opacity.rb in prawn-svg-0.36.0

- old
+ new
@@ -1,15 +1,30 @@
 module Prawn::SVG::Attributes::Opacity
   def parse_opacity_attributes_and_call
-    # We can't do nested opacities quite like the SVG requires, but this is close enough.
-    opacity = properties.opacity.to_f.clamp(0, 1) if properties.opacity
-    fill_opacity = properties.fill_opacity.to_f.clamp(0, 1) if properties.fill_opacity
-    stroke_opacity = properties.stroke_opacity.to_f.clamp(0, 1) if properties.stroke_opacity
+    # The opacity property is not inherited, but the opacity applies to all children underneath the element.
+    #
+    # Having an opacity property on a parent, and again on a child, multiplies the parent and child's opacities
+    # when drawing the children.
+    #
+    # The fill-opacity and stroke-opacity properties are inherited, but children which have a different value
+    # are displayed at that opacity rather than multiplying the parent's fill/stroke opacity with the child's.
+    #
+    # opacity and fill/stroke opacity can both be applied to the same element, and they multiply together.
 
-    if opacity || fill_opacity || stroke_opacity
-      state.fill_opacity *= [opacity || 1, fill_opacity || 1].min
-      state.stroke_opacity *= [opacity || 1, stroke_opacity || 1].min
+    opacity = computed_properties.opacity&.to_f&.clamp(0, 1)
+    fill_opacity = computed_properties.fill_opacity.to_f.clamp(0, 1)
+    stroke_opacity = computed_properties.stroke_opacity.to_f.clamp(0, 1)
 
-      add_call_and_enter 'transparent', state.fill_opacity, state.stroke_opacity
+    state.opacity *= opacity if opacity
+
+    fill_opacity = (fill_opacity || 1) * state.opacity
+    stroke_opacity = (stroke_opacity || 1) * state.opacity
+
+    fill_opacity = stroke_opacity = 0 if computed_properties.visibility != 'visible'
+
+    if state.last_fill_opacity != fill_opacity || state.last_stroke_opacity != stroke_opacity
+      state.last_fill_opacity = fill_opacity
+      state.last_stroke_opacity = stroke_opacity
+      add_call_and_enter 'transparent', fill_opacity, stroke_opacity
     end
   end
 end