LibWeb: Improve `float: right` behavior

- Use the border box of the floated element when testing if something
  needs to flow around it.
- Take the floated element's containing block size into account (instead
  of the BFC root) when calculating available space on a line where a
  right-side float intrudes.

4 files changed, 35 insertions, 9 deletions

diff --git a/Userland/Libraries/LibWeb/Layout/BlockFormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/BlockFormattingContext.cpp
index da7e9ad96e..0513c42f80 100644
--- a/Userland/Libraries/LibWeb/Layout/BlockFormattingContext.cpp
+++ b/Userland/Libraries/LibWeb/Layout/BlockFormattingContext.cpp
@@ -626,7 +626,7 @@ void BlockFormattingContext::layout_floating_box(Box const& box, BlockContainer
                 offset_from_edge = box_state.content_width() + box_state.margin_box_right();
         };
 
-        auto box_in_root_rect = margin_box_rect_in_ancestor_coordinate_space(box, root(), m_state);
+        auto box_in_root_rect = border_box_rect_in_ancestor_coordinate_space(box, root(), m_state);
         float y_in_root = box_in_root_rect.y();
         float y = box_state.offset.y();
 
@@ -649,7 +649,7 @@ void BlockFormattingContext::layout_floating_box(Box const& box, BlockContainer
             }
 
             if (fits_on_line) {
-                auto const previous_rect = margin_box_rect_in_ancestor_coordinate_space(previous_box.box, root(), m_state);
+                auto const previous_rect = border_box_rect_in_ancestor_coordinate_space(previous_box.box, root(), m_state);
                 if (previous_rect.contains_vertically(y_in_root + side_data.y_offset)) {
                     // This box touches another already floating box. Stack after others.
                     offset_from_edge = wanted_offset_from_edge;
@@ -747,7 +747,7 @@ BlockFormattingContext::SpaceUsedByFloats BlockFormattingContext::space_used_by_
     for (auto const& floating_box : m_left_floats.current_boxes.in_reverse()) {
         auto const& floating_box_state = m_state.get(floating_box.box);
         // NOTE: The floating box is *not* in the final horizontal position yet, but the size and vertical position is valid.
-        auto rect = margin_box_rect_in_ancestor_coordinate_space(floating_box.box, root(), m_state);
+        auto rect = border_box_rect_in_ancestor_coordinate_space(floating_box.box, root(), m_state);
         if (rect.contains_vertically(y)) {
             space_used_by_floats.left = floating_box.offset_from_edge
                 + floating_box_state.content_width()
@@ -759,7 +759,7 @@ BlockFormattingContext::SpaceUsedByFloats BlockFormattingContext::space_used_by_
     for (auto const& floating_box : m_right_floats.current_boxes.in_reverse()) {
         auto const& floating_box_state = m_state.get(floating_box.box);
         // NOTE: The floating box is *not* in the final horizontal position yet, but the size and vertical position is valid.
-        auto rect = margin_box_rect_in_ancestor_coordinate_space(floating_box.box, root(), m_state);
+        auto rect = border_box_rect_in_ancestor_coordinate_space(floating_box.box, root(), m_state);
         if (rect.contains_vertically(y)) {
             space_used_by_floats.right = floating_box.offset_from_edge
                 + floating_box_state.margin_box_left();
diff --git a/Userland/Libraries/LibWeb/Layout/InlineFormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/InlineFormattingContext.cpp
index bb4c67e4a9..379425c3e9 100644
--- a/Userland/Libraries/LibWeb/Layout/InlineFormattingContext.cpp
+++ b/Userland/Libraries/LibWeb/Layout/InlineFormattingContext.cpp
@@ -52,7 +52,7 @@ BlockFormattingContext const& InlineFormattingContext::parent() const
 float InlineFormattingContext::leftmost_x_offset_at(float y) const
 {
     // NOTE: Floats are relative to the BFC root box, not necessarily the containing block of this IFC.
-    auto box_in_root_rect = margin_box_rect_in_ancestor_coordinate_space(containing_block(), parent().root(), m_state);
+    auto box_in_root_rect = border_box_rect_in_ancestor_coordinate_space(containing_block(), parent().root(), m_state);
     float y_in_root = box_in_root_rect.y() + y;
     auto space = parent().space_used_by_floats(y_in_root);
     float containing_block_x = m_containing_block_state.offset.x();
@@ -67,14 +67,13 @@ float InlineFormattingContext::available_space_for_line(float y) const
         return INFINITY;
 
     // NOTE: Floats are relative to the BFC root box, not necessarily the containing block of this IFC.
-    auto box_in_root_rect = margin_box_rect_in_ancestor_coordinate_space(containing_block(), parent().root(), m_state);
+    auto& root_block = parent().root();
+    auto box_in_root_rect = border_box_rect_in_ancestor_coordinate_space(containing_block(), root_block, m_state);
     float y_in_root = box_in_root_rect.y() + y;
     auto space = parent().space_used_by_floats(y_in_root);
 
-    auto const& root_block_state = m_state.get(parent().root());
-
     space.left = max(space.left, m_containing_block_state.offset.x()) - m_containing_block_state.offset.x();
-    space.right = min(root_block_state.content_width() - space.right, m_containing_block_state.offset.x() + m_effective_containing_block_width);
+    space.right = min(m_containing_block_state.content_width() - space.right, m_containing_block_state.offset.x() + m_effective_containing_block_width);
 
     return space.right - space.left;
 }
diff --git a/Userland/Libraries/LibWeb/Layout/LayoutState.cpp b/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
index 5535070023..9d8aeae629 100644
--- a/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
+++ b/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
@@ -107,6 +107,31 @@ Gfx::FloatRect margin_box_rect(Box const& box, LayoutState const& state)
     return rect;
 }
 
+Gfx::FloatRect border_box_rect(Box const& box, LayoutState const& state)
+{
+    auto const& box_state = state.get(box);
+    auto rect = Gfx::FloatRect { box_state.offset, { box_state.content_width(), box_state.content_height() } };
+    rect.set_x(rect.x() - box_state.border_box_left());
+    rect.set_width(rect.width() + box_state.border_box_left() + box_state.border_box_right());
+    rect.set_y(rect.y() - box_state.border_box_top());
+    rect.set_height(rect.height() + box_state.border_box_top() + box_state.border_box_bottom());
+    return rect;
+}
+
+Gfx::FloatRect border_box_rect_in_ancestor_coordinate_space(Box const& box, Box const& ancestor_box, LayoutState const& state)
+{
+    auto rect = border_box_rect(box, state);
+    for (auto const* current = box.parent(); current; current = current->parent()) {
+        if (current == &ancestor_box)
+            break;
+        if (is<Box>(*current)) {
+            auto const& current_state = state.get(static_cast<Box const&>(*current));
+            rect.translate_by(current_state.offset);
+        }
+    }
+    return rect;
+}
+
 Gfx::FloatRect margin_box_rect_in_ancestor_coordinate_space(Box const& box, Box const& ancestor_box, LayoutState const& state)
 {
     auto rect = margin_box_rect(box, state);
diff --git a/Userland/Libraries/LibWeb/Layout/LayoutState.h b/Userland/Libraries/LibWeb/Layout/LayoutState.h
index b315068348..ddb4238499 100644
--- a/Userland/Libraries/LibWeb/Layout/LayoutState.h
+++ b/Userland/Libraries/LibWeb/Layout/LayoutState.h
@@ -149,5 +149,7 @@ struct LayoutState {
 Gfx::FloatRect absolute_content_rect(Box const&, LayoutState const&);
 Gfx::FloatRect margin_box_rect(Box const&, LayoutState const&);
 Gfx::FloatRect margin_box_rect_in_ancestor_coordinate_space(Box const& box, Box const& ancestor_box, LayoutState const&);
+Gfx::FloatRect border_box_rect(Box const&, LayoutState const&);
+Gfx::FloatRect border_box_rect_in_ancestor_coordinate_space(Box const& box, Box const& ancestor_box, LayoutState const&);
 
 }