Merge pull request #4 from mtking2/inversion

Inversion Support

CHANGELOG.md

@@ -1,6 +1,10 @@
-### v0.x.x (next)
+### v1.0.x (next)
 
-* Your contribution here.
+* Your contribution here
+
+### v1.0.0 (2019/10/31)
+
+* [#4](https://github.com/mtking2/img2zpl/pull/4): Add ability to invert images - [@mtking2](https://github.com/mtking2).
 
 ### v0.1.3 (2019/10/16)
 

README.md

@@ -27,6 +27,33 @@ img = Img2Zpl::Image.open('foo.jpg')
 zpl = img.to_zpl #=> "^GFA, ... ^FS"
 ```
 
+#### Using ImageMagick commands
+
+The `Img2Zpl::Image` class inherits from the `MiniMagick::Image` class provied by the [minimagick](https://github.com/minimagick/minimagick) gem. So you have the same control when it comes to modifying the image before converting to ZPL.
+
+**Example**:
+```ruby
+img = Img2Zpl::Image.open('foo.jpg')
+
+img.resize '100x100'
+img.trim
+
+zpl = img.to_zpl
+```
+
+#### Options
+
+When calling the `.to_zpl` method there a number of optional parameters you can pass to further customize the resulting image:
+
+- `black_threshold`: A value between 0 and 1 that sets the darkness threshold which determines how dark a pixel should be in order to become black in the resulting b/w image. Use larger value for a more saturated image and smaller value for a less saturated one. Default: `0.5`
+- `invert`: set to `true` to invert which pixels are set to black and which are set to white.
+- `compress`: set to `false` to not perform the ACSII compression in the resulting `^GF` string. For larger images the uncompressed string can become **very** long, so use caution.
+
+**Example**:
+```ruby
+zpl = img.to_zpl black_threshold: 0.65, invert: true
+```
+
 ### Contributing
 
 See [CONTRIBUTING.md](CONTRIBUTING.md)

lib/img2zpl/image.rb

@@ -1,15 +1,16 @@
 module Img2Zpl
   class Image < MiniMagick::Image
 
-    def to_zpl(black_threshold: 0.5, compress: true)
+    def to_zpl(black_threshold: 0.5, invert: false, compress: true)
       bytes_per_row = (width % 8).positive? ? (width / 8) + 1 : (width / 8)
       byte_count = bytes_per_row * height
       data, line, previous_line, byte = '', '', '', ''
 
       get_pixels.each do |row|
         row.each_with_index do |column, i|
           r, g, b = column.map(&:to_i)
-          byte << ((r + g + b) > (black_threshold * 765) ? '0' : '1')
+          b_dot, w_dot = invert ? %w(1 0) : %w(0 1)
+          byte << ((r + g + b) > (black_threshold * 765) ? b_dot : w_dot)
           if (i % 8).zero?
             line << byte.to_i(2).to_s(16).upcase.rjust(2, '0')
             byte = ''

lib/img2zpl/version.rb

@@ -1,3 +1,3 @@
 module Img2Zpl
-  VERSION = '0.1.3'
+  VERSION = '1.0.0'
 end