LibWeb: Make computed opacity always available

No need to store opacity as Optional<float> as there's always a value
(and the default initial value is 1.)

Userland/Libraries/LibWeb/CSS/ComputedValues.h

@@ -36,6 +36,7 @@ public:
     static CSS::PointerEvents pointer_events() { return CSS::PointerEvents::Auto; }
     static float flex_grow() { return 0.0f; }
     static float flex_shrink() { return 1.0f; }
+    static float opacity() { return 1.0f; }
 };
 
 struct BorderData {
@@ -83,7 +84,7 @@ public:
     float flex_grow() const { return m_noninherited.flex_grow; }
     float flex_shrink() const { return m_noninherited.flex_shrink; }
     CSS::AlignItems align_items() const { return m_noninherited.align_items; }
-    Optional<float> const& opacity() const { return m_noninherited.opacity; }
+    float opacity() const { return m_noninherited.opacity; }
     CSS::JustifyContent justify_content() const { return m_noninherited.justify_content; }
     Optional<BoxShadowData> const& box_shadow() const { return m_noninherited.box_shadow; }
     CSS::BoxSizing box_sizing() const { return m_noninherited.box_sizing; }
@@ -183,7 +184,7 @@ protected:
         CSS::JustifyContent justify_content { InitialValues::justify_content() };
         CSS::Overflow overflow_x { InitialValues::overflow() };
         CSS::Overflow overflow_y { InitialValues::overflow() };
-        Optional<float> opacity;
+        float opacity { InitialValues::opacity() };
         Optional<BoxShadowData> box_shadow {};
         Vector<CSS::Transformation> transformations {};
         CSS::BoxSizing box_sizing { InitialValues::box_sizing() };
@@ -236,7 +237,7 @@ public:
     void set_flex_grow(float value) { m_noninherited.flex_grow = value; }
     void set_flex_shrink(float value) { m_noninherited.flex_shrink = value; }
     void set_align_items(CSS::AlignItems value) { m_noninherited.align_items = value; }
-    void set_opacity(Optional<float> value) { m_noninherited.opacity = value; }
+    void set_opacity(float value) { m_noninherited.opacity = value; }
     void set_justify_content(CSS::JustifyContent value) { m_noninherited.justify_content = value; }
     void set_box_shadow(Optional<BoxShadowData> value) { m_noninherited.box_shadow = move(value); }
     void set_transformations(Vector<CSS::Transformation> value) { m_noninherited.transformations = move(value); }

Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp

@@ -501,12 +501,8 @@ RefPtr<StyleValue> ResolvedCSSStyleDeclaration::style_value_for_property(Layout:
         return NumericStyleValue::create_float(layout_node.computed_values().flex_grow());
     case CSS::PropertyID::FlexShrink:
         return NumericStyleValue::create_float(layout_node.computed_values().flex_shrink());
-    case CSS::PropertyID::Opacity: {
-        auto maybe_opacity = layout_node.computed_values().opacity();
-        if (!maybe_opacity.has_value())
-            return {};
-        return NumericStyleValue::create_float(maybe_opacity.release_value());
-    }
+    case CSS::PropertyID::Opacity:
+        return NumericStyleValue::create_float(layout_node.computed_values().opacity());
     case CSS::PropertyID::JustifyContent:
         return IdentifierStyleValue::create(to_css_value_id(layout_node.computed_values().justify_content()));
     case CSS::PropertyID::BoxShadow: {

Userland/Libraries/LibWeb/CSS/StyleProperties.cpp

@@ -121,11 +121,11 @@ Optional<int> StyleProperties::z_index() const
     return {};
 }
 
-Optional<float> StyleProperties::opacity() const
+float StyleProperties::opacity() const
 {
     auto maybe_value = property(CSS::PropertyID::Opacity);
     if (!maybe_value.has_value())
-        return {};
+        return 1.0f;
     auto& value = maybe_value.value();
 
     if (value->has_number())
@@ -137,7 +137,7 @@ Optional<float> StyleProperties::opacity() const
             return clamp(length.raw_value() / 100.0f, 0.0f, 1.0f);
     }
 
-    return {};
+    return 1.0f;
 }
 
 Optional<CSS::FlexDirection> StyleProperties::flex_direction() const

Userland/Libraries/LibWeb/CSS/StyleProperties.h

@@ -59,7 +59,7 @@ public:
     float flex_grow() const;
     float flex_shrink() const;
     Optional<CSS::AlignItems> align_items() const;
-    Optional<float> opacity() const;
+    float opacity() const;
     Optional<CSS::JustifyContent> justify_content() const;
     Optional<CSS::Overflow> overflow_x() const;
     Optional<CSS::Overflow> overflow_y() const;

Userland/Libraries/LibWeb/Layout/Node.cpp

@@ -77,10 +77,7 @@ bool Node::establishes_stacking_context() const
     auto position = computed_values().position();
     if (position == CSS::Position::Absolute || position == CSS::Position::Relative || position == CSS::Position::Fixed || position == CSS::Position::Sticky)
         return true;
-    auto opacity = computed_values().opacity();
-    if (opacity.has_value() && opacity.value() != 1.0f)
-        return true;
-    return false;
+    return computed_values().opacity() < 1.0f;
 }
 
 HitTestResult Node::hit_test(const Gfx::IntPoint& position, HitTestType type) const

Userland/Libraries/LibWeb/Painting/StackingContext.cpp

@@ -113,10 +113,10 @@ void StackingContext::paint(PaintContext& context)
     }
 
     auto opacity = m_box.computed_values().opacity();
-    if (opacity.has_value() && opacity.value() == 0.0f)
+    if (opacity == 0.0f)
         return;
 
-    if (opacity.has_value() && opacity.value() != 1.0f) {
+    if (opacity < 1.0f) {
         auto bitmap = context.painter().target();
         auto new_bitmap = Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, bitmap->size());
         if (!new_bitmap)
@@ -124,7 +124,7 @@ void StackingContext::paint(PaintContext& context)
         Gfx::Painter painter(*new_bitmap);
         PaintContext paint_context(painter, context.palette(), context.scroll_offset());
         paint_internal(paint_context);
-        context.painter().blit(Gfx::IntPoint(m_box.absolute_position()), *new_bitmap, Gfx::IntRect(m_box.absolute_rect()), opacity.value());
+        context.painter().blit(Gfx::IntPoint(m_box.absolute_position()), *new_bitmap, Gfx::IntRect(m_box.absolute_rect()), opacity);
     } else {
         paint_internal(context);
     }