It fixes#18032.
Only use the special inner-backdrop compositing path for nested non-isolated groups that actually need isolation.
This preserves the parent/page backdrop for simple nested groups inside knockout groups, preventing later group
compositing from erasing existing backdrop content.
Test PDF files should never be executable because we only read their
contents, so this commit makes sure that all test PDFs have the same
permissions, namely 0644 (read-only for all groups, and writable for the
owner), to limit their permissions for a least-privilege approach.
In a knockout (KO) group each painting operator ("element") composites against
the group's initial backdrop instead of accumulating onto prior elements
of the same group. The backend renders each element to a per-group pooled
temp canvas (keyed off `#groupStackMeta`), builds a binary alpha mask via
a new `feFuncA` filter (`addKnockoutFilter`), `destination-out`s the
group canvas through that mask, restores the initial backdrop into the
cleared footprint for non-isolated groups (cropped to the same mask so
sparse groups don't bleed the whole rectangle), and finally paints the
element on top with the parent's blend mode. Path / clip / transform ops
are mirrored back to the group canvas via `mirrorContextOperations` so
graphics state stays in sync between elements; only the raster pixels
land on the temp canvas.
The temp canvas is forced to source-over for the element raster (`multiply`
on a transparent backdrop would zero the color) and the original GCO is
restored before `copyCtxState` writes back, so the parent's blend mode
survives for the final composite.
Also handled:
- Nested KO groups (the level is incremented for KO, reset to 0 for
non-KO subgroups so an ancestor KO doesn't leak in).
- Non-isolated non-KO subgroups inside a KO parent (`hasInnerBackdrop`
path: blend the elements against the subgroup's running backdrop for
color, mask with the elements-only canvas).
- Soft masks installed inside a KO element (`applySMaskInPlace` in
`compose`, which runs the SMask destination-in directly on the temp
canvas; the existing blit-to-suspended step is gated by `if (!ctx)`).
- Type-3 text, shading fills, image-mask groups, inline images and the
solid-color mask path: each is wrapped in `#begin/#endKnockoutElement`.
- `endDrawing` cleanup so cancelled rendering doesn't leak pooled
canvases or stale knockout state.
Prepare reusable soft-mask canvases for filtered and backdrop-dependent masks,
and use a faster destination-in composition path where possible.
Handle Alpha SMask /BC correctly, preserve OOB alpha behavior, and mirror canvas path
operations needed while rendering inside soft-mask mode (mirrored clip was buggy).
Add reftest PDFs covering Alpha masks, transfer functions, backdrop/OOB
alpha, and the optimized composition paths.
1. Record `fill` dependencies even if we early return due to `isPatternFill``
2. Isolate the `drawPattern` inner `executeOperationList` in a
`CanvasNestedDependencyTracker` so that it does not consume pending
dependencies from the outer list.
This test-case is an especially "bad" one performance wise given its PostScript function use, when falling back to the (now removed) `PostScriptEvaluator` code.
It fixes#5046.
We just generate a mesh for the pattern rectangle where the color of each vertex is computed from the function.
Since the mesh is generated in the worker we don't really take into account the current transform when it's drawn.
That being said, there are maybe some possible improvements in using directly the gpu for the shading creation
which could then take into account the current transform, but it could only work with ps function we can convert
ino wgsl language and simple enough color spaces (gray and rgb).
This patch adds right-click support for images in the PDF, allowing
users to download them. To minimize memory consumption, we:
- Do not store the images separately, and instead crop them out of the
PDF page canvas
- Only extract the images when needed (i.e. when the user right-clicks
on them), rather than eagery having all of them available.
To do so, we layer one empty 0x0 canvas per image, stretched to cover
the whole image, and only populate its contents on right click.
These images need to be inside the text layer: they cannot be _behind_
it, otherwise they would be covered by the text layer's container and
not be clickable, and they cannot be in front of it, otherwise they
would make the text spans unselectable.
This feature is managed by a new preference, `imagesRightClickMinSize`:
- when it's set to `-1`, right-click support is disabled
- when set to `0`, all images are available for right click
- when set to a positive integer, only images whose width and height are
greater than or equal to that value (in the PDF page frame of
reference) are available for right click.
This features is disabled by default outside of MOZCENTRAL, as it
significantly degrades the text selection experience in non-Firefox
browsers.
This behaviour comes from the initial pdf.js commit but is wrong and
doesn't match other PDF readers like muPDF or pdfium.
From PDF Spec 7.3.3:
A PDF writer shall not use the PostScript language syntax for numbers with non-decimal radices (such
as 16#FFFE) or in exponential format (such as 6.02E23).
