* added some tests for ruler

 * fixed ruler to display tick marks correctly on all cases in test_draw


git-svn-id: svn+ssh://rubyforge.org/var/svn/bio-graphics@37 a2f46d20-7dc0-45cf-9d05-bfa4e4ff58eb

trunk/lib/bio/graphics/ruler.rb

@@ -34,37 +34,42 @@ def initialize(panel, colour = [0,0,0])
     # The base height of minor ticks in pixels
     @tick_height = 5
     # The height of the text in pixels
-    @tick_text_height = 10          
+    @tick_text_height = 10
+
+    @minor_tick_distance = @min_pixels_per_tick ** self.scaling_factor
+    @major_tick_distance = @minor_tick_distance * 10       
   end
   attr_accessor(:panel, :name, :colour, :height,
-                :minor_tick_distance, :major_tick_distance, :min_pixels_per_tick,
-                :tick_height, :tick_text_height)
+                :minor_tick_distance, :major_tick_distance,
+                :min_pixels_per_tick, :tick_height, :tick_text_height)
+
+  def scaling_factor(min_pixels_per_tick = @min_pixels_per_tick,
+                          rescale_factor = @panel.rescale_factor)
+    (Math.log(min_pixels_per_tick * rescale_factor) /
+     Math.log(min_pixels_per_tick)).ceil 
+  end
 
+  def first_tick_position(start = @panel.display_start,
+                          minor_tick = @minor_tick_distance)
+    #  * Find position of first tick.
+    #    Most of the time, we don't want the first tick on the very first
+    #    basepair of the view. Suppose that would be position 333 in the
+    #    sequence. Then the numbers under the major tickmarks would be:
+    #    343, 353, 363, 373 and so on. Instead, we want 350, 360, 370, 380.
+    #    So we want to find the position of the first tick.
+    modulo_from_tick = (start % minor_tick)
+    start + (modulo_from_tick > 0 ? (minor_tick - modulo_from_tick + 1) : 0)
+  end
+
   def draw(panel_drawing)
     ruler_drawing = Cairo::Context.new(panel_drawing)
 
-    # calculate tick distance in basepairs
-    tick_scaling_factor = (Math.log(@min_pixels_per_tick * @panel.rescale_factor) /
-                           Math.log(@min_pixels_per_tick)).ceil 
-    @minor_tick_distance = @min_pixels_per_tick**tick_scaling_factor
-    @major_tick_distance = @minor_tick_distance * 10
-
     # Draw line
     ruler_drawing.move_to(0,10)
     ruler_drawing.line_to(panel.width, 10)
     ruler_drawing.stroke
 
     # Draw ticks
-    #  * Find position of first tick.
-    #    Most of the time, we don't want the first tick on the very first
-    #    basepair of the view. Suppose that would be position 333 in the
-    #    sequence. Then the numbers under the major tickmarks would be:
-    #    343, 353, 363, 373 and so on. Instead, we want 350, 360, 370, 380.
-    #    So we want to find the position of the first tick.
-    modulo_from_tick = (panel.display_start % minor_tick_distance)
-    first_tick_position = panel.display_start + 
-      modulo_from_tick > 0 ? (minor_tick_distance - modulo_from_tick + 1) : 0
-
     #  * And start drawing the rest.
     first_tick_position.step(panel.display_stop, minor_tick_distance) do |tick|
       tick_pixel_position = (tick - panel.display_start) / panel.rescale_factor

trunk/test/unit/test_creation.rb

@@ -39,6 +39,33 @@ def test_track_creation
   end
 end
 
+class TestRuler < Test::Unit::TestCase
+  def test_scaling_factor
+    panel = Bio::Graphics::Panel.new(1000, :width => 600, :display_start => 0, :display_stop => 1000)
+    ruler = Bio::Graphics::Ruler.new(panel)
+    assert_equal(1,ruler.scaling_factor(5,1000/600))
+    assert_equal(2,ruler.scaling_factor(5,1000/500))
+    assert_equal(1,ruler.scaling_factor(5,500/500))
+  end
+
+  def test_drawing
+    panel = Bio::Graphics::Panel.new(375, :display_start => 100, :display_stop => 370, :width => 600)
+    ruler = Bio::Graphics::Ruler.new(panel)
+
+    assert_equal(270.0/600.0,panel.rescale_factor)
+    assert_equal(1,ruler.scaling_factor)
+    assert_equal(5,ruler.minor_tick_distance)
+    assert_equal(50,ruler.major_tick_distance)
+    assert_equal(100,ruler.first_tick_position)
+
+    i = 0
+    ruler.first_tick_position.step(panel.display_stop, ruler.minor_tick_distance) do |tick|
+      assert(i*ruler.min_pixels_per_tick,(tick - panel.display_start) / panel.rescale_factor)
+      i += 1
+    end    
+  end
+end
+
 class TestFeature < Test::Unit::TestCase
   def setup
     @panel = Bio::Graphics::Panel.new(1000, :width => 500)