Adding circle and triangle, and example

Closes #7

lib/squib/api/shapes.rb

@@ -53,5 +53,31 @@ module Squib
       end
     end
 
+    # Draw a triangle using the given coordinates
+    # 
+    # @example 
+    #   triangle :x1 => 0, :y1 => 0, :x2 => 50, :y2 => 50, :x3 => 0, :y3 => 50
+    #
+    # @option opts range [Enumerable, :all] (:all) the range of cards over which this will be rendered. See {file:API.md#label-Specifying+Ranges Specifying Ranges}
+    # @option opts x1 [Integer] (0) the x-coordinate to place
+    # @option opts y1 [Integer] (0) the y-coordinate to place
+    # @option opts x2 [Integer] (50) the x-coordinate to place
+    # @option opts y2 [Integer] (50) the y-coordinate to place
+    # @option opts x3 [Integer] (0) the x-coordinate to place
+    # @option opts y3 [Integer] (50) the y-coordinate to place
+    # @option opts fill_color [String] ('#0000') the color with which to fill the rectangle
+    # @option opts stroke_color [String] (:black) the color with which to stroke the outside of the rectangle
+    # @option opts stroke_width [Decimal] (2.0) the width of the outside stroke
+    # @return [nil] intended to be void
+    # @api public
+    def triangle(opts = {})
+      opts = needs(opts, [:range, :x1, :y1, :x2, :y2, :x3, :y3, :layout,
+                          :fill_color, :stroke_color, :stroke_width])
+      opts[:range].each do |i|
+        @cards[i].triangle(opts[:x1], opts[:y1], opts[:x2], opts[:y2],opts[:x3], opts[:y3], 
+          opts[:fill_color], opts[:stroke_color], opts[:stroke_width])
+      end
+    end
+    
   end
 end

lib/squib/constants.rb

@@ -13,6 +13,12 @@ module Squib
    		:sheet => 0,
    		:x => 0,
    		:y => 0,
+      :x1 => 100,
+      :y1 => 100,
+      :x2 => 150,
+      :y2 => 150,
+      :x3 => 100,
+      :y3 => 150,
       :x_radius => 0, 
       :y_radius => 0,
       :align => :left,

lib/squib/graphics/shapes.rb

@@ -28,5 +28,18 @@ module Squib
       cc.fill
     end
 
+    # :nodoc:
+    # @api private 
+    def triangle(x1, y1, x2, y2, x3, y3, fill_color, stroke_color, stroke_width)
+      cc = cairo_context
+      cc.triangle(x1, y1, x2, y2, x3, y3)
+      cc.set_source_color(stroke_color)
+      cc.set_line_width(stroke_width)
+      cc.stroke
+      cc.triangle(x1, y1, x2, y2, x3, y3)
+      cc.set_source_color(fill_color)
+      cc.fill
+    end
+      
   end
 end

samples/draw_shapes.rb

@@ -0,0 +1,15 @@
+require 'squib'
+
+Squib::Deck.new do 
+  rect x: 300, y: 300, width: 400, height: 400, 
+       fill_color: :blue, stroke_color: :red, stroke_width: 50.0
+
+  circle x: 600, y: 600, radius: 75,
+         fill_color: :gray, stroke_color: :green, stroke_width: 8.0  
+
+  triangle x1: 50, y1: 50, 
+           x2: 150, y2: 150, 
+           x3: 75, y3: 250
+
+  save_png prefix: 'shape_'
+end