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()
This commit is messy due to the Paintable and Layout classes being
tangled together.
The RadioButton, CheckBox and ButtonBox classes are now subclasses of
FormAssociatedLabelableNode. This subclass separates these layout nodes
from LabelableNode, which is also the superclass of non-form associated
labelable nodes (Progress).
ButtonPaintable, CheckBoxPaintable and RadioButtonPaintable no longer
call events on DOM nodes directly from their mouse event handlers;
instead, all the functionality is now directly in EventHandler, which
dispatches the related events. handle_mousedown and related methods
return a bool indicating whether the event handling should proceed.
Paintable classes can now return an alternative DOM::Node which should
be the target of the mouse event. Labels use this to indicate that the
labeled control should be the target of the mouse events.
HTMLInputElement put its activation behavior on run_activation_behavior,
which wasn't actually called anywhere and had to be manually called by
other places. We now use activation_behavior which is used by
EventDispatcher.
This commit also brings HTMLInputElement closer to spec by removing the
did_foo functions that did ad-hoc event dispatching and unifies the
behavior under run_input_activation_behavior.
The absolute rect of a paintable is somewhat expensive to compute. This
is because all coordinates are relative to the nearest containing block,
so we have to traverse the containing block chain and apply each offset
to get the final rect.
Paintables will never move between containing blocks, nor will their
absolute rect change. If anything changes, we'll simpl make a new
paintable and replace the old one.
Take advantage of this by caching the containing block and absolute rect
after first access.
Input events have nothing to do with layout, so let's not send them to
layout nodes.
The job of Paintable starts to become clear. It represents a paintable
item that can be rendered into the viewport, which means it can also
be targeted by the mouse cursor.
This patch adds a bunch of Paintable subclasses, each corresponding to
the Layout::Node subclasses that had a paint() override. All painting
logic is moved from layout nodes into their corresponding paintables.
Paintables are now created by asking a Layout::Box to produce one:
static NonnullOwnPtr<Paintable> Layout::Box::create_paintable()
Note that inline nodes still have their painting logic. Since they
are not boxes, and all paintables have a corresponding box, we'll need
to come up with some other solution for them.
