Improved terminal color depth detection via curses

Closes #244

httpie/context.py

@@ -1,4 +1,3 @@
-import os
 import sys
 
 from requests.compat import is_windows
@@ -18,7 +17,6 @@ class Environment(object):
     """
     is_windows = is_windows
     config_dir = DEFAULT_CONFIG_DIR
-    colors = 256 if '256color' in os.environ.get('TERM', '') else 88
     stdin = sys.stdin
     stdin_isatty = stdin.isatty()
     stdin_encoding = None
@@ -27,13 +25,24 @@ class Environment(object):
     stdout_encoding = None
     stderr = sys.stderr
     stderr_isatty = stderr.isatty()
-    if is_windows:
+    if not is_windows:
+        import curses
+        curses.setupterm()
+        colors = curses.tigetnum('colors')
+        del curses
+    else:
+        colors = 256
         # noinspection PyUnresolvedReferences
-        from colorama.initialise import wrap_stream
-        stdout = wrap_stream(stdout, convert=None, strip=None,
-                             autoreset=True, wrap=True)
-        stderr = wrap_stream(stderr, convert=None, strip=None,
-                             autoreset=True, wrap=True)
+        import colorama.initialise
+        stdout = colorama.initialise.wrap_stream(
+            stdout, convert=None, strip=None,
+            autoreset=True, wrap=True
+        )
+        stderr = colorama.initialise.wrap_stream(
+            stderr, convert=None, strip=None,
+            autoreset=True, wrap=True
+        )
+        del colorama
 
     def __init__(self, **kwargs):
         """
@@ -51,6 +60,7 @@ class Environment(object):
         if self.stdout_encoding is None:
             actual_stdout = self.stdout
             if is_windows:
+                # noinspection PyUnresolvedReferences
                 from colorama import AnsiToWin32
                 if isinstance(self.stdout, AnsiToWin32):
                     actual_stdout = self.stdout.wrapped

httpie/output/formatters/colors.py

@@ -42,7 +42,7 @@ class ColorFormatter(FormatterPlugin):
         except ClassNotFound:
             style_class = Solarized256Style
 
-        if env.is_windows or env.colors == 256:
+        if env.colors == 256:
             fmt_class = Terminal256Formatter
         else:
             fmt_class = TerminalFormatter