LibWeb: Store flex item used sizes as Optional<CSSPixels>

This will allow us to tell whether values have been assigned by the flex
layout algorithm yet.

2 files changed, 23 insertions, 18 deletions

diff --git a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
index a21dbb7461..a290c85047 100644
--- a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
+++ b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
@@ -193,7 +193,7 @@ void FlexFormattingContext::run(Box const& run_box, LayoutMode, AvailableSpace c
         auto const& flex_container_computed_cross_size = is_row_layout() ? flex_container().computed_values().height() : flex_container().computed_values().width();
         if (flex_container_computed_cross_size.is_auto()) {
             for (auto& item : m_flex_items) {
-                set_cross_size(item.box, item.cross_size);
+                set_cross_size(item.box, item.cross_size.value());
             }
         }
     }
@@ -1044,7 +1044,7 @@ void FlexFormattingContext::resolve_flexible_lengths()
         // 6.5.
         for (auto& flex_item : flex_line.items) {
             flex_item->main_size = flex_item->target_main_size;
-            set_main_size(flex_item->box, flex_item->main_size);
+            set_main_size(flex_item->box, flex_item->main_size.value());
         }
 
         flex_line.remaining_free_space = calculate_free_space();
@@ -1089,7 +1089,7 @@ void FlexFormattingContext::determine_hypothetical_cross_size_of_item(FlexItem&
 
         CSSPixels fit_content_cross_size = 0;
         if (is_row_layout()) {
-            auto available_width = AvailableSize::make_definite(item.main_size);
+            auto available_width = item.main_size.has_value() ? AvailableSize::make_definite(item.main_size.value()) : AvailableSize::make_indefinite();
             auto available_height = AvailableSize::make_indefinite();
             fit_content_cross_size = calculate_fit_content_height(item.box, AvailableSpace(available_width, available_height));
         } else {
@@ -1105,9 +1105,9 @@ void FlexFormattingContext::determine_hypothetical_cross_size_of_item(FlexItem&
 
     auto& box_state = throwaway_state.get_mutable(item.box);
     if (is_row_layout()) {
-        box_state.set_content_width(item.main_size);
+        box_state.set_content_width(item.main_size.value());
     } else {
-        box_state.set_content_height(item.main_size);
+        box_state.set_content_height(item.main_size.value());
     }
 
     // Item has definite main size, layout with that as the used main size.
@@ -1115,8 +1115,8 @@ void FlexFormattingContext::determine_hypothetical_cross_size_of_item(FlexItem&
     // NOTE: Flex items should always create an independent formatting context!
     VERIFY(independent_formatting_context);
 
-    auto available_width = is_row_layout() ? AvailableSize::make_definite(item.main_size) : AvailableSize::make_indefinite();
-    auto available_height = is_row_layout() ? AvailableSize::make_indefinite() : AvailableSize::make_definite(item.main_size);
+    auto available_width = is_row_layout() ? AvailableSize::make_definite(item.main_size.value()) : AvailableSize::make_indefinite();
+    auto available_height = is_row_layout() ? AvailableSize::make_indefinite() : AvailableSize::make_definite(item.main_size.value());
 
     independent_formatting_context->run(item.box, LayoutMode::Normal, AvailableSpace(available_width, available_height));
 
@@ -1203,7 +1203,7 @@ void FlexFormattingContext::distribute_any_remaining_free_space()
         CSSPixels used_main_space = 0;
         size_t auto_margins = 0;
         for (auto& flex_item : flex_line.items) {
-            used_main_space += flex_item->main_size;
+            used_main_space += flex_item->main_size.value();
             if (flex_item->margins.main_before_is_auto)
                 ++auto_margins;
 
@@ -1296,7 +1296,7 @@ void FlexFormattingContext::distribute_any_remaining_free_space()
                     item_margin_after = 0;
             }
 
-            auto amount_of_main_size_used = item.main_size
+            auto amount_of_main_size_used = item.main_size.value()
                 + item_margin_before
                 + item.borders.main_before
                 + item.padding.main_before
@@ -1306,7 +1306,7 @@ void FlexFormattingContext::distribute_any_remaining_free_space()
                 + space_between_items;
 
             if (is_direction_reverse()) {
-                item.main_offset = cursor_offset - item.main_size - item_margin_after - item.borders.main_after - item.padding.main_after;
+                item.main_offset = cursor_offset - item.main_size.value() - item_margin_after - item.borders.main_after - item.padding.main_after;
                 cursor_offset -= amount_of_main_size_used;
             } else if (flex_region_render_cursor == FlexRegionRenderCursor::Right) {
                 cursor_offset -= amount_of_main_size_used;
@@ -1338,7 +1338,7 @@ void FlexFormattingContext::dump_items() const
         dbgln("{} flex-line #{}:", flex_container().debug_description(), i);
         for (size_t j = 0; j < m_flex_lines[i].items.size(); ++j) {
             auto& item = *m_flex_lines[i].items[j];
-            dbgln("{}   flex-item #{}: {} (main:{}, cross:{})", flex_container().debug_description(), j, item.box.debug_description(), item.main_size, item.cross_size);
+            dbgln("{}   flex-item #{}: {} (main:{}, cross:{})", flex_container().debug_description(), j, item.box.debug_description(), item.main_size.value_or(-1), item.cross_size.value_or(-1));
         }
     }
 }
@@ -1388,10 +1388,10 @@ void FlexFormattingContext::align_all_flex_items_along_the_cross_axis()
                 flex_item->cross_offset = -half_line_size + flex_item->margins.cross_before + flex_item->borders.cross_before + flex_item->padding.cross_before;
                 break;
             case CSS::AlignItems::FlexEnd:
-                flex_item->cross_offset = half_line_size - flex_item->cross_size - flex_item->margins.cross_after - flex_item->borders.cross_after - flex_item->padding.cross_after;
+                flex_item->cross_offset = half_line_size - flex_item->cross_size.value() - flex_item->margins.cross_after - flex_item->borders.cross_after - flex_item->padding.cross_after;
                 break;
             case CSS::AlignItems::Center:
-                flex_item->cross_offset = -(flex_item->cross_size / 2.0f);
+                flex_item->cross_offset = -(flex_item->cross_size.value() / 2.0f);
                 break;
             default:
                 break;
@@ -1528,8 +1528,8 @@ void FlexFormattingContext::copy_dimensions_from_flex_items_to_boxes()
         box_state.border_top = box.computed_values().border_top().width;
         box_state.border_bottom = box.computed_values().border_bottom().width;
 
-        set_main_size(box, flex_item.main_size);
-        set_cross_size(box, flex_item.cross_size);
+        set_main_size(box, flex_item.main_size.value());
+        set_cross_size(box, flex_item.cross_size.value());
         set_offset(box, flex_item.main_offset, flex_item.cross_offset);
     }
 }
@@ -1928,7 +1928,7 @@ void FlexFormattingContext::resolve_cross_axis_auto_margins()
 
             // If its outer cross size (treating those auto margins as zero) is less than the cross size of its flex line,
             // distribute the difference in those sizes equally to the auto margins.
-            auto outer_cross_size = item->cross_size + item->padding.cross_before + item->padding.cross_after + item->borders.cross_before + item->borders.cross_after;
+            auto outer_cross_size = item->cross_size.value() + item->padding.cross_before + item->padding.cross_after + item->borders.cross_before + item->borders.cross_after;
             if (outer_cross_size < line.cross_size) {
                 CSSPixels remainder = line.cross_size - outer_cross_size;
                 if (item->margins.cross_before_is_auto && item->margins.cross_after_is_auto) {
diff --git a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
index d5aef99bf6..8263821e82 100644
--- a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
+++ b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
@@ -60,8 +60,13 @@ private:
         Optional<float> flex_factor {};
         float scaled_flex_shrink_factor { 0 };
         float desired_flex_fraction { 0 };
-        CSSPixels main_size { 0 };
-        CSSPixels cross_size { 0 };
+
+        // The used main size of this flex item. Empty until determined.
+        Optional<CSSPixels> main_size {};
+
+        // The used cross size of this flex item. Empty until determined.
+        Optional<CSSPixels> cross_size {};
+
         CSSPixels main_offset { 0 };
         CSSPixels cross_offset { 0 };
         DirectionAgnosticMargins margins {};