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.
These allow you to specify the point were the gradient transitions
from one color to the next (without a transition hint the transition
occurs at the point 50% of the way between the two colors).
There is a little bit of guesswork in this implementation as the
specification left out how hints work with the color stop fixup,
though it appears that they are treated the same as color stops.
This commit moves both the ImageStyleValue and LinearGradientStyleValue
to a common base class of AbstractImageStyleValue. This abstracts
getting the natural_width/height, loading/resolving, and painting
the image.
Now for 'free' you get:
- Linear gradients working with the various background sizing/repeat
properties.
- Linear gradients working as list-markers :^) -- best feature ever!
P.s. This commit is a little large as it's tricky to make this change
incrementally without breaking things.
