#300: Added infrastructure for drag and drop dependency creation

app/controllers/todos_controller.rb

@@ -140,6 +140,15 @@ class TodosController < ApplicationController
       format.xml { render :xml => @todo.to_xml( :root => 'todo', :except => :user_id ) }
     end
   end
+  
+  def add_predecessor
+    logger.debug "add_predecessor"
+    @predecessor = Todo.find(params['predecessor'])
+    @successor = Todo.find(params['successor'])
+    respond_to do |format|
+      format.js
+    end
+  end
 
   # Toggles the 'done' status of the action
   #

app/helpers/todos_helper.rb

@@ -106,6 +106,14 @@ module TodosHelper
     end
   end
   
+  def grip_span
+    unless @todo.completed?
+      image_tag('grip.png', :width => '7', :height => '16', :border => '0', 
+        :title => 'Drag onto another action to make it depend on this action',
+        :class => 'grip')
+    end
+  end
+  
   def tag_list_text
     @todo.tags.collect{|t| t.name}.join(', ')
   end

app/views/todos/_todo.html.erb

@@ -22,6 +22,7 @@ parameters += "&_tag_name=#{@tag_name}" if @source_view == 'tag'
         <% end %>
     </ul></ul>
     <div class="description<%= staleness_class( todo ) %>">
+      <%= grip_span %>
       <%= date_span -%>
       <span class="todo.descr"><%= h sanitize(todo.description) %></span>
       <%= successors_span %>
@@ -39,3 +40,13 @@ parameters += "&_tag_name=#{@tag_name}" if @source_view == 'tag'
     <% end -%>
   </div>
 </div>
+<%= 
+draggable_element(dom_id(todo), :revert => "'failure'", :handle =>  "'grip'", :onDrop => "''") 
+%>
+<%=
+drop_receiving_element(dom_id(todo), 
+  :url => {:controller => "todos", :action => "add_predecessor"},
+  :with => "'successor=' + encodeURIComponent(element.id.split('_').last()) + '&predecessor=' + encodeURIComponent(#{todo.id})"
+)
+%>
+

public/stylesheets/standard.css

@@ -381,11 +381,7 @@ input.item-checkbox {
 
 .description, .stale_l1, .stale_l2, .stale_l3 {
     margin-left: 60px;
-    position:relative;    
-}
-
-.stale_l1, .stale_l2, .stale_l3 {
-    padding-left: 3px;
+    position:relative;
 }
 
 .stale_l1 {
@@ -939,6 +935,10 @@ div.message {
     color: #666;
 }
 
+.grip {
+    cursor: move;
+}
+
 /* Error message styles */
 .fieldWithErrors {
     padding: 2px;