Use proxy if it exists

lib/fastimage.rb

@@ -206,8 +206,24 @@ class FastImage
     end
   end
 
+  def proxy_uri
+    begin
+      proxy = ENV['http_proxy'] && ENV['http_proxy'] != "" ? URI.parse(ENV['http_proxy']) : nil
+    rescue URI::InvalidURIError
+      proxy = nil
+    end
+    proxy
+  end
+
   def setup_http
-    @http = Net::HTTP.new(@parsed_uri.host, @parsed_uri.port)
+    proxy = proxy_uri
+
+    if proxy
+      @http = Net::HTTP::Proxy(proxy.host, proxy.port).new(@parsed_uri.host, @parsed_uri.port)
+    else
+      @http = Net::HTTP.new(@parsed_uri.host, @parsed_uri.port)
+    end
+    
     @http.use_ssl = (@parsed_uri.scheme == "https")
     @http.verify_mode = OpenSSL::SSL::VERIFY_NONE
     @http.open_timeout = @timeout

test/test.rb

@@ -191,4 +191,16 @@ class FastImageTest < Test::Unit::TestCase
     assert type_time - time < LargeImageFetchLimit
     assert_equal LargeImageInfo[0], type
   end
+  
+  # This test doesn't actually test the proxy function, but at least
+  # it excercises the code. You could put anything in the http_proxy and it would still pass.
+  # Any ideas on how to actually test this?
+  def test_should_fetch_via_proxy
+    file = "test.gif"
+    actual_size = GoodFixtures[file][1]
+    ENV['http_proxy'] = "http://my.proxy.host:8080"
+    size = FastImage.size(TestUrl + file)
+    ENV['http_proxy'] = nil
+    assert_equal actual_size, size
+  end
 end