Hamza NaveedandHamza
75af6f589a
* PDF interpret: a glyph shown in a clipping mode clips even with no outline
A glyph shown in a clipping render mode (`4 Tr` to `7 Tr`) adds its outline to
the clipping path, and that clip applies to everything painted after `ET` until
the enclosing `Q`. When the glyphs shown have no outline -- a space, say -- the
clip they contribute is empty, and an empty clip admits nothing.
`interpret_window` applied a clip only once a glyph had contributed an outline,
so such a text object applied *no* clip and what followed painted unmasked.
A text object that shows no glyph at all is a different case and is left alone:
the clipping path is unchanged there, as readers leave it, and a glyph whose
outline is unavailable (Type 3) leaves the real clip unknown, so both stay
unclipped. pdf.js draws the same line in `endText`: it builds the clip from the
glyphs shown, empty outlines and all, and applies none when none were shown.
Measured on a page filled red behind the text object, Preview (CoreGraphics)
and Firefox (pdf.js) agreeing on the case this changes:
a space shown in 7 Tr before: the fill paints after: nothing paints
no glyph shown in 7 Tr unchanged: the fill paints
Companion to storytold/pdfcraft#3451.
The first push of this branch also carried 803 build-artifact files from
`crates/pdf/read-only-contract/target/`, which `.gitignore` did not cover: its
`/target` is anchored to the repository root, so a sub-crate's own build
directory is not ignored. Recommitted without them, and `target/` added so the
next one cannot slip in either (#185 review).
* pdf: test visible glyphs in a clipping mode, and what each clip leaves on the page
---------
Co-authored-by: Hamza <mail.hamzanaveed@gmail.com>
hayro-interpret
A crate for interpreting PDF files.
This crate provides an abstraction to interpret the content of a PDF file and render them
into an abstract [Device], which clients can implement as needed. This allows you, for
example, to render PDF files to bitmaps (which is what the hayro crate does), or other formats
such as SVG.
It should be noted that this crate is still very much in development. Therefore it currently lacks pretty much any documentation on how to use it. It's current API also only really makes it useful for rendering to PNG or SVG, though this will be improved upon in the future.
Examples
See the examples folder on the GitHub repository. Apart from that, you can also consult
the implementation of hayro and hayro-svg to get an idea on how to use this crate.
Safety
This crate forbids unsafe code via a crate-level attribute.
Cargo features
This crate has one optional feature:
embed-fonts: PDF processors are required to support 14 predefined fonts that do not need to be embedded into a PDF file. If you enable this feature, hayro will embed a (permissively-licensed) substitute for each font, so that you don't have to implement your custom font loading logic. This will add around ~240KB to your binary.
License
Licensed under either of
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
PdfCraft function limits
The PdfCraft patch rejects function construction after 64 nested functions or 10,000 total
function nodes, including repeated references, and detects cycles on the current path. Shared
children in different branches remain valid. Stitching functions reject empty or unresolved
child lists instead of silently truncating them. Calculator functions have a shared limit of 64
procedure levels and 10,000 parsed tokens (operators and procedure openings); evaluation has
its own 10,000-operator limit across selected branches. These are implementation resource
limits rather than PDF format limits. Rejection returns the existing None, and the optional
logging feature reports the reason and limit; no new interface warning is introduced.
Calculator integer division without an integer result is also rejected. Bit shifting discards bits beyond the 32-bit word and fills with zeroes, including logical right shifts of negative words; rotation accepts the full signed shift range without negating the minimum integer. Fixed-size operand and procedure-stack overflow errors propagate instead of truncating work. Normal function signatures and supported color/transfer-function behavior remain unchanged.