added 'auto-size' option to field agent

util/field_agent/README.md

@@ -9,15 +9,15 @@ This allows them to be scaled to almost any size while staying crisp and sharp.
 This tool is actually a short [Ruby][2] script that calls [ImageMagick][3] to create the distance field.
 So you need both Ruby and ImageMagick installed on your computer.
 
-### MacOS
+### macOS
 
 MacOS already comes with Ruby, so you only need to install ImageMagick.
 For that, my recommendation is to first install [Homebrew][4], a fantastic package manager for macOS.
 Once ready, you can install ImageMagick (like many other tools and libraries) with the following terminal command:
 
     brew install imagemagick
 
-You also optionally make the script executable, which allows you to call it directly (without passing it to Ruby).
+You can also optionally make the script executable, which will allow you to call it directly (without passing it to Ruby).
 
     cd /path/to/starling/util/field_agent
     chmod u+x field_agent.rb
@@ -31,6 +31,8 @@ Once ready, install both Ruby and ImageMagick via the command line (`cmd.exe`).
     choco install ruby
     choco install imagemagick
 
+It also works great with [Cygwin][6].
+
 ## Usage
 
 As input, the "Field Agent" requires a pure black and white bitmap.
@@ -69,10 +71,15 @@ Of course, you can customize that:
 
 Note that the value is given in pixels of the _output_ image.
 
-### Rendering
+### More options
+
+Run the script without any arguments to see a list of all supported options.
+For example, it also supports trimming the texture to the optimal size or inverting its colors.
+
+## Using the Texture in Starling
 
 Inside Starling, load the distance field texture as usual, then assign it to an _Image_ or any other kind of _Mesh_.
-To switch to distance field rendering, simply assign the appropriate [style][6].
+To switch to distance field rendering, simply assign the appropriate [style][7].
 
     var image:Image = new Image(distanceFieldTexture);
     image.style = new DistanceFieldStyle();
@@ -84,4 +91,5 @@ That's it!
 [3]: http://www.imagemagick.org
 [4]: http://brew.sh
 [5]: https://chocolatey.org
-[6]: http://doc.starling-framework.org/current/starling/styles/DistanceFieldStyle.html
+[6]: https://cygwin.com
+[7]: http://doc.starling-framework.org/current/starling/styles/DistanceFieldStyle.html

util/field_agent/field_agent.rb

@@ -14,8 +14,8 @@
 input_file  = nil
 output_file = nil
 
-def windows?
-  (/mswin|mingw|bccwin|wince|emx/ =~ RUBY_PLATFORM) != nil
+def windows_prompt?
+  `echo \\(`.strip != "("
 end
 
 def log(message)
@@ -29,7 +29,7 @@ def fail(message)
 
 # crude workaround so that the call to 'convert' works on Windows, too.
 def system_xp(command)
-  if windows?
+  if windows_prompt?
     command.gsub!("'", '"')
     command.gsub!("%", "%%")
     command.gsub!("\\(", "(")
@@ -43,7 +43,8 @@ def system_xp(command)
 options.spread = 8
 options.quality = 1
 options.scale = 1
-options.convert_path = windows? ? 'magick' : 'convert'
+options.auto_size = false
+options.convert_path = windows_prompt? ? 'magick' : 'convert'
 
 option_parser = OptionParser.new do |opts|
   opts.banner = "Usage: #{File.basename(__FILE__)} input-file output-file [options]"
@@ -66,6 +67,10 @@ def system_xp(command)
     options.invert = true
   end
 
+  opts.on('-a', '--auto-size', 'Extend or trim image to the size required by the DF.') do
+    options.auto_size = true
+  end
+
   opts.on('-c', '--convert-path PATH', String, 'Name or path of the ImageMagick "convert" tool.') do |path|
     options.convert_path = path
   end
@@ -104,9 +109,11 @@ def system_xp(command)
 command << "-negate " if options.invert
 command << "-background white -alpha remove "
 command << "-filter Jinc -resize #{options.quality * 100}\% -threshold 30% " unless options.quality == 1
+command << "-bordercolor white -border #{spread}x#{spread} " if options.auto_size
 command << "\\( +clone -negate -morphology Distance Euclidean:4,'#{spread}!' -level 50%,-50% \\) "
 command << "-morphology Distance Euclidean:4,'#{spread}!' "
 command << "-compose Plus -composite "
+command << "-trim " if options.auto_size
 command << "-resize #{options.scale / options.quality * 100}\% " unless options.scale * options.quality == 1
 command << "-negate -alpha copy -channel RGB -fx '#fff' "
 command << "PNG32:#{output_file}"