Add __main__.py to output basic format and support information

Tests/test_features.py

@@ -1,3 +1,7 @@
+from __future__ import unicode_literals
+
+import io
+
 from .helper import unittest, PillowTestCase
 
 from PIL import features
@@ -63,3 +67,25 @@ def test_unsupported_module(self):
         module = "unsupported_module"
         # Act / Assert
         self.assertRaises(ValueError, features.check_module, module)
+
+    def test_pilinfo(self):
+        buf = io.StringIO()
+        features.pilinfo(buf)
+        out = buf.getvalue()
+        lines = out.splitlines()
+        self.assertEqual(lines[0], "-" * 68)
+        self.assertTrue(lines[1].startswith("Pillow "))
+        self.assertEqual(lines[2], "-" * 68)
+        self.assertTrue(lines[3].startswith("Python modules loaded from "))
+        self.assertTrue(lines[4].startswith("Binary modules loaded from "))
+        self.assertEqual(lines[5], "-" * 68)
+        self.assertTrue(lines[6].startswith("Python "))
+        jpeg = (
+            "\n" +
+            "-" * 68 + "\n" +
+            "JPEG image/jpeg\n" +
+            "Extensions: .jfif, .jpe, .jpeg, .jpg\n" +
+            "Features: open, save\n" +
+            "-" * 68 + "\n"
+        )
+        self.assertIn(jpeg, out)

Tests/test_main.py

@@ -0,0 +1,28 @@
+from __future__ import unicode_literals
+
+import os
+import subprocess
+import sys
+from unittest import TestCase
+
+
+class TestMain(TestCase):
+    def test_main(self):
+        out = subprocess.check_output([sys.executable, "-m", "PIL"]).decode("utf-8")
+        lines = out.splitlines()
+        self.assertEqual(lines[0], "-" * 68)
+        self.assertTrue(lines[1].startswith("Pillow "))
+        self.assertEqual(lines[2], "-" * 68)
+        self.assertTrue(lines[3].startswith("Python modules loaded from "))
+        self.assertTrue(lines[4].startswith("Binary modules loaded from "))
+        self.assertEqual(lines[5], "-" * 68)
+        self.assertTrue(lines[6].startswith("Python "))
+        jpeg = (
+            os.linesep +
+            "-" * 68 + os.linesep +
+            "JPEG image/jpeg" + os.linesep +
+            "Extensions: .jfif, .jpe, .jpeg, .jpg" + os.linesep +
+            "Features: open, save" + os.linesep +
+            "-" * 68 + os.linesep
+        )
+        self.assertIn(jpeg, out)

src/PIL/__main__.py

@@ -0,0 +1,3 @@
+from .features import pilinfo
+
+pilinfo()

src/PIL/features.py

@@ -1,3 +1,10 @@
+from __future__ import print_function, unicode_literals
+
+import collections
+import os
+import sys
+
+import PIL
 from . import Image
 
 modules = {
@@ -84,3 +91,78 @@ def get_supported():
     ret.extend(get_supported_features())
     ret.extend(get_supported_codecs())
     return ret
+
+
+def pilinfo(out=None):
+    if out is None:
+        out = sys.stdout
+
+    Image.init()
+
+    print("-" * 68, file=out)
+    print("Pillow {}".format(PIL.__version__), file=out)
+    print("-" * 68, file=out)
+    print(
+        "Python modules loaded from {}".format(os.path.dirname(Image.__file__)),
+        file=out,
+    )
+    print(
+        "Binary modules loaded from {}".format(os.path.dirname(Image.core.__file__)),
+        file=out,
+    )
+    print("-" * 68, file=out)
+
+    v = sys.version.splitlines()
+    print("Python {}".format(v[0].strip()), file=out)
+    for v in v[1:]:
+        print("       {}".format(v.strip()), file=out)
+    print("-" * 68, file=out)
+
+    for name, feature in [
+        ("pil", "PIL CORE"),
+        ("tkinter", "TKINTER"),
+        ("freetype2", "FREETYPE2"),
+        ("littlecms2", "LITTLECMS2"),
+        ("webp", "WEBP"),
+        ("transp_webp", "WEBP Transparency"),
+        ("webp_mux", "WEBPMUX"),
+        ("webp_anim", "WEBP Animation"),
+        ("jpg", "JPEG"),
+        ("jpg_2000", "OPENJPEG (JPEG2000)"),
+        ("zlib", "ZLIB (PNG/ZIP)"),
+        ("libtiff", "LIBTIFF"),
+        ("raqm", "RAQM (Bidirectional Text)"),
+    ]:
+        if check(name):
+            print("---", feature, "support ok", file=out)
+        else:
+            print("***", feature, "support not installed", file=out)
+    print("-" * 68, file=out)
+
+    extensions = collections.defaultdict(list)
+    for ext, i in Image.EXTENSION.items():
+        extensions[i].append(ext)
+
+    for i in sorted(Image.ID):
+        line = "{}".format(i)
+        if i in Image.MIME:
+            line = "{} {}".format(line, Image.MIME[i])
+        print(line, file=out)
+
+        if i in extensions:
+            print("Extensions: {}".format(", ".join(sorted(extensions[i]))), file=out)
+
+        features = []
+        if i in Image.OPEN:
+            features.append("open")
+        if i in Image.SAVE:
+            features.append("save")
+        if i in Image.SAVE_ALL:
+            features.append("save_all")
+        if i in Image.DECODERS:
+            features.append("decode")
+        if i in Image.ENCODERS:
+            features.append("encode")
+
+        print("Features: {}".format(", ".join(features)), file=out)
+        print("-" * 68, file=out)