LibWeb: Take borders and padding into account when doing Flex layout

Before this the flex layout didn't take into account the applied
borders or padding while laying out the items.

The child's top and left borders would get painted over the
parent's borders, also due to it not taking borders into account,
children with borders would overlap each other.

Due to it not taking padding into account, the children would get
drawn outside the parent element.

Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp

@@ -129,11 +129,31 @@ void FlexFormattingContext::populate_specified_margins(FlexItem& item, CSS::Flex
     auto width_of_containing_block_as_length = CSS::Length::make_px(width_of_containing_block);
     // FIXME: This should also take reverse-ness into account
     if (flex_direction == CSS::FlexDirection::Row || flex_direction == CSS::FlexDirection::RowReverse) {
+        item.borders.main_before = item.box.computed_values().border_left().width;
+        item.borders.main_after = item.box.computed_values().border_right().width;
+        item.borders.cross_before = item.box.computed_values().border_top().width;
+        item.borders.cross_after = item.box.computed_values().border_bottom().width;
+
+        item.padding.main_before = item.box.computed_values().padding().left.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
+        item.padding.main_after = item.box.computed_values().padding().right.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
+        item.padding.cross_before = item.box.computed_values().padding().top.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
+        item.padding.cross_after = item.box.computed_values().padding().bottom.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
+
         item.margins.main_before = item.box.computed_values().margin().left.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
         item.margins.main_after = item.box.computed_values().margin().right.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
         item.margins.cross_before = item.box.computed_values().margin().top.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
         item.margins.cross_after = item.box.computed_values().margin().bottom.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
     } else {
+        item.borders.main_before = item.box.computed_values().border_top().width;
+        item.borders.main_after = item.box.computed_values().border_bottom().width;
+        item.borders.cross_before = item.box.computed_values().border_left().width;
+        item.borders.cross_after = item.box.computed_values().border_right().width;
+
+        item.padding.main_before = item.box.computed_values().padding().top.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
+        item.padding.main_after = item.box.computed_values().padding().bottom.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
+        item.padding.cross_before = item.box.computed_values().padding().left.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
+        item.padding.cross_after = item.box.computed_values().padding().right.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
+
         item.margins.main_before = item.box.computed_values().margin().top.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
         item.margins.main_after = item.box.computed_values().margin().bottom.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
         item.margins.cross_before = item.box.computed_values().margin().left.resolved(item.box, width_of_containing_block_as_length).to_px(item.box);
@@ -561,7 +581,7 @@ void FlexFormattingContext::determine_main_size_of_flex_container(bool const mai
         for (auto& flex_item : m_flex_items) {
             // FIXME: This needs some serious work.
             float max_content_contribution = calculated_main_size(flex_item.box);
-            float max_content_flex_fraction = max_content_contribution - (flex_item.flex_base_size + flex_item.margins.main_before + flex_item.margins.main_after);
+            float max_content_flex_fraction = max_content_contribution - (flex_item.flex_base_size + flex_item.margins.main_before + flex_item.margins.main_after + flex_item.borders.main_before + flex_item.borders.main_after + flex_item.padding.main_before + flex_item.padding.main_after);
             if (max_content_flex_fraction > 0) {
                 max_content_flex_fraction /= max(flex_item.box.computed_values().flex_grow(), 1.0f);
             } else {
@@ -583,7 +603,7 @@ void FlexFormattingContext::determine_main_size_of_flex_container(bool const mai
             } else {
                 product = largest_max_content_flex_fraction * max(flex_item.box.computed_values().flex_shrink(), 1.0f) * flex_item.flex_base_size;
             }
-            result += flex_item.flex_base_size + flex_item.margins.main_before + flex_item.margins.main_after + product;
+            result += flex_item.flex_base_size + flex_item.margins.main_before + flex_item.margins.main_after + flex_item.borders.main_before + flex_item.borders.main_after + flex_item.padding.main_before + flex_item.padding.main_after + product;
         }
         m_available_space->main = clamp(result, main_min_size, main_max_size);
     }
@@ -617,7 +637,7 @@ void FlexFormattingContext::collect_flex_items_into_flex_lines()
     FlexLine line;
     float line_main_size = 0;
     for (auto& flex_item : m_flex_items) {
-        auto outer_hypothetical_main_size = flex_item.hypothetical_main_size + flex_item.margins.main_before + flex_item.margins.main_after;
+        auto outer_hypothetical_main_size = flex_item.hypothetical_main_size + flex_item.margins.main_before + flex_item.margins.main_after + flex_item.borders.main_before + flex_item.borders.main_after + flex_item.padding.main_before + flex_item.padding.main_after;
         if ((line_main_size + outer_hypothetical_main_size) > m_available_space->main.value_or(NumericLimits<float>::max())) {
             m_flex_lines.append(move(line));
             line = {};
@@ -644,7 +664,7 @@ void FlexFormattingContext::resolve_flexible_lengths()
 
         float sum_of_hypothetical_main_sizes = 0;
         for (auto& flex_item : flex_line.items) {
-            sum_of_hypothetical_main_sizes += (flex_item->hypothetical_main_size + flex_item->margins.main_before + flex_item->margins.main_after);
+            sum_of_hypothetical_main_sizes += (flex_item->hypothetical_main_size + flex_item->margins.main_before + flex_item->margins.main_after + flex_item->borders.main_before + flex_item->borders.main_after + flex_item->padding.main_before + flex_item->padding.main_after);
         }
         if (sum_of_hypothetical_main_sizes < m_available_space->main.value_or(NumericLimits<float>::max()))
             used_flex_factor = FlexFactor::FlexGrowFactor;
@@ -684,9 +704,9 @@ void FlexFormattingContext::resolve_flexible_lengths()
             float sum_of_items_on_line = 0;
             for (auto& flex_item : flex_line.items) {
                 if (flex_item->frozen)
-                    sum_of_items_on_line += flex_item->target_main_size + flex_item->margins.main_before + flex_item->margins.main_after;
+                    sum_of_items_on_line += flex_item->target_main_size + flex_item->margins.main_before + flex_item->margins.main_after + flex_item->borders.main_before + flex_item->borders.main_after + flex_item->padding.main_before + flex_item->padding.main_after;
                 else
-                    sum_of_items_on_line += flex_item->flex_base_size + flex_item->margins.main_before + flex_item->margins.main_after;
+                    sum_of_items_on_line += flex_item->flex_base_size + flex_item->margins.main_before + flex_item->margins.main_after + flex_item->borders.main_before + flex_item->borders.main_after + flex_item->padding.main_before + flex_item->padding.main_after;
             }
             return specified_main_size(flex_container()) - sum_of_items_on_line;
         };
@@ -927,12 +947,12 @@ void FlexFormattingContext::distribute_any_remaining_free_space()
             if (is_main_axis_margin_first_auto(flex_item->box))
                 ++auto_margins;
             else
-                used_main_space += flex_item->margins.main_before;
+                used_main_space += flex_item->margins.main_before + flex_item->borders.main_before + flex_item->padding.main_before;
 
             if (is_main_axis_margin_second_auto(flex_item->box))
                 ++auto_margins;
             else
-                used_main_space += flex_item->margins.main_after;
+                used_main_space += flex_item->margins.main_after + flex_item->borders.main_after + flex_item->padding.main_after;
         }
         float remaining_free_space = m_available_space->main.value_or(NumericLimits<float>::max()) - used_main_space;
         if (remaining_free_space > 0) {
@@ -978,8 +998,8 @@ void FlexFormattingContext::distribute_any_remaining_free_space()
         // FIXME: Support reverse
         float main_offset = space_before_first_item;
         for (auto& flex_item : flex_line.items) {
-            flex_item->main_offset = main_offset + flex_item->margins.main_before;
-            main_offset += flex_item->margins.main_before + flex_item->main_size + flex_item->margins.main_after + space_between_items;
+            flex_item->main_offset = main_offset + flex_item->margins.main_before + flex_item->borders.main_before + flex_item->padding.main_before;
+            main_offset += flex_item->margins.main_before + flex_item->borders.main_before + flex_item->padding.main_before + flex_item->main_size + flex_item->margins.main_after + flex_item->borders.main_after + flex_item->padding.main_after + space_between_items;
         }
     }
 }
@@ -1009,7 +1029,7 @@ void FlexFormattingContext::align_all_flex_items_along_the_cross_axis()
                 //  Fallthrough
             case CSS::AlignItems::FlexStart:
             case CSS::AlignItems::Stretch:
-                flex_item->cross_offset = line_cross_offset + flex_item->margins.cross_before;
+                flex_item->cross_offset = line_cross_offset + flex_item->margins.cross_before + flex_item->borders.cross_before + flex_item->padding.cross_before;
                 break;
             case CSS::AlignItems::FlexEnd:
                 flex_item->cross_offset = line_cross_offset + flex_line.cross_size - flex_item->cross_size;

Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h

@@ -37,7 +37,7 @@ private:
         float flex_base_size { 0 };
         float hypothetical_main_size { 0 };
         float hypothetical_cross_size { 0 };
-        float hypothetical_cross_size_with_margins() { return hypothetical_cross_size + margins.cross_before + margins.cross_after; }
+        float hypothetical_cross_size_with_margins() { return hypothetical_cross_size + margins.cross_before + margins.cross_after + borders.cross_after + borders.cross_before + padding.cross_after + padding.cross_before; }
         float target_main_size { 0 };
         bool frozen { false };
         Optional<float> flex_factor {};
@@ -48,6 +48,8 @@ private:
         float main_offset { 0 };
         float cross_offset { 0 };
         DirectionAgnosticMargins margins {};
+        DirectionAgnosticMargins borders {};
+        DirectionAgnosticMargins padding {};
         bool is_min_violation { false };
         bool is_max_violation { false };
     };