Merge branch 'check-colors-startup' into 'master'

Check colors on startup and warn

See merge request poezio/poezio!120

poezio/core/core.py

@@ -543,6 +543,12 @@ class Core:
         default_tab.on_gain_focus()
         self.tabs.append(default_tab)
         self.information('Welcome to poezio!', 'Info')
+        if curses.COLORS < 256:
+            self.information(
+                'Your terminal does not appear to support 256 colors, the UI'
+                ' colors will probably be ugly',
+                'Error',
+            )
         if firstrun:
             self.information(
                 'It seems that it is the first time you start poezio.\n'

poezio/theming.py

@@ -448,7 +448,7 @@ def to_curses_attr(
         colors = color_tuple
 
     bold = False
-    if curses.COLORS != 256:
+    if curses.COLORS < 256:
         # We are not in a term supporting 256 colors, so we convert
         # colors to numbers between -1 and 8
         colors = (color_256_to_16(colors[0]), color_256_to_16(colors[1]))