Make the Gantt zoom images more accessible

* Correct the alt text
* Add text links next to the images
* Size the images in em to support browser scaling

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@3757 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/helpers/issues_helper.rb

@@ -235,23 +235,27 @@ module IssuesHelper
   end
 
   def gantt_zoom_link(gantt, in_or_out)
+    img_attributes = {:style => 'height:1.4em; width:1.4em; margin-left: 3px;'} # em for accessibility
+
     case in_or_out
     when :in
       if gantt.zoom < 4
-        link_to_remote(image_tag('zoom_in.png'),
+        link_to_remote(l(:text_zoom_in) + image_tag('zoom_in.png', img_attributes.merge(:alt => l(:text_zoom_in))),
                        {:url => gantt.params.merge(:zoom => (gantt.zoom+1)), :update => 'content'},
                        {:href => url_for(gantt.params.merge(:zoom => (gantt.zoom+1)))})
       else
-        image_tag('zoom_in_g.png')
+        l(:text_zoom_in) +
+          image_tag('zoom_in_g.png', img_attributes.merge(:alt => l(:text_zoom_in)))
       end
       
     when :out
       if gantt.zoom > 1
-        link_to_remote(image_tag('zoom_out.png'),
+        link_to_remote(l(:text_zoom_out) + image_tag('zoom_out.png', img_attributes.merge(:alt => l(:text_zoom_out))),
                        {:url => gantt.params.merge(:zoom => (gantt.zoom-1)), :update => 'content'},
                        {:href => url_for(gantt.params.merge(:zoom => (gantt.zoom-1)))})
       else
-        image_tag('zoom_out_g.png')
+        l(:text_zoom_out) +
+          image_tag('zoom_out_g.png', img_attributes.merge(:alt => l(:text_zoom_out)))
       end
     end
   end

config/locales/en.yml

@@ -871,6 +871,8 @@ en:
   text_wiki_page_destroy_children: "Delete child pages and all their descendants"
   text_wiki_page_reassign_children: "Reassign child pages to this parent page"
   text_own_membership_delete_confirmation: "You are about to remove some or all of your permissions and may no longer be able to edit this project after that.\nAre you sure you want to continue?"
+  text_zoom_in: Zoom in
+  text_zoom_out: Zoom out
   
   default_role_manager: Manager
   default_role_developper: Developer