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LibWeb: Improve inline flow around floating boxes

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This patch combines a number of techniques to make inline content flow
more correctly around floats:

- During inline layout, BFC now lets LineBuilder decide the Y coordinate
  when inserting a new float. LineBuilder has more information about the
  currently accumulated line, and can make better breaking decisions.

- When inserting a float on one side, and the top of the newly inserted
  float is below the bottommost float on the opposite side, we now reset
  the opposite side back to the start of that edge. This improves
  breaking behavior between opposite-side floats.

- After inserting a float during inline layout, we now recalculate the
  available space on the line, but don't adjust X offsets of already
  existing fragments. This is handled by update_last_line() anyway,
  so it was pointless busywork.

- When measuring whether a line can fit at a given Y coordinate, we now
  consider both the top and bottom Y values of the line. This fixes an
  issue where the bottom part of a line would bleed over other content
  (since we had only checked that the top Y coordinate of that line
  would fit.)

There are some pretty brain-dead algorithms in here that we need to make
smarter, but I didn't want to complicate this any further so I've left
FIXMEs about them instead.
This commit is contained in:
Andreas Kling 2022-09-16 14:21:52 +02:00
parent 54e7359243
commit 412b2313f3
6 changed files with 185 additions and 32 deletions
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19
Userland/Libraries/LibWeb/Layout/InlineFormattingContext.cpp
View file

@ -305,4 +305,23 @@ bool InlineFormattingContext::any_floats_intrude_at_y(float y) const
return space.left > 0 || space.right > 0;
}
bool InlineFormattingContext::can_fit_new_line_at_y(float y) const
{
auto box_in_root_rect = content_box_rect_in_ancestor_coordinate_space(containing_block(), parent().root(), m_state);
float y_in_root = box_in_root_rect.y() + y;
auto space_top = parent().space_used_by_floats(y_in_root);
auto space_bottom = parent().space_used_by_floats(y_in_root + containing_block().line_height() - 1);
[[maybe_unused]] auto top_left_edge = space_top.left;
[[maybe_unused]] auto top_right_edge = m_effective_containing_block_width - space_top.right;
[[maybe_unused]] auto bottom_left_edge = space_bottom.left;
[[maybe_unused]] auto bottom_right_edge = m_effective_containing_block_width - space_bottom.right;
if (top_left_edge > bottom_right_edge)
return false;
if (bottom_left_edge > top_right_edge)
return false;
return true;
}
}