New sample to demonstrate direct cairo access

samples/cairo_access.rb

@@ -0,0 +1,27 @@
+require 'squib'
+
+Squib::Deck.new(cards: 2) do
+
+  # If you really need something custom-made, the underlying cairo context
+  # can be accessed directly via each Squib::Card
+  #
+  # WARNING! Input validation is not done on Squib::Cards. Proceed at your own risk.
+
+  # The recommended approach is to use Deck's Enumerable, which iterates over Squib::Cards
+  # I also recommend wrapping it in a Cairo save/restore, which Squib calls "use_cairo"
+  each do |card|
+    card.use_cairo do |cairo_context|
+      cairo_context.set_source_color(:white)
+      cairo_context.paint
+    end
+  end
+
+  # Or the square bracket accessors []
+  self[1].use_cairo do |cairo_context|
+    cairo_context.circle(50, 50, 50)
+    cairo_context.set_source_color(:red)
+    cairo_context.fill
+  end
+
+  save_png prefix: 'cairo_access_'
+end