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LibWeb: Improve computation of a layout node's containing block

In particular, we now compute the containing block of boxes with
position:absolute and position:fixed (more) correctly.
This commit is contained in:
Andreas Kling 2020-06-05 16:54:28 +02:00
parent 762617a028
commit 7fcf61be35
3 changed files with 43 additions and 5 deletions

View file

@ -29,7 +29,9 @@
#include <LibWeb/DOM/Element.h>
#include <LibWeb/Frame.h>
#include <LibWeb/Layout/LayoutBlock.h>
#include <LibWeb/Layout/LayoutDocument.h>
#include <LibWeb/Layout/LayoutNode.h>
#include <LibWeb/Layout/LayoutReplaced.h>
namespace Web {
@ -53,13 +55,36 @@ void LayoutNode::layout(LayoutMode layout_mode)
});
}
bool LayoutNode::can_contain_boxes_with_position_absolute() const
{
return style().position() != CSS::Position::Static || is_root();
}
const LayoutBlock* LayoutNode::containing_block() const
{
for (auto* ancestor = parent(); ancestor; ancestor = ancestor->parent()) {
if (is<LayoutBlock>(*ancestor))
return to<LayoutBlock>(ancestor);
if (is_text()) {
auto* ancestor = parent();
while (ancestor && ((ancestor->is_inline() && !is<LayoutReplaced>(*ancestor)) || !is<LayoutBlock>(*ancestor)))
ancestor = ancestor->parent();
return to<LayoutBlock>(ancestor);
}
return nullptr;
if (is_absolutely_positioned()) {
auto* ancestor = parent();
while (ancestor && !ancestor->can_contain_boxes_with_position_absolute())
ancestor = ancestor->parent();
while (ancestor && (!is<LayoutBlock>(ancestor) || ancestor->is_anonymous()))
ancestor = ancestor->containing_block();
return to<LayoutBlock>(ancestor);
}
if (style().position() == CSS::Position::Fixed)
return &root();
auto* ancestor = parent();
while (ancestor && ((ancestor->is_inline() && !is<LayoutReplaced>(*ancestor)) || !is<LayoutBlock>(*ancestor)))
ancestor = ancestor->parent();
return to<LayoutBlock>(ancestor);
}
void LayoutNode::render(RenderingContext& context)
@ -155,4 +180,10 @@ Gfx::FloatPoint LayoutNode::box_type_agnostic_position() const
return position;
}
bool LayoutNode::is_absolutely_positioned() const
{
return style().position() == CSS::Position::Absolute;
}
}