Index: lib/redmine/helpers/gantt.rb
===================================================================
--- lib/redmine/helpers/gantt.rb	(revision 4732)
+++ lib/redmine/helpers/gantt.rb	(working copy)
@@ -98,19 +98,30 @@
         common_params.merge({:year => (date_from >> months).year, :month => (date_from >> months).month, :zoom => zoom, :months => months })
       end
 
-            ### Extracted from the HTML view/helpers
+      # Returns the list of projects to render
+      def project_list
+        if @project
+          projects = [@project]
+        else
+          projects = Project.roots.visible.has_module('issue_tracking')
+
+          if @query && @query.has_filter?('project_id')
+            project_filter = @query.filters['project_id']
+            projects.delete_if { |project| (project_filter[:operator] == '=') ^ !project_filter[:values].index(project.id.to_s).nil? }
+          end
+        end
+        projects
+      end
+
+      ### Extracted from the HTML view/helpers
       # Returns the number of rows that will be rendered on the Gantt chart
       def number_of_rows
         return @number_of_rows if @number_of_rows
-        
-        rows = if @project
-          number_of_rows_on_project(@project)
-        else
-          Project.roots.visible.has_module('issue_tracking').inject(0) do |total, project|
-            total += number_of_rows_on_project(project)
-          end
+
+        rows = project_list().each do |total, project|
+          total += number_of_rows_on_project(project)
         end
-        
+
         rows > @max_rows ? @max_rows : rows
       end
 
@@ -161,14 +172,10 @@
         @subjects = '' unless options[:only] == :lines
         @lines = '' unless options[:only] == :subjects
         @number_of_rows = 0
-        
-        if @project
-          render_project(@project, options)
-        else
-          Project.roots.visible.has_module('issue_tracking').each do |project|
-            render_project(project, options)
-            break if abort?
-          end
+
+        project_list().each do |project|
+          render_project(project, options)
+          break if abort?
         end
         
         @subjects_rendered = true unless options[:only] == :lines