
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