Support simple background fallback in the background mixin.

frameworks/compass/stylesheets/compass/css3/_images.scss

@@ -15,12 +15,14 @@
 ) {
   $backgrounds: compact($background-1, $background-2, $background-3, $background-4, $background-5,
                         $background-6, $background-7, $background-8, $background-9, $background-10);
-
+  $mult-bgs: -compass-list-size($backgrounds) > 1;
-  @if $experimental-support-for-svg     and prefixed(-svg,    $backgrounds) {       background:    -svg($backgrounds); }
+  $simple-background: if($mult-bgs or prefixed(-css2, $backgrounds), -css2(-compass-nth($backgrounds, last)), false);
-  @if $experimental-support-for-webkit  and prefixed(-webkit, $backgrounds) {       background: -webkit($backgrounds); }
+  @if not blank($simple-background)                                                       {       background:    $simple-background; }
-  @if $experimental-support-for-mozilla and prefixed(-moz,    $backgrounds) {       background:    -moz($backgrounds); }
+  @if $experimental-support-for-svg     and prefixed(-svg,    $backgrounds)               {       background:    -svg($backgrounds); }
-  @if $experimental-support-for-pie     and (prefixed(-pie,   $backgrounds) or -compass-list-size($backgrounds) > 1) {  -pie-background:    -pie($backgrounds); }
+  @if $experimental-support-for-webkit  and prefixed(-webkit, $backgrounds)               {       background: -webkit($backgrounds); }
-                                                                                    background:         $backgrounds;
+  @if $experimental-support-for-mozilla and prefixed(-moz,    $backgrounds)               {       background:    -moz($backgrounds); }
+  @if $experimental-support-for-pie     and (prefixed(-pie,   $backgrounds) or $mult-bgs) {  -pie-background:    -pie($backgrounds); }
+                                                                                                  background:         $backgrounds;
 }
 
 // Background image property support for vendor prefixing within values.

lib/compass/sass_extensions/functions/gradient_support.rb

@@ -138,10 +138,10 @@ module Compass::SassExtensions::Functions::GradientSupport
       Sass::Script::Bool.new(args.any?{|a| a.respond_to?(method)})
     end
 
-    %w(webkit moz o ms svg pie).each do |prefix|
+    %w(webkit moz o ms svg pie css2).each do |prefix|
       class_eval <<-RUBY, __FILE__, __LINE__ + 1
         def _#{prefix}(*args)
-          List.new(*args.map! {|a| add_prefix(:to_#{prefix}, a)}, :comma)
+          List.new(*args.map! {|a| add_prefix(:to_#{prefix}, a)})
         end
       RUBY
     end
@@ -278,7 +278,7 @@ module Compass::SassExtensions::Functions::GradientSupport
       Sass::Script::Bool.new(args.any?{|a| a.respond_to?(method)})
     end
 
-    %w(webkit moz o ms svg pie).each do |prefix|
+    %w(webkit moz o ms svg pie css2).each do |prefix|
       class_eval <<-RUBY, __FILE__, __LINE__ + 1
         def _#{prefix}(*args)
           Sass::Script::List.new(args.map! {|a| add_prefix(:to_#{prefix}, a)}, :comma)
@@ -395,6 +395,9 @@ module Compass::SassExtensions::Functions::GradientSupport
       Compass::Logger.new.record(:warning, "PIE does not support radial-gradient.")
       Sass::Script::String.new("-pie-radial-gradient(unsupported)")
     end
+    def to_css2(options = self.options)
+      Sass::Script::String.new("")
+    end
   end
 
   class LinearGradient < Sass::Script::Literal
@@ -437,6 +440,9 @@ module Compass::SassExtensions::Functions::GradientSupport
       # the presence of this attribute helps flag when to render a special rule.
       Sass::Script::String.new to_s(options)
     end
+    def to_css2(options = self.options)
+      Sass::Script::String.new("")
+    end
   end
 
   module Functions
@@ -582,6 +588,19 @@ module Compass::SassExtensions::Functions::GradientSupport
       end
     end
 
+    def blank(obj)
+      case obj
+      when Sass::Script::Bool
+        Sass::Script::Bool.new !obj.to_bool
+      when Sass::Script::String
+        Sass::Script::Bool.new obj.value.strip.size == 0
+      when Sass::Script::List
+        Sass::Script::Bool.new obj.value.size == 0 || obj.value.all?{|el| blank(el).to_bool}
+      else
+        Sass::Script::Bool.new false
+      end
+    end
+
     private
 
     # After using the sass script parser to parse a string, this reconstructs

test/fixtures/stylesheets/compass/css/gradients.css

@@ -2,12 +2,14 @@
   background: white url("foo.png"); }
 
 .bg-shortcut-linear-gradient {
+  background: white ;
   background: white url('data:image/svg+xml;base64,PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0idXRmLTgiPz4gPHN2ZyB2ZXJzaW9uPSIxLjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyI+PGRlZnM+PGxpbmVhckdyYWRpZW50IGlkPSJncmFkIiB4MT0iMCUiIHkxPSIwJSIgeDI9IjEwMCUiIHkyPSIxMDAlIj48c3RvcCBvZmZzZXQ9IjAlIiBzdG9wLWNvbG9yPSIjZGRkZGRkIi8+PHN0b3Agb2Zmc2V0PSIxMDAlIiBzdG9wLWNvbG9yPSIjYWFhYWFhIi8+PC9saW5lYXJHcmFkaWVudD48L2RlZnM+PHJlY3QgeD0iMCIgeT0iMCIgd2lkdGg9IjEwMCUiIGhlaWdodD0iMTAwJSIgZmlsbD0idXJsKCNncmFkKSIgLz48L3N2Zz4g');
   background: white -webkit-gradient(linear, 0% 0%, 100% 100%, color-stop(0%, #dddddd), color-stop(100%, #aaaaaa));
   background: white -moz-linear-gradient(top left, #dddddd, #aaaaaa);
   background: white linear-gradient(top left, #dddddd, #aaaaaa); }
 
 .bg-shortcut-radial-gradient {
+  background: white ;
   background: white url('data:image/svg+xml;base64,PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0idXRmLTgiPz4gPHN2ZyB2ZXJzaW9uPSIxLjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyI+PGRlZnM+PHJhZGlhbEdyYWRpZW50IGlkPSJncmFkIiBncmFkaWVudFVuaXRzPSJ1c2VyU3BhY2VPblVzZSIgY3g9IjUwJSIgY3k9IjUwJSIgcj0iMTAwIj48c3RvcCBvZmZzZXQ9IjAlIiBzdG9wLWNvbG9yPSIjZGRkZGRkIi8+PHN0b3Agb2Zmc2V0PSIxMDAlIiBzdG9wLWNvbG9yPSIjYWFhYWFhIi8+PC9yYWRpYWxHcmFkaWVudD48L2RlZnM+PHJlY3QgeD0iMCIgeT0iMCIgd2lkdGg9IjEwMCUiIGhlaWdodD0iMTAwJSIgZmlsbD0idXJsKCNncmFkKSIgLz48L3N2Zz4g');
   background: white -webkit-gradient(radial, 50% 50%, 0, 50% 50%, 100, color-stop(0%, #dddddd), color-stop(100%, #aaaaaa));
   background: white -moz-radial-gradient(center center, #dddddd, #aaaaaa 100px);

test/sass_extensions_test.rb

@@ -81,6 +81,14 @@ class SassExtensionsTest < Test::Unit::TestCase
     assert evaluate("tan(pi()/2 + 0.0001)").to_f < -1000, evaluate("tan(pi()/2 - 0.0001)")
   end
 
+  def test_blank
+    assert_equal "false", evaluate("blank(true)")
+    assert_equal "true", evaluate("blank(false)")
+    assert_equal "true", evaluate("blank('')")
+    assert_equal "true", evaluate("blank(' ')")
+    assert_equal "true", evaluate("blank(-compass-space-list(' '))")
+  end
+
 protected
   def evaluate(value)
     Sass::Script::Parser.parse(value, 0, 0).perform(Sass::Environment.new).to_s