Add support for OpenType.js font engine. (#31)

This includes OpenType.js as a Git submodule, and calls the new
`test-render` command in check.py.

The build step will call `npm install`.

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "src/third_party/raqm/libraqm"]
 	path = src/third_party/raqm/libraqm
 	url = https://github.com/HOST-Oman/libraqm.git
+[submodule "src/third_party/opentypejs/opentype.js"]
+	path = src/third_party/opentypejs/opentype.js
+	url = https://github.com/nodebox/opentype.js.git

README.md

@@ -19,7 +19,7 @@ $ python check.py --output=report.html --engine=FreeStack
 
 ## Supported Platforms
 
-Currently, the test suite supports only two OpenType implementations:
+Currently, the test suite supports only three OpenType implementations:
 
 * With `--engine=FreeStack`, the tests are run on the free/libre
 open-source text rendering stack with [FreeType](https://www.freetype.org/),
@@ -31,6 +31,9 @@ are used by Linux, Android, ChromeOS, and many other systems.
 * With `--engine=CoreText`, the tests are run on Apple’s CoreText.
 This option will work only if you run the test suite on MacOS X.
 
+* With `--engine=OpenType.js`, the tests are run using [OpenType.js](https://github.com/nodebox/opentype.js).
+This option requires Node.js to be installed.
+
 If you’d like to test another OpenType implementation, please go ahead.
 
 

check.py

@@ -31,6 +31,10 @@
 class ConformanceChecker:
     def __init__(self, engine):
         self.engine = engine
+        if self.engine == 'OpenType.js':
+            self.command = 'src/third_party/opentypejs/opentype.js/bin/test-render'
+        else:
+            self.command = 'build/out/Default/fonttest'
         self.datestr = self.make_datestr()
         self.reports = {}  # filename --> HTML ElementTree
         self.conformance = {}  # testcase -> True|False
@@ -51,7 +55,7 @@ def check(self, testfile):
             variation = e.attrib.get(FONTTEST_VARIATION)
             expected_svg = e.find('svg')
             self.normalize_svg(expected_svg)
-            command = ['build/out/Default/fonttest', '--font=' + font,
+            command = [self.command, '--font=' + font,
                        '--testcase=' + testcase, '--engine=' + self.engine]
             if render: command.append('--render=' + render)
             if variation: command.append('--variation=' + variation)
@@ -127,23 +131,26 @@ def write_report(self, path):
             outfile.write(xml)
 
 
-def build():
-    subprocess.check_call(
-        './src/third_party/gyp/gyp -f make --depth . '
-        '--generator-output build  src/fonttest/fonttest.gyp'.split())
-    subprocess.check_call(['make', '-s', '--directory', 'build'])
+def build(engine):
+    if engine == 'OpenType.js':
+        subprocess.check_call(['npm', 'install'], cwd='./src/third_party/opentypejs/opentype.js')
+    else:
+        subprocess.check_call(
+            './src/third_party/gyp/gyp -f make --depth . '
+            '--generator-output build  src/fonttest/fonttest.gyp'.split())
+        subprocess.check_call(['make', '-s', '--directory', 'build'])
 
 
 def main():
     etree.register_namespace('svg', 'http://www.w3.org/2000/svg')
     etree.register_namespace('xlink', 'http://www.w3.org/1999/xlink')
     parser = argparse.ArgumentParser()
     parser.add_argument('--engine',
-                        choices=['FreeStack', 'CoreText', 'DirectWrite'],
+                        choices=['FreeStack', 'CoreText', 'DirectWrite', 'OpenType.js'],
                         default='FreeStack')
     parser.add_argument('--output', help='path to report file being written')
     args = parser.parse_args()
-    build()
+    build(engine=args.engine)
     checker = ConformanceChecker(engine=args.engine)
     for filename in os.listdir('testcases'):
         if (filename == 'index.html'