Sticky positioning is implemented by modifying the algorithm for
assigning and refreshing scroll frames. Now, elements with
"position: sticky" are assigned their own scroll frame, and their
position is refreshed independently from regular scroll boxes.
Refreshing the scroll offsets for sticky boxes does not require display
list invalidation.
A separate hash map is used for the scroll frames of sticky boxes. This
is necessary because a single paintable box can have two scroll frames
if it 1) has "position: sticky" and 2) contains scrollable overflow.
A display list should not contain coordinates shifted by scroll offset.
Instead, "scroll frame id" needs to be used. In the future it's going to
allow us reuse a display list in cases when only scroll offsets need to
be updated.
Moves paint_table_borders() call into PaintableBox::paint() to make
scroll offset and clip rectangle of enclosing scrollable be applied
in ::before_paint().
Having resolution of all properties for all paintable types in a single
function was hard to iterate on, so this change separates it into
smaller functions per paintable type.
Fixes bug when CSS transform is applied twice to clip rect:
- While calculating absolute clip rectangles in `refresh_clip_state()`
- While executing `PushStackingContext` painting command.
Duplicated transform is already removed for PaintableBox and this change
adds this for InlinePaintable.
This removes indirection when asking if a paintable is positioned,
floating, etc.
Removes a bunch of 1-1.5% items in the profile when hovering links
on ziglang.org.
Every single client of this function was immediately calling paintable()
on the result anyway, so there was no need to return a layout node!
This automatically leverages the cached containing block pointer we
already have in Paintable, which melts away a bunch of unnecessary
traversal in hit testing and painting. :^)
This change modifies hit_test() to no longer return the first paintable
encountered at a specified position. Instead, this function accepts a
callback that is invoked for each paintable located at a position, in
hit-testing order.
This modification will allow us to reuse this call for
`Document.elementsFromPoint()` in upcoming changes.
Recently, we moved the resolution of CSS properties that do not affect
layout to occur within LayoutState::commit(). This decision was a
mistake as it breaks invalidation. With this change, we now re-resolve
all properties that do not affect layout before each repaint.
With this change, clip rectangles for boxes with hidden overflow or the
clip property are no longer calculated during the recording of painting
commands. Instead, it has moved to the "pre-paint" phase, along with
the assignment of scrolling offsets, and works in the following way:
1. The paintable tree is traversed to collect all paintable boxes that
have hidden overflow or use the CSS clip property. For each of these
boxes, the "final" clip rectangle is calculated by intersecting clip
rectangles in the containing block chain for a box.
2. The paintable tree is traversed another time, and a clip rectangle
is assigned for each paintable box contained by a node with hidden
overflow or the clip property.
This way, clipping becomes much easier during the painting commands
recording phase, as it only concerns the use of already assigned clip
rectangles. The same approach is applied to handle scrolling offsets.
Also, clip rectangle calculation is now implemented more correctly, as
we no longer stop at the stacking context boundary while intersecting
clip rectangles in the containing block chain.
Fixes:
https://github.com/SerenityOS/serenity/issues/22932https://github.com/SerenityOS/serenity/issues/22883https://github.com/SerenityOS/serenity/issues/22679https://github.com/SerenityOS/serenity/issues/22534
With this change, a stacking context can be established by any
paintable, including inline paintables. The stacking context traversal
is updated to remove the assumption that the stacking context root is
paintable box.
This allows SVG mask elements to have layout computed, but not connected
to the main paint tree. They should only be reachable if (and painted)
if referenced by the "mask" attribute of another element.
This is controlled by the forms_unconnected_subtree() function on the
paintable, which (if it returns true) prevents the paintable from being
added as a child to what would be its parent.
d06d4eb made the `clip` property apply to children of an absolute-
positioned element, but caused it not to be applied to the element the
property was applied to directly.
To fix this, apply the clip in new `before_paint()` and `after_paint()`
functions. Doing so keeps painter state from leaking from `paint()`,
but still allows subclasses of `PaintableBox` clip their contents
correctly without repeating the application of the clip rectangle.
Eventually we should not need the layout tree for anything when painting
and this code will only look at the paint tree. For now, this is just
another step in that direction.
Until now, paint trees have been piggybacking on the layout tree for
traversal, and paintables didn't actually have their own parent/child
pointers.
This patch changes that by making Paintable inherit from TreeNode, and
adding a new pass to LayoutState::commit() where we recursively build
the new paint tree.
Since we deliberately skip positioned elements in paint_descendants(),
we have to make sure we actually paint them in the subsequent
paint_internal() pass.
Before this change, we were only painting positioned elements whose
paintable was a PaintableBox, neglecting inline-level relpos elements.
This simplifies the ownership model between DOM/layout/paint nodes
immensely by deferring to the garbage collector for figuring out what's
live and what's not.
...and also for hit testing, which is involved in most of them.
Much of this is temporary conversions and other awkwardness, which
should resolve itself as the rest of LibWeb is converted to these new
types. Hopefully. :thousandyakstare:
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)
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.
Give the Paintable class some basic helpers for traversing the paint
tree. Note that they actually piggy-back on the layout tree for links
between nodes.
This is a convenience accessor to avoid having to say this everywhere:
result.paintable->layout_node().dom_node()
Instead, you can now do:
result.dom_node()
