Merge pull request #8 from chifung7/fixed_aspect_ratio

Fixed aspect ratio

README.rdoc

@@ -25,17 +25,52 @@ There are a few ways to use the library, at its simplest:
 
 If you want to get the raw barcode data from the PDF417 library:
 
- barcode = PDF417.new("readable barcode data")
- barcode.to_blob  # oops, wrong text
- barcode.text = "ACTUAL barcode data"
- barcode.to_blob
- 
+  barcode = PDF417.new("readable barcode data")
+  barcode.to_blob  # oops, wrong text
+  barcode.text = "ACTUAL barcode data"
+  barcode.to_blob
+
 If you want to get it as an array of strings (each array element representing a line)
+
   barcode.encoding
 
+If you want to use fixed rows or cols
+
+  barcode = PDF417.new(text: "barcode data" * 20, cols: 3) # fixed cols
+  barcode.to_blob
+  [barcode.cols, barcode.rows] # => [3, 42]
+  barcode = PDF417.new(text: "barcode data" * 20, rows: 2) # fixed rows
+  barcode.to_blob
+  [barcode.cols, barcode.rows] # => [30, 5]
+
+If you want to use aspect ratio to determine rows and cols 
+
+  barcode = PDF417.new(text: "barcode data" * 20, aspect_ratio: 0.618)
+  barcode.to_blob
+  [barcode.cols, barcode.rows] # => [4, 31]
+
+If you want to change error level (maximum 8)
+
+  barcode = PDF417.new(text: "barcode data" * 20, error_level: 6)
+  barcode.to_blob
+  [barcode.cols, barcode.rows] # => [8, 32]
+
 If you have chunky_png installed and you'd rather have a PNG
-  barcode.to_png
-
+
+  barcode.to_png # 1x1 scale
+  barcode.to_png(margin: 0, x_scale: 1, y_scale: 3) # stretch 3 times in the vertical direction
+
+If you want to know the barcode image size in pixel
+
+ barcode = PDF417.new(text: "barcode data" * 20, aspect_ratio: 0.618, error_level: 6)
+ cimg = barcode.to_chunky_png(margin: 0, x_scale: 2, y_scale: 6)
+ [cimg.width, cimg.height] # => [376, 216]
+
+If you want to use in Prawn
+
+ pdf.image(StringIO.new(barcode.to_png(margin: 0, x_scale: 2, y_scale: 6)), at: pos)
+ pdf.image(StringIO.new(barcode.to_chunky_png(margin: 0, x_scale: 2, y_scale: 6).to_blob), at: pos)
+
 See the RDocs for more information.
 
 == Note on Patches/Pull Requests

lib/pdf417.rb

@@ -18,8 +18,8 @@ def initialize(*attrs)
     self.text = ""
     @y_height = 3
     @aspect_ratio = 0.5
-    @rows = 1
-    @cols = 0
+    @rows = nil
+    @cols = nil
 
     if attrs.first.is_a?(String)
       self.text = attrs.first
@@ -72,6 +72,8 @@ def aspect_ratio
   end
   def aspect_ratio=(val)
     @blob = nil
+    @rows = nil
+    @cols = nil
     @aspect_ratio = val
   end
 

test/pdf417_test.rb

@@ -16,7 +16,60 @@ class Pdf417Test <  Minitest::Test
     b = PDF417.new("fred")
     assert_equal "fred", b.text
   end
-
+
+  should "defaults rows and cols to nil" do
+    b = PDF417.new("fred")
+    assert_nil b.rows
+    assert_nil b.cols
+  end
+
+  should "allows fixed cols" do
+    b = PDF417.new(text: "01234"*60, error_level: 6, cols: 5)
+    b.to_blob
+    assert_equal [5, 47], [b.cols, b.rows]
+
+    # if it's too small, auto determine the best value
+    b = PDF417.new(text: "01234"*60, error_level: 6, cols: 1)
+    b.to_blob
+    assert_equal [3, 90], [b.cols, b.rows]
+
+    # if it's too big, auto determine the best value
+    b = PDF417.new(text: "01234"*60, error_level: 6, cols: 100)
+    b.to_blob
+    assert_equal [30, 8], [b.cols, b.rows]
+  end
+
+  should "allows fixed rows" do
+    b = PDF417.new(text: "01234"*60, error_level: 6, rows: 10)
+    b.to_blob
+    assert_equal [24, 10], [b.cols, b.rows]
+
+    # if it's too small, auto determine the best value
+    b = PDF417.new(text: "01234"*60, error_level: 6, rows: 6)
+    b.to_blob
+    assert_equal [30, 8], [b.cols, b.rows]
+
+    # if it's too big, auto determine the best value
+    b = PDF417.new(text: "01234"*60, error_level: 6, rows: 100)
+    b.to_blob
+    assert_equal [3, 90], [b.cols, b.rows]
+  end
+
+  should "let default aspect_ratio to define rows and cols" do
+    b = PDF417.new(text: "01234"*60, error_level: 6)
+    b.to_blob
+    assert_equal 7, b.cols
+    assert_equal 34, b.rows
+  end
+
+  should "let custom aspect_ratio to define rows and cols" do
+    b = PDF417.new(text: "01234"*60, aspect_ratio: 0.618,
+                   error_level: 6)
+    b.to_blob
+    assert_equal 6, b.cols
+    assert_equal 39, b.rows
+  end
+
   should "know the right codewords for fred" do
     assert_equal [4, 815, 514, 119], PDF417.encode_text("fred")
     assert_equal [4, 815, 514, 119], PDF417.new(:text => "fred").codewords
@@ -143,11 +196,16 @@ class Pdf417Test <  Minitest::Test
       # reference and make sure there is enough data to have rows and cols
       @barcode.text = "SOME REALLY LONG TEXT HERE! Gonna need some rows...." * 10
       @barcode.rows = nil
-      @barcode.cols = 2
+      @barcode.cols = 10 # fixed cols input
       @barcode.error_level = 3
       @blob = @barcode.to_blob
+      assert_equal [10, 30], [@barcode.cols, @barcode.rows] # cols is fixed at 10
+
       @barcode.aspect_ratio = 1000
-      refute_equal @blob, @barcode.to_blob
+      new_blob = @barcode.to_blob
+      assert_equal [4, 90], [@barcode.cols, @barcode.rows] # new cols and rows are defined
+
+      refute_equal @blob, new_blob
       assert_barcode_start_sequence @barcode
       assert_barcode_end_sequence @barcode
     end