Fix PDF scaling issue

Properly compute the size of the PDF based on DPI and PDF-specific resolution (i.e. 72dpi).

Closes #62

lib/squib/graphics/save_doc.rb

@@ -22,7 +22,8 @@ module Squib
       paper_width  = p[:width]
       paper_height = p[:height]
       file         = "#{p[:dir]}/#{p[:file]}"
-      cc           = Cairo::Context.new(Cairo::PDFSurface.new(file, paper_width, paper_height))
+      cc           = Cairo::Context.new(Cairo::PDFSurface.new(file, paper_width * 72.0 / @dpi, paper_height * 72.0 / @dpi))
+      cc.scale(72.0 / @dpi, 72.0 / @dpi) # for bug #62
       x, y         = p[:margin], p[:margin]
       card_width   = @width  - 2 * p[:trim]
       card_height  = @height - 2 * p[:trim]

samples/foo.rb

@@ -0,0 +1,8 @@
+require 'squib'
+puts "Using Squib #{Squib::VERSION}"
+
+Squib::Deck.new(cards: 3, dpi: 600) do
+  background color: :gray
+  text str: %w(Hello fine world!)
+  save_pdf file: 'foo.pdf', gap: 5, width: '11in', height: '8.5in'
+end

spec/data/samples/custom_config.rb.txt

@@ -35,6 +35,7 @@ cairo: scale([1.0, 1.0])
 cairo: render_rsvg_handle([RSVG::Handle, nil])
 cairo: restore([])
 surface: write_to_png(["_output/custom-config_00.png"])
+cairo: scale([0.24, 0.24])
 cairo: translate([75, 75])
 cairo: rectangle([0, 0, 825, 1125])
 cairo: clip([])

spec/data/samples/saves.rb.txt

@@ -494,6 +494,7 @@ cairo: move_to([0, 0])
 cairo: update_pango_layout([MockDouble])
 cairo: show_pango_layout([MockDouble])
 cairo: restore([])
+cairo: scale([0.24, 0.24])
 cairo: translate([75, 75])
 cairo: rectangle([37, 37, 751, 1051])
 cairo: clip([])
@@ -608,6 +609,7 @@ cairo: paint([])
 cairo: reset_clip([])
 cairo: translate([-2343, -1131])
 cairo: show_page([])
+cairo: scale([0.24, 0.24])
 cairo: translate([75, 75])
 cairo: rectangle([0, 0, 825, 1125])
 cairo: clip([])

spec/graphics/graphics_save_doc_spec.rb

@@ -28,6 +28,7 @@ describe Squib::Deck, '#save_pdf' do
       deck = Squib::Deck.new(cards: 9, width: 825, height: 1125)
       expect(deck).to receive(:dirify) { |arg| arg } #don't create the dir
       expect(Squib.logger).to receive(:debug).at_least(:once)
+      expect(cxt).to receive(:scale).with(0.24, 0.24)
 
       expect_card_place(75, 75)
       expect_card_place(831, 75)
@@ -50,6 +51,7 @@ describe Squib::Deck, '#save_pdf' do
       deck = Squib::Deck.new(cards: num_cards, width: 825, height: 1125)
       expect(Squib.logger).to receive(:debug).at_least(:once)
       expect(deck).to receive(:dirify) { |arg| arg }  #don't create the dir
+      expect(cxt).to receive(:scale).with(0.24, 0.24)
 
       expect_card_place(75, 75)
       expect_card_place(831, 75)