Add UnicodePlot.canvas_types

[Fix GH-42]

Author: mrkn

lib/unicode_plot/canvas.rb

@@ -2,18 +2,13 @@ module UnicodePlot
   class Canvas
     include BorderPrinter
 
+    CANVAS_CLASS_MAP = {}
+
     def self.create(canvas_type, width, height, **kw)
-      case canvas_type
-      when :ascii
-        AsciiCanvas.new(width, height, **kw)
-      when :braille
-        BrailleCanvas.new(width, height, **kw)
-      when :density
-        DensityCanvas.new(width, height, **kw)
-      when :dot
-        DotCanvas.new(width, height, **kw)
-      when :block
-        BlockCanvas.new(width, height, **kw)
+      canvas_class = CANVAS_CLASS_MAP[canvas_type]
+      case canvas_class
+      when Class
+        canvas_class.new(width, height, **kw)
       else
         raise ArgumentError, "unknown canvas type: #{canvas_type}"
       end
@@ -168,10 +163,16 @@ def lines!(x, y, color = :normal)
       raise ArgumentError, "#{name} has to be positive"
     end
   end
+
+  def self.canvas_types
+    Canvas::CANVAS_CLASS_MAP.keys
+  end
 end
 
 require_relative 'canvas/ascii_canvas'
 require_relative 'canvas/block_canvas'
 require_relative 'canvas/braille_canvas'
 require_relative 'canvas/density_canvas'
 require_relative 'canvas/dot_canvas'
+
+UnicodePlot::Canvas::CANVAS_CLASS_MAP.freeze

lib/unicode_plot/canvas/ascii_canvas.rb

@@ -2,6 +2,8 @@
 
 module UnicodePlot
   class AsciiCanvas < LookupCanvas
+    Canvas::CANVAS_CLASS_MAP[:ascii] = self
+
     ASCII_SIGNS = [
       [ 0b100_000_000, 0b000_100_000, 0b000_000_100 ].freeze,
       [ 0b010_000_000, 0b000_010_000, 0b000_000_010 ].freeze,

lib/unicode_plot/canvas/block_canvas.rb

@@ -7,6 +7,8 @@ module UnicodePlot
   # into 4 pixels that can individually be manipulated
   # using binary operations.
   class BlockCanvas < LookupCanvas
+    Canvas::CANVAS_CLASS_MAP[:block] = self
+
     X_PIXEL_PER_CHAR = 2
     Y_PIXEL_PER_CHAR = 2
 

lib/unicode_plot/canvas/braille_canvas.rb

@@ -1,5 +1,7 @@
 module UnicodePlot
   class BrailleCanvas < Canvas
+    Canvas::CANVAS_CLASS_MAP[:braille] = self
+
     X_PIXEL_PER_CHAR = 2
     Y_PIXEL_PER_CHAR = 4
 

lib/unicode_plot/canvas/density_canvas.rb

@@ -1,5 +1,7 @@
 module UnicodePlot
   class DensityCanvas < Canvas
+    Canvas::CANVAS_CLASS_MAP[:density] = self
+
     DENSITY_SIGNS = [" ", "░", "▒", "▓", "█"].freeze
 
     MIN_WIDTH = 5

lib/unicode_plot/canvas/dot_canvas.rb

@@ -1,5 +1,7 @@
 module UnicodePlot
   class DotCanvas < LookupCanvas
+    Canvas::CANVAS_CLASS_MAP[:dot] = self
+
     DOT_SIGNS = [
                   [
                     0b10,

test/test-utils.rb

@@ -0,0 +1,7 @@
+class UnicodePlotTest < Test::Unit::TestCase
+  test("UnicodePlot.canvas_types") do
+    available_canvas_types = [:ascii, :block, :braille, :density, :dot]
+    assert_equal(available_canvas_types,
+                 UnicodePlot.canvas_types)
+  end
+end