Since handling overflow: hidden in PaintableBox::before_children_paint
while following paint traversal order can't result in correctly computed
clip rectangle for elements that create their own stacking context
(because before_children_paint is called only for parent but overflow:
hidden can be set somewhere deeper but not in direct ancestor), here
introduced new function PaintableBox::clip_rect() that computes clip
rectangle by looking into containing block.
should_clip_overflow flag that disables clip for absolutely positioned
elements in before_children_paint and after_children_paint is removed
because after changing clip rectangle to be computed from not parent
but containing block it is not needed anymore (absolutely positioned
item is clipped if it's containing block has hidden overflow)
The container appears to be null for certain elements such as the
"update your browser" box when clicking on the document during certain
parts of loading. Skipping it works fine, but should obviously be
fixed, so it prints a debug output when this happens.
This makes the center position the center of the pixel rather than
the top left corner (which fixes some small artifacts on a few
gradients).
This also now floors the angle used to sample from the gradient line,
this avoids the colors diverging the further away from the center you
get (which is noticeable on hard-edge gradients).
This commit tweaks gradients so resolve_color_stop_positions() no
longer cares about the actual length of the gradient. All stops
are resolved to relative positions along the gradient line
(between 0 and 1), and are only scaled back to pixels (if required)
during the actual painting.
This has no immediate benefit right now, but it might make using
CSS pixels for gradients easier :^)
This also includes some mild refactoring.
We were doing a forward traversal in hit testing which led to sometimes
incorrect results when multiple boxes were occupying the same X and Y
coordinate.
Positioned descendants are now handled entirely by paint_internal()
so we can just skip over positioned children in paint_descendants().
This avoids drawing the same boxes multiple times.
This "worked" before because all positioned elements would create their
own stacking context. When we stopped doing this, there was nobody to
actually paint positioned descendants with `z-index: auto`.
This patch splits up steps 8 and 9 of the paint order algorithm and
implements step 8 as a paint tree traversal. There's more to step 8 than
I've implemented here, so I've left a FIXME for our future selves.
Since positioned elements no longer automatically create stacking
contexts, we can't rely on this assumption when painting descendants of
a stacking context.
In this commit, we fix an issue that manifested as a failure to
Gfx::Painter::restore() in the "Overlay" paint phase. What happened was
that a CSS clip was being applied in the "Background" paint phase, and
then unapplied in the "Overlay" phase. Due to bogus checks in
paint_descendants(), the "Background" phase never ran for positioned
elements, but the "Overlay" phase did.
The check for positioned elements was bogus in the first place and had
never actually worked before, since we would always skip over positioned
descendants due to them having stacking contexts.
This removes a set of complex reference cycles between DOM, layout tree
and browsing context.
It also makes lifetimes much easier to reason about, as the DOM and
layout trees are now free to keep each other alive.
(And BrowsingContextGroup had to come along for the ride as well.)
This solves a number of nasty reference cycles between browsing
contexts, history items, and their documents.
This fixes the Serenity logo vanishing after scrolling on the 4th
birthday post.
The previous check did not account for any translation in the painter.
This now uses the painter's clip rect and translation to work out
if a rect is visible. It also makes use of `absolute_paint_rect()`
rather than `absolute_rect()` which can account for things like
box-shadows.
This fixes some off-by-one wrapping issues that became visible when
running on x86_64. The problem still existed on i686, but by chance
did not show up due to a -/+ 0.000001 difference between the two.
We're supposed to hit test positive z-index stacking contexts first,
and negative z-index stacking contexts later. Instead, we were hit
testing all stacking contexts both times.
This made hit testing unbearably slow on some websites.
While we're here, also add an extra comment about why stacking contexts
are traversed in reverse order. It tripped me up while looking at this,
so I'm sure it could trip someone else up too.
Regressed in 44057c9482.
If the 2D transform in effect is just a simple translation, we don't
need to draw into a temporary bitmap and then transform it. We can
just translate the painter. :^)
This fixes an edge case, where the destination rect falls partly
outside the painter, so is clipped to a smaller size in
`get_region_bitmap()` (which needs to be accounted for with an extra
offset).
This now copies the area under the destination to a new bitmap, that
is then scaled to the size of the source. The element is then painted
into that bitmap, which is then scaled and painted back to
the destination. This is done as many effects such as shadows, border
radii, filters, etc require being able to read pixels from the painter.
This does work (and is not that noticeable in many cases), but it does
mean there may be a few scaling artifacts in the background
around transformed elements. Though that was already the case before
anyway for the elements (since it is just a bitmap scale).
What we really want is to (where possible) just scale the paintable
and its descendants, then paint things normally, which would give
much nicer results (but is much more tricky to achieve).
This also now makes it so only a bitmap of the size of the paintable is
copied/created, rather than the whole page.
This method returns the total area this element will paint to.
Currently, this just means accounting for box-shadows, though
there are likely more effects that need to be accounted for here.
When mousing over twitter, 17% of time was spent computing stacking
context transform origins. Since this never changes after the stacking
context is created, we can cache it and avoid all that work.
63c727a was meant to stop clipping absolutely positioned descendants,
but used `is_positioned()` rather than `is_absolutely_positioned()`,
which meant it disabled clipping in many more cases that it should
have.
Instead of asking Gfx::FontDatabase for the "default font" and the
"default fixed-width font", we now proxy those requests out via
the Platform::FontPlugin. This will allow Ladybird to use other default
fonts as fallback.
This implements all the filters other than `saturate()`,
`hue-rotate()`, and `drop-shadow()`.
There are still a lot of FIXMEs to handle in the actual implementation
though, particularly around supporting transforms, but this handles
the most common use cases :^)
The only accepted syntax for these seems to be
<color> <length percentage> <length percentage>, no other order.
But that's just gathered from looking at other browsers as though
these are supported by all major browsers, they don't appear in
the W3C spec.
